Revese Rotation? |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Posted: September-23-2004 at 4:14pm |
I need more top-end power in my 1968 Mustang so I will probably slip in a new cam shaft and move from a 2V to a 4V carburetor.
But before I buy a cam I really need some clarification. I have been noticing that it is said that marine engines run in the reverse rotation of auto engines. Is this true of all Correct Craft inboards? Does this mean that if I replace my cam shaft,crank shaft, or harmonic balancer I have to use a part specifically for a marine engine? Is the number 1 spark plug in a different location in a marine engine vs. auto? Is the firing order reverse? Is the timing mark tab on the opposite side of the engine? Is the starter a reverse rotating starter? I don't have access to a Ford 289 auto engine to make visual comparisons. I guess my basic question is specifically what all is different in a marine engine? Thanks in advance for you help on this. |
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colinc
Newbie Joined: August-20-2004 Location: United States Status: Offline Points: 10 |
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Jim,
I know that in the case of the ford engines that CC used they all came reverse rotation. My 1965 Mustang is a 260 reverse rotation and I'm in the middle of having it rebuilt at the machine shop. Lots of special parts in these motors that are marine and reverse rotation specific - some that come to mind are: Camshaft Distributor Timing cover (obvious) Exhaust manifolds (obvious) Oil pan Oil pump pickup Crankshaft Front and rear main seals Starter Pistons face the rear of the engine The cylinders are numbered the same as all ford sb v8's The firing order is different than a std rotation engine. My advice to you is to leave the cam alone and add a 4bbl carb and a decent intake. -Coop |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Thanks coop.
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David F
Platinum Member Joined: June-11-2004 Location: United States Status: Offline Points: 1770 |
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I do not think all of what colinc says is true. My thoughts:
1. Not ALL Correct Crafts used reverse rotation engines. My 77 Martinique is LH whereas my 93 Nautique is RH. 2. Not all reverse rotation engines are created equal, but maybe so for PCM. If the camshaft is driven by a gear, then the camshaft, oil pump and distributor rotate in the same direction as a conventional engine. 3. For the life of me, I cannot figure why the exhaust manifold or oil pan would be different for a reverse rotation engine. Likewise for the timing chain/gear cover. 4. The firing order for reverse rotation engines is easy to figure out. Simply swap positions of the #1 and #8 wires at the distributor cap. 5. Do not forget about the water pump, it is special to reverse rotation. 6. The timing mark tab position does not change (if I remember correctly and think about it a bit...you would still attach the timing light to the #1 wire). With everything I have said above, please know that the only reverse rotation engine I have rebuilt was a Chevy 350. Ford engines may be different. Bottom line, just check how the engine is assembled and note special parts. If the engine is reverse rotation and the camshaft is chain driven, then yes, all parts are special and thus more costly. |
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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here's my 2 cent. I agree with David F. everything block related is exactly the same for a std vs. rev rotation, i.e. block, heads, intake, timing covers, mainfolds, even the distributor.
Now what you need to keep in mind for a reverse rotation is that your distributor while need the correct gear to run with the cam in the correct rotation depending upon the rotation. The circulation pump i.e. water pump not raw water pump, may or may not be interchangable, there is a bi-direction as well as a directional water pump. the crank, cam, oil pump, starter, and crank shaft seals are specific for a reverse or std rotation engine. Has far as the pistons go I don't beleave there is a differnce, now compared to auto vs. marine there is and that is the material they are made from are different. I don't beleave that you can simply reverse the firing order as well, check a manaul to compare firing orders it need to be matched to the cam and crank. |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Well, in regards to the cam my commmon sense tells me it must be different to be ground to run in the reverse durection, BUT, I could be wrong. Thinking about it is like looking in the mirror to shave.
