Archived Message
V8 cylinder head swop
Can anyone please advise if standard V8 cylinder heads are interchangable. I have a factory V8 and have been offered a set of 3.9 10 bolt heads which should improve performance. Does anyone know if the 3.9 heads can be simply bolted on to the early 3.5 block or is there a problem with the different bore size or a risk of the larger valves hitting the pistons.
Les Hughes
22/09/2012 @  20:16
Under topic: V8
 
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V8 cylinder head swop
The heads are interchangeable. The valves won’t open more than the 3.5 heads (unless you change the cam) and there is no chance of them hitting the pistons. If you use tin head gaskets the CR will be increased but the composite gaskets are better.
Geoff King
22/09/2012 @  20:41
 
V8 cylinder head swop
As Geoff says.... I would only use comp gaskets with these, as the 10 bolt heads have combustion chambers of approx 28cc making them more suitable for comp gaskets.
Steve Illing
23/09/2012 @  15:58
 
V8 cylinder head swop
…unless you want to increase the compression ratio, but then you would need to check (and probably adjust) the cam follower pre-load as obviously the head would be lower on the block compared to the old Range Rover/GTV8 heads. And then there is the valley/inlet manifold gasket alignment to consider so unless you are prepared to do a little work I agree with Steve it’s easier to use composite head gaskets and just bolt it together.

There is no problem with the different bore size but use composite gaskets for a 3.5 such as these: http://www.dingocroft.co.uk/acatalog/RoverV8.html it doesn’t matter that the gasket has the outer bolt holes.
Geoff King
23/09/2012 @  17:36
 
V8 cylinder head swop
thank you all for the great advice, its very reasuring and I can now look forward to changing the heads sometime during the winter.
Les Hughes
24/09/2012 @  20:10
 
V8 cylinder head swop
Les,
We don't have a registration of an MGBV8 from you so would you like to register your V8 using the convenient online form at: http://www.v8grapevine.net/register.php
V8 Webmaster
24/09/2012 @  20:45
 
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