bbc pump gas pistons

[ejm]

have a 461 with 049 o/c heads wondering what would be a good dome piston to run in it will be running pump gas i have a 544 cam and a 633 lift

[zipper06]

I like probe, and Icon also make a decent piston for the price. A couple hundred $ cheaper than JE, just make sure you don't use JE SRP pistons, or hyperutetic pistons, use the 2618 mat'l pistons.

JMO

Zip.

[markdunlap]

SRP pistons are 4032 alloy for SBC, but are now 2618 for BBC, I believe?

[zipper06]

Sorry Mark, they are still the same, cheap high silicone 4032, which i wouldn't put into a lawnmower.

OPEN CHAMBER - BBC SMALL DOME PROFILE

•Designed to fit Edelbrock STD Series Heads.
•4032 low expansion high silicon aluminum alloy heat treated to SRP specifications
•CNC machined domes with radiused valve reliefs provide optimum flame travel
•Pin fitting and double spiro locks included
•990-2930-150 wall wrist pin (150 grams) included
•CNC Machined ring grooves accept 1/16, 1/16, 3/16 rings, closed chamber accepts 5/64, 5/64, 3/16 rings


JMO

Zip.

[ejm]

zip, so is that a small dome for like a closed chamber and roughly what would the comp be?

[zipper06]

zip, so is that a small dome for like a closed chamber and roughly what would the comp be?

That dome would be roughly 10.25 with OC heads, and 12.0 with Closed chamber heads.

Zip.

[markdunlap]

The pistons I use in 496 combos are SRP 139832 which are full dome and are 2618 alloy. It says so in the instructions that comes in the box and on the site www.srp.com. I have used these in several engines in the last 3 years with no complaints.

But the flat top and mini dome ARE 4032 alloy. That alloy is designed for street/strip use. It allows for tighter cylinder wall clearances and is stronger than a hypertecnic cast piston. 4032 is not recommend for alcohol use either.
But I did build a 421 alcohol SBC with dome 4032 pistons and it has over 200 runs on it now with no complaints, running 5.90s.

I just don't want people to think all BBC SRP pistons are 4032.