New M600 Carb - Issues
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=47489
Printed Date: April-27-2024 at 12:50am
Topic: New M600 Carb - Issues
Posted By: Off Trail
Subject: New M600 Carb - Issues
Date Posted: May-22-2019 at 10:28pm
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I finally got everything put back together on my '79 SN. I did gt40p's, roller rockers, performer intake manifold, brand new QF M600 Carb. On top of the intake manifold i have a gasket, then adapter plate, then gasket, then 1" block that was on the original setup (with the PCV port plugged), then a gasket, then carb (with PCV hose hooked up to carb port). Got the boat fired up on the trailer for the first time this afternoon and seem to be having vacuum issues. I was able to get the engine started pretty easily with a little throttle. Adjusted my float to the proper level, adjusted the idle screws to smoothest/best RPM at idle, and have the idle set screw on the throttle linkage backed all the way off. The boat idles pretty smooth at 750-800 rpms (not perfect, but not loping or stuttering either). If I stab the throttle there is no stumble, seems to rev right up. After warming it up I can start it at idle or maybe a touch of throttle. So here's puzzle #1: I have my vacuum gauge hooked up to the port on the carb and it is reading ZERO at idle. Maybe almost 1, but closer to zero. If I stab the throttle it runs up to the mid teens and holds steady there. But at idle it drops right back to zero. Seems a little odd that it idles smooth but shows no vacuum. Is this because there is no load on the engine - if I try to take it out on the lake will it die at idle in gear? Is my vacuum gauge not working (its brand new and was a higher quality unit on Amazon)? I've read a lot about leaking on the adapter plates and wedges with the Performer intake, so I will likely pull the carb and remove the stock 1" block. Any other thoughts on this? Puzzle #2: When I shut the engine off, I immediately get a couple drips of fuel from the arm beneath the plunger for the Secondaries. This is on the back, drivers side of the carb and I understand it to be the spring/plunger for the secondaries, but I could be wrong. Fuel is running down the brass arm that sticks down below the plunger. I will say that when I first started the engine up, the float level was way high - not sure if this could have pushed fuel somewhere it doesn't belong, and now I am just seeing the residual? But I think it should have cleaned itself out by now (10-15 minutes of run time with plenty of on/off). I am going to pass #2 on to Holley customer service, but would appreciate any thoughts here! OT |
Replies:
Posted By: Orlando76
Date Posted: May-22-2019 at 10:36pm
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You might get better luck if you pass #2 on to QF. ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Posted By: KENO
Date Posted: May-23-2019 at 12:56am
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Puzzle #1 sounds like you're hooked up to the wrong port. You have a full manifold vacuum port and a 2 timed spark ports . Try the manifold vacuum port and your vacuum readings will probably be what you're expecting. In the link are the illustrated instructions with a good explanation of the ports and their locations. https://documents.holley.com/99-mseries.pdf" rel="nofollow - link And Holley tech support will be just fine since Orlando 76 doesn't seem to know who owns Quick Fuel these days  Pictures of the leak and also the vacuum port hookup would be good |
Posted By: KENO
Date Posted: May-23-2019 at 2:08am
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I should mention that the full manifold vacuum port senses vacuum below the throttle plates and the timed spark port senses vacuum above the throttle plates. At idle with the plates almost completely closed the timed vacuum port is seeing very little vacuum and at idle the full manifold vacuum port sees around 14 to 17 inches or so of vacuum |
Posted By: Off Trail
Date Posted: May-23-2019 at 2:12am
Man, thanks Keno. I knew I was doing something stupid - thanks for finding it so quickly! I was definitely hooked up to that timed spark port on the side. I looked high and low for the other 2 ports shown in that photo, but didn't find them. I just assumed that since the manual wasn't really for the 600 (it references 4 corner adjustment that is only available in the 650 and up), my 600 must only have the one port. After seeing your post and taking a harder look, I found the port I should have been on. I'll test that one and get a photo of the leak tomorrow. Thank you thank you 
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KENO wrote:Posted By: Off Trail
Date Posted: May-23-2019 at 2:15am
