Porting sbc heads?

[skinny z]

Ok, I must preface this question by saying this is a budget class so I’m trying to use what I have but make as much power as I can. Rules are:
Engine must be vacuum-pumped and measure no less than 14 inches of vacuum at 900 rpm. Must have a 3/16-inch port in the intake manifold to hook up vacuum gauge. 4412 Holley gauge legal allowed.

6,200 rev limiting device and must weigh a minimum 3,000 lbs., including driver after race. Must run factory cylinder heads (no aftermarket race heads allowed). Must run flat top or dish pistons. Must have a cranking compression no higher than 150. Must run factory-style stamped steel rocker arms.

What I have is an 350(010) block, 4340 used 3.750 stroke crank(20 main/30 rod main, and 991 open chamber heads.
3/8 mile dirt track. Using pump gas but eventually will be running E-85 fuel.

What porting would I need to do and other mods to make the 991 work as efficiently as possible within these rules?

I would use a 441 casting.

No Vortec's?

[vortecpro]

Ok, I must preface this question by saying this is a budget class so I’m trying to use what I have but make as much power as I can. Rules are:
Engine must be vacuum-pumped and measure no less than 14 inches of vacuum at 900 rpm. Must have a 3/16-inch port in the intake manifold to hook up vacuum gauge. 4412 Holley gauge legal allowed.

6,200 rev limiting device and must weigh a minimum 3,000 lbs., including driver after race. Must run factory cylinder heads (no aftermarket race heads allowed). Must run flat top or dish pistons. Must have a cranking compression no higher than 150. Must run factory-style stamped steel rocker arms.

What I have is an 350(010) block, 4340 used 3.750 stroke crank(20 main/30 rod main, and 991 open chamber heads.
3/8 mile dirt track. Using pump gas but eventually will be running E-85 fuel.

What porting would I need to do and other mods to make the 991 work as efficiently as possible within these rules?

I would use a 441 casting.

No Vortec's?

I didn't think of that.

[skinny z]

I would use a 441 casting.

No Vortec's?

I didn't think of that.

Are they worthy of consideration?
For the cheap and fast drag racing hobby guy (as in yours truly), it was the go to for a lot of years.
As for class racing of any sort, I'm not qualified to comment.

[vortecpro]

No Vortec's?

I didn't think of that.

Are they worthy of consideration?
For the cheap and fast drag racing hobby guy (as in yours truly), it was the go to for a lot of years.
As for class racing of any sort, I'm not qualified to comment.

I think you made a valid point

[88bluestar]

I would love to use vortec but seems I can’t find a cheap usable set and more than likely may have to buy new.

[skinny z]

I would love to use vortec but seems I can’t find a cheap usable set and more than likely may have to buy new.

I suppose you'd have to define cheap.
The least expensive iron version I've come across is Summit's knockoff. $550 USD each, assembled. Although assembled with what I can't say.
What I DO know is that there's not member here that wouldn't take them apart and offer a critique.
My RHS versions have gone through too many refreshes and repairs to make sense but having said that, I'd have chewed up any cylinder head the same way. So the cost of ownership is another thing to consider.
But out of the box and go...that's a consistent and constant question for the hobby guy such as myself.
I bought my RHS bare and assembled them with my choice of springs and hardware.
The Vortecs I bought as new were eventually modified with screw-in studs and different seals, which in turn afforded more lift. Not to mention clearancing the pushrod holes for added rocker arm ratio. Where's the economy in that? But that cost incurred was incremental. Like most things in hot rodding and racing.

[88bluestar]

I have one 062, hoping to eventually find another clean core.

[travis]

Where are you located? I might have some usable vortec's that I'd be willing to let go of.

I've never compared ported smog castings versus vortec's, but stock for stock there is no comparison. There is about a 1 full point of compression increase that you would have to take into consideration though (for your cranking compression numbers)

[88bluestar]

What is the opinion on using the 083 corvette head with this combo?
I gather it is a precursor to the vortecs with similar chamber plug boss. I notice Carnut had done a few post in regards to it as well as on youtube.
I'm open to different ideas. Would it match up the a 2701 edelbrock intake?

[F-BIRD'88]

The 083 TPI head was never used on Corvette L98 engines. It was on the Camaro L98's
The Corvette L98 got the Aluminum #128 (early), #113 head. (Later D ex port)
Yes the 083 will fit .Its standard port opening.Flow is modest in as cast form. Gets very good with full porting and larger valves. Blocking the twinned center ex port heat risers is a big +++ too.
Center 4 intake bolts are angled.
The #081 305 TPI version responds to the same thingy.
58cc vs 64 cc chambers.
Considered the camel back heads of the '80's.
(Similar perf potential once modded.)