Carb problems? Electrical? 87 MC w/ ford 351

Ok, the season has not fully started yet so I'm not really bugged, just a little frustrated, We recently bought a Used but clean Holly carb for my boat -87 MC Tristar 220 with Indmar 351 engine. If the engine is cold it will start right up and idle just fine, if you turn off the engine then try to restart it it will start right up. However if you rev the engine then turn it off shortly afterward it won't start and you have to wait it out for about 20 minutes.
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At this point I don't really know what to check, is it the choke, is there something else, has anyone had anything similar to this happen. Thanks

Although I'm no carb expert, it sounds like the choke is stuck to me. You might try loosen the choke and take it out of commision to see what happens.

IMHO. after many Holleys and many vehicles: Toss the carb and buy a new Holley Marine carb. Bolt it on, you probably won't even have to adjust the float levels, enjoy your summer.

Try this, next time it will not start pull or push the neutral pin and open the throttle about 1/3 of the way. Crank on it for about 5 seconds. If it does not start open the throttle farther without stopping cranking. What this will do is lean out the mixture, which is a common problem. Holleys have these wonderfull things called power valves that like to get a pin hole in them and will cause a motor to run very rich. There is no test for these, but replacement is just a matter of taking the float bowl off. Replacement? Parts changer? Hmmmm......If unsure find someone who is.

The engine is still cold when you rev it up? Take the air filter of and check the valves (inclusive the choke valve) if they are open. Check if the power valve is closed when starting.

How does it starts when the engine is warm? When the engine is warm and if you rev it up and shut down it?

If you don't know which valve is which, look at www.holley.com . You can order a rebuilt-kit for your holley, with all the gaskets, floaters and powervalve. It only costs about $30,- and takes about 1,5 hour for a newby. I'll bet after this your engine runs/starts perfect.

I would have just bought a new one but Marine carbs are over $500, while normal holleys are only $200. Just goes to show you put the word marine on something and they kick you in the tail pipe, anyway, the carb I bought looks very very clean. When it is running it seems to run pretty well, with the exception that at high rpms there is a slight blow back (like a back fire, but certainly not ignighted) I already bought a timing light and set it at 12* btdc. The plugs are new, the cables are new. Cap and rotor look good but it has an msd ignition system so parts are hard to get.

Now for the powervalves. I take it that the valve is located just above the jets, Do you need to replace the entire valve or just the gasket? Do you need to remove more than just the float bowl to get access to it? I checked out the technical info quite a bit on the holley site but some of this stuff just isn't clear on there.

Thanks for your help.

timing light would have been my first suggestion but you've done that. my only other is to check the air/fuel mixture with a vacuum guage.

i jacked this from www.boatered.com very helpful people:

SETTING BEST IDLE
Setting the best idle on your marine engine is a very essential step in power tuning your boat. Proper idle speed is very important for transmission/outdrive life, as well as dependable engine operation for docking maneuvers Check your manufacturer's specification for idle speed recommendations and do not exceed these speeds. Engines which are new have greater frictional losses. and, therefore, require higher "green" engine speeds. These engines will require resetting of the idle speed as the engine is broken in. Your boat will handle best with the slower of these two idle speeds.
Engine speed at idle depends on two factors: idle air adjustment (idle speed) and idle fuel adjustment, with a good engine speed tachometer, an engine vacuum gauge, and with the engine warmed up to proper operating temperature. Here is the procedure to follow:

A. First, set engine speed (RPM on tach) to manufacturer's specification.
Example: 600 RPM.

B. Then observe vacuum gauge with engine idling in neutral as idle fuel is set richer and /or leaner. To assure an initial idle fuel balance, with engine off, carefully turn each idle adjusting fuel screw in until it seats in the carburetor casting before setting the speed of Part A. Do not use a large screwdriver or excessive force since the seat may be damaged if the screw is turned in too hard. After establishing that each needle is seated, back out (counter clockwise) the screws one full turn each. (This will be the initial set point at which the speed is set with the idle speed screw.)

C. Balance each idle fuel screw until the highest engine vacuum is realized. It is highly likely that when this point is reached, the engine speed will be higher than that which was set in Step A, The speed screw should be reset until it reads true on the tach. and the idle fuel setting should again be repeated for best idle mixture at the new speed setting.

