Rebuilding a '73 455, using '70 Heads, the Cooling Passages are different between the Block and Heads, what needs to be done? Use '70 Head Gaskets, to match the Heads (to block off the Block passages)? Also, with the '73 Block, can I use a '70 Timing Cover, or will I have to use the '73 Timing Cover? Do they have different size Passages, too? Pretty sure, but just want clarification.:TU:
Scott, I have always been under the impression that when using the old heads with the new style block that you should not use the 70 type head gaskets as they will not seal the oval water passages in the late model block. I am not 100% sure on this though. Back in the 80's when I built my 74 block I used 68 heads and had no problems with Felpro gaskets made for a 74 455.
Use the gaskets for the 70, they are the same for the 73, those passages are supposed to be blocked off, those passages are clean outs from the casting process i do believe, the little hole is to prevent air pockets, this is a commom asked question. i have put early heads on many late blocks, i think there is no difference in the gaskets for the 455. For your info. my 455 in my 70 GS is a 76 block with 70 heads and i used 70 gaskets.
When I say 70 type gaskets, I was refering to the steel shim type, which I was always told could not be used on the later model blocks, can they?
That's why I asked, because I thought the same thing, but I'm sure they CAN be used for that purpose; to "block off" the oval ports, but still allow coolant flow through the round ports (by using the Early Head Gaskets on the Late Block). Thanks, Kelly, that's what I wanted to be confirmed! Thanks, Mike, I was thinking the same way as you, now we both know.:TU: Then, do the Timing Covers have different size passages, too, between '70 and '73? I'd like to use the '70 Timing Cover on the '73 Block, because the '70 is "nicer" than the '73 that I have. Will I have to "drill out" the passages in the '70 Timing Cover to match the '73 Block, or does it even matter?o No: Not that it's even important, I'd just like to know one way or another.
The timing covers do have a larger passage for the oil pickup on later engines. You can either drill out the 70 cover or use the later cover. That is the only difference as far as I know. Someone else will have more info I'm sure... Put them side by side, aft side up, and you will see the difference right away. later Tim
