need some poly to hemi info

lucky13 · Post by **lucky13** » Mon Dec 31, 2007 12:25 am

i'm gonna be picking up a 56 331 poly motor in a few weeks. I've got a set of 354 heads, and a hilborn injection for a 392. Will this stuff actually bolt up and work? What are the differences between a poly and hemi? I'm guessing i'll need 354 pushrods, head gasket, and head bolts. Will the injection work ok with the 354 heads? I am also gonna be putting a viper t56 behind this motor and slapping all of it into my 31 model A.

George · Post by **George** » Mon Dec 31, 2007 8:31 am

You need to change to Hemi pistons also. The heads & FI will work. You do need the push rods, head bolts, ex man. There have been reports of push rod clearance problems were they go through the block, don't know if stock or aftermarket, or if just on a few blocks. Many have been changed over, so just watch out for it.

lucky13 · Post by **lucky13** » Mon Dec 31, 2007 12:56 pm

thanks for the info. I was gonna be running open headers with some sorta baffles in em. So if i got an engine kit for a 331 hemi everything should be ok then right? As you can see im pretty new to hemis and need as much info as possible.

George · Post by **George** » Mon Dec 31, 2007 5:37 pm

I think the '55 331 gasket set is what you need. You might want to check to see what size the head locating dowels are, same as '55 or not If no one can say here, talk to Bob Walker at www.hothemiheads.com (there's also a forum there).

lucky13 · Post by **lucky13** » Thu Jan 03, 2008 9:36 pm

well i decided to actually pull my heads out and really look at them. It turns out they are casting number 1731528. So it turns out what i was thought were 354 heads are really 392 heads. Will these work or will i have to find some other heads?

George · Post by **George** » Fri Jan 04, 2008 8:38 am

Yes, but it's not worth the effort. You would have to make a single log intake for this specific application, or use a twin log, plus a chevy W/P & a hose type aftermarket water crossover. Get '55 331 or '56 354 heads. less desirable would be the 54 331 heads & intake, but better than the 392 heads!

lucky13 · Post by **lucky13** » Sat Jan 05, 2008 3:46 pm

i've got an early hilborn injection setup that im gonna be using

George · Post by **George** » Sun Jan 06, 2008 7:59 am

forgot to mention, you may have valve to cylender wall clearance problems with the 392 heads on a 331. Never payed attention to the Hilborn, is it 2 pieces, one per side? if so it will fit. The 392 heads are wide across where the manifold goes so a stock one piece intake won't fit.

lucky13 · Post by **lucky13** » Sun Jan 06, 2008 8:33 pm

yah its has 2 sides, and the ram tubes come straight off the ports

DblAdigger · Post by **DblAdigger** » Wed Jan 09, 2008 12:00 am

You are going to have 1 GIANT problem trying to run a constant flow HILBORN injector on the street. If you doubt this, call HILBORN, (949)360-0909 and ask them. If you really want to run the stack injectors, ask them about converting them to EFI...which IS streetable.

lucky13 · Post by **lucky13** » Wed Jan 09, 2008 2:29 pm

i am going to be converting it to efi myself, gonna hide it all under a fake valley tray.