400hp ???? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Estanley · 05-06-2002, 03:14 PM

I've got a 73' 4 bolt main 350, Vortec heads aluminum intake, Holley 650 dbl pumper, headers, and I'm not sure what cam. Its has been bored .40 over. When I put it all together I want 400hp. I know without specs on the cam its hard to know what I've got but it is a hotter that a stock cam(I would call it moderate). Anyone got suggestions??

Just found out that the cam is somehwere around 268 duration and maybe a Perfect Circle Cam?????

[This message has been edited by Estanley (edited May 06, 2002).]

tom hand · 05-06-2002, 03:29 PM

More than 1 hp per cubic inch is not practical on pump gas. Might be time to break out the laughing gas.

------------------
72 GMC Sierra SWB almost finished---- 84 Softail
Olive Branch MS

brennecke · 05-06-2002, 03:33 PM

Port those vortechs, get flat top pistons (make sure they won't hit the valves), and you could be pretty close depending on how well your cam matches the rest of your setup. You could always stroke it if you need more HP.

69Chevyc10 · 05-06-2002, 03:34 PM

You should be around 400 hp

Estanley · 05-06-2002, 03:42 PM

You say around 400. How much head work you you think that would include? I was told that the cam was part if a Perfect Circle kit that came with pistons that are flat top with four cutouts(valve reliefs??)on each. Has anyone heard of Perfect Circle?

lux hauler · 05-06-2002, 03:58 PM

Flat top pistons and Vortec heads are going to make your compression pretty high. What are your plans for this motor......daily driver, street/strip, towing......?

I was told that the Vortecs need very little machine work as they are already very good heads. The guy that is going to be doing my machine work (Prototype Machine - Lorain, Ohio) said that all he would do is clean up the surface some and put springs in to work with the cam (a little machining there too).
He also said that no matter what anyone says, don't mess with the valves. I guess he has seen those heads with lower performance numbers after they had valve work done on them.

[This message has been edited by 1972c10_ohio (edited May 06, 2002).]

Estanley · 05-06-2002, 04:00 PM

Street/Strip. I want to drive it on the street but it is strictly a toy. I really don't care about any kind of gas mileage.

[This message has been edited by Estanley (edited May 06, 2002).]

Baradium · 05-06-2002, 04:05 PM

in that case... why did you decide to go with the 350?

Baradium · 05-06-2002, 04:05 PM

in that case... why did you decide to go with the 350?

Estanley · 05-06-2002, 04:07 PM

That's what was in it when I got it. A rebuild with only 2000 miles. I don't want to touch the bottom end. I want advice on what to do with the top end.

[This message has been edited by Estanley (edited May 06, 2002).]

Stroker · 05-06-2002, 04:29 PM

Estanley if you really want a decent chance of hitting you target power level you need to find out all the specs on the cam. There is quite a range of grinds in the 268 area. Some might get you close to 400hp other don't have a prayer. What about the specs on your truck, gearing, transmition, converter...ect. The engine with the vortech heads and flattops will put your compression at about 10.5 to 1, you'll likely need some type of octain booster with the premium pump fuel unless you use a bigger cam to bring the dynamic compression ratio down. What parts for your combination can still be changed? Give us a little more info and I think we can get you pointed in the right dirrection.

Longhorn Man · 05-06-2002, 07:15 PM

1972c10_ohio is right about messing with the heads. Car Craft was going to have a port done on them and there machine shop showed them flow charts that proverds only light clean up is all they need. Same with the valves.

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

Estanley · 05-06-2002, 08:24 PM

Stroker, It's a 72 swb, th350 w/shift kit, 2400 to 2600 stall, , hearders,3.42 or so gear
don't know about tire size yet

As far as the cam goes, I'm going to pull it out and let a buddy check it to get the exact specs.

What I have now is the assembled bottom end, heads, intake, cam, 650 dbl pump Holley, headers transmisstion and rearend.

Thanks for the help

Stroker · 05-06-2002, 10:34 PM

Here is a link to a series of articles done by Chevy HP mag a while back. The engine they built is also a 350 vortech engine and they made about 400HP. With your added compression and stall speed you might be able to step up a bit more on the cam if your not using it for a dailly driver. There is some good info contained in the articles that might help you. Let me know what you think. www.aros.net/~rbuck/chp/Welcome.html

Estanley · 05-07-2002, 09:40 AM

Stroker, that article is right on time. I couldn't have asked for better instructions to get to 400hp. I don't know the details on my cam as far a lift and such YET but atleast the 268 duration is right. THANKS and 400 hear I come!!!!!!!!!!

[This message has been edited by Estanley (edited May 07, 2002).]

05-06-2002, 03:14 PM	#1
Estanley Registered User Join Date: Nov 2001 Location: Eatonton, GA, USA Posts: 191	400hp ???? I've got a 73' 4 bolt main 350, Vortec heads aluminum intake, Holley 650 dbl pumper, headers, and I'm not sure what cam. Its has been bored .40 over. When I put it all together I want 400hp. I know without specs on the cam its hard to know what I've got but it is a hotter that a stock cam(I would call it moderate). Anyone got suggestions?? Just found out that the cam is somehwere around 268 duration and maybe a Perfect Circle Cam????? [This message has been edited by Estanley (edited May 06, 2002).]

