[tjs72lemans]

I have a newly rebuilt 400. I had a co-worker who drag races rebuild the lower end and 7K3 heads. I finished assembling the rest and took it to the machinist that did most of the pre assembly work to dyno it. He replaced the push rods to get the optimal contact patch with the .456 lift flat tappet cam. Broke the cam in fine and had 310 hp with 405 torque. I got it home and pulled the valve covers for a look and one of the roller tip rockers rides off center of the valve stem. It rides on about 2/3 of valve stem. Others look good. The guide plates don't seem to be the problem, because that pushrod has a lot of clearance around the head casting. But, some of the other pushrods seem too close to head casting to be able to loosen and slide guide plate over to help straighten the affected rocker arm ( that pushrod does seem to come up at a slight angle to rocker). I'm pretty sure all 4 guide plates were the same as I installed them. Correct me if they are different. I already installed the engine in my 72 Lemans and am now contemplating if I need to backtrack and pull something apart to fix. Like clearance the pushrod holes in head casting so the guide plates can be slid a bit.
I'd hate to see an early engine failure due to this. Any suggestions?

[steve25]

What ratio are the roller rockers, 1.5, or 1.65?

[HWYSTR455]

Are you sure all the pushrods are the same length?

.

[tjs72lemans]

I.5 ratio and yes all pushrods are the same.

[HWYSTR455]

So it's only one rocker that is riding oddly? When you say 2/3, is that to the side, or across and back, as in from the center of the engine to the outside?

.

[JSPONT]

What size push rods, make sure the guide plate is not for a 3/8 push rod and you have 5/16 push rods. The guide plate should be pretty tight with very little clearance to the push rod. I have an issue and have to use adjustable guide plates on a few, but mine is not a stock head

[Formulas]

Picture ?

[tjs72lemans]

Yes the 2/3 is from side to side. The pushrods are 5/16 in the stock guide plates. They are tight. As I look at the issue, it would solve the problem if I could move that one guide plate slot over a bit (.080 ?) , but the other pushrods don't have clearance in the head casting as they are almost rubbing on some of them now. Or if I somehow was able to cut/weld to remachine the one slot in the guide plate to straighten the pushrod to better align the rocker to valve stem contact. I know a pic would help, but I have a hard time posting that. If I could send it to someone from my phone and they could post it that would work.

[HWYSTR455]

Originally Posted by tjs72lemans

Yes the 2/3 is from side to side. The pushrods are 5/16 in the stock guide plates. They are tight. As I look at the issue, it would solve the problem if I could move that one guide plate slot over a bit (.080 ?) , but the other pushrods don't have clearance in the head casting as they are almost rubbing on some of them now. Or if I somehow was able to cut/weld to remachine the one slot in the guide plate to straighten the pushrod to better align the rocker to valve stem contact. I know a pic would help, but I have a hard time posting that. If I could send it to someone from my phone and they could post it that would work.

Or, use adjustable guide plates:

https://butlerperformance.com/i-3156...tegory:1234792

.

[JSPONT]

The guide plates are made by isky, you can buy them for SBC they will work.

[tjs72lemans]

I didn't know they made adjustable. That's a good alternative.

[Formula8]

I had the same issue. Ended up using 3 adjustible guide plates and put a tack weld on the plate. Fair warning though, they do not weld well for whatever reason.

[chuckies76ta]

I've had that issue on a set of Pontiac heads and I sourced a set of gm guide plates which corrected it..

https://www.ebay.com/itm/PONTIAC-V8-...4AAOSwfGpdiSs9

[Skip Fix]

Down side I had trying to use the Isky adjustables was the pushrod slot was not deep enough to get the pushrod in the rocker cup.

[GOSFAST]

Not a major issue, in fact it is a minor one!

The adjustable guide plates always fix this problem, either Isky's OR Comp cam's, Comp now has them available!

Thanks, Gary in N.Y.

P.S. Here's a shot of some 093's we built a while back, customer wanted exhaust inserts and the adjustable rockers, in this case the Isky guide plates took care of the pushrod/rocker alignment! This was for one our 100% stock-appearing builds!

[krisr]

Comp adjustable guide plates for a SBC also fit Pontiac heads. Note these are for 3/8 pushrods too.
too.

[Formulas]

What I have done in the past on iron heads is cut the guide plate between cylinders so they are independent and your dealing with one cylinder then elongate the stud holes a tad to get better results or share the problem between intake and exhaust valve to get a better average of alignment but I haven't had to do it very much

[tjs72lemans]

That's a good idea Formulas.

[HWYSTR455]

Well, when you cut the OE ones, it's too flimsy, if you cut the Edelbrock ones, there's no good way to keep them lined up, they can move, and loosen the rocker stud.

I still would suggest the Isky ones that are specifically made for Pontiacs. For $70, there's no reason to deviate from the Pontiac ones.

.

[Formulas]

I would not of offered cutting stock guide plates on iron heads in the street section as mentioned if I had not tried it successfully.

Again only the bar in between cylinders I removed most of and ground off rough edge's this does not effect strength of remaining components and no studs came loose for me and I made a cylinders rocker arm contact better

Stock guide plates are not built like a tank anyways Pontiac did a good job for stock mass production passenger engines but may be limited in hi performance use

.