The Stovebolt Site Forums The Shop Area Engine Shop Doesn't want to run!

This is a new thread on an old problem. I have a 1950 3800 with a 1966 250 in it. I have not been able to get it to idle without being choked. I pulled the carb top off (Rochester monojet) and messed with the float level. I don't know what the setting should be but I just wanted to see if any alteration in the float setting would make a difference. It did! The engine runs fine, sounds fine and I was happy as a clam till I tried to drive it. Nothing. Couldn't even get out of the garage. I am able to get the RPM's up while she is sitting but absolutely no power when I put a load on. Up till now I have checked the compression and it is good, replaced all the plug wires, plugs are good, points are a bit corroded but with the right gap, vacuum is good and I am pretty sure the fuel pump is functioning OK. Any help would be appreciated. When I was in high school many decades ago this engine was a treat to play with. How come not now?

timing? vacuum advance stuck or gone? clean those points, always good to do if they been sitting ... in high school it's all a game and ya wanna prove you can win no matter how long it takes, now we just wanna relax and drive'em

Bill

No accelerator pump or power valve operation ??

edit , just remembered , back in my youth , the '39 V8 played up like this , points were bad.

get a rebuild kit. I had my float set wrong and I chased that problem around for months. kits come with all the info you need. as least you can eliminate the carb as a problem

Did you check the metering rod adjustment. It is critical on this carb. With the throttle closed you press down on the bracket holding the rod. Measure the distance from the bottom of the bracket were the rod is & the top of the carb fuel bowl. It is usually 2-3/32 in. Like Nate says you need the speck sheet to adjust the carb acurately. There is a lot of variation from carb to carb. Also make sure your accel pump has a good shot. If you want the specks on it send me the carb number & I can look it up Monday.

Be sure to check the gasket between the intake and the carb, it should have four cut outs on the inside, these let vacuum up into the carb for proper operation.

How much vacuum does it have? 18" to 20" or more?

Sound like its really lean, check the intake to cylinder head gasket for leaks, and any vacuum hoses for cracks.

Double check the timing, (8 to 12 degrees with out vacuum advance).

Joe

looks like I have a few things to do. I will replace the points today. Thanks

I have not checked the metering rod. The carb is a rebuilt I purchased and I am not able to find any numbers stamped on it anywhere. Only that it is a Rochester Monojet. I will pull the carb today and see if there are numbers hidden somewhere. Do I need these numbers to purchase a rebuild kit? Thanks

Joe, I have checked the vacuum and it was around 18 I believe but when it was checked I did the vacuum check with the choke closed as it would not run without being choked. Now it will run without being choked so I will check it again. I have checked the timing but can't remember exactly what it was when it was running the sweetest. It has been so long since I held a timing light I wasn't sure how to do it.

Dusty, regarding your quote, I am quickly slipping from hobby to the mental illness side according to my wife.

Joe, Today I was pumped up to work on the truck, went out and started her up, let it warm up and then took the choke off. It idled Ok for a few minutes then wouldn't idle much at all without help. Yesterday it ran perfectly at idle. I pulled a vacuum line and checked the vacuum. It has been running 17 to 18 and today was only running 12. I tried checking the timing but really couldn't keep it running long enough to check the timing. What I could see with the timing light was the mark was way to the left as I looked down. Don't know if that is advanced or retarded. I think I am retarded, don't know about the truck.

Next time when you start it, be ready to check timing and have the distributor loose. Plug the vacuum at the end of the hose going to distrib. if you have one. If its really that far off of time, that's your problem. quickly rotate distrib to get it going. If it won't stay running, rotate distrib. 45deg at a time ccw and cw until it starts. If this does not work, new rotor, new points, new condenser, NEW CAP and hope it's not a skipped timing chain, but if it was that it would be backfiring like crazy. Another problem (if it's not carb related)that can happen is that the harmonic ballancer can slip, there is a rubber isolator between two rings that gets old. When it slips and you think you are setting the timing, you are not. That's a real good engine, it will be something simple.

This engine was completely rebuilt years ago and has never really been used or run because of this problem. The engine parts should all be new or nearly new. I can't imagine that anything could be worn out. Is there a logical sequence of events to go through to tune this engine. I have gone back and forth through so many systems that I'm afraid everything is screwed up.

For now, forget the timing light and twist the distributor till it runs. You need it to run, no matter how you get it to, so then you can narrow down the problem by tune up and fuel adjustments.

Keep us posted,
Joe

By the way, these engines have gear driven cams, no timing chain.

Find TDC on CYl 1, check rotor pointing at No. 1 Wire hole (you take cap off)on distrib. and see that timing mark on ballancer is at zero. Start there and then we will advise. Here is how you do it: Gently place a loose piece if kleenex down the spark NO. 1 plug hole (plug removed). just into the threads LOOSELY, but enough to lightly plug the entire hole.(thus is the one man procedure) crank engine a little at a time till it POPS out, turn engine by hand to Zero on timing mark and check distrib, If mark on ballancer goes past before you stop cranking, go around TWICE by hand and stop at zero and check per above. Distributor is possibly off by one plug, it will still run but no power and it will die. My V8 did this and it did not pop thru carb, I finally figured it out by the method described.Anyway, you need to check this first. I don't know if you are used to working on engines or not so I am not trying to insult you with this if you already know it. Let us know what your experience.

