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#1
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Want to make a respectable ride
I have a 78 3/4 ton trck with a 400 b block . What are some ideas i need to do to bring it up to at least the specs of the earlier HP 400s . I would like to use stock parts except for intake and carb which i have allready done . I also want to know if i can put 440 style series 300 heads on my block and can this block be bored or stroked any more or is it at its limit already . Thanks for the help .
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#2
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The main thing that 400's lack is compression(7.5:1 factory). Almost all b/rb heads are interchangable, and can be made to breathe with some port work(some castings more than others).
Rebuilding the engine with taller pistons will get you compression. I have done things differently, as I have explained on other boards. First I dissassembled the engine, and had .085" shaved off the block deck. The Stock pistons only come to within .100" of the top of the deck. That, with a set of 516 casting heads(78cc pre 1966 b/rb heads) gets me to 9.95:1 with a .039" compressed head gskt(felpro, actual installed measurement, not a supplied spec) I used the older heads, because of the smaller chamber volume(to help compression), and the "closed" chamber design. The closed design is seen on modern applications, as well as aftermarket performance heads. With the compression, I now going to use, a mild performance cam. The heads have had mild porting, and gasket matching with both the intake and exhaust manifolds. I had to machine .090 off of the intake( a 69 383 intake), so it would fit, and had to fabricate a intake gskt(see thread "custom intake gasket"). the engine bores only have .004" taper, So I have deglazed them, and replaced the rings. No rebore. The heads are "leaded fuel" heads, and I pull a trailer, so I had them rebuilt with new valves, and new seats(seats, on exhaust only). I've got it assembled, and hope to install it in the next 2 weeks. Hoping for 350 horse power( a hp 383 was 335 stock). The 78 400 probably rated in the low 200's originally. As for other options, look at the thread "451 vs 440". A 451 is a 400 bored .030" over with a 440 crank shaft) Gets you RB torque in a B block engine. Also the benifits of less rotating mass. Lots of machining and parts required, but is relatively simple. |
#3
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dave571;
Your post sounds good right down to your sig. Bret; A 400 stroked with a RB crank is a good way to go. If it's out of reach, ($$$), mill your heads to get the comp. up and slide in a Road Runner cam at min. RR's were a respected quick running car even with the 383. With an extra 17 cubes and lite porting, you'll run fine. |
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