Porting

Daniel · Post by **Daniel** » Mon Mar 28, 2011 2:37 am

Hey thechadzone

If your trying to use stock pistons maybe you can get away with it as long as the valves clear the pistons
but the issue on some scale with after market pistons is to much compression if you still want to run on
pump gas .

If you run the 4 mm domed pistons you should be happy with the results and out come of that combination
but the options and interests very a lot on this forum do to many differnet points of view, some of the
guys on here are racers some are into stock none modifcation types of builds and others are some place
in the middle .

The one thing i can say for sure the choices of pistons are very limited these days to stock ( ¹ flat top )
type pistons ( ² 4mm domed ) or ( ³ 8mm Domed pistons ) all of these are cast Aluminum anything else
is going to be expensive to get your hands on . last quote i got from someone on here was around $450.00
before shipping over seas to get a more disirable design . For close to that price range i can just get some
made in Forged Aluminum here in the USA .

fiatfactory · Post by **fiatfactory** » Mon Mar 28, 2011 7:03 am

Daniel · Post by **Daniel** » Mon Mar 28, 2011 7:40 am

Re: Porting
by fiatfactory on Mon Mar 28, 2011 6:03 am

Daniel, Forged custom pistons for around $500us...

When did i ever say $500 steve ? but closer to 600 is about right .
It's great that your passionate about these engines but to school us over and over on pistons is getting a little old .
I used all of the brands you speak about and would use KS still to be honest but supplie and demand does play
a big part to the general Fiat public as Price can weight in more then that extra bit of HP with most people . When
you get a chance share with all of us where to buy the KS Pistons would you ? I will share with the forum where to
buy Custom Forged Aluminum Pistons for a good price . I contacted a company a couple years ago and the price
was pretty good there isn't anything in it for me other then maybe helping someone out with info .

As for Cast Pistons Steve is right they can be abused and handle anything your going to do without breaking a sweat
the only real advantage is forged is weight mostly and a higher thermal load .

Chad. No, decking the head is a compromise... there is precious little meat in the dohc cam head anyway, and removing material will quickly cut into the inlet valve seat, requiring the recutting/recessing of the seat further into the head to get a clean 45 angle to get the valve to seal up on...even worse if you have larger intake valves

This is a head i did that was decked about 50 thou it can be done if your willing to dry build and check clearnces .
Photo one is a 1800 Head I reshaped / Modified the Combustion Chambers for better flow

This is a stock 1800 Head resurfaced only

A side by side comparison now

If you pay close attention you can see the the intake valve seat was milled a bit on the egde and the valve sticks
by about 1mm Ill do a write up on all this later ...

Daniel

fiatfactory · Post by **fiatfactory** » Wed Mar 30, 2011 10:29 pm

engineerted · Post by **engineerted** » Thu Mar 31, 2011 9:29 am

the skinnier Moly faced rings from the later model engines would be a better choice IMO

Steve, can you clarify what you mean by the later model engines, as in the USA stoped Importing the TC cars in 1985.

Thanks

Ted

fiatfactory · Post by **fiatfactory** » Thu Mar 31, 2011 12:54 pm

Daniel · Post by **Daniel** » Fri Apr 01, 2011 11:56 am

Hey Steve

The Valves are the same size and both are 1800 heads it's just the poor photo quality and shot angles
that make them look as if they are different sizes ill do something better soon when i get a chance so
everyone who might be interested can see the differences . As for going into detail over pistons on the
market for these engine i never put much thought into it because the flaw in design on them to start
with . The 1800 (1756cc) and 2000 (1995cc) have off set combustion chambers on 1 and 4 but 2 and 3
are centered as the photo shows below .

So with any Domed Piston off the shelf all the pistons are the same even though the issue of Combustions
1 & 4 are not centered . The only way to correct this is to have Pistons made with 2 centered Domes and 2
off centered that is why i don't bother or trouble myself much over stock or after Market Pistons for these
engines . If someone is running a 1608 0r 1438 they have no issues to deal with like this as the 1800 and
2000 have been delt a poor design flaw because of a lazy engine designer didn't want to solve this problem
way back in the day . I am sure it was all about the cost of re tooling and making new manifolds etc etc for
what ever reason Fiat did what they did .

Any how i wasn't trying to raze you about your method of explaining things i got what your talking about years
ago and discovered a bunch of tricks to solve the problems on these engines . For every problem there is a
answer it's the cost of the answer that is in question is it worth the money or not and to every person in
persuit of performance has a different out look on price !

BEEK · Post by **BEEK** » Sun Apr 03, 2011 1:58 pm

wrong thread, but an opinion, there is also a very easy way to increase compression height. deck the block! as long as you are adjusting the cam timing, why not just take 50thou off the block, i have decked many fiat blocks and never had any problems, i stick the pistons 10 thou out of the top of the deck, this is a great increase without buying pistons as you can run flat tops, i just install the early 1800 with small valve reliefs. compression is up and performance is also up, but not in the realm of race gas.

So Cal Mark · Post by **So Cal Mark** » Sun Apr 03, 2011 3:13 pm

the one issue with decking blocks and milling heads is cam timing. At some point you'll need adjustable gears on the cams

BEEK · Post by **BEEK** » Sun Apr 03, 2011 11:33 pm

yessir thats why i said adjust cam timing, and its much less expensive to buy a pair of millers cam pullies than a set of pistons

Daniel · Post by **Daniel** » Mon Apr 04, 2011 12:09 am

i have decked many fiat blocks and never had any problems, i stick the pistons 10 thou out of the top of the deck,

Beek have you taken any measurements after doing this to see what Compression ratio you ended up with ?

I think the flat Pistons are the best way to go if you can raise the CR into the High 9s by decking the block or
milling the head .

Daniel

BEEK · Post by **BEEK** » Mon Apr 04, 2011 12:19 am

no i didnt, i do remember the compression test being 210psi, granted thats not a real good way to determine racio, i used total seal rings so i had near 0 leakdown

Daniel · Post by **Daniel** » Mon Apr 04, 2011 12:24 am

Ok thats a good number !

BEEK · Post by **BEEK** » Tue Apr 05, 2011 12:17 am

i need to also add i was running 42-82 82-42 cams set at 2deg intake advance and 1deg exhaust retard

Daniel · Post by **Daniel** » Tue Apr 05, 2011 12:28 am

how was your valve to piston clearance ? do you remember what the spacing was at ? roughly ?