Hello!

I bought Procomp BBC 1.7 Aluminum Roller Rockers for my Chevy 250 (and for mine Dad's Chevy
153 L4) but I don't know that the studs fit them.
Everything I know is that the stock rockers for the 250 are 3/8 at top. But I don't know what
are the base thread size, top thread size or effective lenght, etc.
To illustrate my doubt here's an example I found inside of the descripction of an eBay product:

BBC Rocker Arm Studs, 7/16-20 in. Kit
Part Type:Rocker Arm Studs
Base Thread Size:7/16-14 in.
Rocker Arm Nut Thread Size:7/16-20 in.
Guideplate Locator Shank:Yes
Rocker Arm Nut Thread Length (in):0.850 in.
Effective Stud Length (in):1.750 in
Base Thread Length (in):0.800 in.

Is the Chevy 250 base thread 7/16 also or it is 3/8 as well as it top thread?
Can I use the item descripted earlier?
What studs can I use (SBC, BBC, ...)?
I expect that if they fit mine 250, they'll fit my Dad's 153. Won't they???

Please, need your help guys! Thanks a lot!!!

The 250 chevy factory studs are not threaded into the head. They are 3/8 diameter and are a press fit. Some machining of the cast stud bosses on the head is needed to reduce the height and provide a flat surface for the screw in studs to seat on. The original hole will also need to be threaded 7/16 - 14 with a tap to accept the new screw in studs.

You can use BBC studs and yes, the 250 and the 153 heads will use the same studs and need the same machine work. You will also need to round the corners of the first and last roller rockers to clear any stock shaped valve cover on both engines. Easily done on a belt sander as not much has to be removed. Be sure to wash the rockers thoroughly to remove any grit from sanding.

mike, that was put very well. tom

One Other thing you need to watch out for Is the width of the Roller filcum ball. Some roller rockers are wider then others. And Will NOT fit under most aftermarket covers. So that makes to things you need to look out for.

And If your not Running a Monster lift cam there really isn't much need for guide Plates

Well, I bought those Procomp 1.7 for BBC roller rockers and don't know if they will fit now...
I will try to use Engine's aluminum cover that is made for roller rockers...
Now, I'm in doubt, Larry T6...
Anyway, I'll wait them to come to Brazil - I've already ordered...
About the studs, I'll buy BBC 7/16 ones.
Thanks!

Engine companys Cover does have more room in it. Then Either cliffords, offey, Or the marine cover.
So i think you should be ok.