Thanks guys, looks like I'm going to have to continue to play with it. Today I bought a new powervalve and installed it. Everything in the carb looks clean including the jets and floats. I'll definately mess with the idle, it does seem to idle a little rough, and my mechanic said that I could bring it by and he would give it a once over.

I guess I really need to find out if I have a lean or rich condition at this point. Ah so much testing to do, so little time.

Going to triple check to make sure I have the right plugs in, right now I have the autolite platinum in. Thanks for all the help, keep the info coming.

UPDATE: Oke played with it some more. Here are the results, I put in the powervalve, and went down to the shop to play with it. Still popped a bit but sounded alright. Still doing the rev and turn off, won't start. I bought some new champion plugs and pulled out the brand new autolite platinums, the champions were a hotter plug, started right up and sounded great, took it to the lake and it ran awesome , with the exception that above 3/4 throttle it would pop a little. Still hard starting after reving.

My mechanic, who bless his heart is giving me lots of free advice, (which still costs because I buy my parts from him) said that the carb looked pretty good, the next step is to change the oil and put some kind of cleaner in the oil, like slick 50, he suspected that one of my valves was sticking open, causeing a lack of compression which would explain why it was hard to start, I'm hoping that this also takes care of the popping at high RPM's. Wish me luck. If you have any more suggestions let me know.

Oh man do I have a tool for you! At only $9,000.00 This bad boy will clean the oil system statically or running.



In reality a compression test should reveal if there is a problem in the motor. Sticking valves almost never happen unless a spring is broken. Personally you named the two brands of spark plugs I refuse to use, but that is my opinion. Often the pop you hear is caused by a lean miss. I know that is not the original carb and it may not be jetted correctly for the motor that you have. I would also make sure the timing is advancing to at least 32 degrees at over 3500rpm.

Peter is right. Does your timing advancing? I don't know exactly how much but the figure Peter is given can be right.
The problem may be your ignition system, that the springs at the bottom of your ignition are not good or broken. In that way your timing is not increasing when your rev you motor up. Or the weights are in there upper position when you rev your motor and shut it. After then then engine needs a lot off playing when starting before the weights are in its original position. So check the springs at the weights and buy new ones for $0.10 . I think Peter is right and you will have to look in this way and not at the oil system or valves.

Good luck, Tommy

Ok, I finally took the time to do a compression test. I had stalled so long because the way that that the exhaust manifolds were on there they have to be removed to get the tester in there. Anyway, despite my best efforts the popping continued. SO back to the compression test. One one side I had 125, 125, 110, and 110. On the other side I had 70, 120, 100, and an amazing 22 psi. So With the thrilling thought that it might be time to buy a new engine I got some great advice to pour some oil into the piston and re-test. Now because after doing this the pressure did not improve that gave me the great news that the valve was bad.

I then took the next hour, pulled the intake manifold off and the two heads. Sure enough, you could plainly see that one piston was not even firing, and upon closer inspection, the cylinder with only 22psi had some great big cracks in the exhaust valve. The cylinder with only 70psi also had a slight crack in one of the valves. So this is actually good news, because I have now found the problem. I can take it to a machine shop and have them do a valve job and get my psi's back, hopefully mill the head a little and boost all the compression up.

Now here's a couple of questions for anyone who might know. My engine, because it is a marine engine should be the 351 cleveland, however it is the windsor I have seen many cleveland heads for sale, these are the high out put version. If I wanted to buy one of the clevland heads, can I do this? Can I bolt it to the windsor block? Would I need a new manifold? Or should I just get the valve job and call it good? Thanks for all the help.

Your engine is supposed to be a 351W (Windsor), not a 351C (Cleveland). Cleveland heads and Windsor heads are not interchangeable. If you are looking for high-performance heads you could shop around for some GT40 heads.

Its a windsor, not a cleveland.

I have had (bad) experience with windsor heads on a 351W. I should have chimed in a week ago about the compression test, because I figured valves might be your problem.

Sorry, anyway to try to help now, if you can get away from the windsor heads, I think you will be better off. I had a set rebuilt twice and they failed again rapidly. (these were a set from the pre-unleaded gasoline days however).