It does seem to me though the tab that has the timing marks on it must be on the other side of the engine or setting the timing would be very wierd. So, I dont know if a special timing cover is therefore needed or not - but that's academic. The cam is all that looms in my future for now. How much is a "Marine" cam? And, my prop is right hand - is my engine therefore reverse rotation? |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Another note, I remember from back in the day that on old Chevyy engines, if you left the clamp off of the distributor, the distributor would pop out of the engine due to an upward thrust on the gear. Does this mean that on a reverse direction engine there is a downward thrust? Are special distributors required to allow for the change in thrust on the bearings?
Frankly, I'm pretty good at turning bolts and nuts but this reverse rotation stuff is past my area of knowledge. |
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882001
Senior Member Joined: October-21-2003 Location: United States Status: Offline Points: 332 |
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cam is different i got mine from comp cams. these people are confusing. its not as difficult as it sounds. i just had to do a total rebuild. and my timing marks are on the flywheel. btdc and atdc do change places.
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kemah texas
1988 skinautique "2001" |
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SS 201
Senior Member Joined: October-20-2003 Location: United States Status: Offline Points: 232 |
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Some older fords had three different firing orders, be sure you know yours. The raw water pump is just flipped, the dist gear is different, however dist still turns counter clockwise. The cam is different,be sure you tell whomever ginds one you give them the right firing order. All exteral parts remain the same.
CC changed to standard rotation when the went to the 123 PCM box, however they turn the props right hand. Although some barefoot boats with 454 use left hand props. |
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reidp
Platinum Member Joined: December-06-2003 Location: Mooresville, NC Status: Offline Points: 1804 |
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Jim,
I've dedicated a disproportionate (hrs vs. results) chunk of the last 5 years pursuing your same goal. But ultimately the results have been very rewarding in terms of fun. I've got a 70' Mustang 302 powered hull like yours shown in the diaries. I've got to run my two chocolate kids to the vet this AM, but afterwards I can give you a complete lowdown on every step we took, good and worthless, on picking up a solid 10 mph topend. The additional speed also comes with an unsuspected bonus; incredible low end power and pull. |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Many thanks reidp. I'm looking forward to what you have to say. -jim
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reidp
Platinum Member Joined: December-06-2003 Location: Mooresville, NC Status: Offline Points: 1804 |
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Jim,
I think everyone's covered the reverse rotation issue quite well. You've got a reverse engine now, so just make sure that any new parts that are rotation related are indeed reverse parts. They are all available so don't make any exceptions. The upgrades that we made were to a 210 HP Interceptor which was the 4V version. It originally ran 45 mph. I'm assuming yours is either a 165 or 190 HP model. In order of actual upgrades performed here's what we've done: * Short block No. 1: rebuilt short block with flat top pistons and original 302 heads with no modifications; SpeedPro cam: Lift .444"/452", Duration 206-221 @ 050". Edelbrock Perf RPM intake. Original Interceptor square small dia exhausts and 2-1/4" exhaust hose. +/- 50 mph. This piston and low perf head combo netted about 9.5-10.0 compression. We weren't real pleased with this package especially when a head cracked. Don't ask. * Short block No 2: Same block, installed Keith Black KB-116 pistons and 351 heads with the exhausts mildly ported. This woke the boat up very well in term of bottom end torque. +/- 10.5 Comp Ratio. No other changes. 53 mph. * Had previously removed saturated foam from exhaust hose area, so decided to replace 2-1/4" hose and thru-hull fittings with 2-7/8"-3" material. The sound really arrived along with one MPH to 54. I felt this was a good move as the initial expansion of the foam had actually compressed the original hose in a few small areas. I've found that upgrading to the larger exhaust without other engine mods will not net you much if anything, but it sure will sound better. By that time however, Holman Moody and Chrysler engines were already using the bigger exhaust and hose in the Mustangs. * Acquired another set of 351 heads and did extensive exhaust port and intake bowl porting. I did this myself under the close supervision of a retired Ford engineer, but wouldn't suggest paying someone to do this for the additional mph to 55 mph. The previous heads had the mild exhaust porting so basically cylinder head upgrades netted us 2 mph. * Finally replaced the original power-robbing