EarnIt

Can any one tell me what differences there are in cams for automatic and standard transmissions. I have one I used to have in my 70 chevelle 350 auto
and really liked the way it performed. Wondering if it will perform good in my 77 L-48 4 speed. Thanks for any input.

Geoff H

really before any advice can be given, we need to know the camshaft specs of the one u want to use, as much info on the motor/trans/diff/tyres of the car its going in and want u want it for eg, perf only, economy, drivability, straight out racing etc.


:)

EarnIt

Geoff,
I cant remember much about the specs of the cam other than it has a 112
degree centerline. The car I want to put it in is a stock 77 L48 4speed with
225/70/15 tires and a 3.70 rear gear. I am just looking to wake up the L48
a little. I am planning on adding an Edelbrock performer and chambered exhaust not looking for anything too wild. Thanks

Ganey

Since you do not know which cam it is, then was the 70 Chevelle converter stock & which rear gears?

A Comp Cams CS268H or XE262 will work great w/ your 4 spd. 77.
You might want to see my website for 77 Facts.

Jvette73

I dont think there is really a rule of thumb that seperates cams into catagories as far a manual or automatic trannys. The important thing is with an automatic trans, camshaft selection and convertor stall speed need to be matched. A longer duration camshaft will have a powerband that begins at a higher engine rpm. Select a stall speed that is close to the begining of the cams powerband. With a manual tranny its irrelavant since the driver controlls the stall speed with the clutch and can deliver the power to the tranny at any rpm.

Jvette73

I just had another thought on this subject. Difference in compression ratio between the two engines can play a role in wheather the cam will perform good in the other engine. If your Chevelle has higher compresion like 10.5/1 then a longer duration(valve off of seat) cam could work well in it. Take the same long duration cam and put it into a 8.5/1 engine like that of the L48, and it may suffer from lower cylinder pressure which could hurt performance. It also goes the other way. If you put a short duration cam in a high compression engine it may suffer from excessive cylinder pressure leading to pinging and detonation, which is definatly not a good thing. Camshaft duration has a direct relation to cylinder pressure.

With the longer duration cams the valve is off the seat longer leaving less of the piston upstroke to squeezing the mixture to its compressed state. if you pull the cam from the moter you should be able to find the grind # on the back of the rear journal. Maybe you can positively identify it before deciding if it will work in the other engine, which may have a lower comp ratio. Cams need to be matched to the comp ratio of the engine. Just about any cam will work in a 4spd car. Auto tranny equipped cars may need a stall convertor with higher duration cams.

mountainmotor

I would take Ganey's advice but out of curiosity if the cam is out look at the ends and post all Numbers and letters.I might be able to figure out what it is.

EarnIt

Mountain motor, the stamp on the end of the cam reads: C H284 S

Jvette73

Ill take a guess here. While not sure of the manufacturer, those #'s would indicate that the cam has advertised intake duration of 284 degrees. This is on the higher side for a streetable engine setup in my opinion. To get the best out of that cam, one should run low rear gears like 4.11, single plane intake, bigger carb, headers, and no less than 10to1 compression and definatly a higher stall if used in an automatic trans equipped car. Also plan on revving your engine to about 7000rpm to get the full advantage from that cam. Might be to big for a typical L48 8.5to 1 moter.

mountainmotor

I think it is a Crane single pattern 284-228@.050 .480 lift-112 LSA

Teeka56

I have this type of cam in my '73 L48. ( the owner before me added it) .It's terrible. I have an automatic with the higher stall converter and shift kit. It has no real power below 3500 rpm. I debating on yanking it or finishing a 383 that I have on the bench with a high lift short duration cam ( see John Lingenfelters book). Choose wisely it very important for the overall driveability of your car.