Camshaft Question for AMC 360 Engine

[miami-boy]

Hi guys,
I'm just about to overtake my jeep CJ-7 360 AMC engine. He is bored to 390cui and has Ross Pistons, Offenhauser 360 ° dual port manifold, installed 750 2bbl Holley carburetor and MSD distributor with 6AL module. The transmission is a T-18 with Centerforce dual friction clutch and the Dana 20 transfer gear and the AMC20 rear axle. Tires I drive 33x12,5x15 AT's and ride mostly street.
Now comes my question, which camshaft is optimal according to your opinion, if I want to drive a speed range from 800 rpm to 5000 revolutions. The jeep is to burn the strip .... I had a cam installed I chose wrong (CompCam Magnum 292h speed range 2000-6500 rpm) will replace this !!
What opinion did you ??

Greetings from Germany

P. S. : Bulltear Matched Gears for Dizzy are the best !!!!!!!!!!!

[tufcj]

Welcome to Bulltear! What ratio gears are you running? With 33" tires, I'd say 3.73 minimum, 4.10 or even 4.56 depending on how much highway driving you do. I ran an Edelbrock performer cam in my 360 powered CJ. (Howell 590 CFM EFI, T-18, Dana 300, 4.88 gears and 37" tires) It had great torque just off idle for rock crawling, but 5000 was about the top end. The Comp cam you selected would work better with lower (higher numerically) gears.

Cams are a trade off, no cam will do everything. A good torque cam will lack top end HP. A good HP cam will lack low end torque. I'd say keep the lift under .500", LSA in the 110-112 range, and duration in the 280 or less range. this will give you good torque and adequate HP.

Bob
tufcj

[miami-boy]

Thanks for the quick reply,
I'm at the moment not sure but I believe I have a 3.31 (3.33 ??) ratio on the rear axle. the motor rotates at approximately 90-95 mph on the highway between 4500-5000 rpm. The problem I had with the Comp Cams was that I had almost no Vacuum and since I hit in 2nd gear, the engine only goes in the knee before it fired up.
I hope my English is understood a little.
Therefore, I will now once again replace the camshaft.
I have my two camshafts in mind, the first: Lunati Voodoo 250/256 Hyd rpm range is 1000-5200
the second cam: Crane H-260-2 rpm range: 1200-4800
What's with you LSA ??
I forgot to say, the engine has Headman Headers with 2.5 "dual pipes (and H-Pipe). The Tag on the Rear Axle ist "BB"

grüße Siggi

[tufcj]

LSA is "lobe separation angle". the higher the number, like 112*, the smoother the idle and better idle vacuum the engine will pull. A lower number will produce a lopey idle with less vacuum.

I'd definitely swap to 3.73 or 4.10 gears before swapping cams. With 3.31 gears and 33" tires, you're making the engine work harder than it has to, and the cam isn't built for that. The lower gears may put your engine in a better operating RPM. Have you re-calibrated your speedometer? Going from a factory tire to a 33" tire, your speedometer will read about 10 MPH slow at 60 (it will read 60, you're really going 70). Check it against a GPS.

Bob
tufcj

[miami-boy]

hi bob,
Here in Germany I get for the amc 20 only 4.11 / 4.56 / 4.88: 1 ratio. Will I lose not top speed in the translation ???
But you're right to change the axle ratio is cheaper to replace as the camshaft. And I also wanted to include a diff lock which is of course easier.
greetings and thanks for the great feedback !!!!
Siggi

[tufcj]

You may loose a little top speed, but is a Jeep CJ with 33" tires really designed to go over 100 MPH anyway? With 4.10 or 4.11 gear (basically the same) you'll get to top speed quicker, and it will allow the engine to rev higher so top speed loss may not be as much as you think. You're right to swap the diff when you do gears so you only have it apart once. I've always been a fan of the Detroit Locker (I had one in both ends of my rock crawler). For less money, you can go with an EZ-Locker or Lock-Right that replace the spider and side gears in your current carrier. The diff you pick will depend on how you use your vehicle. A true-track may be better for a street driven vehicle.

Bob
tufcj

[miami-boy]

Hello Bob,
thanks again for your quick reply. the speedometer has been aligned before years with a bosch Geardrive. the display does works right.
and you're right, the cj has not been built to race at high speed on the highway.Instead, I drive traffic light sprint prefer.
I will now only times of change the translation for rear axle. is indeed cheaper. will test the 4.10 / 4.11 and 4.56.What is your opinion on the 4.56 ?? Enough power the engine has. In the second step, I will install the locker. but since I still can not decide, but since I mostly on-road ride . I must also look wich locker I get for the amc 20 . i mean in the usa that's easier to find lockers because you will have many more cj-5 / cj-7 / cj-8 moved on street /off-road.
I will continue to report !!
regards Siggi

p.s.: I checked the distributor pinion and it looked like new !!!!! Matched Gears from BullTear are the best !!!

[miami-boy]

Hello Bob,
I have spoken with my workshop. They want to sell a different camshaft me definitely. This mean a different final drive ratio does not alter the correct power emits the current built-up camshaft until 3000 rpm. I must say the have not much idea what terms jeeps.
Now I do not know exactly what should I do. It is now also an Edelbrock RPM Air Gap intake manifold installed, because supposedly the Offenhauser Dual Port 360 ° "Oldscool" and as mixture is not perfect in connection with the cam and the Holley 750 2bb.
What do you mean ?? Should I change the final drive ratio but only ?? Or is a different camshaft, the better choice ??? Both cost money but I want to come to a reasonable result.
Here again are my data:
85' Jeep CJ-7 with 360 Engine bored over to 390 cui.
33x12.5x15 Tires / T-18 transmission with Dana20 / AMC 20 rear Axle with 3:33 gear ratio / 292 ° Comp Cam Magnum / MSD 6AL module Dizzy + / Offenhauser Dual Port 360 ° manifold / Headman Headers with 2.5 "dual exhaust / Ross Pistons / piston Rings Loop / portet heads / bigger valves (but do not know just how much / which brand) / Center Force dual friction clutch

Grüße aus Deutschland
Siggi

[tufcj]

Go with what your shop suggests. They know your vehicle much better that I could. The dual port Offy manifold is a mis-match to your current cam. That manifold is designed more toward low RPM torque. The air-gap or a performer manifold would be my choice.

Here's a RPM calculator. There are many out there if you do a search on RPM calculators.
http://www.ringpinion.com/Calculators/Calc_RPM.aspx

I'd still think about a gear change. With 33" tires and 3.33 gears, you are about the same as a 2.60 gear with 26" tires. Your engine is well below it's power band at highway speeds. For optimum power/mileage, you should be at about 70-80% of where your engine produces it's peak HP. If your engine does peak HP at 4500, you'd want a ratio that puts the engine around 3100-3200 RPMs at cruise. You'll also want a cam that works best in that RPM range.

Bob
tufcj