Olds rocker arms pre-1980 vs post-1980

[kustomkyle]

Maybe this is another "this part does not fit Cutlass Supreme", but I'm finding replacement rocker arms and bridges are different in either side of 1980?

I can see maybe with the 1985/1986 roller cam/lifter 307's, as the push rods are a different length. But I also see some parts that fit the roller engines dip into the late 1970's as far as fitment.

Any insight into what's going on? Just purchased Comp Cams 1242-16 rocker set for a 1986 307, but maybe it won't work.

 

[TURNA]

Says 1980 and up 307's?

 

[olds307 and 403]

Yes, there is a difference. I have both in my shop. The latter have a larger ball end on the pushrods which makes the contact area slightly different. I assume the roller cam 307's also have this?

 

[kustomkyle]

Says 1980 and up 307's?

Says "260-455", with only fine print in varying sources stating up to or around 1980.

Yes, there is a difference. I have both in my shop. The latter have a larger ball end on the pushrods which makes the contact area slightly different. I assume the roller cam 307's also have this?

So, safe to say the 1242-16 kit won't work on a later 307? I went this route because of horror stories about the factory bridges breaking, the aluminum fulcrums cracking and or wearing down.

 

[olds307 and 403]

Purchase them from Summit or somewhere with a good return policy and compare them to your current rocker arms, they may work.

 

[kustomkyle]

Purchase them from Summit or somewhere with a good return policy and compare them to your current rocker arms, they may work.

Well, we'll just have to see. The engine is still in the car, being driven daily but have been getting the last few things I didn't have yet for the rebuild. I have a single stock 1986 rocker to compare, and will be getting pushrods shortly (MPR365 Melling).

Just really assumed all Oldsmobile V8 rocker arms/assemblies were the same.

EDIT: Re-read Summit's application pages for the Comp Cams 1242-16. They claim the set fits 307's 1980-1990. I guess there was a 307 in 1980 (?), always thought it came out in 1981. And that's where the aftermarket is murky water that I try to avoid. Tech support really isn't going to know any more than what the manufacturer puts out in terms of information.

 

[olds307 and 403]

I believe the 307 came out for the 81 model year. I had an 81 Delta 88 built the Oct 80 with a 307. It basically comes down to the ball sitting properly in the rocker. I will take a look tomorrow and see how they ball pushrods sit in the rockers I have lying around.

 

[69hurstolds]

There are 2 part numbers for the Olds V8 rocker arms for the modern-era (without the shafts). 401384 most Olds V8 through 1979 and 22505583 (found in 78 and up Olds V8 Diesels and 80-90 gas Olds V8s). Some 78-79 Diesels used the smaller pushrod ends and the 401384 rockers as well. So 78-79 Diesels could be either.

The 401384 rocker arms were designed for a pushrod with a 0.3125" ball ends. The 22505583 used pushrods with slightly larger 0.375" ball ends. Roller cam made no difference.

 

[kustomkyle]

There are 2 part numbers for the Olds V8 rocker arms for the modern-era (without the shafts). 401384 most Olds V8 through 1979 and 22505583 (found in 78 and up Olds V8 Diesels and 80-90 gas Olds V8s).

The 401384 rocker arms were designed for a pushrod with a 0.3125" ball ends. The 22505583 used pushrods with slightly larger 0.375" ball ends. Roller cam made no difference.

Thanks for the information, that clears up the differences.

But, as to what the rockers in the 1242-16 kit work with still remains a mystery. Hopefully the 22505583/MPR365 push rods.

 

[Kennybill]

I've never worked on a 307 so I can't comment on the sizes. Anything near or over 0.500 lift I always use full roller rockers but the factory stamped with bridges are very durable. I've never seen one break and I seen them used to 0.490 lift. Just my opinion.