Too Hot of CAM?

jeepsr4ever

Dusty wrote
have run the 8601 which is the profile you listed in a couple of stock compression 401's and had no problems towing actually towed really well, woke the motor up more so than most of the so called rv and towing cams out there. i also ran a 270H comp cam in my 360 powered rig with a 670 and that towed really well too, and in a 9.2:1 360 with a performer and the PAW version of that cam i had it in a 74 waggy with t-18 and liked it plently of snort in the 1500-5500rpm range, a little soft off from 1000-2000 but i was never in the 4 barrels at those rpms anyways so the gearing in the truck took care of the soft starts, soft start was just a slight tap of throttle as i was letting clutch out vs some of the other options where i could just let the clutch out and didnt really have to worry about keeping throttle up. I liked being able to down shift on a grade and pull 4000 rpm+ and still having power with a load and then being able to shift back into direct and keep chugging down the highway. most of my rigs have always cruised the highway with a trailer at 2500-3000 rpm at 65-70 mph+ and since that is my cruising rpm i have always liked the rpm buffer of still having 2k ov er that and still having power 1000 rpm under that.

That said i cannot help you with a rockers and bridges motor, all of my 360's, 390's and 401's that i have built if they are rockers and bridges i havent gone over 480 lift but with the stud motors all of my amcs that i have towed with and built have loved bigger cams for towing ect. 401's and 360s alike always get undercammd. also dont forget that nis a 114 lope sep cam its alot more behaved than you might think.

Dusty I just dont know about your builds out there. You seem to get power where it shouldnt be :?:

Sure you aint polish boy? :?: :?: :?:

Dusty

lol just a relative of yours. :razz: shoot you have recommended 1/2 the cams for 1/2 of my builds and a few friends over the last few 5 years. :t: 360-270h 9.2:1 ran good 360- 258EX 9.0:1 ran good 401 - Crower 284hdp? 512/525 lift 112 lobe 9.8:1 r4B combo ran great, towed was lots of fun 401- 8601 9:1 51cc heads on 8.5:1 pistons with the 8601 / performer - good. fun with a t-18 401 - howards .479 222dur@.050 292dur 114 lobe sep- 8.5:1 torker (dotn ask) and 600 - good 401 - Howards .479 cam - 10.2:1 and FI - so so think it may have been the fuel injection hindering performance 401 - 512 lift 274 dur 226@.050 112 lobe sep 10.2:1 with performer and 750 pretty fun mild idle great through to 5000/ 5500 401 - 9.6:1 270H Air gap and 770 so-so with a 670 and performer the same motor picked right up works great as a tower and mileage getter 390 - 10:1 R4B -700 - 276HDP Crower- OK performance done too soon rpm/power wise left a little to be desired on the mid upper and top end. in a 72 Wagoneer with T18 4.10s 32's 401 - 9.8:1 EX262h Comp - airgap and 750 pretty nice combo was snappier off the line with a performer but the airgap opened up mid and tops. tows pretty good in a J20 they said it was a 110 lobe sep but when it arrived the card said 112 360 - 10:1 343 pistons - EP20HYD Engle - Performer/700. Nice combo compression could have been a little lower but overall liked this combo it did really well with a TF727 and 3.92's in a J10. Had no problem on pump gas but towing it liked premium from time to time. :(: theres a few others in there Oh yeah current cherokee is a 401 9.8:1 witht he 260h in it and 354 gears on 31's and a TH400 performer and 750 edelbrock tows great but she is done at 4000 rpm so kicking down to passing gear and trying to extract a few more rpms out of the motor with a trailer is not an option just staying in direct gear does pretty good on most hills loaded i know its always been weird, the power does always seem to be there i can say the 280h in a 360 with a torquer and 800 was Way too much lol on 9.2:1. the PAW cam was close to the 270h in profile not the 8601. On a recent 401 built i liked that 262EX from comp i think it would be pushing it for a low compression 360 but then again maybe not it might be a little large but may offer an interesting package.

jeepsr4ever

:sa: :t: :?: 111!!! :wink: :oops: :? :(: :smile: 8)

Goose

I would love to try a dual plane..I need to find one. I also need to find one for the 304 in the cj..(well ok I need to get off my half moons and finish the 360 for it..)

