Mattyp77

Hey guys I have an Oldsmobile 425 with stock A heads. I need to convert the top end to adjustable rockers without having to take the heads off for machining. The only kit I was able to find that I know fits that criteria for sure is the Harland Sharp S50026A. It's almost $600. Im sure it's a quality product and worth it but this is a stock motor and very low budget. Is there a cheaper alternative? I know some kits are cheaper but require drilling the rocker stud holes to 7/16. But they don't specify if that means you have to take off the head. I won't mind drilling and tapping if I don't have to take off the head.

RandyS

Comp Cams makes them also, and they are much less expensive.

Mattyp77

Do you have a link or a part number? I can't find any. I see roller tip rockers but nothing with adjustability

joe_padavano

Comp Cams 1442-KIT. $265 at Summit. Your only issue will be that these rockers use special studs with 5/16" bottom threads to fit the heads and 3/8" top threads for the rockers. Your A heads are unique in that they have 3/8" threads for the rocker bolts. You will need to get different studs that are 3/8" top and bottom (which are actually much more common).

Of course, one must ask, if "this is a stock motor", why do you need these anyway?

Mattyp77

Their own website doesn't even say that they are adjustable. They don't look like it either.

joe_padavano

They are retained by a nut on a threaded stud. You turn the nut to adjust them, just like any Chevy motor. I have these on one of my 455s.

akspeedy

Mattyp77

Really? Okay I'll try it out. Oh and to answer your question why I need them. It's because I had to charge the lifters. The ones in the motor when I bought it were completely clogged for some reason not allowing any oil to the top. I soaked them in gasoline for a week and tried everything to free them up but no luck. So I bought a new set and I guess the seat height on these lifters were lower than original cause I needed longer pushrods. I had to get custom size but still many of them have some play causing clattering. And I'm glad you asked because this brings up another question...
I'm pretty sure I bought Howard's Cams lifters 91211. (This was years ago it's been a long process and I'm learning as I go). Unfortunately I cannot find any kind of receipt. But I'm pretty sure that's what I bought. They should be the same as original. They say they're hydraulic but it almost seems like they're mechanical. Because I bought larger pushrods to accommodate the lower seat height and the motor would not run because it had no compression. The valves were being held open. So I returned those and bought a set at 50 thousandths shorter and then it had a ton of slop. I ended up having to get a set of pushrods at a custom length from comp cams. Off the shelf pushrods pretty much only come in increments of 50 thousandths. So now I have these custom length pushrods but many of them still have a tiny amount of slop I'm sure it's because the cam is worn. But doesn't this sound like these are mechanical lifters not hydraulic?

joe_padavano

This is called throwing good money after bad. You will be dollars ahead if you simply throw away those lifters and get the correct ones, leaving the rest of your valvetrain stock. First, since these rockers require pushrod guide plates, you will need hardened pushrods. Second, if pushrod length is wrong, even adjustable rockers will contact the tip of the valve stem at the wrong place, potentially leading to valve guide or rocker failure. Third, while these rockers are SUPPPOSED to clear stock valve covers, it may be close and you may need to remove the baffles on the underside. There is a lot of potential collateral damage with this route. Certainly these rockers can be used, but you need to fully understand what that means. For your motor, it's really a waste. Just fix it right. It will cost a lot less and be more reliable.

Mattyp77

Very true your absolutely right. I need to go back to the source of the problem. I appreciate the honesty

BillK

Matty,

Do you still have the original lifters that were in the engine ? If so it might not be a bad idea to have a machine shop look at them for you and make sure that they are indeed hydraulic lifters. Or maybe post a couple of pictures here. They almost have to be if you have the stock rockers on the engine but you never know what somebody might have done.

Also might want to do the same with your present set of lifters. The part number you gave above is for a Ford lifter so it probably is not the right number. The Olds number is 91411

You also need to take a real good look at the camshaft to make sure you don't have one or more lobes wearing badly. That's almost what it sounds like to me.