Hey has anyone on here done a rebuild to there stocko A12? Like port and polish, boring, etc. Just a few questions.

-How well does the block hold up?
-How far is too far?
-What else can be done?

Thanks.

A12. When building for moderate power, don't bother modiying the block. The block, crank, rods and pistons are very strong.

If you engine was smoking and had a loss of compression, just hone the cylinders and fit new rings. Usually there is no reason to change bearings or re-bore the block. Unless some broke like a piston brok, or run it out of oil and it knocking.

Strong units just send your head off for a reco and milled
with more from the sparkplug side to angle the ports up which
increases compression and slightly better port angles.
Strip your block, have it chemically cleaned and put
some bearings, rings, hone the bores and thats about it.

What sorta power am I looking at after doing all of what you mentioned?

flat top pistons ,mild cam,nice head or oval port a14,u need comp to make nice power ;rest depends on carbies,exhaust,ignition its all about the right combo for good power.how much u spend.

after a rebuild you cant expect more power than standard
but with higher comp and better exhaust, match porting
you should get another 5-10hp. More would require what
bige stated. Easier would be clean rebuild with stock
comp and a small diesel turbo with J pipe, Su carb and
stock manifold with pipe from snail for draw-through.

In other words, rebuilding the block adds no power. Changing the pistons to flattops will add 1-3%.

Changing the cam can have an effect too, but only with cylinder head improvements. Converting a A14 oval port head will perform as well as a ported and polished A12 head.

Hello i have been following this thread
And ddgonzal said an a14 head matches a ported and polished a12 head
So what if you P and P your a14 head? More power still?

And would you benefit much from double valve springs with the work mentioned
P and P , cam, flat tops?

Cheers
Jason

some people claim the oval port head fully ported to be sufficient
for mild street performance. The rally guys that I met racing sunnys
preferred the round port heads over the oval ports, the circuit guys
prefer the oval ports over the round ports. Round ports seem to provide
better torque and mid range, oval ports top end.
Look up port and polishing websites, my specialty
http://www.mototuneusa.com/

Sorry for the Hijack but dammm...

D that link is gold!!!!

I'm gettin an a12 head ported to match a GX twin su inlet manifold, Now I wanna go have a chat with the dude who's doin it and make sure he's not killin that sweet velocity, I'm wonderin how applicable that article is to the two valve A series head tho...