log manifolds (These were the later factory cast iron units and not the classic Interceptor logo pieces) so there was no value to holding on to them. I found a set of no-longer-available Barr Marine aluminum center rise exhausts which were easily ported to match the enlarged head ports. Another quick mph to 56 MPH and that's where we sit today. Please note that these are corrected GPS verified speeds as I was saddened to learn several months back that the newer model Teleflex speedo currently used on this boat many others read a bit high. With one person on board, the gauge shows 58-59 and with a large buddy in the back it'll touch 60. I corrected my posting several months back. Recommendations? How fast do you want to go and how much money are you willing to spend? You've said you'd go as far as the cam and carb. I agree. I couldn't be more pleased with the cam we're using. You could go with a more agressive one, but I wouldn't suggest it unless you plan on upgrading much more. You can pick up a Edelbrock intake and 600 CFM marine carb for a combined $500-max new. Tons of good used intakes on ebay, or I'll sell you a factory cast iron for $25. But just going with a carb and intake isn't going to cut it. So if you're doing a partial tear down with the cam install, I would recommend enlarging the historically small Ford head exhaust ports as well as the exhaust manifolds to match. If you've got the Interceptor alum manifolds, I'd keep them for nostalgias sake and you can port them easily. Those changes I estimate would net you 30-40 HP and 4-5 mph. After that you get into more engine internals and head upgrades which will increase your costs somewhat. How far do you want to go? As you've quickly seen, this web-site will support you. Let's get at it! |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Many thanks for the run down. I've got a bid on Ebay for a cast iron intake... if I do not win it I may contact you about your intake. (I am skeptical about putting an aluminum intake in salt water which is where I run my boat.)
Also, porting and polishing might be fun durng the winter at night in my garage/shop but it's going to have to be a next year thing. (I do have the aluminum Interceptor exhausts (and salt flowing through them bothers me.) My boat is new to me and I don't want the downtime right now for a major rebuild - I'm just going for the easy stuff right now. I can see myself tricking out a 302 and doing a complete engine swap next year but I have too many things on my todo list right now. I will save your notes for next year though. Good info.... The boat came with a 12 x 12 prop and I just want to see if I can get the Rs up to 4800-5000 with that prop. (Hence the cam, 4v carb, and ss ignition) (BTW, for all interested I just picked up a rebuilt 4V 460 CFM Holley Marine from ACFI Remanufacturing on Ebay for $245. He probably has more is you email him.) |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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BTW, reidp, where did you get the SpeedPro cam and how is your idle? Rough? How's the low end torque? Did the cam seem to reduce your low end? Is it a hydraulic lifter cam?
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reidp
Platinum Member Joined: December-06-2003 Location: Mooresville, NC Status: Offline Points: 1804 |
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Jim,
The cam came thru the machine shop. It was also purchased about 5 years ago, so I can't say they still produce it. I checked and CompCams has a marine unit with near identical specs, but I didn'call to verify that it was available in a rev rot model. Idle is very smooth. Low-end torque was increased. It's hard for me to say if more torque was gained thru the cam or the increase in compression. It is hydralic. |
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David F
Platinum Member Joined: June-11-2004 Location: United States Status: Offline Points: 1770 |
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Jim:
Not try to beat the reverse rotation issue into the ground, but have you determined whether or not the camshaft is driven via a gear and NOT a chain? I thought all reverse rotation engines utlized a gear to drive the camshaft, but I could be wrong. My point is that if the camshaft is gear driven, then it turns the SAME direction as a conventional rotation engine. This means that the distributor and oil pump also turn conventionally and thus the distributor uses a conventioal drive gear. So, it follows that the major components specific to reverse rotation would be: crank seals, circulation pump and starter. I really do not know if the crank is different via oil ports oriented the opposite direction. Again, the firing order is achieved by taking the conventional rotation firing order and then swapping the #1 and #8 plug wires at the distributor. Since timing is taken from the #1 wire (which has been relocated) the timing reference point stays on the port side of the engine. I hope this helps. |
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colinc
Newbie Joined: August-20-2004 Location: United States Status: Offline Points: 10 |
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FWIW My 260 is RR and is chhain driven.
