I need new heads for 351W
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=2922
Printed Date: April-29-2024 at 10:13am
Topic: I need new heads for 351W
Posted By: rover
Subject: I need new heads for 351W
Date Posted: January-23-2006 at 6:13pm
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I am looking for the best(new)heads for our family '81 SN. Rebuilding engine stock ,maybe mild cam. Who likes what and why??? Considering GT40s cast iron..Roush 180s. Valve size? combustion chamber size?
Thank for your intrest David Wilkins 262.719.5522 2canucks@core.com |
Replies:
Posted By: Jim_In_Houston
Date Posted: January-23-2006 at 7:54pm
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Rover, I could be wrong but I have the understanding that GT-40 heads are designed for the 302 engine. I also understand the the 351W heads are pretty good in stock form. What is wrong with the heads on your 351? Also, consider that heads with smaller valves will force higher velocity fuel mixture at lower engine speeds resulting in better performance during the low speed operation. Going to larger valves with larger ports may only help in high RPM operation which you may never see anyway. Large valves may reduce low RPM performance. I think you should re-think spending money on heads for a boat engine. Go for high torque at low RPMs and a prop with a big pitch - my 2 cents. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 64 Skier
Date Posted: January-23-2006 at 11:21pm
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See this site for more information:
http://www.allfordmustangs.com/Detailed/630.shtml ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: 64 Skier
Date Posted: January-24-2006 at 5:01am
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One more article you should read:
http://www.mustangandfords.com/techarticles/5288/index.html scroll down to the subarticles also for some good reads. JIH is dead on and you can get dissapointed with premium heads depending on what you plan to do with the boat. Big Valves are great above 4500 RPM which is where our boats top out so again, Jim's giving you some good advice. Increased chamber size (will reduce compression) and the larger valves will both hurt low end torque. For semi-displacement hulls IMHO it's all about low end torque. Think water tractor. A friend of mine bought a used set of GT-40's and was bragging about pulling my boat around the lake. He barely got off plane. Like a couple knuckleheads we thought we checked everything... We mainly slalom ski and wakeboard and rebuilt a 289 using my old heads with larger valves punched in, but increased the compression and she pulls great. I spent the extra dollars on forged pistons, mild porting, new intake, electronic ignition and carb. I even kept the old solid cam for the reasons Jim stated so I could play with the lash to get the most of the low end torque. Good Luck! ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: AWhite70
Date Posted: January-24-2006 at 5:20am
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When I rebuilt the engine for my '79 I reused the stock D80E (casting number) heads. I had them machined for slightly bigger valves and gave them a mild port job. I increased the compression ratio slightly with the pistons. I couldn't be happier with the results, she pulls hard.
Be careful that you don't get too much head for your applications. As has been said already boats don't get much above 4500rpm and probably run mostly in the 2500-3500 range. A lot of high end heads are probably mean to flow a lot of air in the 5-7k range. ------------- AWhite70 http://www.correctcraftfan.com/diaries/details.asp?ID=562&sort=revyear&pagenum=5&yrstart=1976&yrend=1980" rel="nofollow - '79 Ski Nautique |
Posted By: David F
Date Posted: January-24-2006 at 11:13am
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I think the GT40 heads can be used on the 351W by simply drilling out the bolt holes to accept the larger diameter head bolts used on the 351W vs 302. Remember, I said "think".
I tend to agree with the other statements. Our boats NEED lots of low end torque. The footers may need some high(er) end HP as well. |
Posted By: JoeinNY
Date Posted: January-24-2006 at 6:34pm
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The gt40 heads are available with the holes already drilled out for a 351w, and were used by pcm with great success on Ski Nautiques from the 90's until the ford marine blocks dried up in about 2002. Combined with a good marine/rv grind cam they will give you more horsepower, going with anything larger than the valve size on the GT-40 would probably start to have an effect on your low end. I have put junkyard GT-40s off a 1996 explorer 302 on a friends 351w in a full size bronco mud bogger it was a huge improvement (we drilled out the holes for the headbolts and had to change the push rods because it was a seventies bronco but other than that it bolted up) You might need updated PCM manifolds if you went with the GT-40s. Compression will of course have a huge impact on engine performance so make sure your piston/head combination gives you the compression you are looking for, or the best heads on the planet won't save you.
-Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Jim_In_Houston
Date Posted: January-24-2006 at 9:34pm
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As I mentioned in other threads I installed a nice set of GT-40P heads on my 289. I lost a little compression and I may have lost some performance but I am happy with the overall performance of the little 289. My reason for installing the heads was purly perverted in that I could not stand the thought of running heads with Ford's stock pressed-in rocker studs. The thought just makes me crazy. The GT-40Ps have threaded rocker studs which is how all studs should be made (IMHO). The pistons are stock original because I did not want to take time playing with clay.
If anyone can recommend pistons that will boost my compression without any risk of hitting a valve I would certainly like to give them a try. I wouldn't mind a little more compression and I am not into head shaving. Also, I am ready to play with some clay during my next rebuild. Thanks... Jim PS: I am now thinking "water tractor". You have to love it. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: GottaSki
Date Posted: January-25-2006 at 5:12am
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Jim, with closed-chamber heads, it might be better to zero-deck the block to boost the CR, you would gain not only better cr but better squish.. (less trapped HC in the areas of the chamber that the flame front can't reach, swirl and burn well...)
A 327 stroker shortblock would boost the CR as well.. 
Changing CR as well as head airflow increases the density of the A/f mix at wot, increasing the speed of the flame, thus requiring less advance. So with a reworked engine, the stock ignition timing one used for stock heads could either be set too advanced at wot, or if reset for wot, would be too retarded at low rpms, giving one the sensation that the heads 'killed' the low-end. Spending quality time with the timing gun, some graph paper and a fully-adjustable distributor is required to see best overall results after changing CR, cam, heads, etc. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Jim_In_Houston
Date Posted: January-25-2006 at 7:47am
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Thanks GottaSki. How do you zero-deck a block? What is involved? ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: JoeinNY
Date Posted: January-25-2006 at 9:56am
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Jim,
What kind of Exhaust logs are you running with those GT-40Ps, have you had any spark plug angle issues. Additionally, you would have had to change the push rods to make this happen correct? Disclaimer..I am making some assumptions here, most of this applys to autos and I am assuming marine as well.. Early 289 heads had a combustion chamber of 54.5 ccs and the resulting compression was about 9.3 to 1. The gt-40p has a combustion chamber of 59-61 ccs dropping your compression to about 8.7 to 1, but they are much better flowing heads with a more efficient plug location than stock I would say a net gain in most set ups. To get that compression back you could deck the head or cylinder a combination of about .030 to .040. Or per your preference change the pistons, a piston that would have been called "10 to 1" with your stock heads would yield you about 9.4. I think it would be pretty easy to find the correct pistons, if your serious we can talk actual measurements and compute out what you would need. Enough of this talk and I will be thinking of replacing the heads on an engine I swore I wouldn't mess with again for at least 2 years... -Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: 79nautique
Date Posted: January-25-2006 at 10:16am
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I beleive what gottaski is refering to is machining down the blocks decks, (surface heads mount to) so that they are flush with the top of the pistion (flat top or dished pistons). This would require no change in parts with the exception of the push rods maybe, depending how much material was removed off of the decks. If you didn't change the length of the push rods then you would be creating more lift on the valves and could posiablely(sp) hit the piston if you did not checked for clearance ahead of time. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: Jim_In_Houston
Date Posted: January-25-2006 at 5:29pm
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Whoa... good point 79. I hadn't considered the need for shorter push rods although it makes perfect sense...
