Just for fun ;-)

Discussion of the 331-354-392 HEMIs.

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DavidBraley
Posts: 163
Joined: Sat Jan 30, 2010 7:40 pm
Location: Fort Collins, Colorado

Just for fun ;-)

Postby DavidBraley » Sun Sep 18, 2011 2:33 pm

Brian Bass's 29 Model A Coupe. This one runs a 331 that sounds just right:

http://www.youtube.com/watch?v=iNETPlz9nPw

As I've mentioned before, this car is a huge inspiration for my own 29 project. :wink:

David
Horsepower determines how fast you hit the wall. Torque determines the size of the hole you make. Holzwarth's Law

Rob
Posts: 208
Joined: Thu May 05, 2011 10:15 pm

Re: Just for fun ;-)

Postby Rob » Sun Sep 18, 2011 6:43 pm

Thanks for posting that, David. I am hoping mine will hit that hard. I just sent the cam to be reground at Oregon Cam Grinders. Going with .435 lift and 240 duration @ .050 on a 106 lobe separation. Solid of course. I wanted the lift low so as not to stress the long exhaust rockers. It should sound mean.

mart
Posts: 536
Joined: Tue Mar 22, 2005 2:06 pm

Re: Just for fun ;-)

Postby mart » Mon Sep 19, 2011 5:41 pm

Rob wrote:Thanks for posting that, David. I am hoping mine will hit that hard. I just sent the cam to be reground at Oregon Cam Grinders. Going with .435 lift and 240 duration @ .050 on a 106 lobe separation. Solid of course. I wanted the lift low so as not to stress the long exhaust rockers. It should sound mean.

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Lookin' good! Your cam specs sound 'right on' for nice 'street motor'. Besides being easy on the exhaust rockers in particular, the .435 inch lift should also be relatively easy on valve springs too. And 240 degrees duration at .050 should give you a nice, just slightly ragged "lope" at idle - and make some killer mid-range power. It sounds like good match for your (very nice) homebrew 2-2bbl. Rochester carb set-up as well. Speaking of valves springs - have you figured out what your gonna' use? The stock truck engine valve springs, even if they seem to be still in good shape, should be replaced. Besides age and loss of tension due to fatigue, I'd be concerned about the possibility of coil bind, even with the relatively mild .435 inch lift. A broken (due to either fatigue and/or coil bind) stock valve spring can cause you to drop a valve and destroy the whole engine in a split-second! (OUCH!!) Dedicated hemi stuff tends to be expensive, but if you do a bit of searching and studying, by using the stock seat diameter and installed height specs as a basis, you can likely find a cross-reference to some fairly common OEM or relatively inexpensive aftermarket spring that will work well. Remember too, when searching for a suitable valve spring, that hemi valves, due to their large size, tend to be heavier than a lot of other - and particularly, heavier than most small-block engine - valves - and that with your cam specs and carb set-up, you'll probably make peak power somewhere right around 6000 rpm - which is about 1.5 to 2 times higher than where the original truck engine would have peaked - you'll want a valve spring with a fair bit more seat pressure than the original truck valve springs had too.

mart
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Rob
Posts: 208
Joined: Thu May 05, 2011 10:15 pm

Re: Just for fun ;-)

Postby Rob » Mon Sep 19, 2011 6:10 pm

Yup. I have a new set of Ultradyne single springs with the just the right seat and open pressure. Got them in a trade.


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