318 doesn't idle 75 F-26

rdj59 · Post by **rdj59** » Sun May 17, 2009 7:46 pm

Hi,
My parents just purchased a 75 F-26 with a 318. So far we have been redoing the interior and now i've moved onto the motor. My parents f'ed up and didn't hear the motor run when they bought it and thought the word of the boat mechanic they bought it from was good enough.
Long story short it runs really rough. I replaced the plugs with the correct heat range and made up a set of wires. I also put on a new cap and rotor. It's using the reverse rotation firing order. I did a compression test to see what the general condition of the motor. Port bank was ok at 118-124, starboard is 2=100, 4=75, 6=90, 8=110. It'll run ok above 1300 rpm but anything below that it'll either stuble till it quits or just shuts down. If i put it at tdc the timing marks on the flywheel are spot on. If i line up the rotor to the #1 tower and try to start it, it back fires like the dist is 180 out.
With the motor running the timing is at 35 degrees and this is the lowest setting that it won't back fire at when starting. When it up in the 40's it seems to smooth out but won't idle. I've rebuilt the q-jet that ended up on it as it was in okay shape and should work fine. When turning the motor by hand, i noticed a decent amount of play from the crank turning to the dist turning. Like an 1/8 of a rotation of the crank. I'm thinking the timing chain is toast but i've never diagnosed a bad one before. The hour meter says it has 2790 hours on it and the motor looks to have had a spray bomb rebuild. If anyone has ideas on what to look at or any ideas what to try please let me know. I've just this bad feeling like ive got to go partially internal on the motor.

Thanks,
Jeramie

kevin babineau · Post by **kevin babineau** » Sun May 17, 2009 8:23 pm

its a tough call to diagnose online...but i can say 75 lbs is low enough to be considered a problem....i could go on to question this or that but that would only question ur skill...u sound as if u know what ur doing...it sounds like the motor needs to be gone over..if u didnt mention the compression it could be timing/dist. problems, firing order, the carb or even a worn tim ing chain/cam....with low compression it could be lifters, push rods, head gasket, head, clylinder wear, rings. a bad timing chain wont lower one cylinder....if u take off the valve covers u can see where #1 is....i will say im not so clear on the reverse firing order unless u have twin engines..can u mentiion why it has a reverse fireing order....or do u have twins...good luck and im sure someone here can help

guglielmo6160 · Post by **guglielmo6160** » Sun May 17, 2009 8:27 pm

Jerimie
there are way to many possible causes for your engine not to be running correctly, seems your checking everything by yourselrf, it may be time to have a qualified tech take a look at it. a 1/8 movement should not cause the runability problem your describing. although in the future you may want to look at that to. Trying to diag a situaltion like yours is going to be hit and miss. you always have to start with the basics and work from that up. fuel sample, spark? coil? points? eledtronic ignition? condensors? air leaks in the intake manifold, etc etc etc, the list goes on and on. as I mentioned, it may be easier to have a qualified tech take a look at it and steer you in the right direction

gjrylands · Post by **gjrylands** » Sun May 17, 2009 8:29 pm

I had 318's in my last Trojan. I had a problem with the timing. It turned out that the lobes on the distributor were badly worn by the points and the timing was off. If I set the timing according to specs it ran poorly at higher RPMs. Advancing the timing helped at higher RPMs but it didn't idle well. With the rounded lobes on the distributor the timing floated all over the place.

I converted the distributor to electronic ignition and it solved the problem. At the same time I converted I also replaced the springs in the mechanical advance mechanism and oiled and made sure the counter weights were moving freely.

You may have some additional problems with low compression and timing chain but the distributor may be something to look at.

For the record, I did this over 20 years ago and have no idea if the electronic conversion kit is still available, but I do remember it was called the â€˜Ignitorâ€™ conversion kit. They sold many different kits for many engines. The 318 was one of them. You used the original distributor and replaced the points with their electronics and slid a magnetic ring over the lobes on the distributor. This truly brought new life to the old engine.

gofish103 · Post by **gofish103** » Sun May 17, 2009 9:22 pm

really sounds like a timing problem. did you pull each spark plug and check for spark since you made up your own wires? Its so easy have the timing off 180 when your sure it isnt.

Check JEG's, I beleive they sell conversion kits from points to pointless distributor. very easy to change over. couple screws and your done.

