Question for Duke on screw in studs and guide plates on 63 shp

[Edward J.]

Duke,

In your article you wrote on screw in studs and guide plates you note that this a no-no on early heads, how early is early? years ago I had my 63 rebuild some years ago, and the machine shop showed me a small crack at one of the stud bosses on one of the heads, his fix for this was to machine all the boss' s down on both heads and install screw in studs and guide plates. Was this a mistake? I have not noticed any bent push rods and really don't know if the push rod holes are round. I suppose I will have to look. Thanks Ed

[Duke W.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

Duke,

In your article you wrote on screw in studs and guide plates you note that this a no-no on early heads, how early is early? years ago I had my 63 rebuild some years ago, and the machine shop showed me a small crack at one of the stud bosses on one of the heads, his fix for this was to machine all the boss' s down on both heads and install screw in studs and guide plates. Was this a mistake? I have not noticed any bent push rods and really don't know if the push rod holes are round. I suppose I will have to look. Thanks Ed

What I actually said was that if early heads had no history of pulling studs and OE EQUIVALENT valve springs are used, I don't consider screw in studs necessary, however, they will do no harm and are a sort of "insurance policy".

As far as guide plates are concerned, if used the pushrod passages should be opened up since the head pushrod passages act as guide plates on early heads. Also hardened tube pushrods must be used. I believe the first production use of guide plates with hardened tube pushrods was the '70 LT-1 with 186 heads, so all earlier heads must be so modified to accommodate guide plates.

If you've had no problem with guide plates up to now then they are probably okay. The pushrod channels were probably opened up and hardened tube pushrods installed.

Duke

[Edward J.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

Duke thanks for your quick reply.

[Joe L.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

Duke thanks for your quick reply.

Edward------


The screw-in studs can be installed without guideplates. If so, a simple spacer is used to simulate the thickness of the guideplates (or the stud bosses are simply machined down to a lesser extent). In fact, if guided type rocker arms are used, no guideplates should be used.

There are two types of screw-in studs. One type does not require the machining down of the stud bosses. The press-in studs are pulled and the bosses tapped as-is. The screw-in studs are flangeless and are installed by double-nutting. I don't like this type but they are the ones to use if one wants to avoid the stud boss machining and maintain original configuration (for judges with x-ray vision). This type of stud does offer the benefit of easy field replacement, though, which press-in studs do not. Of course, this type of stud installation will not correct for a cracked stud boss such as you experienced.

The other type of screw-in stud is, of course, the flanged base type which are commonly, but not necessarily, used in conjunction with guideplates.

[Edward J.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

Great info Joe. thanks Ed

[Joe L.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

What I actually said was that if early heads had no history of pulling studs and OE EQUIVALENT valve springs are used, I don't consider screw in studs necessary, however, they will do no harm and are a sort of "insurance policy".

As far as guide plates are concerned, if used the pushrod passages should be opened up since the head pushrod passages act as guide plates on early heads. Also hardened tube pushrods must be used. I believe the first production use of guide plates with hardened tube pushrods was the '70 LT-1 with 186 heads, so all earlier heads must be so modified to accommodate guide plates.

If you've had no problem with guide plates up to now then they are probably okay. The pushrod channels were probably opened up and hardened tube pushrods installed.

Duke

Duke------


1970 LT-1 was the first use of screw-in rocker studs with guideplates for a small block. However, it was not the first use of hardened stem pushrods. The first use of hardened stem pushrods was for 1962 340 and 360 HP with the introduction of the GM #3796243 pushrod. That pushrod was thereafter used for all 1964-82 Corvettes.

[Jim L.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

Edward------


In fact, if guided type rocker arms are used, no guideplates should be used.

Joe, if the self-guided rocker arms are used, do the push-rod holes in the heads need to be opened up?

TNX,
Jim

[Joe L.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

Joe, if the self-guided rocker arms are used, do the push-rod holes in the heads need to be opened up?

TNX,
Jim

Jim------


I believe they do but I don't know that with absolute certainty. However, the same principle applies as with the guideplates. One doesn't want the pushrods to be "guided" at two different points.

[Jim L.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

Jim------


I believe they do but I don't know that with absolute certainty. However, the same principle applies as with the guideplates. One doesn't want the pushrods to be "guided" at two different points.

Thanks, Joe, that makes sense.

[Tom P.]

Re: Question for Duke on screw in studs and guide plates on 63 shp

Without exception, EVERY small block engine I have built for the past 35-40yrs has been modified for screw-in studs and guide plates.
The most recent engine we built was a SB400 (and it was a 73 casting!!!) for my son's 73 Corvette. It still had its original L48 and he wanted to build it to 383. I recommended pulling and preserving the L48 and replace it with a roller cam SB400. The COMPLETE 400 he bought was virgin and in excellent shape!!! We had the 400 heads worked over, added screw-in studs, guide plates and new stainless valves, and converted it to 2 1/2in Chinese (please forgive me) copy exhaust manifolds and FULL 2 /12in system.
And yes, I paint the inside as well as the outside of all my engines. ZERO issues.













We sorta kinda tried to resemble a 70-72 LT1.



Plus, I add an external, OIL filled oil pressure gauge here.








Big block power, but 150lbs lighter!!!