Cam recommendations needed
Thread Starter
Instructor
Joined: Jul 2005
Posts: 228
Likes: 13
Cam recommendations needed
I'm thinking on doing a cam swap in my Goodwrench 350 based small block. It currently has dished pistons and Vortec heads which add up to about 8.5 or 9.0:1 compression. I have a GMPP dual plane topped with a 625 Street Demon on the intake end and longtube headers on the exhaust end. Currently running 2.73 gears but might go up to 3.08and a 4 spd. I need the gears for decent highway cruising. I've been looking hard at the Comp Cams version of the old 300HP cam. I'm after more power of course but I like my grunt down low and never really spin the engine over 4500-5000 rpm. Any thoughts on my choice?
Drifting
Joined: Oct 2005
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From: Angier nc
Drifting
Joined: Jul 2011
Posts: 1,697
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From: Syracuse NY
Vortec heads can only take 0.420 inch lift without getting the spring pockets machined or running very special springs. You will need to consider this before you buy a cam. They are great heads, but you need to cam them carefully.
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
Look at an isky 262 super cam- 208-208 @ 050 440 lift 108 lsa. Old school cam that works with low c r , auto trans and highway gears. Good mileage and easy on the valve train. Had one in a 305 el camino, nice cam.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
figure 19cc's for the piston dish volume. Heads are more like 80cc's not 76 as advertised. Best case a .017" shim head gasket. 3.48 stroke, 4.00 bore, 5.7" rods.
Given those figures your at about 7.7:1 CR.
Plug those figures into this calculator to get your CR and DCR for a chosen cam.
http://www.jeepstrokers.com/calculator/
Something on a 108 LSA will give more cylinder pressure/torque in the midrange.
Definately going to be down in the 250 ish duration or so range.
Given those figures your at about 7.7:1 CR.
Plug those figures into this calculator to get your CR and DCR for a chosen cam.
http://www.jeepstrokers.com/calculator/
Something on a 108 LSA will give more cylinder pressure/torque in the midrange.
Definately going to be down in the 250 ish duration or so range.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
figure 19cc's for the piston dish volume. Heads are more like 80cc's not 76 as advertised. Best case a .017" shim head gasket. 3.48 stroke, 4.00 bore, 5.7" rods.
Given those figures your at about 7.7:1 CR.
Plug those figures into this calculator to get your CR and DCR for a chosen cam.
http://www.jeepstrokers.com/calculator/
Something on a 108 LSA will give more cylinder pressure/torque in the midrange.
Definately going to be down in the 250 ish duration or so range.
Given those figures your at about 7.7:1 CR.
Plug those figures into this calculator to get your CR and DCR for a chosen cam.
http://www.jeepstrokers.com/calculator/
Something on a 108 LSA will give more cylinder pressure/torque in the midrange.
Definately going to be down in the 250 ish duration or so range.
1.6 rockers on the intakes would be nice.
108 LSA cams with 250 duration are tough to buy off the shelf, limited selection. I would go with a Comp Cams Custom grind.
Part # 12-000-5
Grind # CS 5082/5207-H108 with a 104 ICL Gets you these specs.
Advertised duration 252/260.
Duration @ .050 208/212.
Lift W/ 1.5 rocker Int .447/ Exh .444
LSA 108 with 4 degrees advance ground in.
Check with Comp for correct springs for either cam.
Last edited by 63mako; Jan 13, 2015 at 01:24 AM.
Le Mans Master
Joined: Apr 2011
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From: Hermosa
Sorry I missed that it was vortec heads. That would get you up to 8.8CR. If head gasket is .017 and piston is .025" down the bore.
That being said it's a bit of a guess. So figure maybe 8.5 CR and work from there.
This could get you into a 260 advertised duration cam on a 108 LSA. Careful of the duration @.050. I wouldn't make it much over 210 or so for good torque.
Those 2.73 rear gears have got to be killing your low end and acceleration.
Have you considered a higher stall torque converter?
Have you done the timing and carb tuning for optimal power as well? Not that it would make it a tire burner with a 2.73 out back but it would help.
