A few days ago I installed an L05 into my '85 LG4 automatic camaro. This is kind of long, but I wanted to include as much info as possible.

During the swap I drilled my stock intake to the '87+ intake bolt pattern, changed the distributor gear to a melonized one, installed correct knock sensor and module, and installed an electric fuel pump in place of the mechanical (there isn't a pump in the tank), and put on a different flywheel for '86+ engines.

After everything was hooked up, I fired it up and it sounds ok in idle, but in gear it sounds like it's missing a cylinder. I broke in the engine according to Scoggin Dickey's procedure (between 2000-3000 rpm for 20 mins.). During that time, the oil pressure stayed at 60 psi or so and after 17 mins. it got up to 240 degrees, at which point I shut it down. Also I didn't realize it was missing until I put it in gear.

My timing light was broken so I just took it over to a shop and had them time it real quick. He noticed that there was a vacuum leak at the front of the intake manifold, it was sucking RTV into the engine. So I went and got some of those black gaskets on the front and back between the manifold and the engine, and pulled the intake manifold off, replaced all gaskets, measured all bolts for length, torqued them to spec in sequence, and hooked it all back up. Does the same thing.

Then I pulled off the spark plug wires one at a time and each one had an effect on the idle. I replaced my accel coil back to the stock coil and changed the distributor cap. My plugs are gapped to 0.045 (reused from old engine, only 1 month old). I have some new ones gapped to 0.035 but I haven't put them in yet.

Electrically, the fuel pump is operating properly. My fuel pressure starts at 6.5 psi and after a few minutes drops and levels out to 5 psi in idle. In gear it bounces between 4 and 5 psi. I checked the vacuum at the base of the carburetor and in idle it read a steady 21 or so (normal I think) and in gear it bounces between 14 and 18(faulty carburetor adjustment I think).

Also, at a steady speed of 45 mph on the highway, it runs at 220 degrees with a 180 degree stat, water wetter, and 50/50 coolant.

Does anyone have suggestions or ideas to what this could be? Thanks for reading.

 

Run a compression check when you do the plugs... that will tell you a little more about the internal condition of the engine.

Look for consistency. Don't worry so much about what the number is, just that all 8 are the same within 5 or 10 psi.

 

just a WAG but i'd be running the valves again to make sure, and looking for bend push rod

 

I forgot to mention it's a brand new crate engine, and I didn't touch the valvetrain or any internal components.

 

What is your timing set at? If it is set too retarded(most likely) or advance too much then it wont run right. Dont worry about setting the valves or doing a compression check until you get a timing light and set the timing where the engine needs it to be.

 

Should be at 0 degrees. My timing light is broken so I took it up to a shop a block or two away and they timed it for me.

 

Maybe you arent understanding what I am saying. Each engine is different and therefore might need to have its timing set differently . Advance the timing and dont go off ANYTHING but what the engine runs best at. Every symptom you describe is exactly what timing that is too retarded causes.

 

Might stop for the night, but I got a new timing light and it was set at 10 degrees before top dead center. Brought it back to 6 degrees before top dead center and it sounded better in idle but still sounds the same in gear and after it's been driven for a few minutes. I was setting it with the EST disconnected and at 750 rpm in idle out of gear. Also I changed all the spark plugs.

 

***He noticed that there was a vacuum leak at the front of the intake manifold, it was sucking RTV into the engine.***

Do you mean there was vacuum under the intake?
Shouldn't be.
Pull the PCV valve and the fresh air intake from the other valve cover.
Place your palms over the holes to seal them. If you feel vacuum, you have an internal vacuum leak. The head-to-intake gasket is probably not sealing.

The PCV valve sucks air/fumes from the crankcase while fresh air is introduced on the other valve cover, so no real vacuum should be present in the crankcase.
Check the fresh air intake for restrictions.

