Discussion on 215V8 yahoogroups.com on fitting Buick cranks to P76 blocks

Andrew Kloot

greg55_99 wrote:

To: 215V8@yahoogroups.com

Date: Sat, 16 Feb 2002 18:12:42 -0000

Subject: [215V8] Re: 340-350 buick crank

Reply-to: 215V8@yahoogroups.com

Well, I'll tell ya. See'in as how I'm stalled with my own project, I can tell you a few things about fitting a 340/350 crank into a P76 or 215 style block. You can cut a 350 crank down to 2.5" with no problems. HOWEVER, if you are going to fit it into a P76 block, things get awful close in the crankcase. If using stock 73-80 Buick 350 rods with capscrews (as I want to), one of the rod bolts just touches an oil gallery in the side of the block. You'd need at least 60 thousands clearance.

Chris recommends DE-STROKING the crank 20 thousands and a bit of grinding on the gallery. That should get the clearance needed. If attempting the same thing on the 215/Rover block, you've got a bigger problem. You can't use the 350 rods (they are to long). You'd need a rod that will not only clear the crankcase but the shoulder of the rod has to clear the cam at full swing as well. 215/Rover rods will strike the cam lobes. P76 rods are longer but the same problem I believe remains.

Things get a little better in the Buick 300 block. The crankcase is wider and the deck is taller than the 215 (but shorter than the P76). You might be able to get away with using stock 350 rods but you'd have some pretty short pistons compression height wise.

Had a conversation with John Harcourt in New Zealand some months back and he said he knew a gent that had dropped a 350 crank into a P76 block. So I know it can be done. The bad part is that he said the motor was a slow revver. He didn't know much more about it than that. (If the engine is using stock or ported P76 heads this doesn't surprise me.)

A fellow I know flowed aluminium Buick 300 head for me on a humbug last year. No numbers, but, he confessed that in stock, unported form, it wouldn't support more than five litres. Remember that Buick 340/300 cast iron heads have larger valves and ports than the alloy ones. Putting the alloy 300 heads on a big motor would probably wind up choking it.

Now that I've been activated by the US Air Force, I've got a little coin to play around with. I'll see if I can't get this pig back on the bench. I'm investigating using Chevy LS1 main bearings and having the block align bored to suit.

Reply to Greg

Andrew Kloot wrote:

Seems too much like hard work to me. If you really insist on getting more capacity out of the engine have larger liners inserted into the block with a set of Holden 253 pistons which will take it out to 5 litres and call it a day

regards Andrew

Reply from Greg

greg55_99 wrote:

So. tell me about that sleeving thing. Pitfalls and all.

Reply from Andrew to the discussion above

Andrew Kloot

If you go to an engine shop and have the dry liners removed and larger ones put in you can then use a bigger diameter piston from a holden {GMH Australia}253 cubic inch engine this is a lot more cost effective

way of getting more cubic inches out of the engine it will give you approximately a 5 litre capacity the messing around with cranks is all to hard the engine was developed here in the early seventies by Repco {gold star} to be raced in the formula Brabham cars with what I believe to be reasonable results the best person to contact in Queensland about this job is Neville Humphries as he has one already fitted to his car, good luck regards Andrew Kloot

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