Mysterious problem

[1lostsoldier]

Hey fellas,
Ok I just got finished installing a set of Comp cams pro magnum roller rockers on my 85' 318. Its was an easy process but when I was finished and went to fire the car back up its only running on 4 cylinders 1,2,5,8 aren't firing off. They are getting spark, I can put a plug on those leads and it sparking. I never even pulled a spark plug wire. I have triple checked the timing and firing order and still no luck. I also rechecked the valve lash completely 3 times.(thinking that maybe they where adjusted to tight and not allowing the valves to close)
I havent had any troubles with this engine ever. It was completely rebuilt about 4k ago. It ran perfect right before changing the rockers but now its a no go. Any help would be great.

 

[1wild&crazyguy]

check the plugs and is it a hyd cam? try taking some lash out for fun.


wet plugs or lash adjustment?

 

[1wild&crazyguy]

whats the carb,cam, & intake combo ?

 

[1lostsoldier]

its hyd cam. I took a bunch of lash out of it until they where taping real bad still to no avail. I took the plugs out and they all were dry but very black. I then put some new plugs in with the same results.

 

[1lostsoldier]

whats the carb,cam, & intake combo ?

600 holley 4160, eldabrock performer intake, and a stock 85' roller cam.
Like i said it ran perfect before the rocker swap.

 

[1wild&crazyguy]

Well just the 1 2 5 8 plugs black is weird.

swap back and see what happens, you say all is well on the ignition and carb but somethings up.

 

[1lostsoldier]

I just finished doing a compression check and all cylinders were ~ 110psi. I also swap the plug wires with the running cylinders and no change.

 

[daredevil]

you sure about the firing order and rotation?

 

[Badart]

Did you degree the cam?

 

[1lostsoldier]

you sure about the firing order and rotation?

I never touched the distributor or wires during install but i triple checked the firing order 1-8-4-3-6-5-7-2 rotation clockwise.

 

[1lostsoldier]

Did you degree the cam?

No not for this install. The motor ran perfect prior to the rocker swap.

 

[RedFish]

Seems it would have to be in the rocker arrangement. Do they offset a little left or right ?

 

[1lostsoldier]

Seems it would have to be in the rocker arrangement. Do they offset a little left or right ?

No there just standard design, they picture below. What weird is if it were the rockers why is there good compression. I'm stumped right now.

 

[1wild&crazyguy]

points or electronic ignition?

 

[1lostsoldier]

points or electronic ignition?

Electronic

 

[1wild&crazyguy]

If all's adjusted right and the push rods aren't too long hanging the valves open, you didn't touch the wires or plugs....

then all I can say for now is to fire it and rev it up, maybe it's just loaded up?

with only a 110psi, I might of advanced the cam a lil=2-4*

 

[1lostsoldier]

If all's adjusted right and the push rods aren't too long hanging the valves open, you didn't touch the wires or plugs....

then all I can say for now is to fire it and rev it up, maybe it's just loaded up?

with only a 110psi, I might of advanced the cam a lil=2-4*

You read my mind, late last night I thought the same and was cold and pissed and rev the crap out of it, but alas it no worky.

 

[SpeedThrills]

Did you have only 110# before the swap? That's pretty low. Are the rockers hitting the retainers, holding the valves open at the wrong time?
If you swap to the stockers, try the compression then.

 

[SoulSurvivor]

I put a set of the exact rocker assembly on my engine. I had to order new pushrods. And I made sure that they were shimmed perfect. I assume you purchased the stock 1.5 ratio? Its all in the adjustment since this is the only thing you changed.

 

[1lostsoldier]

I put a set of the exact rocker assembly on my engine. I had to order new pushrods. And I made sure that they were shimmed perfect. I assume you purchased the stock 1.5 ratio? Its all in the adjustment since this is the only thing you changed.

Yup i got the new push rods and the geometry is right on. I know the rocker are in no way hitting the spring retainer. I can see plenty of clearance around them.

I guess when I get home tonight I try putting the stock rockers back on. One step forward two strps back.:angry7:

 

[WIKD71RICK]

After all this cranking I would put some oil down the cylinders.The ring might be washed out.Do a wet compression test to see if the comp comes up.

 

[1lostsoldier]

I'll try that. Surprizingly the engine starts rightup it just shakes like a diesel from only running on 4 cylinders

 

['64 Cuda]

Did the pushrods get caught on the edge of the lifter bores instead of in the cups of the lifters? I'm sure you didn't do this but it's all I can think of.

 

[demon seed]

Your compression is low. Try this, pull the entire rocker assembly off one bank then go to the valves of the cylinders that aren't putting out and pry up on the valve retainer/spring. The valves might be stuck partially off their seats, wouldn't take much.

 

[fishy68]

Double check that the rockers aren't hitting the retainers and holding open the valves. I had that happen once with a set of crane rockers. Didn't even think to check for clearance when I installed them and when I started it up it only ran on 5 cylinders. I could just barely see when I looked close but when I backed off the hold down bolts I saw the valves come up just a little bit. That was enough. Put the stock rockers back on and it ran fine.