Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
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ABSOLUTELY NOT the 3rd one. For a clue as to why, look at the difference in the .050" duration and the "advertised" duration; 224, vs. 282. That means, the valve spends 58 degrees just sprt of hanging out around the seat, just cracked open, but not really flowing anything, basically just leaking. Now look at the 2nd cam; 219 vs 262. That's 45 degrees around there. In other words, only 5 less degrees of uselful flow, but 13 degrees less of just leaking and giving you poor idle, low vacuum, and bad gas mileage. Those old el cheeepo grinds from the Civil War days are never the "best" choice; although sometimes they're an "OK" choice. But for this, that one is not even "OK", it's just all-around bad.
The 1st is better. But, it's symmetrical, and therefore is set up for a low compression smogger motor with poor intake flow relative to its exhaust (not ported, small valves, etc.) which isn't what you've got. Still a mismatch to your combo.
The 2nd is the best of the 3 for your particular combo.
it's also very similar to the comp xe262, so that's another worthwhile choice.
these are mild, sure you don't want to step up to the 60103 by lunati / comp268? If you want to keep it mild, and keep your stall speed, then you're on the right track.
I would go with the second as well. It has the better ramp rates and allows more time for exhaust flow. Single pattern cams are best for cylinder heads with good flowing exhaust ports and low restriction larger primary headers.
__________________ 4-bolt 355. Ported Trick Flows. LT4 Hot cam. Ported and Siamesed TPI setup. 10 bolt with 3.42's. 730 ecm that I tune. LS1 brakes.
Use comp cams #12-208-2 Its "just right" for your purpose.
12-208-2
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS 265DEH-10
Description
Intake Exhaust
Valve Adjustment 0.0 0.0
Gross Valve Lift 0.442 0.465
Duration At 0.006 Tappet Lift 265 269
Valve Timing At 0.006
Open Close
Intake 27 58
Exhaust 69 20
These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 211 221
Lobe Lift 0.295 0.31
Lobe Separation 110
Isn't that one a little on the small side versus what I had listed? I was told to stay somewhere around 225-235 on the duration. Can you tell me why the CL12-208-2 is "just right" for my application?
I would think that the 110* LSA would give more of a chance to bleed of compression. Although as long as it is on a 110* LSA it could suite. I would rather go with a cam with more duration and less LSA though.
__________________ 4-bolt 355. Ported Trick Flows. LT4 Hot cam. Ported and Siamesed TPI setup. 10 bolt with 3.42's. 730 ecm that I tune. LS1 brakes.
A cam with that much duraqtion 225-235@.050" needs some rear gear. a cam with 235@.050 will definatly be lacking low end torque and want a 3000+stall converter and lots of gear. Not what you want for a daily drive with 3.08's.
Its all about best average torque output over the rpm band you'll use the most.
Ya really need to resist the temptation of putting a big cam in it. that is the most common mistake people make.
The cam I recomended will give you a lot of power between 2000 and 5500 with good efficientcy while cruising. Remember you'll be spending the majority of the time at part throttle and under 3000 rpm. The overdrive will not return a fuel savings if the motor is operating at a rpm that is out of the best range for the cam. That cam is enough cam to run 12's yet deliver good efficiency in a daily driver. I'd even recomend a little more rear gear. Torque is what makes a performance car fun to drive. maximise torque output in the rpm you'll be using and you'll go fast and save fuel. Don;t kill a good combination with too much cam. Street cars make good race cars but race cars don;t make good street cars. Try it , you'll like it. pop in a set of 3.73's and a small nitrous kit and your running 11's yet driving it bacvk and forth to work and away on trips without going breaking the bank on fuel consumption. This is the right performance cam for your car.
A cam with that much duraqtion 225-235@.050" needs some rear gear. a cam with 235@.050 will definatly be lacking low end torque and want a 3000+stall converter and lots of gear. Not what you want for a daily drive with 3.08's.
Its all about best average torque output over the rpm band you'll use the most.
Ya really need to resist the temptation of putting a big cam in it. that is the most common mistake people make.
The cam I recomended will give you a lot of power between 2000 and 5500 with good efficientcy while cruising. Remember you'll be spending the majority of the time at part throttle and under 3000 rpm. The overdrive will not return a fuel savings if the motor is operating at a rpm that is out of the best range for the cam. That cam is enough cam to run 12's yet deliver good efficiency in a daily driver. I'd even recomend a little more rear gear. Torque is what makes a performance car fun to drive. maximise torque output in the rpm you'll be using and you'll go fast and save fuel. Don;t kill a good combination with too much cam. Street cars make good race cars but race cars don;t make good street cars. Try it , you'll like it. pop in a set of 3.73's and a small nitrous kit and your running 11's yet driving it bacvk and forth to work and away on trips without going breaking the bank on fuel consumption. This is the right performance cam for your car.
Thanks for the help. I'm going to take your advice and order it up through Summit today. Should be able to install it over the weekend.
Thanks for the help. I'm going to take your advice and order it up through Summit today. Should be able to install it over the weekend.
Don't forget the 3.73's. It will really increase the Fun Factor.
Your RPM, while cruising at 60 MPH in overdrive is only increased by 336rpm.
barely noticable. but changing from 308's to 3.73's will definatly get you the effect you're looking for when you hammer it from a stop light.