 

I'm with the timing idea. Don't know what kinda cam you are running but my 350 with a xe262 cam with 218/224 duration @ .050 it wants a lot of timing. I can forget running at 10 TDC. It wants around 20 degrees of timing to run right.


Tom

 

Well I checked for vacuum in the PCV system and only felt air trying to come out of the fresh air hole. I advanced my timing to somewhere in the neighborhood of twenty degrees and worked my way down. At some points the idle was a little better but in every case when I put it into gear it still sounds like crap. Stock cam by the way, I don't know the specs, but certainly not anything significant.

 

I agree also that it sounds like a ignition/timing issue. I see that in your sig that you have headers. One trick I've learned over the years is how to find a dead cylinder on an engine with headers. Take a squirt bottle one like you would spray Windex with and fill with water. Squirt each header tube while its missing. The cylinders that are firing correctly should burn the water off faster than the one that is missing. If you can narrow down the hole thats missing your half way home.

Another thought is could it be your carb having a flat spot in the fuel curve?

Jay

 

Have you tried adjusting the idle mixture yet??

 

Now we're getting somewhere. I sprayed water on the primaries and all of them steamed...except for number one. I'm gonna pull the spark plug out and make sure it's firing, but what are all the reasons besides ignition that it wouldn't be working right (just to make sure I don't miss any)?

My carb is CCC, and I'm not sure adjusting the idle mixture screws would have much effect.

 

Yep, now you're getting somewhere alright.

Swap the plug with another and see if the problem follows the plug.

The cyl has to have 3 things to fire.
1. Compression= compression check.
2. Spark= swap plugs and wires around.
3. A fuel/air mixture within certian ratios.= Vacuum leak..

Does #1 cyl miss with tranny in park, or does it only miss in drive.
If it only misses in drive, I'm leaning towards a vacuum leak.

 

In regards to the idle mixture screws having an effect with a computer carb; it has been over 10 years since I worked on cars professionally. I don't remember for sure if the M/C solenoid controls mixture at idle. I don't think it does, but I'm not sure abt that..
It would be a good question for the Carb board

 

i had a similiar problem.....idled fine but sounded like a miss in gear......turns out one of my wires was bad.....replaced it with a friends one at a time till i found the bad one......fixed my prob........and yes i gave the wire back to my friend and bought new ones.......

 

Update: Runs great!

Conclusion: The valve lash was adjusted very inconsistently, and the number one cylinder valves weren't opening and closing like they should've been. Adjusted the valve lash to 3/4 turn back from zero on all valves and it runs just fine.

Thanks a lot for all of your help, I appreciate it.

 

Glad your up and running. Thanks for updating us on the fix. I have one question though, incorrect valve timing should make the cylinder miss whether in gear or not. Can someone enlighten me on why incorrect valve timing would make a cylinder miss under load {in gear idling} and not at idle not under load? Putting the car in gear does not affect valve timing in the slightest bit other than the fact of only slighty lower oil pressure to the lifters due to RPM drop. How far were the valves out or adjustment? They would have to be very far out of adjustment to cause a miss. Not trying to sound like a Butt head here, I was just trying to understand what happened to you. Didn't you say this was a Scoggin Dickey's motor? Anyway, glad your engine is running well!

Jay

 

my thinking is that improper valve lash would result in the valve timing being a half degree advanced/retarded which in park doesn't have an effect because of no load but under load (drive) that minute amount of maladjustment is enough to suck enough power from that one cylinder for the engine to run smoothly.

 

The valves on the number one cylinder were two full turns out from zero lash, and some of the others were over one full turn. I believe the miss was more pronounced in gear mostly because of the RPM drop, it dropped from about 900 or so down to 500 RPM. The idle never sounded perfect, it just wasn't anywhere near as bad as it was in gear. When I revved the engine up to about 900-1000 in gear, it sounded similar to the way it did in idle.

The valves should've been preset at the factory, I'm not sure that Scoggin-Dickey really had much to do with it (I could be wrong though).