05-06-2002, 03:29 PM	#2
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	More than 1 hp per cubic inch is not practical on pump gas. Might be time to break out the laughing gas. ------------------ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

05-06-2002, 03:33 PM	#3
brennecke Registered User Join Date: Apr 2000 Location: Missouri Posts: 469	Port those vortechs, get flat top pistons (make sure they won't hit the valves), and you could be pretty close depending on how well your cam matches the rest of your setup. You could always stroke it if you need more HP. __________________ Never tire of doing what is right II Thess. 3:13 Northeast Missouri 71 LWB original 350 3/speed Soon to be 500

05-06-2002, 03:58 PM	#6
lux hauler Psycho-billy Member Join Date: Jul 2001 Location: about 40 miles west of Cleveland, Ohio Posts: 2,591	Flat top pistons and Vortec heads are going to make your compression pretty high. What are your plans for this motor......daily driver, street/strip, towing......? I was told that the Vortecs need very little machine work as they are already very good heads. The guy that is going to be doing my machine work (Prototype Machine - Lorain, Ohio) said that all he would do is clean up the surface some and put springs in to work with the cam (a little machining there too). He also said that no matter what anyone says, don't mess with the valves. I guess he has seen those heads with lower performance numbers after they had valve work done on them. [This message has been edited by 1972c10_ohio (edited May 06, 2002).] __________________ '72 C-10 350 w/Lunati Voodoo cam (207/213, .437/.454), Performer intake, 625 Road Demon Jr. and Hooker headers. Support your community, support yourself. Buy local, buy American (or Canadian).

05-06-2002, 04:29 PM	#11
Stroker Registered User Join Date: Mar 2001 Location: Moore, Ok Posts: 1,149	Estanley if you really want a decent chance of hitting you target power level you need to find out all the specs on the cam. There is quite a range of grinds in the 268 area. Some might get you close to 400hp other don't have a prayer. What about the specs on your truck, gearing, transmition, converter...ect. The engine with the vortech heads and flattops will put your compression at about 10.5 to 1, you'll likely need some type of octain booster with the premium pump fuel unless you use a bigger cam to bring the dynamic compression ratio down. What parts for your combination can still be changed? Give us a little more info and I think we can get you pointed in the right dirrection. __________________ 72 SWB parts and pieces Oklahoma

05-06-2002, 03:34 PM	#4
69Chevyc10 Registered User Join Date: Mar 2002 Location: ND USA Posts: 122	You should be around 400 hp

05-06-2002, 03:42 PM	#5
Estanley Registered User Join Date: Nov 2001 Location: Eatonton, GA, USA Posts: 191	You say around 400. How much head work you you think that would include? I was told that the cam was part if a Perfect Circle kit that came with pistons that are flat top with four cutouts(valve reliefs??)on each. Has anyone heard of Perfect Circle?

05-06-2002, 04:00 PM	#7
Estanley Registered User Join Date: Nov 2001 Location: Eatonton, GA, USA Posts: 191	Street/Strip. I want to drive it on the street but it is strictly a toy. I really don't care about any kind of gas mileage. [This message has been edited by Estanley (edited May 06, 2002).]

05-06-2002, 04:05 PM	#8
Baradium Binder Rep Join Date: Jan 2001 Location: Salcha, AK Posts: 1,506	in that case... why did you decide to go with the 350?

05-06-2002, 04:07 PM	#10
Estanley Registered User Join Date: Nov 2001 Location: Eatonton, GA, USA Posts: 191	That's what was in it when I got it. A rebuild with only 2000 miles. I don't want to touch the bottom end. I want advice on what to do with the top end. [This message has been edited by Estanley (edited May 06, 2002).]

05-06-2002, 07:15 PM	#12
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	1972c10_ohio is right about messing with the heads. Car Craft was going to have a port done on them and there machine shop showed them flow charts that proverds only light clean up is all they need. Same with the valves. ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio

05-06-2002, 08:24 PM	#13
Estanley Registered User Join Date: Nov 2001 Location: Eatonton, GA, USA Posts: 191	Stroker, It's a 72 swb, th350 w/shift kit, 2400 to 2600 stall, , hearders,3.42 or so gear don't know about tire size yet As far as the cam goes, I'm going to pull it out and let a buddy check it to get the exact specs. What I have now is the assembled bottom end, heads, intake, cam, 650 dbl pump Holley, headers transmisstion and rearend. Thanks for the help

05-06-2002, 10:34 PM	#14
Stroker Registered User Join Date: Mar 2001 Location: Moore, Ok Posts: 1,149	Here is a link to a series of articles done by Chevy HP mag a while back. The engine they built is also a 350 vortech engine and they made about 400HP. With your added compression and stall speed you might be able to step up a bit more on the cam if your not using it for a dailly driver. There is some good info contained in the articles that might help you. Let me know what you think. www.aros.net/~rbuck/chp/Welcome.html __________________ 72 SWB parts and pieces Oklahoma

05-07-2002, 09:40 AM	#15
Estanley Registered User Join Date: Nov 2001 Location: Eatonton, GA, USA Posts: 191	Stroker, that article is right on time. I couldn't have asked for better instructions to get to 400hp. I don't know the details on my cam as far a lift and such YET but atleast the 268 duration is right. THANKS and 400 hear I come!!!!!!!!!! [This message has been edited by Estanley (edited May 07, 2002).]



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