Cam help needed?
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Cam help needed?
Can some make a suggestion as what cam to use in my sb? Please excuse my ignorance,I just don't quite understand the choices. The car will be driven on the street, not raced (much)
I'm trying to build a nice driver w/ a little more to it. The rear is a stock 3:36, crank is shaved .30? My son telling me to build a 9.5 compression? Block has been bored .30 using flat headed pistons. Also, the car has an auto trans that I'm returning to it's original 4 speed. Heads and block will be shaved, along with a head job. Also, my kid is telling me to go with a new aluminum intake and change the exhaust to headers in stead of the stock manifolds. Any help is appreciated
WB
I'm trying to build a nice driver w/ a little more to it. The rear is a stock 3:36, crank is shaved .30? My son telling me to build a 9.5 compression? Block has been bored .30 using flat headed pistons. Also, the car has an auto trans that I'm returning to it's original 4 speed. Heads and block will be shaved, along with a head job. Also, my kid is telling me to go with a new aluminum intake and change the exhaust to headers in stead of the stock manifolds. Any help is appreciated WB
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by War Bonnet
The rear is a stock 3:36, crank is shaved .30? My son telling me to build a 9.5 compression? Block has been bored .30 using flat headed pistons. Heads and block will be shaved, along with a head job. Also, my kid is telling me to go with a new aluminum intake and change the exhaust to headers in stead of the stock manifolds. Any help is appreciated WB
WBheaders are a good thing and the aluminum intake will save weight but the vette intakes are pretty good......you have lots of cam choices from the mild to the wild...remember you need new lifters when you get the cam and mabye even new springs....so do your home work and if they offer a kit it may be the least expensive way to go.....its really easy to wipe a cam on startup so you really need to have the car be able to fire right up and run for the first 20 minutes....i have a Comp Cams XE268 and i like it.....but you have so many choices...and it sounds like you have a machine shop doing your work so why not ask them....also you can buy books of SBC buildups and see what they did and what the dyno results were.....good luck.....don't rule out the GMPP hot cam
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Originally Posted by bobs77vet
headers are a good thing and the aluminum intake will save weight but the vette intakes are pretty good......you have lots of cam choices from the mild to the wild...remember you need new lifters when you get the cam and mabye even new springs....so do your home work and if they offer a kit it may be the least expensive way to go.....its really easy to wipe a cam on startup so you really need to have the car be able to fire right up and run for the first 20 minutes....i have a Comp Cams XE268 and i like it.....but you have so many choices...and it sounds like you have a machine shop doing your work so why not ask them....also you can buy books of SBC buildups and see what they did and what the dyno results were.....good luck.....don't rule out the GMPP hot cam
WB
Le Mans Master
Joined: Apr 2005
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From: Seattle Area WA
You might consider looking at Summit's 1103K, their kits are great deals. It is ground on 112 centers to reduce the overlap and would work well for a daily driver with 9.5:1. Make sure you know Exactly what your static compression is so you can compute your DCR Dynamic compression by using the inlet valve closing point.
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Originally Posted by Scott Marzahl
You might consider looking at Summit's 1103K, their kits are great deals. It is ground on 112 centers to reduce the overlap and would work well for a daily driver with 9.5:1. Make sure you know Exactly what your static compression is so you can compute your DCR Dynamic compression by using the inlet valve closing point.
Thank you Scott! I will look at Summit's products. WB
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
not for nothing.....but if the shop is going to warranty the work let them have the last word on cam selection......no need to get into a pissing contest if you get a wiped lobe and have them say well its what you wanted......
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Originally Posted by bobs77vet
not for nothing.....but if the shop is going to warranty the work let them have the last word on cam selection......no need to get into a pissing contest if you get a wiped lobe and have them say well its what you wanted......
