Hello,

I need some advice and evaluations weather my cam/pushrods and rocker combination is correct or maybe not, as a new cam once was installed in this engine, and the original pushrods and rockers were kept.

Engine is a 350 from 71. The heads used are labelled A. The cam is Crane, and I have attached the camcard herewith. Can anyone tell out from this, that this combo is correct and will work OK, or maybe I need other rockers with different ratio perhaps?


I had this engine with a my 71 Cutlass that I got in 2009. This engine was built by someone called Coleman Brohers (told to make good work at that time) 25 years ago (!), probably intended for some Oldsmobile at that time, and then plans changed and the engine stayed unused until i put it in my Cutlass. I have recepts and camcard with it. Everything seems to have been done to the engine, and all vital parts were changed except for the pushrods and the rocker arms. I do wonder why, couse when I fired up the engine in the car, after priming it thorougly with the oil pump, there was obviously a slack in the rocker lift. I fixed this placing lash caps on the valve stem, which took up the slack, and the car has been on the road maybe 600 miles last summer. Somehow I have a feeling something that something isn't optimal with this engine setup, at I feel it lack some power.

Hope for some good advice on this..
Regards Tom

 

Can you share the casting number from the block?

 

If it was Coleman Brothers in Maryland, you should have a good one. I really can't say for sure but they were not the type of machine shop and engine builders to use used parts, especially something as inexpensive and readilly available as rocker arms and pushrods. Sometimes things get changed for who knows what reasons. Also, I would have a real expert check and make sure exactly what you do have and for safety's sake check the geometry between the tops of the valves and the tips of the rockers. If you have the wrong length pushrod, a lack of power is going to be the least of your worries.

 

If it turns out to truely be a 71 that means it's 8.5:1 at best. That cam is too big for that combo. That would explain the lack of power. Still have to make sure your valvetrain is correct though.

 

Wouldn't A heads on a 350 produce an unusually low compression ratio?

- Eric

 

If it's stock CR I'd have to agree that the cam is too big for that engine. Do a compression check and tell us what the numbers are for each cylinder.

 

It is the Coleman Brothers from Maryland, yes! I was thinking maybe Crane tech dept could give me some hints weather the combination should work or not?
Allso, I wil do the checking on the geometry to se if the rocker arm meets the lash cap on the valve stem in center, as you indicate. I'm not sure tough, what would be the consequences of short pushrods? Won't the lash caps do the job if the geometry seems to be OK?