OK i changed manifolds on my camaro to a prefomer rpm manifold and now the motor shakes and backfires on the driverside iver checked all vaccum leaks and there arent any trust me, and ive messed with the timing and still nothing, i also had to adjust the rocker arms but im pretty sure i got them right is there anything else it could be.

 

carb settings?

 

yeah but the they worked just fine on the old manifold and theres not much difference between the two.

 

Have you rechecked things like the firing order you put the wires back on?

 

adjust your air screws, a different manifold makes different power for a reason... because it flows differently!

wow thats alot of differents in one line...

 

350WHT,

Pretty Sure?
Did you follow the proper procedure?
If you didn't that could certainly give you some backfiring!!!

In order to adjust them properly, the #1 Cylinder must be at TDC. That said..... You can only adjust certain valves at each instance of TDC.

#1 - at TDC (NOT on compression stroke ON the Exhaust Stroke!).
Intakes - 1,2,5,7
Exhaust - 1,3,4,8
#1 - at TDC of THE COMPRESSION STROKE
Intakes - 3,4,6,8
Exhaust - 2,5,6,7

Some guys set them at 1/2 turn past Zero-Lash. Some guys crank 'em down a little more. I've found 3/4 turn to be pretty good for a starting point to preload the lifters.

If you didn't adjust them in the above fashion..... You didn't do it correctly. I should know...... I've screwed it up myself. and the car ran like crap. It also backfired badly!

Sincerely,
Kurt

 

kurt, that is the opposite of what my manual says as far as compression stroke. the grouping is correct, just not the position of the crank. for the first group, you want it on the compression stroke(#1 int. and exh. valves NOT moving)

 

i'd say readjust your rockers back to where they were. no chance in the world they got out of adjustment by doing a manifold swap. have you put a vacuum gauge on the engine? what is the timing set at, base and total?

 

Well the roker arms needed adjusted there was one clattering in the valve cover i havent adjusted them to those specs i usually cut the top out of old pair of valve covers and loosen them up till i hear them clattering and then once they stop i turn it half a turn and that what i have done in the past and it always seemed to work, but this time theres somthing wrong i tried adjusting the carb but no luck there, i dont have a vaccum guage guess i better get one and check it tonight, but i cant figure out why the motor shakes so badly it didnt do this before till i put the new intake on its weird theres got to be a vaccum leak somewhere im just not finding it now there was some water that got down inside that motor and i changed the oil and filter will this hurt it at all, cause when i drained the oil it was white. U guys think i should change the intake gasket again?

 

87ZJeff,
Thanks for catching that screw up.... Don't know what the heck I was typing.... I really actually do know better...

Anyway, I screwed that up thank you for catching it!
Kurt

 

Check your fresh oil, is it showing water again? If not, it isn't getting water in the oil. Make sure your plug wires are correct. You can check for a vaccuum leak with a can of starting fluid. Just spray a little around the manifold base gaskets and your vaccuum lines with the engine running at idle. If the engine speeds up, you have a leak.

 

You never answered this question,ARE YOU ABSOLUTELY SURE that you got the firing order correct?
18436572

If this is right,and the timing is correct,you need to read your spark plugs,you may have an extreme lean condition.If your plugs are white,or even grayish,it's way too lean.could need carb rejetted,or could point to a definate vaccum leak.

 

Propane is MUCH safer