Got it. That gives me a good target. I've seen a lot of different ways to figure out a target vacuum pressure and wasn't sure what I was going to find. I knew Zero was wrong though. I'm wondering how much my elevation (8,200ft) will affect the vacuum pressure. My plan is to just tune the idle screws to max vacuum at idle - as long as it is somewhere in the teen's I should be good. |
Posted By: Off Trail
Date Posted: May-23-2019 at 2:18am
| And while we're solving all my problems - does the tilt of the engine affect the float adjustment? I have been just using the forward bowl/sight glass for adjustment. The rear, being lower is completely 'full' ie the fuel is above the top of the sight glass. I'm targeting lower middle on the front sight glass and that seems to be working. |
Posted By: KENO
Date Posted: May-23-2019 at 2:35am
I knew you were high, just didn't think you were that high You could be around 11 to 14 or so (kinda a guess here). General rule of thumb is 1 inch worse per 1000 ft You'll also want to do final adjustment of the idle mixture in the water idling in gear for the best off idle throttle response. If the rear bowl is overflowing or seems high , I'd adjust that too |
Posted By: Orlando76
Date Posted: May-23-2019 at 8:02am
Whoops....  ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Posted By: KENO
Date Posted: May-23-2019 at 9:11am
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As far as vacuum readings, put the gauge on your Malibu to get an idea what would be a good reading to be looking for. You'd figure it should be pretty close to that reading |
Posted By: KENO
Date Posted: May-23-2019 at 9:12am
I think you knew and just forgot
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Posted By: GottaSki
Date Posted: May-23-2019 at 9:38am
Very good to hear you have it sorted and running!
Consider this idle mix procedure - set for max vacuum when in gear and in the water for best results, else it will be on the too-lean side and be a little dull off-idle, plus other issues will manifest. After this it will be an off-idle beast with lots of snap, no hesitation. This will also provide best conditions for no-throttle starting This simulates the auto-trans carb setup procedure (in gear - wheels chocked) of yesteryears. Will also minimize the delta-rpm from in-gear to out-of-gear because your are setting for best idle torque, not just raw rpm ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Off Trail
Date Posted: May-23-2019 at 10:47am
I'll check that out when the Malibu re-emerges from hibernation. I didn't know if fuel injection and different brand motor would be representative, but now that you say it it makes sense. It was snowing while I was messing with the Nautique yesterday, so not sure when I'll pull the Malibu out..... |
Posted By: Duane in Indy
Date Posted: May-23-2019 at 10:50am
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For "Optimum" performance the carb should be level as poss. With all your plates under the carb it seems as though you should get it a little more level with some work. First pic shows my wedge plate. Pic #2 shows the carb level and the engine at normal angle. You are going to really like the QF/Holley carb. ps. Follow KENO's directions. He will steer you straight!   ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: Off Trail
Date Posted: May-23-2019 at 10:51am
Thanks Gottaski and Keno - I read about tuning at idle under load and planned to do this when it stops snowing and I get out on the water. Ahh, heck, why wait. |
Posted By: Off Trail
Date Posted: May-23-2019 at 11:04am
What a novel idea, a separate adjustment for the rear bowl. How did I miss that??  I swear I looked, but it was partially hidden under the spark arrestor and I didn't give it another thought. This is becoming the 'stupid questions about carbs by a newb' thread. Sorry. |
Posted By: Off Trail
Date Posted: May-23-2019 at 11:06am
Looks like I need to buy me a wedge plate. I've already got the extra long carb studs I bought maxed out with all the other nonsense, so I may ditch the factory 1" spacer and replace it with the wedge. |
Posted By: phatsat67
Date Posted: May-23-2019 at 11:33am
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You will have no problem running that carb without a wedge plate. Edelbrock/Carter style carbs are much more sensitive to angle of the engine. On a 4160 style carb you run the front bowl pretty low and the rear bowl a little higher than normal to compensate for the rearward angle. While a wedge may be the best possible setup for a carb to be level it's certainly not necessary. Get the bowls adjusted exactly where you want them before messing around much with idle settings. The rear has no idle settings and differences in bowl level will cause slight idle changes. |
Posted By: KENO
Date Posted: May-23-2019 at 11:51am