I still don't like the idea of shaving anything. In my mind that's a fix that can't be undone. I will look into pistons though. No hurry here - just thinkin. I gotta get my '66 in the water before I pull down the '68. That's why we have a "back-up" boat right? Joe, the GT-40Ps were a direct bolt-in on the 289. Very easy. I am running stock Interceptor aluminum manifolds. Absolutly no problem with the spark plug angle. The only problem I had was selecting the spark plugs. When you walk into Autozone, or anywhere else, the fisrt thing they ask is what type of car you have. I ended up ordering up plugs for a 1998 Explorer, which is what I was told the heads came off. I am not at home right now so before anyone runs off and orders 1998 Explorer plugs for their GT-40Ps check with me first so I can go to my records. Maybe it was a 1996 but who cares right now. Make no doubt, even with the lower compression the engine is much stronger than prior to the head change. Maybe it was the cam or the carb or the heads - I don't know - it just worked. I installed a mildly warm SpeedPro marine cam which has a little more lift than stock and a little more duration on the intake but not much. Pushrods are stock and original. I did not replace them. (I did replace the lifters however.) At this point, so I can check prices, if you can recommend some possible pistons I would appreciate it. Don't spend time on this. Before I order we can go thru the exercises. This could easily be a next winter project. The boats runs pretty strong as it is. It throws you back in the seat and holds you there when you hit it. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: rover
Date Posted: January-25-2006 at 9:19pm
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Thanks for the great responses....
My heads have many cracks between valves due to over heating. Everyone has been very helpful here, glad I found it. This is one of a few SN we plan to restore in the near future. Thanks again david |
Posted By: JoeinNY
Date Posted: January-25-2006 at 9:30pm
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1998 Explorer sounds about right, asking for a 1996 would muddy the waters a little as they started that year with GT40s and then changed to GT40Ps very early 1997. The spark plugs interfere with most automotive headers on the GT40P, glad to hear not so with the interceptor logs. What pistons have you got in the motor now?
-Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: 79nautique
Date Posted: January-26-2006 at 5:41am
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Rover
I believe there are a set of DOOE heads on ebay right now and they would be perfect for a 351W most hot roders use these heads over gt-40 if you can get them. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 79nautique
Date Posted: January-26-2006 at 5:44am
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Here they are the auction ends today!!
http://cgi.ebay.com/1970-FORD-DOOE-351W-HEADS_W0QQitemZ8031858865QQcategoryZ33617QQssPageNameZWDVWQQrdZ1QQcmdZViewItem ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: Jim_In_Houston
Date Posted: January-26-2006 at 7:20am
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Joe, the pistons are 289 original flat top. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: JoeinNY
Date Posted: January-27-2006 at 2:39pm
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Jim,
I will pull out the catalogs over the weekend and check on options for pistons. I think I have irrevocably convinced myself to install some GT40p's on my 302, between them and the new floor, interior/seats, windshield, gauges, perfect pass, flitepipe, swim platform, and the large pile of stereo equipment all waiting for installation spring better get here soon if I am to finish before wetsuit season. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Jim_In_Houston
Date Posted: January-27-2006 at 8:45pm
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Joe, I'll be waiting to see how you like the GT-40Ps. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 81nautique
Date Posted: January-28-2006 at 4:53am
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Hey Guys,
Skidim sells GT-40 heads and i was talking to Vince about the benefit of adding them to my 351w. Unless I wasn't listening very good it sounded like they were a simple bolt on and would add 35-40 HP and would turn an additional 400 rpm. I'm not serious about adding them right now but more curious, your posts above seem to differ from the info I got. Any comments? Thanks ------------- |
Posted By: JoeinNY
Date Posted: January-28-2006 at 12:44pm
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Jim,
I think you should check out the Keith Black KB116 pistons, maybe a little extreme but I am guessing you would end up about 10 to 1 with them and your current setup. Summit has them at about 220 a set. They are hypereutectic cast pistions which are IMHO the best way to go for boat engine. They are lighter and cheaper than forged and more thermally stable so they won't expand as much reducing the chance of scuffing. If you dropped them in your block you would probably gain enough clyinder wall clearence with a little honing to drop them in without any such worries. I found a set of GT40p's at a wrecker down the road for 300, autozone has them rebuilt for 350 a piece, I think I will pick up the ones from the wrecker and find some stainless valves and do a rebuild on them... Alan, I would think that you would see improvements with the GT-40 bolt on.. I see no reason to doubt Vince on it... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Jim_In_Houston
Date Posted: January-28-2006 at 3:44pm
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Joe. If I understand what you are saying you are about to spend at least $300 + $700 + new valves.
