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Topic Review (Newest First)
06-19-2002 04:59 PM
Tom I did this quite a few years ago for the shop tow truck, it had a 402bbc that blew up and we couldn't find another big block at the time so we built a 400 sm block and used 305 heads for the torque factor this engine pulled better than the big block,pinged a bit but would haul anything. it had a stock 2bbl and exhaust manifolds
06-18-2002 09:50 PM
agb1758 According to the engine calculator, if you run standard bore (4.126")with 3.75 stroke, gasket bore 4.190, compressed gasket thickness .039, 60cc 305 heads, with .083 dish pistons, it calculates out to 12.92:1 compression. You can download the engine calculator,but I don't remember the web site. If you look back through the bulletin board postings under engines you can find it. Be sure to check valve clearances.

[ June 18, 2002: Message edited by: agb1758 ]</p>
06-17-2002 06:24 AM
CrazyT Man that sounds pretty awesome, i had already decided not to use the 305 heads, but now i don't know what to do. How much difference will there be with using the 400 rod? The casting on my 305 heads is 354434.
Thanks for the info
06-16-2002 09:40 PM
agb1758 I built a 400 and used 305 heads, drilled steam holes. Motor runs strong, got it in a 83 suburban, turning 15's in 1/4. It has .083 dish pistons with 400 crank and 350 rods, and cam 462/480 lift. Not having any heating problems. I did find out that with the 305 heads I'm running 12.35:1 comp. and around 490 hp. You'll also be running 1.84 intake valves with the 305 heads instead of the 1.72 intakes.

[ June 16, 2002: Message edited by: agb1758 ]</p>
06-16-2002 07:39 AM
CrazyT What i am trying to do is get more compression without changing pistons. I want to be around 10:1 or maybe 10.5:1, could i mill a little off the heads and put in a .015 head gasket and do what i want. That would keep the 76cc heads on the motor and would get my compression up some. I have access to a machine shop so machine work is free, but new heads and pistons aren't.
06-15-2002 01:41 AM
deuce_454 honestly with the money youll have in valvesprings, retainers, valves and labour....

you wouldnt go ahead and bolt old worn heads on a motor you intend to use yourself would you...?

and wrench turner is right in saying that there is a lot of edges.. 400 have bigger bore than a 305 so you need some pocket porting also.. now it would be much cheaper, and give you way way better results to buy a set of Dart or Motown heads..

and if you cant afford the propper heads now then save up your money till you can.. remember that the heads are where the horsepower is made

hope it helps
06-14-2002 11:29 PM
wrenchturner I dont know if yuo should attemped that with out doing some work on those heads you would have a lot of sharp egdes hanging in them bores.I think I would stick with the 76cc heads.just a opinion (wrenchturner)
06-14-2002 10:33 PM
How about 305 heads on a 400

I just bought a street stock circle track car and i need to throw a motor together quickly and i have not money. It is a 400 out of a 73 monte with dish pistons, should i go with the 305 heads and drill the steam holes or stick with the original 76cc heads. The car i suppose to top out a 5500 rpm, any help is appreciated.


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