Posted By: moparmattkos
Could someone tell me what this works out to?? - 09/20/10 04:27 AM
I was thinking about this piston for a forged replacement for a 400bb standard stroke ,standard length rods. Can anyone tell me what the compression ratio would be with these and 75cc heads??
http://cgi.ebay.com/ebaymotors/Wiseco-63...sQ5fAccessories
Posted By: 1_WILD_RT
Re: Could someone tell me what this works out to?? - 09/20/10 04:42 AM
You do realize that auction is for a single piston, they only have two in stock & there are R&L hand versions of those pistons
Posted By: moparmattkos
Re: Could someone tell me what this works out to?? - 09/20/10 04:48 AM
Yes I know. I have found a set of these cheap. I think i could make them work for a .035 overbore 400 but i didnt know if i would have to have any milled off the top of the piston. I can get a set of these new for 100.
Posted By: 1_WILD_RT
Re: Could someone tell me what this works out to?? - 09/20/10 05:00 AM
Well with a stroke of 3.38 divided in half is 1.69... a rod length of 6.358 & a C/H of 2.06 you get a combo height of 10.108 & the deck height spec of 9.98 you have .128 above deck to account for... A thick head gasket, an open chamber head & likely some milling on the dome... Is it worth it, you decide...
Posted By: moparmattkos
Re: Could someone tell me what this works out to?? - 09/20/10 05:00 AM
Bill I have this calculator also but with this one i cant put in the compression height of the piston or the deck height. So I dont think it will be very accurate for me.
Posted By: 451Mopar
Re: Could someone tell me what this works out to?? - 09/20/10 05:22 AM
That piston has a 2.060" compression height for a 440 RB block. In a 400 'B' block it will be 0.128" above the deck. I don't know if the piston can be milled that much, and you would still need valve pockets. Also, the top ring is going to be very close to the top of the deck.
Posted By: moparmattkos
Re: Could someone tell me what this works out to?? - 09/20/10 05:30 AM
So if this is right then this piston will be - .072 in the hole before decking the block right?
Bore Blck Comp height 73cc
232453 4.375 10.699 1.858 10.1
Dome Vol Gram weight
-28.9 710 grams
What would compression ratio on this be with a 75cc head and a .20 head gasket with surfacing .010 off the block????
Posted By: moparmattkos
Re: Could someone tell me what this works out to?? - 09/20/10 05:45 AM
Yes I have a option on these 2 different sets of pistons. Im thinking the second other one could work out better.
Posted By: 1_WILD_RT
Re: Could someone tell me what this works out to?? - 09/20/10 05:49 AM
A c/h of 1.858 will leave you .074 in the hole.. Not real good either..
Posted By: moparmattkos
Re: Could someone tell me what this works out to?? - 09/20/10 05:52 AM
Oh and I forgot to mention my compression goal is about
8.5 to 1 compression. Boosted set up
Posted By: 1_WILD_RT
Re: Could someone tell me what this works out to?? - 09/20/10 05:58 AM
Are there valve reliefs? Without reliefs, with a .021 gasket your around 9.4-1... With a .039 gasket & 4cc valve reliefs your down to 8.75-1 so that set is pretty workable for what you want..
Posted By: moparmattkos
Re: Could someone tell me what this works out to?? - 09/20/10 06:12 AM
no reliefs it is a dish with a -28.9 cc dish
Posted By: 1_WILD_RT
Re: Could someone tell me what this works out to?? - 09/20/10 06:19 AM
Back to a .021 head gasket & the C/R drops to 7.52
