Team MightyBoy

engine build from scratch - F8B.

gday all,

I bought a m/b as a parts car this week. got a whole bunch of crap
and paid too much. gonna part out some stuff + keep some stuff....

in the box is the following:

1 x F5A block
1 x F8B block
2 x cyl heads (type unknown)
1 x g/box in a million pieces (type unknown)
1 x g/box complete (type unknown)
1 x mikuni carby
1 x solex carby
2 x sumps (type unknown)

now I should build a new stock F8B for my green machine but need lots of advise please
so lets start at the start.

1. are F5A + F8B parts interchangeable - F8B bottom end on an F5A cyl head?

2. can bolt up F8B new engine to stock F5A manual g/box in my car?

3. think I found the F8B crank - same as F5A as I only have 1 x crank.

F8B engine is in a million bits too - gotta find the main caps etc.

really need help on this one so I will find all the engine parts before xmas
then start in new year - stock motor only (still on a budget)

all advise appreciated - I am in perth.

1. Yes, but the smaller ports/valves in the F5A head will stifle performance when used on an F8B block.
2. Yes, but the ratios difference will not suit the F8B very well.
3. F8B has a longer stroke, so the cranks are different.

thanks Brayden,

so how do I know which cyl head is to suit f8b please?

same with the g/box - any markings to look for?

any specs on the crank so I can measure what I have.

any thoughts on the china f8b engs for sale on alibaba website?

F8B head is most easily identified by its larger ports and valves.
Gearbox will have an A or B marking on the round inspection plate (bottom).
No specs on the crank off hand, but it might be in the workshop manual.

F8B engines from China are reverse-engineered from Suzuki OEM, and there are question marks over the quality of metal and castings. When you consider the price is cheaper than a rebuilding an old motor locally then you can probably afford to bin one if/when it breaks.

so I need to strip the head to measure the valves?

a or b marking = F8B g/box or is it:
a = f8b
b = f5a

or visa versa?

got some good news today:

the seller found the missing motors that were part of the sale.
like xmas again - not sure whats in store.

I pulled out 2 x a1 front guards for the rolling car this arvo.
they are really good - no holes, straight + light rust only
on the inside area.

maybe I will get my monies worth yet.....

You can measure the intake/exhaust ports without removing the head.
Markings on the box are A for F5A and B for F8B.

cant find this A or B marking as yet.
is it down near the g/box mount that is
still fitted to my g/box or am I looking
in the wrong area please Brayden?

I will get some verniers and measure the
valves on both heads - I hope one is bigger
or I have 2 x heads the same.
do you know what size the F8B inlet + exh valves
are please?

thanks again - good tech advise...