Want more power.....
Thread Starter
Instructor
Joined: Jul 2015
Posts: 121
Likes: 3
From: Maryland
Want more power.....
1973 Coupe L48 4 speed 3:36 rear.
As the end of the driving season nears I have been thinking about making some engine changes. I rebuilt the L48 last winter and it seems to run fine. Would like a little more power though.
My build now consist of a stock dished piston bottom end with the lunati voodo 10120702 cam. I have the 416 305 HO heads with a shim head gasket, a performer intake and stock quadrajet carb. Stock exhaust manifolds with true 2 1/2 dual exhaust.
I was thinking of getting a set of vortec heads and intake. Would this be much of an improvement?
Any other suggestions welcome. Don't want to spend a fortune.....
As the end of the driving season nears I have been thinking about making some engine changes. I rebuilt the L48 last winter and it seems to run fine. Would like a little more power though.
My build now consist of a stock dished piston bottom end with the lunati voodo 10120702 cam. I have the 416 305 HO heads with a shim head gasket, a performer intake and stock quadrajet carb. Stock exhaust manifolds with true 2 1/2 dual exhaust.
I was thinking of getting a set of vortec heads and intake. Would this be much of an improvement?
Any other suggestions welcome. Don't want to spend a fortune.....
Le Mans Master
Joined: Apr 2001
Posts: 5,436
Likes: 1,253
From: Sarver Pa
2021 C1 of the Year Finalist - Modified
Vortec heads are good performing low budget way to go. You should be able to modify the performer intake to fit. There are some good low budget aluminum heads out there too for a few dollars more.
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
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Heads are where it's at. You gained compression but no airflow. With dumped pistons you're in a tough spot. Are they the original ones or replacements? Any idea on deck height?
Jim
Jim
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
Depends what you consider breaking the bank, but you won't find a better deal on a top-tier US-made head that's a simple head swap than these guys: http://www.high-performance-engines....p/sbc64195.htm
If you become a member on chevelles.com you get a 5% discount, too which brings them down to $983.25 for an assembled pair with free shipping.
They're essentially the 195cc / 64cc Profiler heads but with normal height exhaust ports to ensure that they work with your existing exhaust headers / manifolds.
They flow 250 CFM @ 0.400 and 268 CFM @ 0.500.
Your split on your existing Voodoo cam looks about perfect for these heads; but to take full advantage you'd want 1.6 ratio rockers to get the lift up a bit.
If the rebuild on the L48 ensured that the deck was perfectly flat, use the Felpro 0.015" ultra thin gasket and get that CR up.
Call and ask if they'd put flat tappet-appropriate springs on them and replace all your Ujoints before you break them all from the torque. ;-)
Keep your existing intake and carb and make it a very Merry Christmas to yourself.
Adam
If you become a member on chevelles.com you get a 5% discount, too which brings them down to $983.25 for an assembled pair with free shipping.
They're essentially the 195cc / 64cc Profiler heads but with normal height exhaust ports to ensure that they work with your existing exhaust headers / manifolds.
They flow 250 CFM @ 0.400 and 268 CFM @ 0.500.
Your split on your existing Voodoo cam looks about perfect for these heads; but to take full advantage you'd want 1.6 ratio rockers to get the lift up a bit.
If the rebuild on the L48 ensured that the deck was perfectly flat, use the Felpro 0.015" ultra thin gasket and get that CR up.
Call and ask if they'd put flat tappet-appropriate springs on them and replace all your Ujoints before you break them all from the torque. ;-)
Keep your existing intake and carb and make it a very Merry Christmas to yourself.
Adam
Thread Starter
Instructor
Joined: Jul 2015
Posts: 121
Likes: 3
From: Maryland
Pistons are stock dished.
Distributor was recurved and yes I have the Ruggles quadrajet book and have rebuilt the carb.
Car runs just OK. Thought it would be better but think the heads are holding me back somewhat.
Thanks for the suggestions so far.....
Distributor was recurved and yes I have the Ruggles quadrajet book and have rebuilt the carb.
Car runs just OK. Thought it would be better but think the heads are holding me back somewhat.
Thanks for the suggestions so far.....
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Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
I've been playing with the free "Dyno2000" software package and I just modeled your engine in there with the 195cc ATK heads' airflow, a dual-plane intake manifold, a QJet carb, your voodoo cam, and what I believe is the software's setting for manifold and dual exhaust with mufflers.
Take it with a grain of salt, but it spits out 398 ft lbs peak torque @ 3,500 and 328 peak hp @ 5,000 RPM -flywheel #'s, obviously.
The torque peak hits this weird long plateau that appears to be based upon flow restrictions from the exhaust manifolds. If I take that same combo and just change it to full-length 1 5/8th" headers and mufflers, the #'s jump to: 437 ft lbs peak torque @ 4,000 RPM and 384 HP @ 5,500 RPM. It's pretty awesome to see just how restrictive the manifolds become when you put modern good heads on these engines.
--The morale of the story is that if you go with some good top-tier heads, you'll want to replace those iron manifolds with some headers. The summit brand ones are dirt cheap and fit perfectly (search this forum back 1-3 weeks) and if you want shiny coated headers the Flowtech 31106FLT (owned by Holley) fit perfectly and are very reasonable at $319.
By sticking with "normal" SBC heads instead of going the Vortec route, you won't need to buy a new intake either and can just take that money to get those headers and really get some huge torque and HP increases for your money.
