Catalina 400 with 14 heads - Pontiac GTO Forum
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post #1 of 5 (permalink) Old 03-05-2018, 08:08 AM Thread Starter
 
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Catalina 400 with 14 heads

I have a motor that appears to have come out of a 68 Catalina - 400 with 14 heads. According to my research this was a low compression motor that produced only ~265 hp. That said the previous owner setup the tri power on the car and might have done a cam as I cannot find a vacuum leak and am only getting 11 - 12" vacuum. (Car idles like butter and pulls hard to 5k.)

My question is how did standard GTO 77 head gain ~100 hp over the 14? According to Wallace Racing's compression hp calculator , the increased compression of the 77 head certainly should not have been that much. The 77's had 1.92/1.60 valves and 10.5 c.r., whereas the 14's had 1.96/1.66 valves and 8.6 c.r. I've been told that the heads for the most part are all the same (minor differences), with the exception of a few special high compression heads. So does that mean the original cam in this motor was a stump puller? Can much (50+ hp) of the "lost hp" be gained by a better cam?

Thanks in advance!

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #2 of 5 (permalink) Old 03-05-2018, 03:09 PM
 
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"...My question is how did standard GTO 77 head gain ~100 hp over the 14..."


The engine with #14 heads had less compression(less than 9:1), and came with a 2-barrel carb & small cam.

http://www.wallaceracing.com/enginesearch4.htm


"...Can much (50+ hp) of the "lost hp" be gained by a better cam?..."

It's possible, depending on how small the old cam is, and how correct for the engine the "better" cam is. A small Voodoo cam, such as a 256 or 262, will increase cylinder pressure, vac, and power/torque in the lower rpm range, compared to a cam with too much duration.

http://www.lunatipower.com/Product.aspx?id=1774

http://www.lunatipower.com/Product.aspx?id=1775

These cams will also require stronger than stock valve springs.
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Last edited by bigD; 03-05-2018 at 03:32 PM.
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post #3 of 5 (permalink) Old 03-06-2018, 07:11 AM Thread Starter
 
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Originally Posted by bigD View Post
"...My question is how did standard GTO 77 head gain ~100 hp over the 14..."


The engine with #14 heads had less compression(less than 9:1), and came with a 2-barrel carb & small cam.

Wallace Racing's Pontiac Engine Search


"...Can much (50+ hp) of the "lost hp" be gained by a better cam?..."

It's possible, depending on how small the old cam is, and how correct for the engine the "better" cam is. A small Voodoo cam, such as a 256 or 262, will increase cylinder pressure, vac, and power/torque in the lower rpm range, compared to a cam with too much duration.

Voodoo Hydraulic Flat Tappet Cam - Pontiac V8 256/262 - Lunati Power

Voodoo Hydraulic Flat Tappet Cam - Pontiac V8 262/268 - Lunati Power

These cams will also require stronger than stock valve springs.
Thanks BigD !

Any thoughts on the Comp Cams XE series ?

My car is a manual with a 3.55 rear and 26" tire/wheel package. Generally I am in the 2,500 + rpm range and love to let her run hard to 5500. Thanks again for your help.

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #4 of 5 (permalink) Old 03-06-2018, 01:25 PM
 
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"...Any thoughts on the Comp Cams XE series ?..."


Don't recommend 'em at all !

Most Pontiac guys that have tried one said they make lots of unwanted noise, because they slap the valves shut too hard. This is because of the very aggressive closing ramps. They also have a 110 LSA. The smaller Voodoo cams, have a 112 LSA, which many Pontiac engine builders like better for street engines, especially those smaller than 455 cubes.

The Voodoo cams have a milder closing ramp, eliminating the extra noise.
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post #5 of 5 (permalink) Old 03-06-2018, 08:49 PM Thread Starter
 
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Originally Posted by bigD View Post
"...Any thoughts on the Comp Cams XE series ?..."


Don't recommend 'em at all !

Most Pontiac guys that have tried one said they make lots of unwanted noise, because they slap the valves shut too hard. This is because of the very aggressive closing ramps. They also have a 110 LSA. The smaller Voodoo cams, have a 112 LSA, which many Pontiac engine builders like better for street engines, especially those smaller than 455 cubes.

The Voodoo cams have a milder closing ramp, eliminating the extra noise.
Thanks!

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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