F5A cyl head vs F8B cyl head specs.

[g man]

Gday MB professors - heres some good maths for you on a sundie night:

I have 2 x old Suzuki 3 cyl heads here.
1 x cyl head has F5A written on it with a paint pen.
The other cyl head looks the same and has F5A cast on the cyl head.

Today I measured the valves in both heads with digital verniers and got the following:
Inlet valve dia = 31.60mm
Exhaust valve dia = 28.4mm
It was hard to measure as the valves are still in both heads but I am quite close.

I cannot find valve sizes for F5A on the net (I looked last night).
I only found valve sizes for F8B and they are as follows:
Inlet = 31.6mm
Exhaust = 27.6mm

The question is simple - what are the 2 x heads in my shed???
Have a good week all + m/boy on!!!!

[blown lsx]

Got 2 F5A heads here, they measure out at 31.59 Intake & 27.57 Exhaust.

Johno

[g man]

cheers j man but the specs I found on the net tell me you + me have
f5a heads with f8b size valves - how can that be?

do the heads run the same size valves??
doesn't sound right to me??

all the massive hp from 550cc to 800cc would need a bigger inlet
valve surely??

im new to mb eng so what you think??

who got a genuine 800cc head to measure valves pls?

thanks all....

[Brayden]

Ignore the F5 casting on the head, it doesn't match the engine model.

[g man]

right but are my 2 x heads F5A or F8B heads please based on my sizes?

so F5A + F8B run the same size valves??

I just need to know what I have so I can clear out before Xmas.
I don't need any F5A heads - shame as they are in good nick.....

[Brayden]

The answer isn't black and white. This discussion has popped up a few times over the years and some people have found F5A heads with the same valves as F8B. Yet other F5A heads have noticeably smaller valves, as verified by myself and another forum member. Stupidly I didn't ever bother to take measurements before tossing the small valve F5A heads.

The best way to tell the difference between F5A/F8b heads is to measure the diameter of the inlet ports. ~22mm for F5A and ~28mm for F8B. (There are other size/shape variations on later model heads with emissions control)

[g man]

thxs again captain - top knowledge and a good site you have here.

preety sure the 2 x heads will go in the bin if thy are f5a.
only want to hold f8b heads for future use.

p.s - need to have a private chat regarding f8b carby eng turbo set up.

p.s.s - merry xmas to all on this site - g man.

[g man]

FYI - bare head has small inlet ports - off to scrap man.
cant measure complete head as manifold is still on board.

what a waste as they are good cyl heads but only crappy f5a.