-I believe the 195cc intake version of the profiler/ATK heads are a 1206 felpro gasket size and the 185ccs are 1205. If your existing intake is 1205 and you want a perfectly matched intake to head transition without any port work, go with the 185cc version; you'll lose a little HP at 5,500, but you should gain a little torque off idle and through the mid RPM range if my wild guess is correct (haven't modeled those heads in the tool yet).
Adam
Take it with a grain of salt, but it spits out 398 ft lbs peak torque @ 3,500 and 328 peak hp @ 5,000 RPM -flywheel #'s, obviously.
The torque peak hits this weird long plateau that appears to be based upon flow restrictions from the exhaust manifolds. If I take that same combo and just change it to full-length 1 5/8th" headers and mufflers, the #'s jump to: 437 ft lbs peak torque @ 4,000 RPM and 384 HP @ 5,500 RPM. It's pretty awesome to see just how restrictive the manifolds become when you put modern good heads on these engines.
--The morale of the story is that if you go with some good top-tier heads, you'll want to replace those iron manifolds with some headers. The summit brand ones are dirt cheap and fit perfectly (search this forum back 1-3 weeks) and if you want shiny coated headers the Flowtech 31106FLT (owned by Holley) fit perfectly and are very reasonable at $319.
By sticking with "normal" SBC heads instead of going the Vortec route, you won't need to buy a new intake either and can just take that money to get those headers and really get some huge torque and HP increases for your money.
-I believe the 195cc intake version of the profiler/ATK heads are a 1206 felpro gasket size and the 185ccs are 1205. If your existing intake is 1205 and you want a perfectly matched intake to head transition without any port work, go with the 185cc version; you'll lose a little HP at 5,500, but you should gain a little torque off idle and through the mid RPM range if my wild guess is correct (haven't modeled those heads in the tool yet).
Adam
Last edited by NewbVetteGuy; Oct 26, 2016 at 04:23 PM.
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Spend some SERIOUS time with a grinder on those 2.5" manifolds and they will carry you into the 11s. Headers are better but manifolds can be made much better than they are.
Jim
Jim
Thread Starter
Instructor
Joined: Jul 2015
Posts: 121
Likes: 3
From: Maryland
Wow, very informative! I had no idea headers would make that much difference. Sure gives me something to think about now.
I've been playing with the free "Dyno2000" software package and I just modeled your engine in there with the 195cc ATK heads' airflow, a dual-plane intake manifold, a QJet carb, your voodoo cam, and what I believe is the software's setting for manifold and dual exhaust with mufflers.
Take it with a grain of salt, but it spits out 398 ft lbs peak torque @ 3,500 and 328 peak hp @ 5,000 RPM -flywheel #'s, obviously.
The torque peak hits this weird long plateau that appears to be based upon flow restrictions from the exhaust manifolds. If I take that same combo and just change it to full-length 1 5/8th" headers and mufflers, the #'s jump to: 437 ft lbs peak torque @ 4,000 RPM and 384 HP @ 5,500 RPM. It's pretty awesome to see just how restrictive the manifolds become when you put modern good heads on these engines.
--The morale of the story is that if you go with some good top-tier heads, you'll want to replace those iron manifolds with some headers. The summit brand ones are dirt cheap and fit perfectly (search this forum back 1-3 weeks) and if you want shiny coated headers the Flowtech 31106FLT (owned by Holley) fit perfectly and are very reasonable at $319.
By sticking with "normal" SBC heads instead of going the Vortec route, you won't need to buy a new intake either and can just take that money to get those headers and really get some huge torque and HP increases for your money.
-I believe the 195cc intake version of the profiler/ATK heads are a 1206 felpro gasket size and the 185ccs are 1205. If your existing intake is 1205 and you want a perfectly matched intake to head transition without any port work, go with the 185cc version; you'll lose a little HP at 5,500, but you should gain a little torque off idle and through the mid RPM range if my wild guess is correct (haven't modeled those heads in the tool yet).
Adam
Take it with a grain of salt, but it spits out 398 ft lbs peak torque @ 3,500 and 328 peak hp @ 5,000 RPM -flywheel #'s, obviously.
The torque peak hits this weird long plateau that appears to be based upon flow restrictions from the exhaust manifolds. If I take that same combo and just change it to full-length 1 5/8th" headers and mufflers, the #'s jump to: 437 ft lbs peak torque @ 4,000 RPM and 384 HP @ 5,500 RPM. It's pretty awesome to see just how restrictive the manifolds become when you put modern good heads on these engines.
--The morale of the story is that if you go with some good top-tier heads, you'll want to replace those iron manifolds with some headers. The summit brand ones are dirt cheap and fit perfectly (search this forum back 1-3 weeks) and if you want shiny coated headers the Flowtech 31106FLT (owned by Holley) fit perfectly and are very reasonable at $319.
By sticking with "normal" SBC heads instead of going the Vortec route, you won't need to buy a new intake either and can just take that money to get those headers and really get some huge torque and HP increases for your money.
-I believe the 195cc intake version of the profiler/ATK heads are a 1206 felpro gasket size and the 185ccs are 1205. If your existing intake is 1205 and you want a perfectly matched intake to head transition without any port work, go with the 185cc version; you'll lose a little HP at 5,500, but you should gain a little torque off idle and through the mid RPM range if my wild guess is correct (haven't modeled those heads in the tool yet).
Adam