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F8A block with F5A crank which rods?

Posted: Sun Feb 26, 2012 11:52 am
by 8
Heya Fellas just wondering if its possible for someone to tell me the different length rods that come in 3 cyl F series engines?

Im wondering also if the F8a block is the same height as the F5a?

Re: F8A block with F5A crank which rods?

Posted: Mon Feb 27, 2012 11:40 pm
by gadj
Don't know if the info came across from tamon.org but likely in the guides. memory says F5a & F8b same core block with different bore sizes as well as different manifolds. F8a is 4 cylinder - info not hard to find.

Re: F8A block with F5A crank which rods?

Posted: Tue Feb 28, 2012 12:44 pm
by 8
only interested to know if the 3 cyl f5 and f8 blocks share the same height?

I want to keep small capacity but with bigger bores to allow more compression
and slightly bigger valves. It will be geared quite low and interested in
MPG challenges to reduce fuel consumption. Otherwise will rebuild an F5
with 12:1 compression, singh lines and water injection.

Re: F8A block with F5A crank which rods?

Posted: Tue Feb 28, 2012 9:46 pm
by Brayden
F8B block is taller. Larger bore and longer rods.

Re: F8A block with F5A crank which rods?

Posted: Tue Feb 28, 2012 11:38 pm
by 8
Brayden wrote:F8B block is taller. Larger bore and longer rods.
Thank you Brayden! Lots of questions but does anyone know the lengths of the rods?
I know the piston data from ACL catalogue but rod lengths are a mystery
eg f5 f6 and f8 etc

From wikipedia (probably wrong!)
f5 bore x stroke 62mm x 60mm
f6 bore x stroke 65mm x 55mm
f8 bore x stroke 68.5mm x 66mm

If I combine an F8a block with F5a crank for 663cc but Im stuck on the rods department :(
Love a big bore long rod high revving F baby! 70mm bored (if possible) f8 will allow many kinds of pistons from other makes.

I might just have to source an F5B
65mm bore and 55mm stroke!?

Re: F8A block with F5A crank which rods?

Posted: Wed Feb 29, 2012 12:41 am
by Brayden
I'm assuming when you say F8A you really mean F8B, in which case boring to 70mm will be a real stretch. I know one guy who tried and ended up with cylinder warp when it got hot. If you want bigger bores then G10A is the answer.

I have a spare F8B rod here, so I'll measure it next time I'm in the workshop.