I built this engine 1n 1993 with my then young children. When we couldn't get it running it kind if was placed on a back burner and I would kind of work on it every now and then. I do have some mechanical experience but never have had much luck when it came to tuning cars or trucks up. Your advice no matter what won't insult me. I am just frustrated at the moment as I remember working on these engines in the 60's with no problems. Well actually I had carb problems back then as well now that I think about it. I will keep you posted. Thanks.

Bob,
somewhere you have a vacum leak. Intake manifold to head, carb., there is a hole on the side of the manifold for a vacum source for power brakes/pcv is it plugged or open needs to be plugged.Since you had the same problem in 1993 with the engine I would think you need to step back and look at the simple things first.

The intake/exhaust manifold: this is a two piece unit that bolts together under the carb with 4 bolts. I don't know if when you rebuilt the engine you seperated them, but if you did they may not be straight, alowing for a vacum leak. You can check this by spraying some carb cleaner/ ether around the intake to cylinder head surface and if the engine speeds up you found your vacum leak. If that is the case, remove the manifold and replace the gaskets, however, you need to check for a straight surface on the manifolds, loosen the 4 bolts between the intake/exhaust manifold, a gasket should come with the gasket set, and change the gasket, reassemble but don't tighten these 4 bolts untill after installing on the engine, this will allow the manifolds to fit tightly to the head, then tighten the 4 bolts.

Timing: like Bartamos said, sometimes the ring on the balancer will slip, especially if the balancer was installed by the hammer method( beating on it) instead of using a bolt in the center of the crank to pull it on. Try turning the distributor and see if that makes a difference. Check the vacum advance, pull the line off and suck on it if the dist advances your ok if not you need a new advance.

These are simple well built engines it will turn out to be something simple, we all have had these same gremlins over the years and will help you through this.

Being inconsistant like it is the first thing I would do is check the point gap. If it is to close where the points are barely breaking it can cause this. Check the gap with the rubbing block on top of a lobe. Then like Tommy says look for a vacuum leak. If the gasket between the manifolds is leaking it will not cause a vacuum leak though. It is stricktly exhaust. Tighten the bolts that hold the manifolds to the engine. There are 2 different geaskets that go between the throttle body & fuel bowl. Both come in the kit. It the wrong one is put in or put in backwards it can cause this kind of problem. I would try moveing the dist back & forth till it runs the best. You can make the final timing settings after you get it to run. If that doesn't do it take the carb off & go into it. They are not that hard to work on. What about the gas. Is it real old or have water in it.

Bob, Wrenchbender is right the gasket between the manifolds is for heat to the intake it will not be a source for a vacum leak.

What I was refering to, is that if the manifolds were seperated and put back together tightly, before being mounted to the head, the mounting surfaces may not be flat and there could be a vacum leak. Bolt the manifolds together loosely, then bolt them to the engine and torque in place then tighten the four bolts.

Change the points and condeser they aren't expensive, is your coil wired correctly,It will be something simple.

Thanks for all the info! I pulled the #1 plug and am pretty sure it is on the mark. I pulled the manifold off and checked for any cracks and couldn't find any. I replaced the manifolds and tightened them up cold and then again after I ran the engine for awhile and still no change. Today I am going to try new points and plugs. I was going to just file the points but that elusive file I once owned is hiding and points are pretty cheap. I am running AC44 plugs and I think the specs for that engine call for 46. I sprayed the engine at all the suspect spots and never had any RPM change. I had to order a carb kit so as soon as that comes in I will be into that. I didn't know about the different gaskets so that might be my problem. There were a lot of gaskets in the rebuild kit and I still have all the extra parts laying about.

When a person changes points, is there any special tricks? It seems to me I just bumped the engine to get the cam to a high spot and then I set the gap and made everything tight. Did I leave anything out in that process?

Why do you ask? Does it not run? I usually turn the engine and recheck the gap.

It runs! Sometimes well most of the time bad. Never well enough to drive. What I mean, last week I fooled with something and got it to idle wonderful, thought I had problem solved. went to drive it and couldn't get it out of the garage. Gave up for the day at that point.

Read up on the basic How to tune up your car. Pay particular attention to the dwell meter section. Once the ignition is correct the only thing left will be carburetor. stalling out under load makes me suspect the accelerator pump in the carburetor.

Thanks for the info. If I can make it out to my shop today I will give it a try. One thing about the accelerator pump, I peeked down the carb throat and pumped the throttle and I did notice gas squirting in, if that means anything without knowing the volume that should be going in. I used to have a 1953 Chev sedan in 1962 when I was in High School. Wonderful old car as I remember. Not very cool at school as it was a four door, solid green with a visor. I liked it anyway.

What about the fuel delivery like the fuel pump, filters, lines & gas tank.

New fuel lines from tank to fuel pump. Fuel pump pressure was 6 , new inline fuel filter. I was told to just throw out the one in the carb body and replace it with an inline filter. I haven't had a chance to get out and do the basic tune up but was wondering if fuel pumps pump good and then bad?