-Coop |
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SS 201
Senior Member Joined: October-20-2003 Location: United States Status: Offline Points: 232 |
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Some cam grinds firing orders are different, to lessen the wear on the critical areas of the crank. You just dont' move wires, that is why there is different firing orders. Manufactures preference.
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reidp
Platinum Member Joined: December-06-2003 Location: Mooresville, NC Status: Offline Points: 1804 |
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David,
The Fords, and on the V8's at least, use the chain as Coop mentioned. We normally upgrade to a double roller chain/gears. These rev rot camshafts have their gear cut in the opp direction of the standard cam and as someone mentioned previously the distributor gear also has the teeth running in the opp direction to mesh with the cam gear and so that the dist still spins the same way as std rotation, which is CCW, ON A FORD. The GMs and Mopars are different. Firing orders; and again this is for the small block early Fords and as SS 201 Bill mentioned, there indeed were several. But I got lost on the swapping of the #1 and #8 wires at the dist as I don't know if that applies here, unless I'm missing something basic. For the std rot, an early 260-289 F.O. is 1-5-4-2-6-3-7-8 while the RR is 1-8-7-3-6-2-4-5. This comes from the Interceptor manual as well as valve cover decal. #1 stays in the same location while the remaining 7 are completely flip-flopped or reversed, which makes sense, since you're firing it in the complete opposite order. This same SR/RR sequencing applies to all Ford marine engines I've seen. Later 4V 302's used the same firing order as the 351 as they began using the same camshaft which and your firing order must match the cam lobe profile. Reid |
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reidp
Platinum Member Joined: December-06-2003 Location: Mooresville, NC Status: Offline Points: 1804 |
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SS 201 Bill,
Could you call me or give me your number again when you get a chance. I lost it somehow. Thanks. 704-451-5080 |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Follow up to finish the story:
I installed the SpeedPro Cam mentioned by ReidP above (thanks ReidP for the recommendation), SpeedPro hydraulic lifters, CompCams roller timing chain and gears, GT40P heads, Holley 460CFM 4V (it may be 450 CFM, I have not found clarification on the CFM rating), stock cast-iron 4V manifold, and a Petronix solid-state points conversion module. I gained about 1000 RPMs, to 5300 RPMs, and the boat goes to 50MPH as indicated on my newly installed Airglide speedo. I do not have access to a GPS so I calibrated the speedo with air pressure. Therefore the calibration is only as good as my uncalibrated pressure gauge on my air compressor. Also, the speedo sending unit (a pitot tube) is mounted on the rear of the boat so it sits at a slight angle in the water. I wouldn't bet my life savings on the accuracy of the 50MPH reading. But, I am very happy with the performance of the boat. I can live well with it. I recommend the above changes to anyone with an old 2V 289 or 260. (Personally I think the top speed of this old boat is fast enough as it gets a little "floaty".) I will probably gain some speed, however, when I finally attack the flooring and remove what honestly feels like 500 to 750 pounds of water soaked foam. (The boat is just heavier than it should be.) By-the-way, my compression dropped from 110PSI to 90PSI on all cylinders with the new heads. This is a little alarming but I saw it coming. This winter, if I can make time to attack the bottom of the engine, I will install new pistons to see if I can get the compression up a bit. (The 90PSI was measured on the 3rd compression stroke on each cylinder with the engine at operating temperature. It will go up a pound or two if I keep spinning the engine.) And, like ReidP mentioned above, the choice of cams could be a little more agressive but with this cam idle is fairly smooth (about 900RPMs) and the boat will stand up and push you hard back into the seat when you hit it. The prop I am currently using is a very old, 1960s, 12 x 12. One final note, when the engine is cold and hasn't ran for a day or two, I usually just have to bump the starter and the engine fires right up. (This is very rewarding.) I attribute this to the low compression and the Petronix conversion. |
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Happy owner of a '66 and a '68 Mustang
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Rocco
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The best way to find out about the Motor..
