427 SBC Pump gas - Trying to get that 700Hp

[garthpe]

After reading much I was determined to get that 700Hp from SBC on pump gas but failing so far so please please help!

Dart Block (Little M)
AFR 235 heads w crower shaft mount 1.7 rockers
11:1 Compression
Bullet cam .680/.675 lift , 290/302 duration
degree intake lobe 104
Separation 108
ported Super Victor Intake
1 7/8 headers
The tech also did a valve job which eliminated the run out from the factory heads

the best we have gotten so far (tried different carbs) is 630Hp at 6500 and 566 torque at 5300.

We spent a lot of money and time trying get that 700hp....

My motor when built new was 10:1 compression / different cam and just had regular rockers and actually had better stats

Stock carb was quick fuel 850
cam was crower
.653/.645 lift 277/289 duration 110 lobe separation
(these are with 1.7 rockers)

it made 630 hp and 590 Torque...

590 torque at 4700/630 hp at 6500
i do have the dyno sheets of the original build.

so i spent a lot of time and money and kind of went backwards....very frustrating

PLEASE anyone advise!

It doesnt make sense we made things better (more compression , more lift/duration/ valve job) and ended up same horsepower and less torque, and had to fight to get that (different carb). with the stock QF 850 we had 610 HP
.. The goal (other then the 700HP)was to also have it pull harder on top then the original build as It just seemed make lot of noise after 5000 rpm and not pull that great...My engine builder said i might lose some torque to gain that top end HP which I thought was fine as these motors SOO much bottom torque

[Tom68]

Retard the cam, use a Dominator, bigger primaries and if the heads (700's tough without a raised port) and valves are good enough you can rev it up.

[steve cowan]

After reading much I was determined to get that 700Hp from SBC on pump gas but failing so far so please please help!

Dart Block (Little M)
AFR 235 heads w crower shaft mount 1.7 rockers
11:1 Compression
Bullet cam .680/.675 lift , 290/302 duration
degree intake lobe 104
Separation 108
ported Super Victor Intake
1 7/8 headers
The tech also did a valve job which eliminated the run out from the factory heads

the best we have gotten so far (tried different carbs) is 630Hp at 6500 and 566 torque at 5300.

We spent a lot of money and time trying get that 700hp....

My motor when built new was 10:1 compression / different cam and just had regular rockers and actually had better stats

Stock carb was quick fuel 850
cam was crower
.653/.645 lift 277/289 duration 110 lobe separation
(these are with 1.7 rockers)

it made 630 hp and 590 Torque...

590 torque at 4700/630 hp at 6500
i do have the dyno sheets of the original build.

so i spent a lot of time and money and kind of went backwards....very frustrating

PLEASE anyone advise!

It doesnt make sense we made things better (more compression , more lift/duration/ valve job) and ended up same horsepower and less torque, and had to fight to get that (different carb). with the stock QF 850 we had 610 HP
.. The goal (other then the 700HP)was to also have it pull harder on top then the original build as It just seemed make lot of noise after 5000 rpm and not pull that great...My engine builder said i might lose some torque to gain that top end HP which I thought was fine as these motors SOO much bottom torque

590 ft/lbs is 1.38 ft/lbs per cube which is pretty good for pumpgas.
For 700hp you still need to be making 565 ft/ lbs at 6500rpm.
That new cam seems like alot of duration for the rpm/ compression.
Induction system is king.
Are the 235 heads sized for the application?
What valve size,minimum CSA and average cross section for the Induction system?
Need more information if possible.

