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Old 03-04-2007, 03:15 PM
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Too much camshaft!?

i just got a 66 olds with a 350,tunnel ram 2 holley 4barrel carbs(450cfm) the previous owner stated he installed a 270 comp cam. the engine runs good but very rough at idle and most of the time sputters thru one of the carbs when you try to take off from a stop..i really just want a reliable cruiser, I like the looks of the tunnel ram and 2 fours but the rough idle is not very street friendly, what cam do you guys suggest. its a 4 speed with 3.08 gears. Or should i just loose the tunnel ram and 2 fours as well...?? im more of a cruiser than a racer..

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Old 03-04-2007, 03:20 PM
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I bought that cam for the idle. Its supposed to idle rough. 224 duration @ 50. .470 lift. It's still a pretty mild cam. They recommend a 3.73 rear gear for it.

About the sputtering. Does the exhaust smell like the engine running really rich?
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Old 03-04-2007, 03:24 PM
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That cam and induction system will not work well under 3500 rpm.

If you want the sound, keep the cam. If you want drivability go to a street intake with a vac secondary 650-750.

Heavy car 3.08 gear. The only thing you have correct is the stick trans.
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Old 03-04-2007, 03:27 PM
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Quote:
Originally Posted by DeathRattle
I bought that cam for the idle. Its supposed to idle rough. 224 duration @ 50. .470 lift. It's still a pretty mild cam. They recommend a 3.73 rear gear for it.

About the sputtering. Does the exhaust smell like the engine running really rich?
yes the exhaust smells very raw, like gas.
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Old 03-04-2007, 03:30 PM
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Quote:
Originally Posted by pi71
yes the exhaust smells very raw, like gas.
Bob is very right. Your motor is over carbed. You could tune em to lean em or just pick up a dual plane manifold with a 650 vacuum carb.
OR
Swap rear gears and keep the RPMs way up
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Old 03-04-2007, 03:41 PM
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So the cam with work for what i want, and i should either tune,or lean, the ones i have, or go to a single carb, and intake,, with a 600-650cfm carb and some lower gears. sounds easier than what i was gonna tackle.
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Old 03-04-2007, 04:25 PM
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Just a FYI-the RPM range for that cam is 1800-5800.
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Old 03-04-2007, 04:54 PM
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It's all in the set up of the distributor and carbs.
Your tunnel ram will idle and drive fine once properly set up.
Ideally you should have a 4.10:1 rear gear. Thats another story.
You need to recurve the distributor and resetup the carbs after a few simple mods.
For the Comp 270H magnum cam you want a lot of ignition timing at idle. Like 24deg BTC. The typical stock 6 to 14deg is not enough.
You want to limit the amount of mechanical advance travel in the distributor to allow increased timing at idle but the same typical 31 to 36deg max timing at high rpm.
What distributor are you using.
Further, you need to remove both carbs. Flip the carbs upside down, look at the bottom. You need to reset the throttle blades on both the carbs equally so that all 8 barrels throttles are open slightly, the same at idle. The idle transfer slot should just be barely exposed (.020") at the edge of the throttle blade on each barrel.
Then, you need to swap the power valve in both carbs for a 4.5" power valve. The stock jetting is fine for now. Just make sure the jets are stock for that model carb. the primary throttle opening @idle is adjusted by the curb idle screw. the secondary throttles are adjusted by a tiny set screw on the bottom of the throttle base. re- set them all equaly so that about .020" of each idle fuel transfter slot is exposed under the edge of the throttle blade.
re install the carbs with the new 4.5" power valves installed and do not touch the idle speed screws.
replace the spark plugs with new ones. they are fouled.
Start the motor up and adjust the ignition timing to 30deg at idle. (vacuum advance disconnected.) Let the car warm up. (takes a good while with a tunnel ram) and then readjust the idle mixture screws for best idle quality. Do not touch the idle speed screws. ONCE THE MOTOR IS FULLY WARMED UP If the idle speed is too high reduce the timing a few deg. If it is too low increase the timing. Do not drive the car. just set it up as discribed at idle. and tell me how you made out.
The motor must be warmed up fully to adjust the carb mixture screws and timing for best idle. Do not touch the idle speed screws or drive the car.
the idle mixture screw should be all just about equally adjusted. Takes patience to get them all balanced equally and the idle right. Work slowly. Remember use the ignition timing adjustment at idle to adjust the idle speed rpm.

DO NOT TOUCH THE CURB IDLE SCREWS AT ALL.
At what rpm does it idle at? should be around 750 to 950rpm What is the timing set at? Should be between 20 to 32deg BTDC at idle.
The throttle response should be much better now. Do not drive the car. The distributor needs to be removed and modified first.
Don't forget the new spark plugs and two new 4.5" holley power valves.
Once fully warmed up:
The idle should be rough, but rock steady at about 750 to 950rpm. The exhaust should not smell of fuel.

You're not done yet but set it up as above and tell me how ya made out. You'll need a selection of different size accelerator pump shooters, they are stamped with a number. and you may or may not need to adjust the carb jetting (later) You will have to modify the distributor advance curve. Need to know how much base timing is best at idle and what distributor you have. Leave the vacuum advance disconnected for now.

Last edited by F-BIRD'88; 03-04-2007 at 05:32 PM.
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Old 03-04-2007, 05:23 PM
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You got a leaky spark tube...
 
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You've got Holleys, does one or both of them have a blown power valve?
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Old 03-04-2007, 05:23 PM
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put u a progressive linkage and youll be fine
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Old 03-04-2007, 05:47 PM
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Quote:
Originally Posted by F-BIRD'88
It's all in the set up of the distributor and carbs.
Your tunnel ram will idle and drive fine once properly set up.........

.......Leave the vacuum advance disconnected for now.

good post
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Old 03-04-2007, 06:42 PM
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Quote:
Originally Posted by Blazin72
You've got Holleys, does one or both of them have a blown power valve?

no idea i just got it home today. ill check.
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Old 03-04-2007, 06:56 PM
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update: It has a mallory unilite dist. and a Holley blue electric fuel pump, Too much gas ? not enough timing? does it really need this caliber fuel pump? i didnt see a regulator..
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Old 03-04-2007, 07:20 PM
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Ok , i think i want to remove the whole intake setup and go with a single carb, while im there ,I might as well put in the cam i want. so thats where you guys come in. it has a comp 270 cam, with 224 dur/470 lift. what would be a better cam for my application? 66 cutlass is a pretty heavy car (3600lbs) and im more of a cruiser not a racer. i dont really care for the rough idle but a little more power from idle to 1500 would be good. what do ya think? it is a 4 speed car and i will prob go from the 3.08 to 3.42 gears soon. thanks guys. (anyone looking for a tunnel ram setup?

Last edited by pi71; 03-04-2007 at 07:25 PM.
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Old 03-04-2007, 07:32 PM
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You got a leaky spark tube...
 
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That cam should work just fine for your car, with the exception of maybe adding a lower gear like a 3.55 or maybe even a 3.73. The engine probably just needs to be tuned and have a few bugs worked out of it. Start with simple things like performing a full tune up on it, checking/setting the timing, cleaning and repairing the carbs if needed, etc... Try getting what you've got to work before you start tearing into things.
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