If it is the PCM... Call Mark at PCM in little Mountain S.C. 1-803-345-1337 ext---4.. he could tell you about the PCM Motor's |
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79nautique
Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872 |
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If you are using a 450 CFM carb I would keep a close eye on your plugs. This seems like a very small carb for the changes you have made and should create a lean condition so don't burn a valve because of it if the plugs are really clean and white looking then the engine is running lean. They should be a light chocolate color to the porcelen part of the plug.
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jameski
Senior Member Joined: May-18-2004 Location: United States Status: Offline Points: 368 |
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The 450CFM carb will not make it run lean unless it is jetted too lean. If so, just increase the size of your main jets to enrich your mixture as much as you want.
The spark plug check is always a good idea when you make changes, but keep in mind your running conditions prior to plug removal. Read the plugs after idling for a while to get an idea of your idle mixture (and idle enrichment screws setting). Then read them again after running at speed to get an idea of your main jet size. If you ever read them after a cold idle, they will show some black carbon, but that is normal because you are running on a “choked” enriched mixture – so only check them after your engine has had ample time to warm up. |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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The plugs ARE white! I discovered that yesterday! Man 'o man. Now I have to worry about fuel mixture. Mucho gracias guys.
If I can cure the problem by changing jets I am curious as to how much is "as much as I want". Are you saying I can't over-richen? |
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Happy owner of a '66 and a '68 Mustang
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jameski
Senior Member Joined: May-18-2004 Location: United States Status: Offline Points: 368 |
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Most Automotive shop manuals have a couple pages of good color photos of spark plugs with descriptions of how to "read" them. Black is too rich, white is too lean, light brown (rust) is perfect. One thing to keep in mind is that they can change colors throughout the operation of your boat. They might get some black carbon on them when your engine is cold and choked, and then (ten minutes later) if you have undersized jets they might burn off the carbon and turn white. Then, if your idle mixture screws are set too rich, they might turn black again while you are idling around for five minutes while loading onto your trailer. So, just because they are white when you get home, doesn't necessarily mean your jets are too small - you might just need to back out your idle enrichment screws a tad.
The technicians at Holley's tech support line could probably recommend a good starting point for jet size if you give them all of your specs and upgrades. Then, go play for a couple of hours and just after some hard running, kill the engine and check the plugs (without doing ANY idling). |
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Jim_In_Houston
Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120 |
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Gotcha.
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Happy owner of a '66 and a '68 Mustang
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SS 201
Senior Member Joined: October-20-2003 Location: United States Status: Offline Points: 232 |
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With the additives in gas sometimes takes time to color. Add some octane booster and it will color the tips red then read how much color, jet as necessary. Those GT 40 heads are usually 63 CC.
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3333 |
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Hi Jim
White plugs are clean plugs. What you want to avoid is GREY plugs. They mean you are sputtering off Al. Ceramic self-cleans above 400C, the carbon turns to CO and CO2. SO if your combustion is creating chocolate-tan-whatever plugs, you loosing power somewhere in your mix. To read a plug you need to remove the threads with a hacksaw, or use a scope to view the soot ring at the base of the insulator; should be 1.5-2 mm wide. Wider is richer, narrow is lean. Don't freak over white plugs. It means your combution temps are nice and high and then means power and efficiency; and less stench out the back. Check the soot ring without, then with, the secondaries connected so you know the jetting of each circuit. BTW reading plugs for idle mix is not fruitful. Best set the idle for smoothest, strongest idle (in gear, not out of gear) with a helper. Setting to highest idle out of gear guarantees diaing in an off idle stumble/flat spot. Don't set the air screws to fix anything but idle mix; take the bowls off and swap jets to jet; there is no substitute. Use vacuum gauge to check if WOT vacuum creeps back up when above 4000, as you approach max rpms; if it does, your CFM rating may be too low for that engine and you may have to bump up to 600 cfm jameski's proceedure is called a 'plug chop' Run an extended period at one throttle setting, then kill the engine and read the plugs. Operating at any other throttle setting before yanking a plug to read will skew the observation. |
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