82Waggy

Found an interesting comparison of two 401 builds in this forum complete with cam cards and dyno sheets. One is donwag's shown in the general chat section, and the other is jeep_man_401 shown in the general tech section. donwag's uses a perfomer manifold, 670 Holley, 9:1 compression, and a Comp XE256H cam (110LSA with 42degrees overlap) with Edelbrock heads yielding 428ftlbs at 3400rpm, over 400ftlbs from 2000-4600rpm, and 348hp at 4800rpm. jeep_man_401 uses a dual quad set up, 10.5:1 compression, a custom Crower 288/306 split duration cam (108LSA with gobs of overlap) with about 550 lift, and ported Indy heads yielding a little over 450ftlbs from 3000-5200 and 450hp at 5500rpm. At 4800RPM where donwag's hp peaks, jeep_man makes an additional 25ftlbs torque and 50hp. At 3400 RPM where donwag's makes peak torque, the HP output of the two is about the same. jeep_man_401 notes his truck is "b_tch" to drive below 30mph and comes to life around 2300rpm - but he built his to kill street rods. Things that make you go "hmmmmm".

82Waggy

Interesting mix of engines you have there Dusty. Your assessments would seem to coincide with the combination of cams and compression ratios used. Do you have a favorite? KJMac: Don't confuse "stock replacement" with "stock specifications". The 246HDP is designed to increase power in a stock compression engine with stock heads by closing the intake valve earlier to help build cylinder pressure, and optimizes valve lift to the flow characteristics of stock heads to increase port velocity. This is not a stock smog spec cam. Bottom line is if you are not going to increase compression ratio from stock, stay away from long duration cams.

Goose

ok Waggy.. you get the eloquence award..You just said what I have been mumbling about.. the difference is you said it clearly!! good job.(and with the facts to back it up rather than the observations I used.) :?

82Waggy

Here is a general assessment of the effects of various cam characteristics: More LSA = Widens power band, More peak power, Smoother idle with higher vac, Decreases overlap Less LSA = Increases mid-range torque, Narrows power band, Faster reving, Increases overlap More Duration = Moves power band up In RPM range - approx 500RPM/10 degree increase in duration, loss of low rpm torque due to later intake valve closing point can usually be gained back with increased compression Less Duration = More Low RPM Torque More Overlap = Better high RPM cylinder scavenging, Decreases vacuum, Rougher idle Less Overlap = More low end response and torque, better fuel economy Lift = Should be sized against ports for best velocity.

82Waggy

Goose wrote
ok Waggy.. you get the eloquence award..You just said what I have been mumbling about.. the difference is you said it clearly!! good job.(and with the facts to back it up rather than the observations I used.) :?

Awe shucks Goose!

How 'bout you hook' em and I'll clean'em and fry'em!

1980_Cj7

Here's the specs on our Clevite cam. It's LINE NO. 2 on the following charts. Not to high jack this thread, but how do you experts think the engine will work if we go to 8.5 to 1 pistons and keep this cam. If you recall, we were having pinging problems, on top of all our other problems, when we had the Ross 9.8 to 1 forged pistons with this cam. Those pistons also were .017 down the hole rather than 0 like they should have been.

We're getting ready to put this thing back together and try again. One of the problems with this cam seemed to be the early intake closing coupled with the high compression pistons. I'm wondering if it might actually help the lower CR pistons though.

82Waggy

cj7, You had Ross forged pistons in there before, correct? That cam has a lot of duration and valve overlap for Jeep motor. the actual intake closing point is considerably later than what you used in your calculation. I know KB says use the intake closing point at .050 lift plus 15 degees, but this is just a guess to help people use the cam card specs. The actual closing point with 294 duration at .006 tappet lift is 72 degrees - assuming the intake CL was set as specified. To shorten up the discussion, I don't know what you finally arrived at for bore diameter after clean up but I would choose a piston that closes that quench distance to .045 (zero deck) and gets your static compression closer to 9:1 - coupled with a dish piston such as the KB 354 (28cc) you may also need to open up the head chambers to around 65cc to acheive this. For a good torque motor in a Jeep, I would then choose a cam with a 112LSA and overlap of about 32-35 degrees. An intake closing point of 56 degrees ABDC should keep cylinder pressure in check with the above setup. You are running stock unported heads, right? If so, an Engle 5016H cam or something similar would fit the bill. PS: Those are some really slow lobe ramps on that Clevite cam = 294 duration @ .006 and 218 @ .050. Compare that to an Engle 5020H = 270 dur @ .006 and 226 @ .050.

