Pulling truck engine "again" BBC

[af2]

Sounds to me like you have it all figured out, so why are you asking anybody here on what to do and what will get your client in the winners circle at those pulls.

Just come back and tell us how your idea worked and how many pulling competitions this engine won!

Sorry to have taken your time trying to confuse you.

Since the crank and rods he has won't work,
What crank and rods do you use in the pulling truck engines you build at this type of power level ?

Randy

LOL Randy brings out the best every time!!! And not a dis at Randy at all..

[Newold1]

I don't build engines for free, so I guess I am in the dark here even more than I should have thought before commenting on this post. No mention of class limiting cubic inch rule or otherwise. No mention that much of the added at free and just a few mentions of budget. Kinda just a lot of small pieces of mud thrown at the wall and most not sticking so, I apologize for trying to possibly help, so I am out. Enjoy!

[steve316]

newold1 now you are sounding like that other guy.

[randy331]

Sounds to me like you have it all figured out, so why are you asking anybody here on what to do and what will get your client in the winners circle at those pulls.

Just come back and tell us how your idea worked and how many pulling competitions this engine won!

Sorry to have taken your time trying to confuse you.

Since the crank and rods he has won't work,
What crank and rods do you use in the pulling truck engines you build at this type of power level ?

Randy

LOL Randy brings out the best every time!!! And not a dis at Randy at all..

LOL, just trying to put a value on advise given.

Randy

[randy331]

I decided to do a little fitting and testing on the heads I have for the BBC pulling truck engine this thread is about.

I fit them to the block and reached up in the bores and scribed the top of the bore where the chamber over hangs the bore and they overhang past the notch in top of the bore. Someone has already been grinding on the chamber some. I'll need to address that fit to the bore.

So I flowed one in a few positions on the test bore on my flow bench. It seems sensitive to hanging over the test bore some.


What have others been getting for cfm on a rec port head ? This head has a 2.25 intake valve.
And has anyone else done any testing with the chamber not lined up with the bore ?
If so what were the results ?


Maybe I need to find a way to move the heads over .100" on the block ??


Randy

[zums]

I decided to do a little fitting and testing on the heads I have for the BBC pulling truck engine this thread is about.

I fit them to the block and reached up in the bores and scribed the top of the bore where the chamber over hangs the bore and they overhang past the notch in top of the bore. Someone has already been grinding on the chamber some. I'll need to address that fit to the bore.

So I flowed one in a few positions on the test bore on my flow bench. It seems sensitive to hanging over the test bore some.


What have others been getting for cfm on a rec port head ? This head has a 2.25 intake valve.
And has anyone else done any testing with the chamber not lined up with the bore ?
If so what were the results ?


Maybe I need to find a way to move the heads over .100" on the block ??


Randy

[zums]

I decided to do a little fitting and testing on the heads I have for the BBC pulling truck engine this thread is about.

I fit them to the block and reached up in the bores and scribed the top of the bore where the chamber over hangs the bore and they overhang past the notch in top of the bore. Someone has already been grinding on the chamber some. I'll need to address that fit to the bore.

So I flowed one in a few positions on the test bore on my flow bench. It seems sensitive to hanging over the test bore some.


What have others been getting for cfm on a rec port head ? This head has a 2.25 intake valve.
And has anyone else done any testing with the chamber not lined up with the bore ?
If so what were the results ?


Maybe I need to find a way to move the heads over .100" on the block ??


Randy

Funny you say that, i just bought a 1" slab of plastic to mill to fit on the bench perch to notch and test, dont have any before and afters yet but offset dowels and moving the head toward the intake can take a little major valve diameter out of the bore wall
Tom

[randy331]

Tom, what kinda cfm have you got from BBC factory rec port stuff ?

Randy

[zums]

Tom, what kinda cfm have you got from BBC factory rec port stuff ?

Randy

I should have been more clear, still 23* sbc stuff, latest build need some bore notching on in side, wanted to check how much if any the .160 deep notch helps
Tom

[Old School]

If you find an easy way to move the heads let me know. I moved a set .060 and it was very time consuming. Bolt holes had to be elongated, intake bolt holes elongated, ports epoxyed and aligned just to get the major work. Smaller washers under the head bolts or mill the recesses larger, check pushrod clearance are some more issues.

The customer will have to realize how much work this is and how much time it takes. Its something one would do on their own engine is the last few horsepower is needed. I picked up about .06 in a drag car running low 10's in the quarter after moving the heads. That was many years ago and with a 45 degree valve job.

If you can get the GM rectangle head to flow in the 350's thats not bad on a 4.31 bore or less. I see a lot of flow numbers on the internet of 370-380, very good if on a small bore. The good/bad ports have more difference on the GM heads than the better later after market heads.

[randy331]

Tom, I'd still be interested in what you find out on your 23* tests.

Oldschool, thanks for the info. .06 sec. would be some power for sure. This is on the dragster you race ?

These heads had the "short burr" port job on them. Whoever did it radiused the throat/seat area out to where there isn't any angles to speak of below the 45* angle. The last BBC pulling truck engine I did had the same type of porting done to them as this set of heads does. They were 990 castings. Radiused the throat/seat area etc. Almost looks like the same guy did these 2 sets of heads. Interesting thing is, that last one didn't make as much power as the oval port one I did before. All that cfm don't seem to show up as power.

This set will get a valve job and some port work.
He has a sniper jr. for this one and it's the one with the small exits for port matching, so if I move the heads I can get that part matched up.

As you said,.. it's just a bunch of time. LOL
But,.. he's paid ahead on things so far,...


Randy

[CGT]

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.

[Roadknee]

I'm a little late regarding short block rotating torque, but I feel another data point doesn't hurt. I have a street 496 on the stand with 1.5/1.5/3.0 total seal file fit rings in what I think are well prepped bores. It takes between 17 and 20 ft-lbs to roll over depending on how many pistons are dwelling at TDC or BDC.

Regarding BBC rectangular port flow, Vizard's latest BBC book references a set of Chad Spier 088 castings with 2.3/1.88 valves. The average good/bad intake port flow starts to nose over at about 0.700 lift and makes 360 cfm. Flow at 1" looks to be about 380 cfm. Exhaust flows about 230 cfm at 0.700" lift.

[Newold1]

This is a pretty nice reference material on a lot of BBC chevy heads.

http://users.erols.com/srweiss/tablehdc ... _Big_Block

[GARY C]

I decided to do a little fitting and testing on the heads I have for the BBC pulling truck engine this thread is about.

I fit them to the block and reached up in the bores and scribed the top of the bore where the chamber over hangs the bore and they overhang past the notch in top of the bore. Someone has already been grinding on the chamber some. I'll need to address that fit to the bore.

So I flowed one in a few positions on the test bore on my flow bench. It seems sensitive to hanging over the test bore some.


What have others been getting for cfm on a rec port head ? This head has a 2.25 intake valve.
And has anyone else done any testing with the chamber not lined up with the bore ?
If so what were the results ?


Maybe I need to find a way to move the heads over .100" on the block ??


Randy

DV told me in his test of matching the chamber bore and piston on a BBC he gained about 12 hp. Not sure about flow #.