engine not fast as it should be

[Furby]

I built a motor following David's book, and the results are less than expected.
It's a 355" sbc with Hyperutechtic flat tops 9/1 comp.
A performer rpm intake.
750 holley carb.
1 3/4" headers.
I found a set of the heads (882 castings)David talks about being a good deal, cause you get them for free, and that's just what happened. The guy at the salvage yard gave them to me.
I had the parts guy at the NAPA store spec a cam out, and as luck would have it he had it in stock.
It's a TRW hydraulic grind with .420" lift on the intake, and .450" lift on the ex. the duration @ .50" lift is 204* for the intake, and 214* for the ex.

I followed David's book, and did a pocket porting , and gasket match job on the heads. Not sure what they flow, but I know a guy with a flow bench that could flow them if you all think that's the problem.

The car started out at 2900lbs, and I got a 7.30 @ 91 MPH in the 1/8 mi. Then the track owner made me install a cage. That slowed the car down to a 7.44 @ 89 MPH.

Then I made some more changes, and got a 7.22 @ 94 MPH out of it.

I seriously thought this combo. would run in the sub 7 sec. range @ 96-97 MPH. Ive had the engine apart and did a re-pocket port and that seemed to help a little but still not the E.T. I expected.

What could be holding this combonation back from it's potential?

[MCEcomp]

Needs more cam and more compression IMO

What stall and rear gear?

[old blue 75]

What is the LCA of that cam? Even thought the 882's were free David has said
that heads with that chamber design are not the best to have. If they were the
small closed chamber design I believe he said you would pick up 30 hp just
from the different chamber design.

old blue 75

[Cammer]

Your engine is performing well for what it is.

IMHO, you need to find an engine builder instead of just throwing parts together.

Do it right the first time and save yourself time, money, and frustration.

[rookie]

I would have to agree with Cammer.

Also if you change anything in a combo ie: air flow, cam, intake, then you are no longer building an engine following David’s book.

If you change anything on a well speced engine then the results will not be as expected.

I would go back and reread David's book and run the same parts, then you will get the same results .

[Furby]

The LSA on the cam is 112*
The converter is a 2800-3200rpm Boss-hog converter, but seems to stall higher than what it's rated to stall. (powerglide)
The gear is 5.38, just what the rearend had in it when I bought it.

So David didn't recommend the 882 csating heads?
I though he said they flowed better, and they were usualy free, making them a good deal.

I know some more compression would probably help, but I want to run 87octain pump gas. Can I run more compression with 87 gas.


Furby

[BlackCat13]

You have a mild street engine with an RV cam/intake in a drag car with 5.38 gears.

You need to step up to 230* @ .050 with a 107-108 LSA,
and of course, the springs, etc. to run that cam.
which of course means...... 10/1 compression.
At that point your intake manifold and heads becomes the cork in the system.

The cam alone MIGHT get you to 7.0.

[rookie]

I don’t know about the 882 castings, I know in his budget small block book he uses a lot of 186 castings.

My point was, if you copy a build that has a head that flows 230 cfm and a cam of a given spec and separation, then you can’t change any of that.

I do know that David would not have the cam on a 112 separation on a NA.motor.

I would lean more toward what Black Cat 13 has advised and find a good converter.

The Boss Hog is a Generic type of conv. And is why it stalls so high.

Is this a race only car?

What are you looking to gat out of it?

[Furby]

I didn't follow one of the builds in the back of the book, just read the book from cover to cover, and followed it as far as trying to port my own heads, and decide on parts, etc.
The car is a bracket car. (drag strip only)

rookie, my converter stalls too much??

Blackcat13, my cam is too small, or wrong?
A bigger cam will get a 7.0?, but no 6.9?


Furby

[99R/T]

Originally Posted by Furby

I didn't follow one of the builds in the back of the book, just read the book from cover to cover, and followed it as far as trying to port my own heads, and decide on parts, etc.
The car is a bracket car. (drag strip only)

rookie, my converter stalls too much??

Blackcat13, my cam is too small, or wrong?
A bigger cam will get a 7.0?, but no 6.9?


Furby

What's the converter stalling at? Tire size?

What's your launch RPM, shift RPM, and finishline RPM?

How does the car behave during the run?