Too Hot of CAM?

[The PIG Smith]

I am planning soon to install a Summit 8601 Cam and lifters in the 360 in my '81 J20 tow rig.

Here are the specs of the SUM-8601 cam I have:

Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,000-5,000 RPM
Intake Duration at 050 inch Lift: 224
Exhaust Duration at 050 inch Lift: 234
Duration at 050 inch Lift: 224 int./234 exh.
Advertised Intake Duration: 282
Advertised Exhaust Duration: 292
Advertised Duration: 282 int./292 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.496 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.521 in.
Valve Lift with Factory Rocker Arm Ratio: 0.496 int./0.521 exh. lift
Lobe Separation (degrees): 114
Intake Valve Lash: 0.000 in.
Exhaust Valve Lash: 0.000 in.


I got this cam as a bargain.
I wanted a cam that was little less radical, but I was assured that if I recurve my dizzy for an initial 14 degrees,
I should be fine.
I currently have a Edelbrock Performer 2131 intake, with the EGR blocked off
and a Edelbrock Performer carb that needs rebuilt or replaced.
I have a single 2.5" exhaust that dumps right in front of the rear axle via a Flowmaster Series 40 muffler.
My 360 retains its stock Motorcrap ignition.
I have the parts for a TFI, but I desire a GM HEI.

My J20 is a dedicated tow rig that will see mostly the highway.
Before I start tearing my 360 apart, any comments or concerns about using this 8601 cam in my J20?

[82Waggy]

Assuming you have stock heads with that exhaust system, you probably won't be happy with that cam - too much duration and unecessary lift for a tow motor. Too much intake dilution for good torque at lower to mid rpms with that exhaust.

For towing and/or a wide torque range, look for something with about 30 degrees of overlap, at least 112lsa, and less than 260 adv duration . Not much need to exceed .450 lift with stock heads.

[The PIG Smith]

Assuming you have stock heads with that exhaust system, you probably won't be happy with that cam

Well, as I mentioned, this cam, lifters and timing chain set, NIB was a excellent deal.
I was hoping I could make it work for my rig.
Short of throwing this cam in the trash and buying a 8600, what could I do to make this work?
Would a port and polish the stock heads with headers?
Both were things I considered of doing.

Other than a Summit 8600 or a ComCam's 260H, what cam would you suggest?
Cam selection has been a royal pain.

[zero cool]

A friend of mine has the Summit 8601/Edelbrock 2131/600 CFM carb in his Wagoneer. He's running stock exhaust. The engine runs great from idle all the way to redline.

I have the 8601 in the 360 I'm swapping into my Cherokee. I also put it in the 401 that's going into my CJ. I've just gotten the 401 to run a little with GM TBI only to find out that the freeze plugs leak. It was way out of tune so I don't know how well it runs with that 8601 yet. I'll know more over the next couple of weeks.

I'll be firing up that 360 in the Cherokee over this weekend or next and it's using a full GM TBI from a 350 so it should run a lot better than the mix/match job I did with 350/454 parts on the 401. At least as far as initial tune goes.

[jeepsr4ever]

That camshaft is horrible for low end grunt. Speaking from first hand experience your alot better off with a 8600

[82Waggy]

Are you running stock compression ratio and stock heads? If so, neither of the Summit cams would be your best choice.

You need something that will help build cylinder pressure (earlier intake closing point helps build cylinder pressure=generally short duration).

With the valve size to displacement ratio of the 360 (similar to an SBC) you do not need a lot of duration to get the job done.

You are also talking about a relatively heavy vehicle pulling a load - long duration/valve overlap is bad for this and will likely fall flat on its' face. All the timing in the world won't help it do anything but ping.

Not saying it won't run, but seems everybody overcams their Jeeps as though they have a big block chevy (small valve to displacement ratio).

[82Waggy]

Check out Crower's 246HDP at www.crower.com

This, or something similar, is what I would put in a stock 360 with headers. Should help snatch your trailer, and snap your neck.

[Goose]

what is that I hear?? Too much cam in Jeeps.. Sacrilage! blasphemy!.. but it's true..

[The PIG Smith]

Check out Crower's 246HDP at www.crower.com

This, or something similar, is what I would put in a stock 360 with headers. Should help snatch your trailer, and snap your neck.

Thanx for advice.
I am happy that I've asked before turning wrenches.

[The PIG Smith]

Would my Summit Lifters work with a Crower Cam?
I am sure they would, but just confirming the obvious.

Also, what are your comments about having Crower grind a roller cam to the specs of their Hydraulic 246HDP.
Yes, I know my Summit hydraulic lifters would not work and I would need to get roller lifters.
Would I need to machine my block for such a setup?
I know nothing about a roller valve train.

I was thinking a roller cam and roller tipped 1:6 rockers while may not increase HP by that much may increase the efficiency.
Doesn't a more efficient engine run cooler, use less fuel, last longer?