That seems like a lot. I bought my pair of heads off ebay from a guy that sells them there from time to time. I bought both of my heads, either low mileage or reworked (I don't remember but I do remember they looked like new) for around $400 if I recall. (Complete with valves and springs.) Keep and eye on Ebay and don't get in a hurry to buy them. Thanks for the tip on the pistons. I turn your info over to the CCFC research department. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: JoeinNY
Date Posted: January-28-2006 at 4:35pm
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Jim,
Sorry for the confusion... I can get used ones from the wrecker for 300 for the pair including valves springs etc, they have 35000 miles on them. If I go that route I would probably put on new springs, stainless valves, light machining, and replace the steel plugs with bronze ones. The ones from autozone are 350 each for completely reconditioned heads with all springs and valves included, they are actually 250 but they have a 100 dollar core charge... if I bought those I would just install them and run them as is... I am leaning towards getting the used ones... stainless valves would set me back about 200 incidentals will probably put the whole thing at 600 dollars installed and done right... not too bad. It would cost 695 a side for the GT40's from skidim and the GT40ps flow a little better and have a smaller and more efficient combustion chamber. Sure the boat already runs perfect, tops out about 46, sounds awesome, and has easily pulled big three slalom skiers up at once but it can always run better right? -Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: nuttyskier2002
Date Posted: January-29-2006 at 5:07am
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I read earlier in this thread that the plugs in the GT40p heads would not interfere with the aluminum interceptor exhaust logs, but what about the standard cast iron logs used on most PCM and Indmar engines in the 80's and early 90's. ------------- 95 Malibu Echelon w/Mercruiser 350 Magnum Skier Former boats: 88 Ski Centurion Tru Trac II 59 Chris Craft Capri (woody) |
Posted By: reidp
Date Posted: January-29-2006 at 10:00am
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Jim, the Keith Black KB116 pistons Joe referenced are the exact ones I've been running for about 5 years now in our 69 blue Mustang 302. They are a domed piston and with the good 60cc D0OE heads which '79 suggested, and which I'm using, they're supposed to yield about a 10.5:1 C.R. according to the Ford Tech Line, with a 302 stroke. Some may feel this to be a bit high, but mine's been bullet proof for some 300 hrs. I'm also using that same cam you mentioned along with the Barr Marine aluminum 3" exhausts, gasket-matched to the ported heads. The holeshot of this boat simple a rush.
These KB116 pistons with the 58cc GT40P heads (I believe Ps are 58 and std GT40s are 60cc, right Joe?) might have you somewhere close to 10.5 with a 289 or 11.0 with a 302 based off the application specs in the PAW parts catalog. It also mentioned that these pistons with the small 54cc 289 factory heads, will need mods done to the piston or head for clearance. We are putting together a new engine right now with these pistons and World/Roush 180 58cc iron heads which have just been ported, after reading that the factory flow specs were sub-par to the 40s on the intake side, even with bigger 1.94 vs 1.84 valves. I'll let you know how it runs unless it ends up in infinium like so many other of our projects. As for the GT40 heads on Alan's '81, I believe that to be the best example of where you'll see the largest power gain with the GT40 heads. That vintage 351, if indeed it has the small spark plug (5/8") heads, is basically a 302 head with the smallest valves (1.78" intake) combined with the largest chamber (+/- 69cc). You could pick up in the neighborhood of 2 full points of torque-building compression, whereas you sometimes loose a tad bit as Jim did, as he ended up with a slightly larger chamber than stock. Just make sure it's not too much compression, but Vince I'm sure has seen this combo numerous times. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: JoeinNY
Date Posted: January-29-2006 at 11:46am
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Nominal compression chamber size for the Gt40p is 59cc, listed by ford with tolerance as 59-61cc. The Gt40 is actually significantly higher at 64.5cc nominal. I have been told that marine GT40 heads such as those used by pcm were a unique beast with a slightly larger chamber at 67-68 cc, but I have never seen that in reputable print so we will just call it a rumor...
-Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Jim_In_Houston
Date Posted: January-29-2006 at 1:19pm
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Thanks ReidP ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: pmt2234
Date Posted: February-09-2006 at 11:19am
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I put a set of GT40P heads on my 84 2001. The PCM manifolds cleared the spark plugs without a problem. In fact, I think there's more clearance now than before.
I CC'd everything when I had it apart, and my CR is now about 9.33:1. |
Posted By: JoeinNY
Date Posted: February-09-2006 at 10:03pm
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Alright so I found a set of gt40p's with a 5 angle valve job, new springs, new stainless valves (slightly larger than stock) basically all ready to go for 500 so off I go (anyone need a set of 1978 302 heads, they have about half a season on them since being rebuilt and I will sell them very very cheap). Anyway now that I am getting in there again, I am starting to think roller rockers, anyone using anything they would recommend and if so what valve covers are you using. I am a little worried that I would drop the money for the rollers and then not be able to find a valve cover that would clear both them and the exhause logs. The cheapie chrome valve covers I have on now specifically state they will not clear rollers. Any suggestions?
-Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: 79nautique
Date Posted: February-10-2006 at 6:32am
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Joe do you have the PCM pyramid style manifolds or commander style logs? Because if you have the log style then I would think that you wouldn't have and issue at all and could use any cover available. With the center riser style you can't get the valve covers to tall or the hit, which I think is what you have. You could measure your existing set-up and see how tall of a valve cover you could use then check and see if they would clear the rockers. I think Awhite70 has rollers on his. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: AWhite70
Date Posted: February-10-2006 at 6:34am
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JoeinNY, are your new gt40-P's machined for rocker studs (adjustable) or are they still set up for the pedestal mount rockers (non-adjustable)?
When I rebuilt my engine I had the heads cut for bigger valves, ported and installed new springs and retainers, but I did not have them machined for rocker studs. I still chose to use roller rockers but for pedestal mounts the selection is pretty slim. I chose http://store.summitracing.com/default.asp?target=partdetail.asp&part=FMS%2DM%2D6564%2DB351&N=115+4294925232+4294924497+4294839885+400070+4294840125+4294925054+4294804215+4294900391&autoview=sku - Ford Racing Performance Parts and I am using the following http://store.summitracing.com/default.asp?target=partdetail.asp&autofilter=1&part=FMS%2DM%2D6582%2DA301R&N=115+4294925232+4294839018+4294919746+400070+4294900924&autoview=sku - Ford Racing Valve Covers . These valve covers say they don't work with roller rockers but mine fit fine. I think, but I'm not positive that standard valve covers will work with pedestal mount rockers but not stud mount rockers. Now for some advice. Since your heads have been machined and you're putting them on an old engine if they haven't been already I would have them machined for rocker studs so you have adjustable valvetrain. With a modified engine it is very difficult to get the proper geometry and lifter preload with non-adjustable rockers. I ended up having to measure the needed pushrod length individually and then shim a few pedestals to get all of the rockers in an acceptable window for pushrod length. I then had to order custom length pushrods. I'm only talking a few thousandths of an inch but in valvetrain it makes a difference. If I would have had adjustable rockers I wouldn't have had to go through any of that trouble. Either way a pushrod length checker is a cheap and necessary tool. Sorry for the long post ------------- AWhite70 http://www.correctcraftfan.com/diaries/details.asp?ID=562&sort=revyear&pagenum=5&yrstart=1976&yrend=1980" rel="nofollow - '79 Ski Nautique |
Posted By: JoeinNY
Date Posted: February-10-2006 at 7:11am
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79,
I am running the original aluminum interceptor logs and I have one extra as a backup so I hope to be runnign them for a while, I haven't looked at them in a while but they appear to be fairly snug (maybe a half inch?) to my valve covers? I will get in the garage and start taking pictures this weekend. Awhite70, The heads are currently set up for pedestal mount, but still at the machine shop I am buying them from I will discuss with them the cost to machine them to adjustable. I am getting pretty excited about this project as last year when I built the motor the only thing that was not upgraded from stock was the heads, in the interest of time and money I just rebuilt the originals. I did spring for new hardened pushrods at the time so it would be nice to not have to replace them again. I figure I should go for the rollers this time out or I will probably be opening this thing up again next winter to do it, besides it will be easier this year as the engine is back on a stand while I replace the stringers. Thanks for the info. -Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: jos1
