smallblock power
12-14-2004, 09:03 AM
#31
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Re: smallblock power
Hey Dave,
What's the difference between the two intakes?
I put a regular performer on my Nova. My friend put the RPMs on his Donzi.
If I don't have a major fiberglass crisis I was gonna go through the blocks and maybe do intakes. I need exhaust manifold gaskets on both blocks. I thought I would do exhaust manifolds too. Not gonna cam them or anything though.
Maybe upgrade ignition systems. Maybe.
No wonder you can go faster than me. I'm running stock 260s.
What's the difference between the two intakes?
I put a regular performer on my Nova. My friend put the RPMs on his Donzi.
If I don't have a major fiberglass crisis I was gonna go through the blocks and maybe do intakes. I need exhaust manifold gaskets on both blocks. I thought I would do exhaust manifolds too. Not gonna cam them or anything though.
Maybe upgrade ignition systems. Maybe.
No wonder you can go faster than me. I'm running stock 260s.
12-14-2004, 10:23 AM
#32
MarineKinetics
Platinum Member
Re: smallblock power
Blkhorse,
If you choose to upgrade the performance on this engine there are some economical ways to significantly increase your HP/torque output. I would suggest you look at the new GM Bowtie Vortec cylinder heads, part#25534421 ($499.00 complete), 25534351 ($269.00 bare). They are a much-improved design compared to the standard Vortec small block head. They are standard with 2.00”/1.55” stainless valves compared to 1.94”/1.5” for the original head, 65cc chamber fast burn combustion chamber design vs. 64cc, 175cc rated intake runner (actual 185cc) vs. 170cc and a 65cc exhaust port. They are standard with screw in studs vs. press fit, large valve pocket machining, and will accommodate up to a .530” lift without any additional cutting vs. .475” max lift on the original, and will accept both center and perimeter bolt valve covers. The runner size and cross section are ideal for your application making more power above 4000 rpm where the std Vortecs begin to nose over. Both this head and the large port Bowtie (rates 206cc, actual 215cc, 84cc exhaust port) are essentially iron versions of the aluminum Fast Burn cylinder head. I would suggest using the Performer intake as the additional runner volume is not required running a max WOT of 5500 rpm.
Because your block is a 1989 you are already set up for a roller and that will eliminate the expense of a retro conversion. The factory roller (197*/207* .430”/. 450”) will definitely be cam limited for this application. I would recommend not selecting a replacement cam until your component selection is complete when the numbers can be run accurately.
Bob
If you choose to upgrade the performance on this engine there are some economical ways to significantly increase your HP/torque output. I would suggest you look at the new GM Bowtie Vortec cylinder heads, part#25534421 ($499.00 complete), 25534351 ($269.00 bare). They are a much-improved design compared to the standard Vortec small block head. They are standard with 2.00”/1.55” stainless valves compared to 1.94”/1.5” for the original head, 65cc chamber fast burn combustion chamber design vs. 64cc, 175cc rated intake runner (actual 185cc) vs. 170cc and a 65cc exhaust port. They are standard with screw in studs vs. press fit, large valve pocket machining, and will accommodate up to a .530” lift without any additional cutting vs. .475” max lift on the original, and will accept both center and perimeter bolt valve covers. The runner size and cross section are ideal for your application making more power above 4000 rpm where the std Vortecs begin to nose over. Both this head and the large port Bowtie (rates 206cc, actual 215cc, 84cc exhaust port) are essentially iron versions of the aluminum Fast Burn cylinder head. I would suggest using the Performer intake as the additional runner volume is not required running a max WOT of 5500 rpm.
Because your block is a 1989 you are already set up for a roller and that will eliminate the expense of a retro conversion. The factory roller (197*/207* .430”/. 450”) will definitely be cam limited for this application. I would recommend not selecting a replacement cam until your component selection is complete when the numbers can be run accurately.
Bob
12-14-2004, 10:47 AM
#33
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Re: smallblock power
Originally Posted by rmbuilder
Blkhorse,
If you choose to upgrade the performance on this engine there are some economical ways to significantly increase your HP/torque output. I would suggest you look at the new GM Bowtie Vortec cylinder heads, part#25534421 ($499.00 complete), 25534351 ($269.00 bare). They are a much-improved design compared to the standard Vortec small block head. They are standard with 2.00”/1.55” stainless valves compared to 1.94”/1.5” for the original head, 65cc chamber fast burn combustion chamber design vs. 64cc, 175cc rated intake runner (actual 185cc) vs. 170cc and a 65cc exhaust port. They are standard with screw in studs vs. press fit, large valve pocket machining, and will accommodate up to a .530” lift without any additional cutting vs. .475” max lift on the original, and will accept both center and perimeter bolt valve covers. The runner size and cross section are ideal for your application making more power above 4000 rpm where the std Vortecs begin to nose over. Both this head and the large port Bowtie (rates 206cc, actual 215cc, 84cc exhaust port) are essentially iron versions of the aluminum Fast Burn cylinder head. I would suggest using the Performer intake as the additional runner volume is not required running a max WOT of 5500 rpm.
