5/16 vs 3/8 push rods

[jrpontiac]

I have a set of hipo 348 heads I'd like to put a 3/8 push rod it. I read somewhere that the guidehole can be machined out to fit a 3/8 pushrod. The existing hole is an oval shaped hole, if it is machined out to 3/8th is it as simple as drilling a 3/8 hole.

 

[Fathead Racing]

Why do ypou want to put 3/8" pushrods in?

 

[chevykid]

I have a set of hipo 348 heads I'd like to put a 3/8 push rod it. I read somewhere that the guidehole can be machined out to fit a 3/8 pushrod. The existing hole is an oval shaped hole, if it is machined out to 3/8th is it as simple as drilling a 3/8 hole.

I don't think you will have any problems with the stock pushrods. Spend your money somewhere else.

 

[jrpontiac]

The heads currently have a small amount of wear on the guide hole. The engine shop indicated that could be a problem and to solve the problem I could go with screw in studs and guide plates. My thoughts were to just drill the hole for the 3/8 push rods.

Also at what point should I be thinking about going with the screw in studs. I'm looking at using a cam with approx. .500 - .510 lift. I'm not planning on using roller rockers.

 

[Dond409]

roller rockers

at the price you can get roller rockers for. I wouldn't use anything else but those. With the stamped steel rockers you are asking for problems

 

[SS425HP]

Rockers

Don is right on the rockers. The stamped rockers available, today, are marginal at best. And, they wear and need adjusting more often. The roller rockers are the only way to go. You will save money in the long run, and it won't be a very long run at that. They solve clearance problems with valve springs and you don't have to worry about the slot being long enough for the lift your cam has.

Rollers would be a wise choice

 

[W Head]

roller rockers

Don't you have to go a longer stud for roller rockers because there is not enough threads on the origional stud to hold the rollers?

W Head

59 El Camino 348-3,2s
59 Impala 409-2,4s

 

[Fathead Racing]

These will work fine also without changing anything.

http://compcams.com/technical/Catalogs/106-07/268.pdf

 

[W Head]

rollers

I believe you still have change to the 7/16 studs to use the 1.72 BB roller tip rockers.

W Head

59 El Camino 348-3,2s
59 Impala 409-2,4s

 

[dq409]

Roller rockers also extend the life of the valve stems dramatically !!!
dq

 

[jim_ss409]

The pushrod hole has to be oblong because the top of the pushrod moves back and forth a bit. So just drilling it to 3/8" won't work. I don't think you would really need screw in studs, but if it comes down to a choice between getting new pushrod holes machined or getting them to install screw in studs,,, I'd probably go with the studs. By the way you can get Scorpion brand rockers that fit a 3/8" stud but it'd probably be best to the more common 7/16" studs. I'm no expert on any of this though.