Date Posted: February-10-2006 at 11:28am
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A lot of topics on GT40 heads P or no P.
Not only here but also other forums. Which will fit on what. On early type CC and on type 2001 CC before 1990 and on after 1990 type CCSN 196. Above mentioned have different styled exhaust manifolds as far I have read and seen pictured. The story is plugs will hit the manifold, is it just a story or will it hit. I have a 1991 CCSN 196 with a 351W as time comes upgrade should be nice. Cannot afford to buy those that will not fit. Should be nice to figure it out and put it in the review section as official. ------------- jos |
Posted By: JoeinNY
Date Posted: February-10-2006 at 2:00pm
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Jos,
I have it on good authority (JimInHouston), that on the interceptor logs the gt40p head spark plug location will not interfere. I actually believe it will be better then the heads i have now where the spark plug is angled more and comes very close to the exhaust manifold (I break at least one plug every time I remove them). As for the later manifolds perhaps others can help. -Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Jim_In_Houston
Date Posted: February-10-2006 at 10:51pm
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Keep in mind that my Interceptor, with GT40P heads, is a 1968 vintage 289. I do not know if the 351 manifolds will interfer with the GT40P heads.
Joe, imho, roller rockers are really only usefull when extreme high RPMs require very high valve spring pressures to keep the lifters from floating. High spring pressures will wipe the cam lobe hence the need of roller rockers. I doubt that your RPMs in boat will ever get much over 5K so standard valve springs should be adaquate and therefore no need for roller rockers. Spend your money in another direction (imho). Am I having a deja vue here? BTW, I finally pulled my boat out of the water just long enough to install my new ACME 540. Interesting results. I start a new thread. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 79nautique
Date Posted: February-10-2006 at 11:44pm
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I alsways thought the main purpose of roller cams and rockets where less drag/friction less power lose, same reason to use under drive pulleys. I could see an advantage in high rpm applications as you discribe but I would think that you would gain some on the bottom end as well, and thru the whole rpm range. I would also think that due to the prophile of the lobe of the cam riding against the flat surface of a hyd or solid lifter vs a cylindrical prophile of a roller lifter that the roller would yield a smoother prophile of the valve opening and closing and actually yield more duration (slightly) with the same lift. It's a geometery issue with two cyclinders the normals(tangents) of each are always going to be equall or pass through each others arc centers, with a solid or flat bottom lifter the normal of the lift will only pass thru the arc center of the lobe at one spot, the max lift of the cam lobe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: JoeinNY
Date Posted: February-11-2006 at 7:22am
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They claim better horsepower due to lower friction and all that, maybe. They claim to be easier on the valves, push rods, and cam lobes, probably. They are more stable at high rpms which I plan to never reach (unless you get really heavy roller rockers then combined with heavy valves your your going to actually increase the chance of valve float). All I know is I like the concept, there seems something archaic about rocker arms that have to wobble back and forth billions of times (alright I did the math it was like only like 3 million wobbles last summer) having nothing but a ball and cup joint (albiet a well lubricated one) to work with. I am a big fan of bearings, I like the concept I am going to give them a try, even though it is possibly a case of more money than brains. Oh and I found a set of slightly used (owner had them on long enough to dyno them and a set of 1.7s and decided to keep the 1.7s) scorpion adjustable pedestal mount roller rockers that my machine shop is selling me for 80 dollars which is just plain cheap. Nice to be doing this in the off season this time so I can hunt for deals and not pay overnight shipping charges on everything.