I have a couple pontiacs that I did this to and made a world of difference.

Check the voltage regulator.

talunn · Post by **talunn** » Sun May 17, 2009 9:29 pm

Get yourself a vacuum gauge, it's readings will tell you if you have any head issue's.

James

rdj59 · Post by **rdj59** » Sun May 17, 2009 9:36 pm

The boat is a single 318 that is a reverse rotation. I first wired it as as a standard 18436572 but that was a no go. The velvet drive is a 71c. The engines id plate is long gone. Looking at the trojan plate by the 12v dist panel it say engine RH. LM318R which from what i've read means right hand rotation. If it doesn't sound like a chain thats cool. I'm tempted to just take the carb and dist out and start like im installing a new engine. Plus to put a little more salt in the wound it has a auto dist. It is an electronic ignition with the vac canister still attached. This brings me to my next question. Is the reverse rotation dist different from a standard rotation dist? I should have pulled the dist out anyway to go through it and make sure it was in good operating condition. I'll pull it out tomorrow to see whats up with it. I'm no longer using the Chrysler ignition module and wired in a msd-6a in its place. It came off of a running boat that i'm also redoing. I'm still wondering why if i set the dist to point at the #1 tower when then engine is at tdc and try to start it, it back fires out the carb. But it i advance the carb 30 degrees it will start but won't idle. I've got a bunch of possibilities to check out tomorrow.

Jeramie

gofish103 · Post by **gofish103** » Sun May 17, 2009 10:03 pm

cause your turning the distributor and your getting close to being on time but you dont have enough rotation. Sounds like your just off a smidgen.

I think my vac advance lines are also still connected to the distributor, even with the elec. change over.

try capping them off and see what happens.

Dan Faith · Post by **Dan Faith** » Mon May 18, 2009 9:53 am

The electronic ign. conversion is still available, a shop near me sells them all the time. You should not have an auto distributor in there (this is a safety problem spark and explosion proof marine is what your want). Also confirm left hand rotation The cam and matchine distributor are cut different for left hand rotation. Check for vacum leaks this will cause poor low speed operatio. 75 pound is sufficient for a normally aspirated engine problems will begin under 60 but there is a problem with that kind of deviation between the port bank.

rdj59 · Post by **rdj59** » Mon May 18, 2009 3:47 pm

I took off the valve covers to verify that the valve were opening and events were happening at the right time. Everything was good there. Chain slack was measured at less than 10 degrees. Good there to. I've tripple checked the firing order today and it's right for the reverse rotating engine. Here's a good question. If the motor was 180 out and wired for the reverse rotation when it should be standard rotation would it still run? I'm not one to give up, i might rip out a few hairs and say some encouraging words but it'll eventually run. When looking at the valves in comparison to the rotor it looks like 1 is firing on 8. But when i change it all to be right the marks on the flywheel and balancer are all way off. The dist is turning the same direction as the flywheel which is all turning clockwise.

kevin babineau · Post by **kevin babineau** » Mon May 18, 2009 4:16 pm

if ur standing in front on the engine like its a car which way is the crank turning? the difference between a counter rotating and regular is the cam shaft, firing order, starter and in most cases the distributor (actually the gear on the bottom if applicable) chrylsers had carter carbs if notmistaken...

prowlersfish · Post by **prowlersfish** » Mon May 18, 2009 5:56 pm

If it was wire for the wrong rotation it would not run only one cly would be able to fire on time and thats # 1 .

look for vac leaks sence it runs ok above 1300 , did I read that you have a q-jet carb ? on a 318 ? thats sure not the right carb .

can post a photo of the engine and carb .

foofer b · Post by **foofer b** » Mon May 18, 2009 6:25 pm

I was about to order an Ignitor kit, electronic ignition, from JEGS.com, an online high performance mail order catalog. Will this be alright or do I need a special marine version?

prowlersfish · Post by **prowlersfish** » Mon May 18, 2009 6:48 pm

You need maine

rdj59 · Post by **rdj59** » Mon May 18, 2009 7:27 pm

The crankshaft is rotating clockwise. I figured it would have a carter on it. Swapped dist with a known working one. Made it worse and would only run so far advanced that it was misfiring. Will the motor have a timing chain or gear? Something isn't right, ive never had this much problems with an ignition or an engine in general. They'll usually idle even if timings off, same thing with the carb just not well but at least they try.