Over the past week, I have replaced the cam, intake, heads, and put headers on the car, when we started it up today we had some problems. The engine wont idle right. It wont idle at anything below about 1300rpm, it just shakes, spurts fuel from the carb and dies. I turned the idle screw way up to get it to stay running at 1300rpm and everytime I try to drop it lower than that it will die like I described. The A/C compressor will kill it even, so will putting it in gear (auto).

I got it to drive by sorta pushing on the gas as I dropped it in gear. And it has like no power whatsoever to accelerate. Mainly it just wont run at a low idle, im pretty sure all the other stuff is just caused by that.

I am thinking perhaps the timing it off by too much. Unfortunatly, I can't really set the timing without it at idle, so I need to get it close enough to do so. Would this stuff be caused by too much advance or would it be too retarded? Or is it something else entirely?

 

It's just a guess , but how did you adjust the lifters? It sounds like you might have them to tight and a valve is staying open. Or you have a couple plug wires switched on the distributor, I've done that.
Scott

 

The lifters were adjusted by the method of bringing the #1 piston to TDC on compression stroke, and adjusting those lifters by spinning the rod in my hand untill drag was felt, and then another 1/2 turn from there. Then the little allen head screw is tightened down to hold it in place. Then rotate the crank 90deg and do the next one in the firing order.

I'll go double check the spark plug wires right now, brb

 

wires quadruple checked.... all in order

 

Fire that puppy up and adjust your lifters with the engine running......I'm assuming you have hydrualic lifters.... :seeya Cappy

 

Lets see you did cam, heads and intake. You have no leaks fluid wise, so they other things to check are vacuum leaks. A badly sealed intake might give you those kind of symptons. Then it's in a matter of "timing", ignition and valves.
Plug wires are right and your valve adjusting sounds right. Timing chain? you line up the dots or symbols at 12 and 6 o'clock? Hope that helps some.
Scott

 

I was really careful with the timing chain and took a long time to make sure it was lined up right.

 

I'm afraid the symptoms are very much like a cam that is not timed correctly, but if you are sure it lined up then next is vacuum too low to keep the idle system working in the carb...check it with a vacuum gauge, you should be getting at least 15psi manifold vacuum. If you set the Ignition timing by eyeball with the cap off then that should be good enough to get it to idle below 1300...might need a tweeking to get an idle below 800 though, so that should not be a problem.

Which brings me back to:which is THE indication that the problem is camshaft timing...fuel spiting from the carb means that somehow the intake valve is opening back up after compressing the mixture. Is it possible for you to have the cam 180 degrees out of timing or something like that? Or maybe ignition timing 180 degrees out?

 

You can't have a cam 180 out. TDC on the compression/firing stoke would occur relative to the cam.

It really sounds like you've got the lash/preload too tight or you have a severe vacuum leak. I hope you read the installation instructions on your lifters and didn't just follow convention.

 

List your mods again.
Cam
Intake
Heads

You could be getting coil bind or the old wrong intake with vortec heads. It's probably not a big issue. I would limit the driving until you get the cam broke in.

 

Sounds like another case of the "twisty-turny blues" to me. The valves are not closing because the lash is too tight.

Wherever you read that poop about turning the lifters "until resistance" is felt... trash can the source.

I wish someone would write a "correct paper" on hydraulic lifter adjustment based on the "real world" and not just some engineers concept of how the world "should" be.

I recently put on a seminar/clinic on basic Chevy smallblock engine assembly for a local C3 club...
and I picked 4 lifters from a pile of lifters recently removed from a 327.

I passed them around the room for all to examine.
2 of them could be compressed easily, and two were rock-solid, with no compression possible.

This is typical of the "state of the lifters" at any given time.... some will resist compression, some won't. This means that you cannot tell if a lifter is at "zero lash" by turning it between your fingers. Some will bind quickly, some will not. This method will only work if you are lucky.

Following the proper sequence, you need to rock the rocker gently until there is no clearance between the rocker tip and the pushrod... this requires a "surgeons touch", rather than a Bubbas hammer. Once the clearance is removed (basically zero lash), then turn the nut the additional amount. The amount varies... it's not always 1 turn, 1/2 turn, or 3/4 turn. It depends on the thread pitch of the stud, and the lifter design.

The running/hot method is always a good follow up, I use it occasionally, but in most cases, my (hydraulic lifter) engines fire right up and run correctly with no further adjustment necessary. And I've done quite a few.... professionally.

Now.... this is only a guess based on what you posted... if you find out that there was a gerble stuck in the exhaust pipe...

Tom

 

I had a similar problem on a mechanical lifter 350. I had two problems. First, my TDC was not "true" because the outer ring on the damper spun relative to the inner hub (solution-new damper), therefore, my valve lash was way off. After adjusting the valves properly I still had a high (1900rpm), unstable idle (beyond the fast idel on the carb). Turns out my distributor was put back one gear off (easy to do). When at TDC check to make sure distributor rotor is pointing to number one. Also check to make sure number one plug wire is routed properly. Hope you get it running smoothly.

 

I agree completely with Tom454!!!!!!!!

I've tried and failed with the 'twisty' method. The 'jiggle' method of adjustment is MUCH MUCH better for initial adjustment, but believe in final analysis, setting while running on a warm engine is the best.

 

I got the cam broken in before I drove it. Like I said, it will run fine above 1300rpm or so. So I could run it for 30mins at like 1800 like the instructions say.

Ok, the common thought is the lifter preload. I think that I got it right when i did it, it seemed pretty easy to figure out where no lash was and then turn it 1/2 turn more. Also, I know that i have compression in the cylinders because it prevents me from turning the crank more than about 15degrees with a socket and breaker bar. But if nothing else, I guess that I will have to pull those valve covers off there and try it again.

Maybee the lifters pumped up with oil after the first startup? I though lifters would spring up to be full size when they were out of the engine... but is it possible that they did not? They are new lifters by the way. I got the comp cams kit with cam and lifters.

 

>Put on a clinic ... for a C3 club.

Now this is a neat club - where's the Dallas version?

 

Vacuum leaks will cause your problems.

 

I agree. You could also have your distributor installed incorrectly. Have you put a timing light on it to see where you're at? Also, have you made sure that the mechanical and vacuum advance are working properly and that the vacuum to the distributor is on a timed port and not a constant vacuum port? Just some thoughts.

 

All of the posts have good info that you should check for ... BUT ... I didn't see mention of this: I see you changed intake manifold. Have you verified that the intake bolt(s) are not touching the pushrod(s)? Interferance there is a common mistake and can hold valve(s) open or closed (or both) ... OR WORSE! Intake flange thickness varies a great deal from one model to another... with thinner flanges the bolts can easily bottom on pushrods. Pull the pushrods & see if bolt-scarring has occured.

 

This is the EXACT same thing that happened to me after an intake install. Thanks to Lars and Rock 'n Roll I found out it was two things:

1. Distributor was 1 tooth off. Brought the car to TDC and sure enough I had put it back in close, but not quite right.

2. There was a slight vacuum leak. On mine, it turned out I didn't seal the EGR valve properly causing the leak. Tightened down the bolts and problem solved.

Took me a couple hours of investigating and 10 min of fixing :)

 

Based on this I have some confusion about whether the cam was actually broken in. Running it for 30 mins. at 1,800 RPM upon initial startup per the instructions IS the break-in for flat-tappet cams. But if you wiped a cam lobe because of improper break in or because of valve springs that are too heavy for your cam it wouldn't run fine after 1,300--it would sputter and fart back through the carb at all RPMs, particularly if you wiped an exhaust lobe.