Like Zach said, you don't really have to worry about the wedge plate. All those PCM 351's over the years ran fine without them Duane's kinda like a mad scientist. Word on the street is that he built himself a gyroscopic carb levelizer (GCL for short) to automatically keep the carb level at all angles of pitch and yaw and whatever terms might apply. It's kinda complicated He was too cheap to buy some raw water pump parts, so he got a big ol' chunk of metal and made them himself |
Posted By: Duane in Indy
Date Posted: May-23-2019 at 12:10pm
Aw come on Ken, which pump???     ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: phatsat67
Date Posted: May-23-2019 at 12:14pm
| Ken's pump service, if it's liquid we move it. How can we help you? |
Posted By: Jonny Quest
Date Posted: May-23-2019 at 12:52pm
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Did you change your jet sizes to match the altitude? I've had 2 QuickFuel carbs running at 4,400+ feet of elevation in the Salt Lake City area. Both carbs ran rich with the stock jet settings (sea-level is stock). I went 2 sizes smaller for jets in both the primary and secondary metering blocks. That solved the "too rich" condition. Checking the float level is critical -- as mentioned above. the QF carbs should come from the factory with pre-set float levels, but my M-650 came from the factory with the secondary float out of adjustment -- waaaay too high of fuel level in the bowl. The only real problem I've had with QF is that the primary bowl needle/seat assembly had a small piece of brass / metal shaving that somehow became lodged and prevented the needle from closing. QF sent me a needle/seat assembly. Super easy fix. No problems since, only high performance. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: Off Trail
Date Posted: May-24-2019 at 12:18am
That is the one thing I was ahead of and got right (it seems). Bought a good array of jets and installed the recommended size for my altitude before I put the carb in the boat. I'll check the plugs after a couple good runs. Thanks for the reminder though. |
Posted By: Off Trail
Date Posted: May-24-2019 at 12:22am
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Thanks to all the rest! I'll get my float levels dialed before I go to the lake and will worry about the wedge plate if I get bored this summer. Mounted the Alloy Marine platform mounts, and put a drain plug in the rear this afternoon....since it was snowing again and I had a nice fire going in the barn. Might put the replacement hour meter and depth/water temp gauge in tomorrow evening. Will get back to motor tuning when spring hits. Maybe July this year? |
Posted By: MrMcD
Date Posted: May-24-2019 at 5:08am
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I believe at your altitude you can benefit from a little more timing in your engine. This adjustment can be dangerous if you happen to take this engine to low altitude and fail to adjust back to low altitude settings. I am thinking 2 degrees but maybe some with more experience at altitude can chime in. You have less air/oxygen for the engine to compress so your tune will be very unique. A supercharger or Turbo could really help at your altitude.  I took my 78 Nautique up to Lake Tahoe, 6,200 ft and it only had about 2/3 it's normal power and I was modified with performance heads and more compression than stock.. I can only imagine how much 8,200 ft will hurt your performance. ------------- |
Posted By: KENO
Date Posted: May-24-2019 at 9:02am
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Now you don't have to imagine. Here's what he said last fall
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Posted By: GottaSki
Date Posted: May-24-2019 at 10:04am
Good point. Very much the opposite scenario of pulling back advance when increasing compression Altitude = Less dense charge, slower flame , later peak pressure - wold benefit from advance ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Off Trail
Date Posted: May-24-2019 at 10:49am
I've thought about that..... But the boat may end up living at my parents place in Wisconsin...so I don't think I'll adjust timing until I make that decision. As far as I can tell timing is a whole new realm to figure out and I don't have the tools or knowledge to mess with it yet. If I keep it here in the mountains, it will be worth figuring out though. |
Posted By: KENO
Date Posted: May-24-2019 at 9:54pm
Does this mean that you left the distributor in place during the head and manifold job and that you don't know what the timing is set at right now? If so, I think I'd get a timing light and at least check the timing to see what it is at idle and watch it advance with RPM's so you'll know initial and total advance for future reference You have a Prestolite with a clip down cap and on those full advance isn't usually in till about 4000 rpm, so don't stop checking till you're at 4000. to see your full advance. You can check the timing in neutral with no problem. The engine doesn't need to be running under load. |
Posted By: Off Trail
Date Posted: May-24-2019 at 10:11pm