[garthpe]

The heads are AFR 235 which are perfect for large small blocks..flow info here:

235cc Competition Flow Chart
.200 .300 .400 .500 .550 .600 .650 .700 .800
Int 159 221 261 295 311 318 327 331 336
Exh 120 165 214 228 237 238 243 245 250

Material
A356 Aluminum
Intake Port Volume
235cc
Intake Port Dimension
2.200" H x 1.290" W 5/16 Radius
Intake Port Location
Stock
Exhaust Port Volume
80cc
Exhaust Port Dimension
1.430" H x 1.540" W
Exhaust Port Location
.250" Raised
Combustion Chamber Size
70cc or 80cc
Valve Cover Bolt Pattern
Perimeter Bolt
Valve Angle
23°
Valve Spring Pocket Diameter
1.580" O.D
Max Valve Spring Pocket Machining
1.680" O.D
Warning: Do not machine spring pad any deeper.
Deck Thickness
.750"
Minimum Bore Diameter
4.000"
Flat Mill
.006" per cc 65cc Maximum
Angle Mill
.009" per cc 60cc Maximum
Note: Angle mills might require .120" Thick intake gasket.
Minimum Cross Sectional Area
2.470 sq. in.
Spark Plug Dimensions
14mm x .750" w/Gasket Seat

[RevTheory]

I'd sure want to know if those heads are backing up at higher lifts. Some AFRs seem to be pretty good at that.

Ha! The above post wasn't there when I started typing my two-sentence response, lol

[AA Performance]

Have you got pics of the S/Victor plenum porting? They are crap out of the box. Did a B to B on a ported and standard and was worth 39 HP and 35 ft lbs on a 422ci. That cam 290 / 302 @ .050" is too big and your comp is too low as a start.

[GARY C]

The heads are AFR 235 which are perfect for large small blocks..flow info here:

235cc Competition Flow Chart
.200 .300 .400 .500 .550 .600 .650 .700 .800
Int 159 221 261 295 311 318 327 331 336
Exh 120 165 214 228 237 238 243 245 250

Material
A356 Aluminum
Intake Port Volume
235cc
Intake Port Dimension
2.200" H x 1.290" W 5/16 Radius
Intake Port Location
Stock
Exhaust Port Volume
80cc
Exhaust Port Dimension
1.430" H x 1.540" W
Exhaust Port Location
.250" Raised
Combustion Chamber Size
70cc or 80cc
Valve Cover Bolt Pattern
Perimeter Bolt
Valve Angle
23°
Valve Spring Pocket Diameter
1.580" O.D
Max Valve Spring Pocket Machining
1.680" O.D
Warning: Do not machine spring pad any deeper.
Deck Thickness
.750"
Minimum Bore Diameter
4.000"
Flat Mill
.006" per cc 65cc Maximum
Angle Mill
.009" per cc 60cc Maximum
Note: Angle mills might require .120" Thick intake gasket.
Minimum Cross Sectional Area
2.470 sq. in.
Spark Plug Dimensions
14mm x .750" w/Gasket Seat

Keep in mind that your engine will not see all of the claimed or measured lift so you could be giving up 30 cfm also any instability in the valve train can drastically hurt power.

Here is a very in depth video showing the effects just from a valve spring with a little to much pressure.
https://www.youtube.com/watch?v=Xzt6np8N3p0

[steve cowan]

I'd sure want to know if those heads are backing up at higher lifts. Some AFRs seem to be pretty good at that.

Ha! The above post wasn't there when I started typing my two-sentence response, lol

If they are as cast they probably won't flow those numbers at those lift points.
427 cubes at 6500rpm needs 340cfm ,at 7000rpm needs 365cfm as reference. Not absolute but need something to shoot for.

[garthpe]

Have you got pics of the S/Victor plenum porting? They are crap out of the box. Did a B to B on a ported and standard and was worth 39 HP and 35 ft lbs on a 422ci. That cam 290 / 302 @ .050" is too big and your comp is too low as a start.

I dont have pics but do know it was done by expert , Intake was initially intended for a 355CI race car but ended up being too much and the porter predicted it would be perfect for a bigger small block...We did compare to some other intakes (5 -7 years ago) and the ported victor proved to be decent THEN...