WB
Le Mans Master
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From: Seattle Area WA
WB,
Here is a link to a calculator so you can understand what is happening with your engine. Comp cams grinds just about everything on 110 LSAs which tends to kill your bottom end torque. I'd suggest asking them about grinding whatever you want on at least 112 centers to reduce overlap and increase your bottom end power.
http://www.kb-silvolite.com/calc.php?action=comp
Here is a link to a calculator so you can understand what is happening with your engine. Comp cams grinds just about everything on 110 LSAs which tends to kill your bottom end torque. I'd suggest asking them about grinding whatever you want on at least 112 centers to reduce overlap and increase your bottom end power.
http://www.kb-silvolite.com/calc.php?action=comp
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Thread Starter
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Originally Posted by Scott Marzahl
WB,
Here is a link to a calculator so you can understand what is happening with your engine. Comp cams grinds just about everything on 110 LSAs which tends to kill your bottom end torque. I'd suggest asking them about grinding whatever you want on at least 112 centers to reduce overlap and increase your bottom end power.
http://www.kb-silvolite.com/calc.php?action=comp
Here is a link to a calculator so you can understand what is happening with your engine. Comp cams grinds just about everything on 110 LSAs which tends to kill your bottom end torque. I'd suggest asking them about grinding whatever you want on at least 112 centers to reduce overlap and increase your bottom end power.
http://www.kb-silvolite.com/calc.php?action=comp
link I'll try to get the info to fill it in tomorrow! WB
Le Mans Master
Joined: Apr 2005
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From: Seattle Area WA
WB, also don't discount the stock GM cams for a car with a stock automatic with 3.36 gears. The base cam retarded 4 degrees works very well with a 9.5-9.75 SCR engine. The L-79 and L-82 cams like 10-10.25:1 SCR much better. Many folks don't like them because they don't sound bad a** enough but they do work well and are dead reliable and are cheap. Here are some numbers to chew on:
Here are very accurate numbers from Engine Analyzer for a .030" over 350, 9.75:1 SCR, an OE manifold with a 750 CFM carb, stock 2" manifolds and 2.5" exhaust pipes. Equiped with full front end accessories - SAE net, peak torque, 80 percent bandwidth, peak power.
839 cam, OE indexed....356@3500, 1800-4800, 269@4500
839 cam, 4 deg. retard..358@3500, 1800-5000, 281@4500
151 cam, OE indexing...352@4000, 2300-5700, 313@5500
151 can, 4 deg adv........349@3500, 1950-5500, 307@5000
Headers gain you about 8% more torque in the midrange.
Scott
Here are very accurate numbers from Engine Analyzer for a .030" over 350, 9.75:1 SCR, an OE manifold with a 750 CFM carb, stock 2" manifolds and 2.5" exhaust pipes. Equiped with full front end accessories - SAE net, peak torque, 80 percent bandwidth, peak power.
839 cam, OE indexed....356@3500, 1800-4800, 269@4500
839 cam, 4 deg. retard..358@3500, 1800-5000, 281@4500
151 cam, OE indexing...352@4000, 2300-5700, 313@5500
151 can, 4 deg adv........349@3500, 1950-5500, 307@5000
Headers gain you about 8% more torque in the midrange.
Scott
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My machine shop gave me this number.... Comp Cam 12-238-2, do you guys think this is a good choice? Thanks WB
ps: those are pretty impressive numbers Scott!
ps: those are pretty impressive numbers Scott!
Burning Brakes
Joined: Oct 2004
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From: Loveland Colo
Why don't you go to the bookstore and pick up a few books about building street engines? Take some time to read and learn and you will come to better understand how it all works together. Then you can ask better questions and make better decisions about your motor.
I'm not trying to flame you at all, just help you to not regret something in the future. It's not rocket science, and even basic knowledge will serve you better than blindly accepting others opinions without understanding why.
John
I'm not trying to flame you at all, just help you to not regret something in the future. It's not rocket science, and even basic knowledge will serve you better than blindly accepting others opinions without understanding why.
John
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
thats an excellent cam xe262h....its one step below my cam although pulls the same HP and torque numbers.....if this fits all your other needs it is a good cam....