what pistons?

BMFB

BMFB

Not to scale
so, im rebuilding my ty motor, and im going to bore the cylinders out, just to freshin it up, so i need to buy new pistions. beleive the stock pistons were hypereutectic (sp?) im thinking im going to replace the stock rods with some eagle i-beams, but for the pistions, im stuck. id like to get somw forged, but man are they pricey, and for my build i dont know if i need to go that far. its mostly stock, im running code 59, and my boost pressures are at 18. should i go with a set of say, speed pro hypereutechtic pistions with the same compression ratio?

also, what is the stock compression ratio

also, are 350 parts compatible with these motors? like will those eagle i beams work if i get them for a 350? or are they different. same question goes for the pistions
 
BoostedSUV

BoostedSUV

Active member
Re: what pistons?

I believe the rods are the same, however the pistons are not due the compression ration of an NA motor vs Forced induction.

A lot of guys run SRP, TRW, or JE pistons with great luck... JE's are a bit more pricey. TRW or SRP are best for daily drivers...
 
midnightbluS10

midnightbluS10

Banned
Re: what pistons?

Rods are different. V8 pistons will work as long as compression ratio is correct.

Stock comp ratio is 8.35:1 IIRC.
 
BoostedSUV

BoostedSUV

Active member
Re: what pistons?

What's different about the rods? I'm pretty sure the part # on my Eagles were the same as a 350 minus 2 rods? Could be wrong...
 
midnightbluS10

midnightbluS10

Banned
Re: what pistons?

The big end is a different size because the 4.3 uses a split journal crank. SBC uses a shared journal crank. The big end is also a bit thinner, IIRC. We just went over this exact thing not long ago.

edit: SBC has 2.1" crank pins and the 4.3 has 2.25"

edit #2: we did just go over this. http://www.syty.net/forums/showthread.php?t=75208
 
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BMFB

BMFB

Not to scale
Re: what pistons?

ok, so i see that a 4.3 has .015 inch larger journals, so thats no good, although i did see a few people mention that using new style rods would be a decent alternative, although i would still need to buy them and have them reconditioned, and ill do some research, but i bet id still be better off with some Eagle i beams...If anyone had an extra set of those i could maybe haul them away for you?

I also did some research and found that 350 pistons are for the most part the same, a couple places said that the placement of the pin was slightly different, but they never gave an actual value, and said that it wasn't worth noting, although to make TRIPLE SURE THAT THEY CLEARED THE CROSSFIRE CRANK. They seemed to stress that...

so that leaves me with my final question, are hypereutectic pistons a sin going into my mostly stock rebuild? Im looking at speed pros or Keith blacks or somethin, dont really know, gonna talk to my builder tomorrow.

thanks for all the super info so far!
 
S

synsoup

New member
Re: what pistons?

The rods for a 4.3 are different. The Eagle rod # that you will need is crs570063d. Carshopinc.com sells the set for $369.00.... That's where I bought mine (cheapest price). You will not want to run cheap hyperuetectic piston in your motor. The SRP forged pistons can be had at a decent price if you look around. The SRP piston # you want is 139632 if you go .030 over. I found a set of eight on E-bay that were brand new for my motor and only paid $350.00 for them. Compression is advertised at 8.5:1 with the SRP pistons listed above. That's very close to stock.
 
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dgoodhue

dgoodhue

BuSTeD 4.3
Re: what pistons?

The pistons are probably the weakest link in the stock engine. I wouldn't use an even cheaper set of pistons (Keith Blacks). If you on a budget, I will still spend the extra money on the SRP's.
 
turbodig

turbodig

Active member
Re: what pistons?

Probe makes an economical forged piston, more or less a clone of the TRW L2441-F30.
Wiseco also makes a blower piston.

Honestly, despite the conventional wisdom, the rods hold up ok if you don't ping them to death.
If you do let it ping, it doesn't matter what you put in there for parts, it'll die too. Maybe not as fast, but it'll let go.
 
alwayscode390

alwayscode390

pppssssshhhhhtttttttttttt
Re: what pistons?

I have a set of TRW pistons mated with eagle h-beams, with kenne bell rings, for sale in the classifieds right now :) ---
 
ghettosled

ghettosled

SYTY SUPERSTORE
Re: what pistons?

i have a set of SRP 139632 4.030 pistons on consignment the customer only wants $395 for. Brand new SRP 4.030 8.5:1
 
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