Tower shims or adjustable shiny bits? pistons forged or cast

[Alphabettispaghetti]

I've a friend having some work item shipped over from CA so i've a free route to get some stuff across the pond. Its company gear that comes over and goes back a few times a year, so some useful other savings too

I was thinking what would be useful engine wise to bring over.

Whats the general consensus regarding cam geometry and shaved heads, Better to shim the towers to take up any slack or go for an adjustable camchain tensioner? I was going to go for a adjustable cam sprocket to enable me to dial the cam in properly anway.

Which is the best way to go about it? I want to do it properly. I'm aware there'll be considerations with valve length/springs etc too.

Given there's about £300 between a set of cast and forged pistons, at what point do you need forged?

Weight wise i'm thinking cam sprocket/tensioner/pistons/brakes/weather seals.

 

[SKiddell]

Without doubt the Kameari chain tensioner is the best option for any significant amount of head "skim"
It is however not without its drawbacks

1. Cost, not a cheap item but if you want the best you have to pay
2. Noise, it can be a little intrusive, I happen to like it

BUT the plus points are
1. Very stable chain
2. Very stable valve train
3. Very stable valve timing
4. No more "popped out" chain tensioners
5. Oh did I mention very stable valve train, timing and chain (dont underestimate the value of this)

Shim towers work ok but they are a halfway house

As for forged pistons, ask yourself, am I going to rev the car well into the limits, am I going to run high compression, aggresive fueling and spark, big cams etc......if yes then buy forged, if no, buy cast

But beware buying forged often means floating pins which means machined or forged rods

 

[Alphabettispaghetti]

Thanks for the reply mr Skiddell.

The Kameari tensioner is about $200, which in the scheme of things isn't much to pay IMO on a build. Or are you thinking of the twin idle gear setup at$700?

I'd like an engine that can rev to a tickle over 7k, about 7300rpm, I was thinking a 10.5:1 compression ratio and a slightly lumpy cam, something that will give me a nice 3400-6800ish type sweet spot.

Would that warrant forged pistons? I guess it does future proof my engine a little, and with a nicely balanced crank/flywheel should make it a more rev happy.

I was looking at these pistons as a few american cars run them, on stock rods, or do you have any better ideas?

The Z Store! Nissan-Datsun 240Z-260Z-280Z-280ZX-300ZX(Z31/Z32)-350Z-370Z Parts: ROSS Forged Piston Kit for L-28 Engines



Or a 'engine kit' like this and (maybe) getting domed pistons to save taking too much off the head. I'm just not sure of the right way to go about it yet.

Import Performance Parts - Nissan HP Engine Kits

However I need to consider the cost implications but the VAT+shipping savings are not to be sniffed at.

 

[andrew muir]

I thought that the standard engine's pistons and rods were internally balanced to a pretty high tolerance anyway. I have heard some people say it is safe to nearly 8000rpm? Changing to different rod pistons would only mess that up. And would need an expensive rebalance?
Please correct me, I may be entirely wrong!!
Andrew

Thanks for the reply mr Skiddell.


I'd like an engine that can rev to a tickle over 7k, about 7300rpm, I was thinking a 10.5:1 compression ratio and a slightly lumpy cam, something that will give me a nice 3400-6800ish type sweet spot.

Would that warrant forged pistons? I guess it does future proof my engine a little, and with a nicely balanced crank/flywheel should make it a more rev happy.

 

[pmac]

Please correct me, I may be entirely wrong!!

You are.
A chap called Frank Hansowetz will correct you if you read his book.
"How to modify Your Nissan/Datsun Engine."

 

[tel240z]

http://zclub.net/forum/240z-260z/18401-take-last-look.html

Have a browse through this franky thats my engine home built 2nd time round due to a crack in the block!
forged pistons + 2mm 240z con rods (beter crank angle) balanced to the hilt, multi angle valve grind, mildish cam 45mm webers, fluid crank damper and a home bench match port and polish revs 7800 no probs (often) 104 mph in 3rd 3.7 diff s14 box 225 45 17 rubber oh i forgot some off the head and a bit of the block its all writen down somwhere

 

[SKiddell]

You are.
A chap called Frank Hansowetz will correct you if you read his book.
"How to modify Your Nissan/Datsun Engine."

Indeed, we have seen 15 gram delta between rods.
On my all steel setup (some £15,000 worth) we built it to 0.5 of a gram delta

Yes Frankly I was referring to the twin idler