N/A 4age race Build piston Q's

[samham]

Howdy,
I'm building up a smallport 4age for race, here's what Im doing/done so far:

smallport
silvertoprods/ pistons?
blacktop flywheel
balanced crank, flywheel, clutch cover, front pully, (cam gears?)
.5mm headgasket
will shave a little off head to bring compression up?
new seals and bearings
3 angle valve job
hone and new piston rings
280ish and 270ish cams 8.5ish lift
adjustable cam gears
dellorto carbs (please dont hassle them Im using them at the moment and happy with them).

I am a bit unsure about the pistons though, I have redtop and silvertop available. I think if useing silvertop the engine will be interferance, not too worried about that, but are there definite advantages to using one over the other?

Any comments on the build: go hard

I searched around a bit and cant find anything difinitive.

cheers team

[crispy'86]

Only thing is what head are you going to use? 20 valves have the recess in the top of the piston , so do 16 valves but 20v have the 5 recessess unlike 16 with 4 recessess for valve clearance. 16v 4ages aren't interference but i don't think 20v have clearance. This would call for comment from Redmist

[AceSniper]

would be best to stick to smallport ones you wont gain anything and make it interference(using smallport head), the headgasket should bump your comp up a decent amount.

[samham]

yeah was thinkn to use the smallport head as Ive already got it, mind due never really thought about 20v head(carbs)?

something to think about this lovely labour weelend, in the tropical paridise of parmy!

[crnkin]

what about, silvertop rods, smallport pistons, and a .5mm head gasket?

Or, get a bluetop block, rebore the small ends of the rods, run smallport pistons, and a .5mm headgasket?

Combined with a deck of the block and a minor head skim, you should be able to make a good 11.0:1 - 11.5:1 engine with light internals, and barely interference.

just a thought

[crnkin]

Oh, and go for 304 9 lift cams like in gary's ae86, MEAN power

[AceSniper]

also get rods/pistons balanced
ARP's on the rods
Look at getting your pistons procoated/HPC top and skirts

[suberimakuri]

gary's cams were not 304 or 9mm lift.. think bigger.
mine are 304/288 8.5mm.
arp rods..

heck, buy my engine, it's all there.

[samham]

yip, check on the arp rod bolts and rod/piston balancing.

Whats the advantages of coating piston tops and skirts, how much $ ?

Not to sure about more duration/lift, sort of wanted to stay on a budget, could be costly new valve springs, shim under bucket etc. And not have the power way at the top range, although have never driven a car with those cam specs.

[Dell'Orto]

Whats the advantages of coating piston tops and skirts, how much $ ?

Supposedly better resistance to detonation and on the skirts reduces friction. I think its something like $170 for 4 pistons?

[suberimakuri]

springs are cheap, and you'll want to do them if you're doing cams.

[crnkin]

gary's cams were not 304 or 9mm lift.. think bigger.
mine are 304/288 8.5mm.
arp rods..

heck, buy my engine, it's all there.

Real what were his cam specs? [edit: cant find the nzpc mag]

[AceSniper]

procoat do 4 for $120

[samham]

Was just cleaning up my pistons and it looks like they already have a coating on them? one type of coating on the top? one type on edge?, but none on the skirts?

[AceSniper]

ah true I think the high comp redtop pistons were coated stock