<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" UNSELECTABLE="on" width="100%"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">G'day, a quick question if I may, as I'm in the process of ordering parts for a rebuild, in particular custom forged pistons, and need a bit of guidance / direction. Here's the basic storyline..... "In a small shed far, far away....." My friend Jim and I both are in the process of building our hemi's, both are 1951 331" Chrysler HEMI's, with mine being mildly blown(is there such a thing?), and Jims being the same, except his will be naturally aspirated (twin 4's). My block is virgin, and having had it checked over, will be leaving it that way, with a standard bore size, factory crank, nothing off the deck height required, mild tidy up of heads, keeping the valves the same size. Basically new consumables, cam, odds and ends, everything given the once over to check its fine and serviceable, with a blower pumping a 5-6psi, nothing flash, just consistant, reliable, and as basic (read budget minded) as I could get without giving up my dream of having a blown hemi. Jim's engine is a tad crankier, with the block recieving a +030 thou bore, a 20 thou deck tidyup, larger valves and tidy up, cranky cam, and a few other mods to wake the old girl from it's sleep. Anyhow, our dilema, we each want to order custom forged pistons, and since we're talking custom (read: $$$) we want to get this right. Now, my understanding is that we need two variables identified, those being the actual deck height, and the head cc (we know the crank, rod/gasket crush sizes). Now, for the deck height, my understanding is that our 331's are supposed to have a deck height of 10.32", but we've measured Jims block and keep coming up with a number of 10.4" (10 3/8")....WTF? Note: yes we understand that there is a little lip where the main cap sits, and allowed for that....measuring very carefully from the centre of the crank to the deck.... and then the head (1951 small valve) cc....we sat the head flat, closed the valves, used a syring filled with water and came up with a number of 100cc....does that sound about right? 1. does the above number sound about right? 2. is varience in head height (when compared with listed info) a common thing amongst the early hemi's, or should I keep measuring till I get 10.32" Any of you experienced guys have any suggestions or reccomendations on what to do? </TD></TR><TR UNSELECTABLE="on" hb_tag="1"><TD style="FONT-SIZE: 1pt" height=1 UNSELECTABLE="on"> </TD></TR></TBODY></TABLE> Cheers, Drewfus
Drew~ A good set of 12" calipers will get you close enough. Infact, all the piston people need to know is stroke, rod length, deck height and they can move the pin height wherever it's needed. I'll do some checking today to see what the 331's normal cc's are. We got TONS and TONS of 392's here and some 331's I think. Whats your guys' casting numbers? Hemi's are usually a little closer than that from what I've seen. Mike
On Webrodder Doc Fromader did a long tail block build. On the one he had the two banks were different heights, & they wern't square to the bore front to back or top to bottom. You might want to look up the thread, may have the measurements you need.
Not sure if this any help Drufus, but this is what I have found so far. Hot Heads Product: Hot Heads Material: Aluminum Head Fitment: 331/354/392 Hemi Port Job: As Cast/Race Port Combustion Chamber Shape: Hemi Combustion Chamber Volume (cc): 100 Intake Runner Volume (cc): Based off of the 331 Exhaust Runner Volume (cc): Based off of the 331 Intake Flow at 0.600 Lift With 28 Inches of Vacuum: 274/367 Other Applications: None For more information, contact: Hot Heads Research and Racing Inc. (336) 352-4866 www.hothemiheads.com
<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" UNSELECTABLE="on" width="100%"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">'Class A', the block number is C51-8 566 7I Thanks Glenn for that head info, confident we're sorted there now thanks. As for the 'deck height' issue, after a few more 'checks' and 're-checks', and a few more 'checks' for good measure, we came up with a number of 10.376", so looks like we'll run with that....Note: we've since decided to up the compression to 9.5:1 (on the un blown engine). Cheers, Drewfus </TD></TR><TR UNSELECTABLE="on" hb_tag="1"><TD style="FONT-SIZE: 1pt" height=1 UNSELECTABLE="on"> </TD></TR></TBODY></TABLE>
The Jalopy Journal