Because your block is a 1989 you are already set up for a roller and that will eliminate the expense of a retro conversion. The factory roller (197*/207* .430”/. 450”) will definitely be cam limited for this application. I would recommend not selecting a replacement cam until your component selection is complete when the numbers can be run accurately.
Bob
If you choose to upgrade the performance on this engine there are some economical ways to significantly increase your HP/torque output. I would suggest you look at the new GM Bowtie Vortec cylinder heads, part#25534421 ($499.00 complete), 25534351 ($269.00 bare). They are a much-improved design compared to the standard Vortec small block head. They are standard with 2.00”/1.55” stainless valves compared to 1.94”/1.5” for the original head, 65cc chamber fast burn combustion chamber design vs. 64cc, 175cc rated intake runner (actual 185cc) vs. 170cc and a 65cc exhaust port. They are standard with screw in studs vs. press fit, large valve pocket machining, and will accommodate up to a .530” lift without any additional cutting vs. .475” max lift on the original, and will accept both center and perimeter bolt valve covers. The runner size and cross section are ideal for your application making more power above 4000 rpm where the std Vortecs begin to nose over. Both this head and the large port Bowtie (rates 206cc, actual 215cc, 84cc exhaust port) are essentially iron versions of the aluminum Fast Burn cylinder head. I would suggest using the Performer intake as the additional runner volume is not required running a max WOT of 5500 rpm.
Because your block is a 1989 you are already set up for a roller and that will eliminate the expense of a retro conversion. The factory roller (197*/207* .430”/. 450”) will definitely be cam limited for this application. I would recommend not selecting a replacement cam until your component selection is complete when the numbers can be run accurately.
Bob
12-14-2004, 12:20 PM
#35
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Re: smallblock power
are the 350 magnum(1989 carb model) roller or flat tappet? what is the comp. ratio? cast or forge crank? 2 or 4 bolt block? or where can I find out what pieces are on these motors?
Thanks
Thanks
12-14-2004, 01:16 PM
#36
MarineKinetics
Platinum Member
Re: smallblock power
blkhorse,
The switch from flat to roller blocks took place in 1987. However some 350 Alphas came with the flat tappet cams post 1987. If you can provide the engine serial # it's possible to verify what exactly you have. The block however should be the one piece rear seal with machined lifter bores and guide retainer thereby allowing the use of the roller cam even if you have a flat now. I suggest you don't take anything for granted (being a used boat) and pull the intake or check pushrod (roller cams utilize the shorter pushrod) length to determine exactly what parts are currently installed. You have a cast crank, 2 bolt mains, and 8.8-1 compression ratio with 76 cc and 160cc intake port heads.
The switch from flat to roller blocks took place in 1987. However some 350 Alphas came with the flat tappet cams post 1987. If you can provide the engine serial # it's possible to verify what exactly you have. The block however should be the one piece rear seal with machined lifter bores and guide retainer thereby allowing the use of the roller cam even if you have a flat now. I suggest you don't take anything for granted (being a used boat) and pull the intake or check pushrod (roller cams utilize the shorter pushrod) length to determine exactly what parts are currently installed. You have a cast crank, 2 bolt mains, and 8.8-1 compression ratio with 76 cc and 160cc intake port heads.
12-14-2004, 03:55 PM
#38
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Re: smallblock power
My 87 320 EFI had a flat tappet cam.
The reason I didn't go to standard Vortec was because it's damn near impossible to find a cast iron manifold for them, and I run in salt. Also the issue with the max lift, though the one I chose would have been at the upper limit of it without machining.
The reason I didn't go to standard Vortec was because it's damn near impossible to find a cast iron manifold for them, and I run in salt. Also the issue with the max lift, though the one I chose would have been at the upper limit of it without machining.
12-14-2004, 05:23 PM
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Re: smallblock power
Originally Posted by Gary Anderson
Sorry, bad news. You can probably do quite a few SBC mods for $2K, but anything that would considerably increase top end would kill the alpha drive. Merc put out a 330hp 454/alpha package that had a habit of grenading.
My $0.02
Keep the 2K for gas, maintenence, repairs, booze, etc and enjoy the boat. Spend the time you would have taken building up the engine and use it to learn to maintain the boat, engine, drive you have.
Gary
My $0.02
Keep the 2K for gas, maintenence, repairs, booze, etc and enjoy the boat. Spend the time you would have taken building up the engine and use it to learn to maintain the boat, engine, drive you have.
Gary
12-14-2004, 07:15 PM
#40
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Re: smallblock power
Originally Posted by cuda
My 87 320 EFI had a flat tappet cam.
The reason I didn't go to standard Vortec was because it's damn near impossible to find a cast iron manifold for them, and I run in salt. Also the issue with the max lift, though the one I chose would have been at the upper limit of it without machining.
The reason I didn't go to standard Vortec was because it's damn near impossible to find a cast iron manifold for them, and I run in salt. Also the issue with the max lift, though the one I chose would have been at the upper limit of it without machining.