1980_Cj7

Yes, sorry, we had Ross forged pistons. I edited my post above. And yes, stock unported heads.

82Waggy

OK. I forgot to clarify in my previous post that closing the quench distance should improve detonation resistance - in theory if you have good compression (9.5:1 for example)and then lower it by increasing quench distance (piston to head clearance) it is possible that the engine would be more prone to detonation due to a more non-definate combustion event - which is kind of the situation you had.

eight

The only cam I find that matches your low overlap numbers is the Comp 252 which has 206/206 at .050, .433/.433 lift, 110 LCA, and 32 degrees overlap. That's a very small cam. What do you think of the comp 260? It's 212/212 at .050, with .447/.447 lift, 110 LCA, and 40 degrees overlap. There is also a crane pt#863904 that is 260/272 total with 204/216 at .050, .456/.484 lift, 112 LCA, and 42 degrees overlap. And there's another comp I don't know the name of, think it's one of their 4x4 cams, but it's 256/268 total with 212/218 at .050, .447/.484 lift, 110 LCA, and 42 degrees overlap. These are the only cams I found with low overlap, most others with durations close to these are 50+. The little edelbrock has 63 and the summit 8600 is 53.

Dusty

82Waggy wrote
Interesting mix of engines you have there Dusty. Your assessments would seem to coincide with the combination of cams and compression ratios used. Do you have a favorite?

Bottom line is if you are not going to increase compression ratio from stock, stay away from long duration cams.

Personally the 8600 was too small for the 401's i felt it really cut the motor off at its knees

i would say the 9.8:1 with the comp 262EX w/Performer a holley 670 or/ with a edelborck 750 was a really fun, worked well. but thats just because its most recent

Though Let me say that the Custom grind single pattern from crower 274 dur with 226@.050 and .512 lift on a 112 lobe sep that was in the 10.2:1 motor now has 58cc cast iron heads on it with mild Exh port and polish w/ gasket matching and cc's out to 9.72:1 with a performer and the Edelbrock 750 is near the top of my list. We put my buddys 670 on it and it picked up a little bottom end get up and go but the 750 is what i have sitting here so its what is on there now. I really like this combo very mild lope at idle.... idles at 650-700 rpm.

I'll say on stock compression that 292 dur 222@.050 dur .479 lift and 114 lobe seperation on the 8.5:1 motor worked really well

82Waggy

eight wrote
The only cam I find that matches your low overlap numbers is the Comp 252 which has 206/206 at .050, .433/.433 lift, 110 LCA, and 32 degrees overlap. That's a very small cam.

What do you think of the comp 260?

There are several cams with overlaps less than 40 degrees from Engle or Crower.

What compression ratio and heads are you running?

82Waggy

Here are several cams along the lines of what I have been talking about. Note the fast ramps of the Engle's - lower overlap for low rpm torque and high .050 duration. This is one of the advantages of the AMC - its' large diameter lifters can handle faster lobe ramp rates. CRW258H,Eng35018H,Eng5052H,Eng5016H,Eng5018H,Eng5054H ILCL, 109, 109, 109, 109, 109, 109 ELCL, 115, 115, 115, 115, 115, 115 LSA, 112, 112, 112, 112, 112, 112 Int@006 258, 248, 254, 256, 260, 260 Exh@006 264, 260, 254, 256, 260, 260 Int@050 204, 207, 209, 210, 216, 214 Exh@050 210, 216, 209, 210, 216, 214 Int Lift, 445, 466, 488, 472, 488, 501 Exh Lift, 448, 496, 488, 472, 488 501 IntOATDC,-20, -15, -18, -19, -21, -21 IntCABDC , 58, 53, 56, 57, 59, 59 ExhOBBDC, 67, 65, 62, 63, 65, 65 ExhCBTDC,-17, -15, -12, -13, -15, -15 Overlap, 37, 30, 30, 32, 36, 36 PS: dual plane intake manifolds, free flowing exhaust (headers and dual pipes), and higher displacement to intake valve size can handle more overlap. Higher compression ratios need to follow later intake closing points.

« Previous Page