3.800-3.830in Bore Forged FLAT TOP pistons

[CTX-SLPR]

Howdy,

I'm looking for a set of flattop (flat top) stock to 0.030in over bore forged pistons with something around stock compression height and any of the common wrist pin diameters. This means ~1.785-1.835in compression hieght but I can deal with some outside of the range. I can't bust the 0.030in over limit or it pushes my displacement too high for my engine class and as such I'd like smaller bore (3.810in would be ideal so I can clean the bores up) pistons as it means I can have a chance of recovering from something damaging the bores.

Thanks,

 

[charlief1]

Look for some Buick 350 pistons for 68-69 and I think you might have what you need. Same bore ect but the 68-69 had somewhere in the 10:1 compression range so you should be able to get about 9.5:1 or so.

 

[CTX-SLPR]

These are for my 3.0L destroker so just a plain flattop yeilds a 10.0 compression while 2.5cc's of dish (might be valve notches) gives me the 9.5:1 I'm looking for. I'm bushing down BBC rods so I can use a pretty wide variety of compression heights and just put the pin bore where I want it on the rod plus I do have some stroke flexiblity in turning the rods down to 2.200. I'm also looking for Forged units as I can get a stock replacement 3.0L flattop in a casting already but I don't trust it over 3mi of WOT with a blow through carb and my tuning skills.

Something else to add, while I listed 0.030in over.... I'd really like to avoid that since it leaves me on the ragged edge of the displacement limit where I'd rather not be.

 

[VinceNY]

Hi
I have a new set of 6, TRW L2481, .030 over, Stock compression pistons, mounted on Turbo rods that are rebuilt with ARP rod bolts, magnafluxed, shotpeened, beams polished with plasma moly rings and standard size rod bearings. Asking $375- for everything. You pay shipping. Pictures attached. email me if interested v426235m@aol.com Thanks Vince.View attachment 182822View attachment 182822

 

[CTX-SLPR]

Thanks Vince but with the short stroke of the motor I have no use for the rods. 0.030 over is also pushing my limits for displacement as well.

 

[CTX-SLPR]

Might be back in the market for a set of forged flat top pistons in 3.810-3.830in bore with 0.927in pins though I'd rather stick to the small end of that. Also looking for 0.874-0.927 (or more if the crown is thick enough) compression height.

The block I ended up with is likely sketchy for using the standard bore pistons I already have.

 

[earlbrown]

how soon do you need them and what is your budget?

 

[CTX-SLPR]

I can get customs for ~$1000 with pins and rings on a variety of timelines depending on manufacturer, Probe seemed to offer the nicest for the dollar.

I'm looking for much cheaper 2nd hand parts as I need every penny I can for parts. I'm not in a terrible hurry and at this point I've not even got the block to the machine shop (or checked it with my own equipment) yet to see if the TRW 3.800in bore slugs I have will work.

 

[earlbrown]

I'm working with a piston manufacturer to make 'off the shelf' custom pistons (with an off the shelf price). The price will be a little over half of the $1000 you've been quoted with and infinitely adjustable OD and CH. What is your current stroke, head CC and desired compression?

So you basically need a chevy flattop with a 3.805~.810 buick bore, and an oddball CH?


(and based on my research (and conversations with their 'tech' dept) I wouldn't use Probes to keep papers from flying off my desk)

 

[CTX-SLPR]

It's a 3.0L oddfire destroker for Bonneville so 2.66in crank set up for SBC rods, 6.300in rods with SBC pins and bearings, I'm also running production 84 block and heads. Since I'm using a late intake closing cam, I'm compensating for the reduced dynamic compression with more static so the target is 9.5-10:1 which is flat top territory with 46cc production heads.

 

[earlbrown]

that's going to be a tough one. with a completely flat piston with no valve reliefs .040" off the head is 10:25. 060" quench would get you 9.6:1.

Are you running a short enough cam to achieve those kinds of clearances? I'll be talking to my piston guys tomorrow, I might be able to hook you up with a custom set without breaking the bank.

 

[CTX-SLPR]

You're numbers are running a bit different from mine and the cam will be quite big as well. My current combo with STD bore pistons with 3.7cc valve reliefs, 0.053in down the hole, and a 0.018 HA head gasket and 46cc chambers (taken from Champion, mine are still stock) gives me 9.0. I'm shooting for 0.040 piston to head clearance and if I raised the compression height of the units I have but keep the same valve reliefs (good point on them with the cam) it would get me 9.31: at 0.023 in the hole with the same HG. I'd be happy enough with that since it's what I can get.

 

[CTX-SLPR]

Any luck with your piston connections? Interested to see what they come up with.

Also did you see a number that we are assuming different values for that's driving the difference in static compression ratios?

 

[CTX-SLPR]

Still hoping someone may have a set of 3.810 or 3.820 bore flat tops laying around. Anybody?