[swampbuggy]

If it were possible for you to do this you could try installing 1.5 ratio rocker arms on the Intakes only, open up the lash some, and see what happens. Are the Duration numbers at .050" lifter rise ?? Sorry if i missed this . Mark H.

[garthpe]

After reading much I was determined to get that 700Hp from SBC on pump gas but failing so far so please please help!

Dart Block (Little M)
AFR 235 heads w crower shaft mount 1.6 rockers
11:1 Compression
Bullet cam .680/.675 lift , 290/302 duration
degree intake lobe 104
Separation 108
ported Super Victor Intake
1 7/8 headers
The tech also did a valve job which eliminated the run out from the factory heads

the best we have gotten so far (tried different carbs) is 630Hp at 6500 and 566 torque at 5300.

We spent a lot of money and time trying get that 700hp....

My motor when built new was 10:1 compression / different cam and just had regular rockers and actually had better stats

Stock carb was quick fuel 850
cam was crower
.653/.645 lift 277/289 duration 110 lobe separation
(these are with 1.6 rockers)

it made 630 hp and 590 Torque...

590 torque at 4700/630 hp at 6500
i do have the dyno sheets of the original build.

so i spent a lot of time and money and kind of went backwards....very frustrating

PLEASE anyone advise!

It doesnt make sense we made things better (more compression , more lift/duration/ valve job) and ended up same horsepower and less torque, and had to fight to get that (different carb). with the stock QF 850 we had 610 HP
.. The goal (other then the 700HP)was to also have it pull harder on top then the original build as It just seemed make lot of noise after 5000 rpm and not pull that great...My engine builder said i might lose some torque to gain that top end HP which I thought was fine as these motors SOO much bottom torque

[garthpe]

After reading much I was determined to get that 700Hp from SBC on pump gas but failing so far so please please help!

Dart Block (Little M)
AFR 235 heads w crower shaft mount 1.6 rockers
11.2:1 Compression
Bullet cam .680/.675 lift , 290/302 duration
degree intake lobe 104
Separation 108
ported Super Victor Intake
1 7/8 headers
The tech also did a valve job which eliminated the run out from the factory heads

the best we have gotten so far (tried different carbs) is 630Hp at 6500 and 566 torque at 5300.

We spent a lot of money and time trying get that 700hp....

My motor when built new was 10:1 compression / different cam and just had regular rockers and actually had better stats

Stock carb was quick fuel 850
cam was crower
.653/.645 lift 277/289 duration 110 lobe separation
(these are with 1.6 rockers)

it made 630 hp and 590 Torque...

590 torque at 4700/630 hp at 6500
i do have the dyno sheets of the original build.

so i spent a lot of time and money and kind of went backwards....very frustrating

PLEASE anyone advise!

It doesnt make sense we made things better (more compression , more lift/duration/ valve job) and ended up same horsepower and less torque, and had to fight to get that (different carb). with the stock QF 850 we had 610 HP
.. The goal (other then the 700HP)was to also have it pull harder on top then the original build as It just seemed make lot of noise after 5000 rpm and not pull that great...My engine builder said i might lose some torque to gain that top end HP which I thought was fine as these motors SOO much bottom torque

Sorry I'm having troubles with editing my post .. the Rockers are 1.6...Compression is 11.2:1 and the headers they are using on the dyno are 1.75/1.875 with 3.5 collector....

[ClassAct]

Post the best dyno sheet so we can see the numbers. Someone said that 1.38 TQ/CID was very good for pump gas. I agree.

[garthpe]

Post the best dyno sheet so we can see the numbers. Someone said that 1.38 TQ/CID was very good for pump gas. I agree.
[/quote]

002.jpg

001.jpg

001.jpg

[garthpe]

Post the best dyno sheet so we can see the numbers. Someone said that 1.38 TQ/CID was very good for pump gas. I agree.

002.jpg

001.jpg001.jpg
[/quote]

these are dynos are original build, I dont have dyno of current...its still on dyno

Right we at 630hp at 6500 and 566 Torq. at 5300