I'll try again

[FASTDARTCHESTER]

I posted a while back but didn't get any hits back. Any ideas?

Did a compression test on my 318 and found the following:

#1 160 psi
#2 175 psi
#3 170 psi
#4 162 psi
#5 162 psi
#6 160 psi
#7 170 psi
#8 152 psi


When at idle, I remove #1, 2, 7, 8 plug wires, idle slows drastically and gets rough. When I remove #3, 4, 5, and 6, there is little, if no, slow down in idle speed.

I have a new cap, rotor, wires and the plugs seem to be burning OK. The "weak" cylinders also are getting spark as I tested them. The engine does not smoke AT ALL.

The only thing I haven't done is make sure all valves are lifting properly. I did notice the cam looked great when I had the intake off last month.

Why aren't 3, 4, 5, and 6 slowing the idle down????? It seems strange and tells me there may still be an ignition problem???

[horatio102]

what's the firing order?

seems funny that the engine isn't bogging at all when you pull half of the plug wires.

Compression looks pretty good though, #8 is a touch low but not dramatic at all.

[toad490]

I'd switch plugs, one at at time, between a bad cylinder and good and see what hapens. If it still does the same thing then do the same with the plug wires. That will at least tell you if you have a problem with them, also check the cap carefully, even new ones can have a problem. Trouble shooting is a processe of careful elimanation or you can try my method, run it till it brakes then you know what to fix!

[Twisted360]

Is it running ok?

[turbododge]

What intake and carb are on it, and as was said, what firing order? Could easily be a relation of a two plane manifold/side to side carb imbalance/ firing order.

[FASTDARTCHESTER]

Hi guys,

I just popped an Eddy RPM air gap (dual plane) on it; 600 cfm worked over Holley. It's std smallblock firing order: 1-8-4-3-6-5-7-2 (if I am remembering correctly).

At the end of the season last year it went 12.90@104 (12.16@112 with 100 hp shot of nitrous) with an M1 dual plane. I thought I'd up the ante with the Eddy and pull a few more top end hp because they are spoken of so highly (I dumped the nitrous to see if I can pull mid 12's with the 318...also lightening the car).

The car seems to pull harder than before in the top end but I haven't had it at the strip yet so there are no hard numbers. It just seemed strange that certain cylinders won't slow the idle down.

Maybe it is the design of the Eddy and how the engine pulses at idle. It's definitely set up different (runner design) than the M1, as you all know.

Any other possible thoughts?

[MOPARMANJAMES]

As was stated before, it could be the manifold design and the carbuetor idle metering circuit.
Is there a divider in the plenum?
If so it is dividing the carburetor metering circuit in two and one side of the idle circuit could have a blockage or be running lean.
This would explain why it runs well off idle,
but doesn't during idle.
Try cleaning the idle circuit and see if it helps.

[MOPARMANJAMES]

I just checked out the Edelbrock web site and sure enough, there is a spacer that extends all the way up and across the base of the Carb.
This is most likely yor problem.

[MoparMarcIdaho]

to notch it to help equalize the mixture?Ive been told that on a dual plane that chrysler motors are prone to run richer on the passenger side.But his is a single plane so that would not be the case.

[creative1]

i think what chester is trying to say is that the engine runs ok. what he is wondering is why the idle speed does not drop noticebly when certain spark plug wires are removed, creating a misfire condition.

i have the same "problem". dont remember right off hand which cylinders, but the engine doesnt seem to miss these cylinders very much at idle. try to drive it, though, and you can instantly tell something is haywire! by the same token, there are some OTHER cylinders that if the plug wires are removed (one at a time) the engine speed drops by almost 50%. maybe i should note here that my engine WILL start and run and idle wirh all of the wires on the left side of the engine hanging out in the air... lol... dont ask how i know... never saw a V8 that would idle with half of the wires off till i put this one together. hell, most of them wont even start!

anyone else ever hear of or have similar experiences?

[MOPARMANJAMES]

If you read my post, I described exactly how this can happen, has happened, and will happen again.

The manifold carburetor flange(where thr carb mounts), has a hole for air and fuel to enter, this "hole" has a divider in the middle of it that separates each side of the carburetor(notice I said carburetor, not "each side of the engine").
Since this is a "dual plane" intake, not a "single plane" intake,
the air/fuel mixture from one side of the carburetor feeds 1,2,7,and 8, these are working at Idle so the carburetor idle circuit on this side works.
The other side of the carb that feeds 3,4,5, and 6 has a blockage or defect in it's idle circuit.
Chester also stated that it is running well off idle (pulling hard)so this is a classic idle circuit problem with these type manifold designs.
In your case however, it sounds like you have more pressing issues.

[FASTDARTCHESTER]

Moparman,

That makes good sense to me for the following reason: I am using a 4-hole spacer, not an open. So yes, the plenum is physically divided from each idle circuit.

I will check the idle circuit and get back with you on the results. Prolly go with an open spacer too.

One more question: why don't I get a notification in my email when you guys respond anymore? I haven't posted in a while either; has something changed?

Tom

[waldo67]

i had a simular problem with my 318 also but with torker 340 intake and a brand new carb on the passenger side of the engine the copmresssion was 170 to 175 psi on the driver side it would show zero psi and i it was the over lap in the camshaft that was causing this how i figured this out was i did a leakdown check in each cylinder and the all were arond 10% leakage which is awsome i i know what you all r gong to say is that the lifter preload was set wrong well i run a hyd cam at zero lash no preload and i did the lea check with the rockers remove so you cant get me there lol mopar cams sre in truth groun really crappy and the quality control just sucks i have seen this same problem a few times with their cam shafts when i tried a comp cams cam i seen even cylnder pressure so i came t the conclusion that ma mopar dosent care about the quaity of alot of their stuff ie camshafts so that is my thoughts on the matter later all