I am having my engine shutter when I get into the throttle. Timing is fine. 36 at 3000 rpm and around 12 at idle. The wires are new as with the ignition module. New cap and rotor button also. Sometime when I shut the engine off it wants to keep on running and spits a mist of fuel above the carburetor. It acts like the timing is too high but it isn't according to my timing light. It's a dial back.

If it's in park and I hold it at 2000 rpm it will miss occasionally. That's another thing that makes me think it's not the timing. Can what I have described happen if the valves are too tight? When I adjusted the valves I only went 1/4 turn past zero lash and they aren't rattling. Maybe one of the lifters have pumped up or something. The engine is pretty fresh. Please help. My engine is in the sig.

 

Try getting the engine up to temp and then readjusting the valves to a 1/4 past.

 

I do think that I'll try to go through the valves again tomorrow. This really bugs me. I have built lots of engines and tuned even more cars and now my own is giving me fits.

 

It usually works out that way. Dont forget that your more likely to look over small things on your own car because theres alot less pressure.

 

O.K. I have the problem diagnosed but am not sure how to fix it. The timing at idle went from 8 to 18 in a matter of seconds and stayed there. It jumps around quite a bit. I thought the pick up in the distributor was bad so I put in another one. Still the same thing. The only thing I can think of is camshaft endplay is off and causing the cam to slide back and forth a little. The result is the distributor is advancing and retading. Could this be the problem? 10 degrees seems like a lot.

 

Is it a vacuum advance distributor?

 

Yes, but it was unhooked while checking the timing.

 

The weights in the distributor could may be sticking causing that problem. You balancers outer ring may also be moving around. Ive never heard of to much cam endplay causing a problem like that. I guess its a possiblity thou.

 

Is this a steady rythmic miss?

What about plugs? If they haven't been replaced, have you pulled them to check for damage, wear, and/or inconsistencies between cylinders?

Timing will not cause a steady miss, so I think you're barking up the wrong tree there. I also doubt that it's your valve adjustment since the miss comes and goes. if you're not entirely sure about your lash adjustment though, it wouldn't hurt to double-check it.

Best bet it to hold it at an rpm at which it misses constantly (if possible), and start shorting plug wires until you isolate the cylinder that's acting up. From there, you should be able to nail down the specific problem fairly quickly.

One other thing - did the onset of this problem correspond with any changes that were made to the engine, or did it just start out of the blue?

-B

 

this isnt a insult.

matter of fact, ive done this twice in the past month while swapping motors and messing with it....


are you SURE you have the plug wires on right? trace them down with your fingers.. somtimes whey they "cross" over or under, they play tricks on ya and you get them mixed up.

 

I have checked the weights and have even locked out the advance. Even put in a different distributor and still does this. The balancer is a new SFI approved piece that only has about 100 or less miles on it. When the engine timing goes way up it trys to stay running when I shut the key off so I know that the timing is moving and not the outer ring.

This is something that just started out of the blue. When I hold it at 2000 rpm it will miss occasionally like I stated before. But when I actually drive the car and accellerate it loses all power and "shutters". That's the best way I can describe that. I do have all of the plug wires on straight. I have checked over and over because I have done that before also so I don't take that as an insult by no means.

I did pull the plugs and all of those look fine. The miss isn't consistent just every now and then. I still think it's endplay for some reason. What else could make the timing move like that?

 

Missing slightly under no load and then missing heavily while under a load just screams ignition - a bad/cracked plug, a wire problem (are the new replacements of good quality?), something arcing internally under the cap, etc...I just don't know what else to suggest you look at.

This engine is carbureted, right?

-B

 

The engine is carbureted. A cracked plug is something I didn't check for though. That still wouldn't cause the timing to rise from 8 to 18 at idle. The cap and rotor is Borg-Warner and the wires are Accell.

 

Any chance that the little metal ground strap didn't make it back into the new cap (although it would probably run much worse or not at all if it were not in place), or that it's poorly connected at the coil end?

Was this a universal set where you assemble the ends yourself, or a custom tailored set?

Right, but timing won't cause a miss. I don't doubt there's a timing problem, I'm just suggesting that it is in all probability a seperate issue.

-Bob

 

The wires are a custom set already made up with 90 degree boots on all 8 wires. The metal ground strap hasn't been in there for about 7 years and has ran fine so I don't think it's that. I do agree that it should probably be in there but hasn't ever been a problem before. Thanks for the help. Maybe if we all can put our heads together we can figure this out.

 

Just to be sure we're on the same page, this is the strap I'm talking about:



If it's missing, you really need to get one in there, even though it's been running without it for all this time. I think NAPA stocks them for a couple of bucks.

-B

 

Yep, that's the strap that isn't there anymore. I'll get one in the next few days.

 

This is the first roller cam that I have ever used and a guy told me that there is a piece of metal on the bottom of my edelbrock water pump that hangs down with a threaded hole in it. It's used to put a bolt through and holds pressure on the timing cover. Supposedly, the cam can try to walk out of the block and bend the timing cover since it's thin sheet metal. There is a way to set up camshaft endplay using this bolt to set how much to let the cam go back and forth. Remember, this is a non-roller block so there isn't a retainer or anything to hold it in. I am using a cam button that bumps against the timing cover.

I need to know the correct way to set up endplay using this method. Maybe I'll call the cam manufacturer if nobody here has done this.