I hope i am in the rite section. New to site.

I have a 1968 G396026 400 motor that I am going to rebuild soon. It has C heads. I also have a 389244D 425 that is all rebuilt already. The 425 has C heads as well. I dont know if the 425 is a 39 degree or 45 degree, but I am wondering if I can put the 425's heads on the 400. The main reason I would like to do this is to save money. The 425's heads are all set up for unleaded fuel and only have about 20 hours on them.
Any thoughts or opinions would be appreciated.
Also, is there a easy way to tell what degree the 425 is? It is still in the car. Is there a way to see what cam would be in the engine as well, with out tearing down?

Thank you
Adam

 

The 'C' heads should interchange, as the degree difference only pertained to the angle of the lifters to the cam.
6 degrees aren't enough to affect the lift or any other part of the valvetrain, especially split by 2 sides! [3 per side]

 

Depending on the year of the block & casting on the lifter angle in the 425, you may have to open up the pushrod holes in the 425 heads. Here's some of the best info I've been able to find on Olds engines.

http://www.442.com/oldsfaq/ofbbb.htm

http://www.442.com/oldsfaq/ofeng.htm

I can't recall the exact page I found the info on as to the exact procedure for opening up the pushrod holes, but from what I remember, it's not too complicated, but it needs to be done for correct clearance, or you risk damage to the valvetrain.

-Jeff

 

If it is questionable, I will just stay with the 400's original heads. I dont think I want to open up the pushrod holes.

Thank You
Adam

 

i believe that it was only the A & B heads that need the pushrod holes opened up. the C heads would be '67... what model is the car?

what is the diameter of the pushrod holes?

 

The 425 was in a 67 Delta 88. I built the motor around 8 years ago so I can not remember to much about the engine. It is still in my 442. I do remember that the heads were ported and polished along with putting the hardened valve seats in it. This is the main reason I am thinking about using these heads on my 68 400 motor. I read on one of these forums that my stock 400 heads would handle unleaded gas just fine. Is that true?
And would it matter what degree the 425 motor is?

Thank you
Adam

 

GTI you are correct, on the Olds engine site it mentions: Heads
45 degree blocks used 45 degree heads, and the same for 39 degree blocks and heads. Actually, the only difference is the size of the pushrod hole to accomodate a 45 or 39° pushrod angle (or CBA). If swapping heads between 45 and 39 degree blocks, you must watch for pushrod interference at the bottom of the head. To put 45 degree heads on a (455) 39 degree block, you have to bore the push rod holes to .562" i.d. Applies to "A" heads and some "B" heads. The simplist solution for pushrod interference is to just check for interference when test assembling the engine. That said my 67E(39 degrees) has 65A heads (45 degrees) and have no problems since the rebuild. I did not have to bore the holes out-probably luck Thanks GTI for bringing up the info site its still a great resource.

 

From the sound of it (I have never done so) you could most likely accomplish this adjustment with a dremel, a little time & patience, and no negative effect if they ever wanted to be used back on the correct engine application.

Thanks Robski for the details. I knew I had seen it somewhere in there, but wasn't finding the exact specs you posted.

-Jeff

 

No problem and I bet you could open the holes with a dremel and call it a day. Have a nice set of heads all ready to go.