Pulling truck engine "again" BBC

[Newold1]

Back in the 60's Smokey Yunick and Grumpy Jenkins were pulling flow down cylinder bores with heads on the blocks to improve chambers and valve orientation and their winning record seem to point to the fact that there was some power to be found there!

This is also why most head designers, porters, head shops and and knowledgeable flow bench operators make sure they flow particular heads on specific bore size fixtures to make sure heads and chambers are as optimized as possible for particular bore diameters.

However as many know the particular shape and size of combustion chambers especially diameters can radically affect the flow of air into the chamber sometimes irrespective of the bore size unless shrouding occurs.

[randy331]

Well, I noticed from looking at the pistons that were delivered last night that you did some work to the dome, that almost has to help....at the very least it should keep it from beating the plugs shut. Its amazing that big block chevies in that form do what they do, wicked crude in so many ways. But tough I suppose is an advantage they have.

Its kinda of hard to believe that a BBC is roughly a 10yr newer design than a sbc. Look at what happens in engine design in a decade span now.

BBC do seem a little,.... well not designed for pulling trucks. LOL

Got the go ahead to do some work on the heads. like some more compression, but it ain't easy on these things.
I'd like to weld the chambers up some to get some compression.

Local sanctioning body took our class on for next year. (NWMO) We pulled IAMO last year.
I can already see it getting outta control. OEM heads but almost unlimited what you can do to them.
Got one truck with welded up heads that will be running next year.
A couple I've built engines for are talkin big bore short stroke, welded head engines.


Be fun along the way to out of control. LOL

Randy

[randy331]

Total Seal has a oil ring that's rated at 8 LBs for this BBC engine.

Is 8 LB too low with vacuum ?

Randy

[Walter R. Malik]

Total Seal has a oil ring that's rated at 8 LBs for this BBC engine.

Is 8 LB too low with vacuum ?

Randy

That will depend upon the flexibility of that particular ring.

[randy331]

Well, the 8 pound rings are on the way.

Guess we'll see how it works out.

Randy

[steve316]

They will work just like you think they will.( great )

[swampbuggy]

Will 8lb. rings work WITH vacuum ? Randy.......HOW MUCH vacuum will be produced by your pump, specifics are extremely important on this forum ! Mark H.

[Newold1]

I am curious what can be done to the chamber on an early 396 BBC head with some port,bowl, throat and valve work? If compression is the ultimate goal the closed chamber could be shaved a bit and even with a little opening up on the plug and shrouding around a 2.19" intake and come in with less cc's in the chamber? A custom flat top dome on a custom piston could probably get the compression up pretty well and still have some decent flow closer to iron rectangle ports.

Remember a closed chamber 396 head we cut open back in 1969 when we were experimenting with what we could do with oval port heads, but I can't remember how much material was around the chamber on the plug side?

Anybody else here cut one of those old antiques apart? Just a thought versus welding an iron head chamber.

[randy331]

Will 8lb. rings work WITH vacuum ? Randy.......HOW MUCH vacuum will be produced by your pump, specifics are extremely important on this forum ! Mark H.

Whatever a GZ pro pump will pull.
Probably 15-16 inches.

Sorry for leaving out the details


Randy

[swampbuggy]

Sure my friend, thats pretty darn good vacuum, if you got that much i'm bettin you will be good to go. Not an expert on this topic, but i would be optimistic ! Mark H.

[steve316]

I have pulled as little as 6" and was ok with 8# rings, any more than that would just be less HP left on the table

[randy331]

Well,.... if it would help us reach our goals,... we'd be willing to get rid of "The Stock 90 Chevy Truck Hood" !!!


Randy

[CGT]

1120181308-001.jpg

Holy Carb!

[randy331]

Does that carb look big enough ?

Randy

[CGT]

Does that carb look big enough ?

Randy

Is it a high lift flow carb or a low lift flow carb?