Btw, these are the heads that I went with http://www.tristatecylinderhead.com/catalog/product_info.php?products_id=40&osCsid=b2c959669790e86cdbc7fd6519f01294 - Tristate Cylinder heads . They also were recommended by my local machine shop, I will let you know when the heads arrive how they look. Jim, I am very interested on your new prop results can't wait to read them... -Joe. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Jim_In_Houston
Date Posted: February-12-2006 at 3:23am
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I am a firm believer that is you want to do something, do and have fun. I spent a few dollars on a chrome distributor. (I just know that was good for 5 HP.) Judge not be ye judged, right? Let us know how the roller lifters work out. I may go for a set also. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 64 Skier
Date Posted: February-12-2006 at 4:31am
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Joe...great heads...big valves...notice they almost touch.
I've been on the Dyno (very expensive exercise but a great learning experience) and the roller rockers with the bearings add HP/Torque from top to bottom....not 25 HP as advertised but close enough. I bought mine from Ford Racing. JIH is right, if it makes it more fun then buy them! I have Edelbrock tall valve covers with Holman Moody exhaust. Fits good. If JIH got 5 HP from a chrome distributor there's no telling how much HP I got from those shiny valve covers. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: Jim_In_Houston
Date Posted: February-12-2006 at 12:15pm
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64 Skier, tell me what I am reading is true: you actually gain about 25 HP throughout the entire speed range by just adding roller lifters? A change in the cam profile must have had something to do with it. Right? Clue me in here 'cause inquiring minds need to know.
I just visited that Tri-State Cylinder Heads site. Awesome. It looks like a good deal on GT40P heads to me, complete with spark plugs! ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 64 Skier
Date Posted: February-12-2006 at 11:03pm
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JIH, not roller lifters/cam, but roller rockers with the pedestal bearing and roller tip in them to reduce friction while rotating. Ford Racing has roller tips with the roller bearing. Some cheaper versions have the same metal stamped pressed rocker with only a roller tip.
The HP gain was 10-15 HP in the 2000 to 4000 RPM range. Since (on the boat) I was working the heads over to larger valves and mild porting I thought it would be another good add since I had seen them work in a 351 on the Dyno. With the Roller Lifter/Cam and premium Roller Rockers I think 25 HP is a pretty accurate estimate. We slalom ski a lot and at 3200 to 3600 RPM running down the lake for hours on end IMHO this is very hard on an engine thus the roller rockers. If you need to run greater piston to cylinder wall clearance due to heavy loads like truck engines etc then again, I was focused on the application and tried every trick in the book to make the little 289 run harder. Right after break-in we ran 4 tanks of gas per day for a week trying to make it around all 6 balls. SOme of the guy's are pretty big and that 289 never lost rpm, but she did very throaty on the Pull Outs. I also recall you saying you lost a little compression with your new heads. If you can't run a thinner gasket to increase compression, you may get the performance back by adding roller rockers with a little more ratio/valve lift since you probably have plenty of valve clearance. Call Ford Racing and they can maybe help. Good Luck ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: Jim_In_Houston
Date Posted: February-13-2006 at 6:03am
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Interesting. ------------- Happy owner of a '66 and a '68 Mustang |