Rover/Buick V8 bore/stroke

Rover/Buick V8 bore/stroke

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RoverP6B

Original Poster:

4,174 posts

84 months

Monday 2nd January 2017
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The received wisdom seems to be that Rover V8s are limited to about 5 litres' displacement, with a 3.7in bore and 3.54in stroke.

However, while Buick also took their version of the V8 out to 4.9 litres (300ci), albeit recasting it in iron, they bored it out to 3.75in, with a 3.4in stroke. They then took it out to 340ci (5.6 litres) with a 3.85in stroke. They then bored it out again to 350ci, with a 3.8in bore. All this on the same 4.24in bore spacing. Some people machine out a bit more metal for another 10ci, taking it up to 360, but that's as far as it goes, and stroking it further is difficult, although it's been done (again, only gaining another 10ci) with custom cranks and Honda(!) rods.

The question has to be, can one build a Buick 350 out of a Rover aluminium block? I understand the Buick 340/350 is a wee bit taller in deck height than the 215/300/Rover, but they ran such low compression ratios in the smog era that one might be able to make the 350 crank (.310" longer than the Rover 5.0 crank) work in the Rover block at a high CR, even if it needed shorter rods.

I am also vaguely aware of a "Wildcat" Rover block, with enlarged 4" bore and what look like siamesed liners - are they siamesed, or has the bore spacing been increased? Or both? I note it uses the Oldsmobile-type 6-bolt block as per the Repco-Brabham.

Edited by RoverP6B on Monday 2nd January 16:41

Boosted LS1

19,114 posts

216 months

Monday 2nd January 2017
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Rover blocks can go to 5.5l using bore/stroke combo's. After that you'd need a siamesed block or an iron block. If you go to long on stroke the rod bolts will hit a couple of the cam lobes. I once got to 5.4 using something like 98 x 94 and then I had to use 300 heads in order to run low boost. I certainly used the stock 94mm bore on that engine. I also did a 5.1 turbo using 96mm pinto pistons but again there was a lot of additional machining to do.

At the end of the day, it's not worth the effort and cost unless you want to do it for a challenge.

The wildcat engine retains the same rover bore spacing so I imagine the block's siamesed. Iirc Ian plumped for chevy pistons and a 4" bore.

RoverP6B

Original Poster:

4,174 posts

84 months

Tuesday 3rd January 2017
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Right... so what's the difference between a 5-litre Rover block and the Buick 350 in terms of the space between cam and crank? It's interesting that Wildcat used the Oldsmobile block rather than the Rover.

Even with iron block and heads, the Buick 350 only weighs 450lb. Stick Rover aluminium heads on it... oh wait, it's a 4-bolt pattern, that won't work. Apparently Rover-derived aluminium heads for the 350 have been under development for some time and the first batch are being delivered imminently...

Boosted LS1

19,114 posts

216 months

Tuesday 3rd January 2017
quotequote all
I don't know with certainty about the 350 cam spacing, it could be higher but I'm not sure. A 5.0 rover block has the same cam height as any other rover. If 350 cam gears and chains fit a rover then the cam height will be the same, it probably is.

Can you clarify what you mean when you say 'Wildcat used the oldsmobile block'? I'm pretty sure Ian's heads were heavily based on the buick v6, design wise but with an additional cylinder.

I can say that I've had buick 300 and 340 parts to look at albeit a long time ago. Witha friend we also considered doing a conversion. It was going to be a ball ache with no real gains. Even the rear of the cranks different and everything is much heavier then on a rover. You could fit a buick and paint it silver, few would notice ;-)

Edited by Boosted LS1 on Tuesday 3rd January 09:50

RoverP6B

Original Poster:

4,174 posts

84 months

Tuesday 3rd January 2017
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The Wildcat has six head bolts per cylinder, as per the Oldsmobile/Repco block.

Boosted LS1

19,114 posts

216 months

Tuesday 3rd January 2017
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RoverP6B said:
The Wildcat has six head bolts per cylinder, as per the Oldsmobile/Repco block.
Ah, then this is Ian's own cast block? Or have supports been welded in the 'V' to accept extra bolts?

RoverP6B

Original Poster:

4,174 posts

84 months

Wednesday 11th January 2017
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I've absolutely no idea what block he used as the basis of his builds, just that it's got the Olds/Repco six-bolt pattern, as seen in several photos.

Boosted LS1

19,114 posts

216 months

Wednesday 11th January 2017
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I suspect that a tabs have been welded into the'v'.

mr-scott

80 posts

238 months

Monday 14th January 2019
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Buick and Oldsmobile 215 blocks are the same die cast block, I had a Buick block and it had the bosses (undrilled) for the 6th bolt in the inlet side in the block valley. The 6th bolt was in line and held down the rocker gear on the Olds 215 V8 heads.