QUICK QUESTION 231786 HEADS?

Hi, I'm starting my low budget 455 project. I have a low mileage (48K) 1975 455 block and I plan on leaving the stock rotating assembly alone but, will change out cam. My question is, I found a set of 1970 455 231786 heads and I was wondering how these will work on 75 block. I understand that I may need to use a special set of head gaskets but, other then that they should work?? Does anyone have any thoughts on this approach? I will be on workers disability for the next few months so, this is the perfect time to start this project but, with a low budget so, any advice/insight will be appreciated. Thanks, Gene

 

I’m in the process of putting 1231876 heads(converted to Stage 1) on my 1973 block.

As far as I know & have been told the 876 heads have round water passage holes where as the later blocks passages are oval.

Seems you should just need the correct head gaskets & you should be golden. That being said I’d also get some advice from the gurus here. They’ve forgotten more than I know about Buick’s.

Kyle

 

So you currently have no heads ?
Just note that any pair of heads with over 40k miles should get a full rebuild done to them , in which case if you have heads now you might as well rebuild them, mill them to get a 9 to 1 comp and stuff bigger valves in them which have a side plus of helping with the compression ratio.

 

His 75 heads will find better use as a doorstop, performance wise. Jim

 

The mid 72 and newer blocks with the 2 scallops on the top of the deck in the middle front to back and the oval water holes along the top of the block will accept any of the cylinder heads.
However do not try to use the early factory steel shim head gaskets.
The newer over the counter head gaskets will work on all of the blocks and heads.

Do not try to use the 72 and newer heads on the older blocks. You will leak coolant into the lifter galley and crankcase due to the missing scallop on the block.

 

Dave , I own a 71' block with 70' heads, currently running FelPro Blue gaskets.
I have a set of NOS Steel head gaskets on the shelf. Will there be any issues using the steel gaskets when I swap out this set of 70' small valve heads for a set of 70' Stage 1 Irons I have on the shelf? Apologies for hi-jack . Jim

 

Thanks everyone for the responses. Good info, I'll buy those 70 heads and beware of which headgaskets to buy. When I get to that point, I'll update this thread. The heads I'm buying need a full rebuild, hopefully no cracks and I'll go from there. Cab anyone a set of head gaskets? I don't need them yet but, it's better to research way in advanced so, I get no surprises later on....Thanks again!