Here is some Isky cams to consider.
http://www.iskycams.com/onlinecatalog.html
That being said it's a bit of a guess. So figure maybe 8.5 CR and work from there.
This could get you into a 260 advertised duration cam on a 108 LSA. Careful of the duration @.050. I wouldn't make it much over 210 or so for good torque.
Those 2.73 rear gears have got to be killing your low end and acceleration.
Have you considered a higher stall torque converter?
Have you done the timing and carb tuning for optimal power as well? Not that it would make it a tire burner with a 2.73 out back but it would help.
Here is some Isky cams to consider.
http://www.iskycams.com/onlinecatalog.html
Last edited by REELAV8R; Jan 13, 2015 at 06:15 PM.
Thread Starter
Instructor
Joined: Jul 2005
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Yes, I've re-curved the distributor. The car has a Saginaw 4spd in it of all things. It does have a 3.11 first gear which makes the 2.73s a bit more livable. Still, putting around town I don't always use 4th. There seems to be some debate on just how much lift the stock Vortecs will take. The current cam specs at .383 int, .401 ex with a LSA of 112.
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Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
Here is a complete cam kit with timing chain and springs.
http://www.summitracing.com/parts/cc...make/chevrolet
Lift is .432 and .444 respectively. If those heads are limited in lift then maybe a 1.4 ratio rockers instead of 1.5 and something like this could be used.
Stock ratio GM rockers are supposed to be 1.5 ratio. However they usually measure out to 1.4ish instead.
Maybe you could measure your valve lift and compare it to advertised lift to see what yours are at.
Just an option.
http://www.summitracing.com/parts/cc...make/chevrolet
Lift is .432 and .444 respectively. If those heads are limited in lift then maybe a 1.4 ratio rockers instead of 1.5 and something like this could be used.
Stock ratio GM rockers are supposed to be 1.5 ratio. However they usually measure out to 1.4ish instead.
Maybe you could measure your valve lift and compare it to advertised lift to see what yours are at.
Just an option.
Last edited by REELAV8R; Jan 13, 2015 at 07:01 PM.
Race Director
Joined: May 2005
Posts: 10,674
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From: Millington Illinois
St. Jude Donor '08-'09
Yes, I've re-curved the distributor. The car has a Saginaw 4spd in it of all things. It does have a 3.11 first gear which makes the 2.73s a bit more livable. Still, putting around town I don't always use 4th. There seems to be some debate on just how much lift the stock Vortecs will take. The current cam specs at .383 int, .401 ex with a LSA of 112.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Here is a complete cam kit with timing chain and springs.
Lift is .432 and .444 respectively. If those heads are limited to 1.4 ratio rockers instead of 1.5 then something like this could be used.
Stock ratio GM rockers are supposed to be 1.5 ratio. However they usually measure out to 1.4ish instead.
Maybe you could measure your valve lift and compare it to advertised lift to see what yours are at.
Just an option.
Lift is .432 and .444 respectively. If those heads are limited to 1.4 ratio rockers instead of 1.5 then something like this could be used.
Stock ratio GM rockers are supposed to be 1.5 ratio. However they usually measure out to 1.4ish instead.
Maybe you could measure your valve lift and compare it to advertised lift to see what yours are at.
Just an option.
Could get it ground on 108 LSA for a little extra if you order the kit from Comp.
Thread Starter
Instructor
Joined: Jul 2005
Posts: 228
Likes: 13
Vortec heads can only take 0.420 inch lift without getting the spring pockets machined or running very special springs. You will need to consider this before you buy a cam. They are great heads, but you need to cam them carefully.
Instructor
Joined: Jun 2014
Posts: 178
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From: Pensacola FL
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
See post 1. Guy never spins past 4500-5000. LOTS of bad things happen with high rpm valve float, bouncing the retainers off the guides is the least of your worries, bouncing valves off the top of pistons is a much bigger concern. That said there are a couple economical ways to get vortecs to handle .525 or higher with no machining.