Which Block for an 85 C4?
Thread Starter
Instructor
Joined: Sep 2007
Posts: 175
Likes: 1
From: Fort Worth Texas
As mentioned in an earlier post in your string, the only difference in pre 86 blocks may be the side the dipstick is on. This of course requires the matching oil pan. If the block you are buying has the dipstick on the same side as your 85, you won't know the differance from it and rebuilding your original block. Some are 2 bolt and some are 4 bolt, Other than that, most will slip right into your 85 just fine. There were some variations in metalurgy over the years and I've heard of some crappy castings made in Mexico ( that may be bullsht). I used a 79 400 cid block in my 87. The 400 block has differant coolant holes for the head and larger mains, but after assembly, all the factory accessories fit perfectly and the installation went off without a hitch.
Thanks for the reply, thats exactly what I needed to know. Ok, heres another question, the Corvettes use a 4 bolt main, right?
Also, do you guys think I should get a 350 block and make it a 383, or go with a 400 block? And let me just say that buying a new crate engine is out of the question. I cant spend that much money at one time, thats why I want to get a block and have my uncle help me build the motor. Thanks, Zak.
Burning Brakes
Joined: Sep 2005
Posts: 993
Likes: 3
From: Iowa
Buy a 400 block; if you run it as is at 406 cid they run well. If you take the plunge and go into a 4" stroke crank you can get away with 427 cid without a raised cam or spread pan rails. A word of caution about that; without a tall deck block you will have around 1" of compression height with a 6" rod. This is not a problem but dictates the use of a premium forged piston that costs around 600-800$ a set. Just something to thing about.... 350's have their place (mostly where the rules don't allow us to race any bigger!) but 400's are the kings of sbc power. Components that you are talking about replacing won't cost you any more to go 400cid. Can you tell I grew up in the sprint car world?
Thread Starter
Instructor
Joined: Sep 2007
Posts: 175
Likes: 1
From: Fort Worth Texas
Buy a 400 block; if you run it as is at 406 cid they run well. If you take the plunge and go into a 4" stroke crank you can get away with 427 cid without a raised cam or spread pan rails. A word of caution about that; without a tall deck block you will have around 1" of compression height with a 6" rod. This is not a problem but dictates the use of a premium forged piston that costs around 600-800$ a set. Just something to thing about.... 350's have their place (mostly where the rules don't allow us to race any bigger!) but 400's are the kings of sbc power. Components that you are talking about replacing won't cost you any more to go 400cid. Can you tell I grew up in the sprint car world?
Yeah, I think it will be worth it to go with the 400. Thanks for the information. Zak.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
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Thread Starter
Instructor
Joined: Sep 2007
Posts: 175
Likes: 1
From: Fort Worth Texas