I don't know if you can just bolt on cleveland heads. The bolt pattern may be different and the intake pattern certainly may be different.

Good luck!

Well I found a good machine shop, They took a look at my heads and started laughing, "Does that thing actually run like that?" Is all they had to say, upon further inspection, one of the heads had a crack in it, and the seats were pretty bad on both, so I called up the local junk yard and got a set for $35 each, then I ran those back to the shop where they will now do a valve job on them for $90. Can't wait to have my compression back up.

Yes it is a windsor, from what I learned, if I wanted to change to a cleveland I would need to change just about everything, new intake manifold, exhaust manifolds, and maybe cams. Not worth it. The boat should have plenty of power compared to the way it has been running, and should certainly solve most of the problems I've been having. I am curious about the GT40 heads, but maybe if I have a problem in the future I'll search for some. If anyone has the torque specs for everything that would be great.

Update, Ok did the valve job, started and ran great for a few minutes, did some messing around, got frustrated, spent some more money, and thought I had solved the problem, then we went to the lake, it ran awesome for about 3 minutes, then it died and wouldn't start again. I resisted the temptation to pull the plug, let it sink to the bottom of the harbor and walk away.

Finally after messing with it for a while, we have come to the conclusion that it is flooding, the choke lever is open but it still floods, we already jetted down.

Ran great once we got it started, had to set idle fairly high, amazing hole shot, great top end. No popping any more, just if you let it die, it will flood and won't start for a long time.


any suggestions?

Is this a girl boat If you still have your old carb maybe it would be worth a try. At least you can get on the water. It is snowing in Lethbridge and suppose to be like this all week

Sure sounds like a bad power valve to me. If it were me I would rebuild the original carb (Or have it rebuilt) and put it back on. Have you tried restarting it by opening the throttle half way and cranking on it? Do not crank for more than 15 seconds at a time and do not move the throttle around or you will just add more fuel.

I'm Having the a similar problem with my boat aand not being able to fix it. BIg problem is holley doesn't make a rebuild kit for their marine carb. you can get a universal kit and get new gaskets and needles and seats, but the power valve according to the holley rep in my area won't be the proper one. It's very frustrating, since a rebuild kit cost me $35 and a new carb is going to run about $400.

You should be able to order a rebuild kit for any Holley #4160 marine carb. Power valves are also available separately if for some reason the kit does not come with the right one. If you have trouble with your local source try www.skidim.com

It is a brand new power valve actually, I'm wondering if it might be the screws on the side? Again,if you let it idle for a while and then restart it it's fine, just if you rev, then kill it you have problems, We're headed to Lake Mead this weekend, so hopefully we'll have it all worked out.

I did find a re-build kit for the marine carb, but it is like $90 not $35. And yes it is frustrating.

As for going back to the old carb, it is so badly corroded by salt that I really don't want to try it. There are some parts I can canibalize from it though, for example if I need some floats I can get the others, The other reason I am hesitant to try it is because a couple of the gaskets were so old that they tore apart when getting into it and I really don't want to buy another rebuild kit.

One more thing we found, The ignition system was replaced with a msd electronic ignition, when they put on the distributor the cap was turned 180 degrees from where it was supposed to be, the wires were in the right place but the locking pin couldn't do it's job, which would let the cap slip just a little, changing the timing just a little.

Well why would you rev it before shutting it down? What that causes to happen is for the engine to get a shot of fuel causing a rich condition. That is where opening the throttle 3/4's or so and then cranking without moving the throttle until it starts should solve the problem. I could go into a long story about adjusting the carb but the short end of it is too set the idle speed so that in gear it idles smoothly. Then adjust the two side screws one at a time. Turn one in until the rpm drops, and a very slight miss starts. Back the screw out about one turn and go to the other side. This may take a couple of shots and it really is a seat of the pants adjustment. Often the idle adjustment will change too.

Now this MSD deal???? Do you have the base timing set correctly now? Is the timimg advancing up to at least 30 degrees over 2500 rpm?

Another thought is you would be amazed at just how clean a carb that has been dipped will look. Something to think about before damaging or throwing away the original carb. You might want to use the jets out of the original but at that point all the other parts that determine fuel mixture might come into play.