Need info on Summit Cam 8600

[SwampRat]

The flat spot your speaking of could be from many things. What size of carb? what intake manifold? what lobe seperation on the cam? How much compression? What kind of tranny (and stall)? What does your engine have for manifold vacuum? Is your idle set correctly? What kind of timing are you running?

In the several instances I've seen rhodes used in small block fords, small block chevys, and big block chevys there has been no problems. I have no idea about the claim of them being made in the USA, but that wouldn't be as important to me as how it would effect the valvetrain.

The cam timing is most likely something that should be messed with, you need to address the individuality of ANY and EVERY combination, it is just a tuning tool that can help decide what kind of tune you prefer.

[shawn]

Wow, this thread sure took off!

So, you will give me a recomendation? Here is what I have, and it's in a Trail CJ.

304, stock, exept the Edel Performer Intake, and a different 2100 carb but soon to get a Truck Avenger probably the 470 cfm (not sure on that one either. This think gets punished on the trails, but I also drive to alot of trails at 70 mph (like about 3000rpm). Nothing to fancy, just looking for an RV style cam to help out, what you thing?

[jeepsr4ever]

Mellings RV cam

[SwampRat]

The Mellings brand name would be included in that list I gave above, of CMC Grinds, so "jeeps4ever" knows as well as I do that it would be a great stock replacement grind for a good increase in power everywhere in the rev range, and especially good at making average torque from a low RPM up unlike some aftermarket cams. Search for 112-114 LCA of 200-210* of duration @.050" tappet lift.

[tarior]

I was running a Holley dual feed 750 cfm vac sec carb, total timing was around 38 degrees. About 9:1 compression, Torker intake, Hedman headers, full length 2-1/4" pipes. It seems like it pulled 14-15" hg @ 800 rpm. IIRC the LSA is 108 degrees. The heads used 2.08 intakes and 1.72 exhaust valves, bowl hawged, port matched intake, heads and headers. 727 TF trans, stock converter. It wasn't flat below 2500, in fact all I had to do was bump the throttle and the tires would squawk, it was VERY responsive, just if you stomped it, it would occasionally bog until it came up to 2500 rpm, then the tires would just go up in smoke. If I got into it easy, then no bog, but no matter what, if you floored it in low, both rear tires were spinning, even at 40mph.
I'm just planning to freshen it this motor up and put it into my old Jeep truck, I want to use the same cam, I just want to shift the power band down a little.
Oh, the motor was originally in my '73 Jav/AMX, the back tires were 295/50-15 and were bald in no time at all.
The Jav is getting an aluminum headed 401, hopefully soon.

[SwampRat]

Those are huge primaries, you may be eliminating the "vacuum effect" that a well-sized header can create during the overlap period. The cam's LCA is also too narrow for my liking, combine this with a single plane intake and big valves it is very good evidence to me to make the engine's use of the fuel quite a bit less than perfect at RPM's such as 2500 and under. It may have liked a little converter and some lower gears to simply get it into the RPM's the engine is prepped for.

[tarior]

I agree about the converter, I was just too impatient to wait and save up $300 for a new one. I think the Jav has 3.73's. I wish I would have taken it down to PIR and run it, just to see what kind of 1/4 mile times I could get. I definitely needed some traction aids, that car was a tire fryer.

[radjeeper]

How about a cam recommendation?

-'78 Wagoneer
-2" body lift, 4"suspension lift, 35" MTRs w/ a anti-wrap bar in rear.
-401 w/ stock bore and pistons
-39 small chamber heads in stock form (about 10 to 1 comp.)
-Edelborck Performer intake
-Holley #4010 750 cfm carb
-Doug Thorley Tri-Y headers
-MSD Pro Billet Dist. w/ Jocobs Omni Coil 'n wires
-Turbo 400 with lower first and second gears
-2000 stall converter (probably)
-4.56 ring and pinions (D60 rear)

Primary uses: Cruising main, Moab type four wheeling, trails, dunes, playing.

Currently have an Edelbrock Performer cam but wondering what some porting of the heads and the "right" cam would do? I could have the porting done if I choose to pull the heads in order to properly install the roller rockers, being they currently do not have guide plates or hardened push rods. Either that or forget about roller rockers for now.

Further More: I spent the night researching some of this. Erson Cam states on their AMC page that they "...recommend the use of hardened pushrods and guide plates when using roller rocker arms." Then they say, "Guide plates and hardened pushrods must be used with adjustable/roller rockers on 1974-91 AMC heads. I have 1970 39 #319-6291 heads with Harlan Sharp roller rockers on ARP studs. Heads are on a 1978 401 block.

What do you think?

[jeepsr4ever]

Well the reason for hardened pushrods is that they are rubbing on the guidplates trying to keep the rocker from twisting due to the large through hole provided on most 72-74 and all 75-91 heads. The single rocker heads (common 090, 291 ect) have slots in the head that guide the pushrod and the soft cast isnt hard on the pushrod so you dont need hardened pushrods.

As far as camshaft goes your nearing the ability to use the advantage of some higher lift cams however that wouldnt be advisable seeing as you dont want a race car engine you want a low rpm grumbler. I would look to a rv cam like a 8600 or a comp 262.

[radjeeper]

That's great knews about the push rods and guide plates! We about have everything put back together and I was hoping not to have to take it all apart. Thanks for the help.

On the cam issue, another one I was thinking of was the Howards .479/.479 lift 292/292 duration, 222/222 dir. @ .50, and 114 LSA. Dusty on here was raving about it compared to the CC 270H. He stated how smooth it cam in at all RPMs compared to the 270H. I know it is a little more cam than the 262H that you recommended.