That is correct. I'll look into it. Wouldn't there be some outward signs of a timing issue (not running stronger than it did before the head swap, detonation etc.)? |
Posted By: KENO
Date Posted: May-24-2019 at 10:19pm
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There would be, but it's just plain silly not to know what your timing is set at. Don't be afraid of checking/adjusting timing Do a little reading, get a timing light and at least check it Sooner or later you'll have to adjust or replace your points or maybe put in an electronic conversion and you'll have to check the timing. One of your earlier pictures tells me that you have points, but you should verify that You did all the engine work, you can easily handle timing checks/adjustment
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Posted By: 8122pbrainard
Date Posted: May-24-2019 at 10:21pm
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https://www.bing.com/videos/search?q=How%20to%20Set%20Timing%20351Ford%20Engine&qs=n&form=QBVR&sp=-1&pq=how%20to%20set%20timing%20351ford%20engine&sc=0-32&sk=&cvid=E9DD20D0EDE044289C08FA0EC4E24D6F" rel="nofollow - There are lots of videos out there on how to set timing ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Off Trail
Date Posted: May-25-2019 at 11:17am
| Got the timing light ordered. I'll post back when I check it. |
Posted By: Off Trail
Date Posted: May-26-2019 at 10:12pm
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Took her out for a spin and some carb tuning yesterday. She rips! Dumped it in and idled around trying to get the idle screws dialed. Couldn't get above 10-11 on the vacuum gauge. Ended up about 1 1/2 turns out on both to get max idle and vacuum. Took it up to full throttle (light stumble on takeoff) and it ran up to 5,000 rpm quickly. Got about 43 MPH on the gps. About 3mph faster than it was last fall, and 1 mph faster than my Malibu is here. Pretty happy with that! I continued to have very slight stumble on acceleration, and it would stall if I put it in gear at idle and didn't add throttle. Started messing with the screws again, but then noticed that both floats were running pretty low (I had just set them at the right level at the house before I left). I raised both floats to where I thought they should be (just above 1/2 way up sight glass on rear, and just below 1/2 in front. I was still having the stalling issue, so I started messing with the screws. Found that RPM and vacuum were the same anywhere from 1.25 turns out to 2.25 turns out so I shot for the middle at about 1.75 turns out. I continued to have the stall issue so after some trial and error discovered I need to be at the rich end of the plateau. So I settled for roughly 2.25 turns out and it now idles well at about 900rpm, goes in to gear smoothly and settles in at 750-800rpm, and revs clean right off idle to 5,000 rpm. I'm still getting max vacuum at idle (in gear) of about 11 . Maybe it's an elevation thing. I'm afraid to mess with the carb any more because it seems to be running well all-around. Will be interesting to see what the plugs and the timing look like after another run. Pretty excited about how it shook out and how easy it was to adjust the M600. Hope I can keep it dialed. Hitting 5,000rpm pretty easily (at 8,200 feet with an acme 542) is making me think I'm going to need a prop with a lot more pitch if i bring it back to the midwest. I might even be able to run a bit more cup out here. But i like the hole shot right now. |
Posted By: Jonny Quest
Date Posted: May-27-2019 at 12:43am
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I believe that elevation is causing your manifold vacuum to be a bit lower than expected. Mine is the same -- I'm at 4,400 feet. If you are getting a slight hesitation or stumble, give a quick look at the accelerator pump circuit. On my old Holley 4160, I had to change nozzle (squirter) size to cure my stumble 100%. The Holley and QuickFulel are very similar in design, so you may want to look at the following video about accelerator pump tuning. https://www.youtube.com/watch?v=tMKxD_OFuCA" rel="nofollow - LINK TO VIDEO JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: KENO
Date Posted: May-27-2019 at 7:53am
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And I believe that what JQ believes is what was said earlier in this thread. 11 inches at 8000 ft under load at idle is good. |
Posted By: Jonny Quest
Date Posted: May-27-2019 at 11:27am
KENO: At my age, remembering what I said 20 minutes ago can be a problem. This year I hid my own Easter Eggs and was stumped for hours... ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: KENO
Date Posted: May-27-2019 at 11:45am
Wait till you get to be my age, I'm almost as old as Pete. I can't remember what I just remembered We're just backing each other up on that 11 inches of vacuum being normal Make those eggs RED and they'll be easier to find PS it took me 15 minutes to remember how to make those letters red. |