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street manners of a Comp XS268s in a 499 #2936615
06/25/21 07:53 AM
06/25/21 07:53 AM
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Pittsburgh, Pa
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Jeff_383 Offline OP
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I think I know the answer, but what would be the street manners be of this cam in a 499? I'm thinking it would be like a stock 440. Which would be ok with me.

Last edited by Jeff_383; 06/25/21 10:46 AM.
Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2936955
06/26/21 12:04 PM
06/26/21 12:04 PM
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Idle like stock and make gobs of torque. Also gonna run out of steam pretty early but you know that. If that fits your intended usage then have at it.

Re: street manners of a Comp XS268s in a 499 [Re: gch] #2936985
06/26/21 01:32 PM
06/26/21 01:32 PM
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Dont be suprised if it runs out of steam at 5200 or so.



Re: street manners of a Comp XS268s in a 499 [Re: Jeremiah] #2937051
06/26/21 05:06 PM
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Jeff_383 Offline OP
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I can handle that. I want a cruiser type. Lots of torque and lugging around in 4th with 3.23's.

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937064
06/26/21 05:45 PM
06/26/21 05:45 PM
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So Near, Yet So Far
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So, 230/236 @.050, .488/.501 lift, on 110...
Sounds like smooth torque, good vacuum & mild manners to me @ 499 CI.
I've run a similar spec Engle cam with 446 CI in an early B wagon street car & was very happy with it.

Re: street manners of a Comp XS268s in a 499 [Re: topside] #2937092
06/26/21 07:57 PM
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Then I may put it in

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937134
06/26/21 10:27 PM
06/26/21 10:27 PM
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Big C.I. BB Mopars with decent heads like big camshafts, not little or tiny ones like stock are tsk twocents


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: street manners of a Comp XS268s in a 499 [Re: Cab_Burge] #2937147
06/26/21 11:24 PM
06/26/21 11:24 PM
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Well I have a 247/255 in there now. Lift is not a concern at 549/571. I can't stop it from bucking when trying to lug it around. I can get idle down to about 800.

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937162
06/27/21 02:17 AM
06/27/21 02:17 AM
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Originally Posted by Jeff_383
Well I have a 247/255 in there now. Lift is not a concern at 549/571. I can't stop it from bucking when trying to lug it around. I can get idle down to about 800.

The smaller XS268S cam at .050 with 230 degree on the intake valves and 236 @.050 on the exhaust may or may not have the same rate of valve opening as the one you have now.
What brand and grind is the one in the motor now?
The reason I bring this up is you need to compare opening rate as well as lift when shopping for cams, same advertised duration can be way different at .050 on the same brand cams, let alone from different cam companies shruggy work
I've been checking camshafts since the early 1970 from a bunch of different cam companies, the newer grind like the Extreme Energy compared to a older grind like the Mopar cams have or a older Isky or Engle grind is like comparing a 1962 Corvette to a 2010 Corvette or a 1970 Challenger 383 Magnum to a new SRT-10 Challenger shruggy twocents
The last Isky solid roller grind 440 cam I checked, RR602 grind, 260@.050 on both valves, open the valves so slowly that it really shock me shock It took probably 60 crankshaft degrees to open to .050 confused
On your deal not wanting to keep the engine revs up above 1200 RPM in any gear to cruising your probably doing the correct thing for your desires up
I'm the opposite, big cams and rev them babies up devil boogie
My last street car had a Comp Cams solid roller cam that was 260@.050 on the intakes and had 266 @.050 on the the exhaust ground on 108 LSA and installed at 106 ILC, It sounded milder idling at 850 RPM in gear than it did at 1700 RPM cruising in second gear at light part throttle shruggy It would really cackled and bark at 1200 to 2000 RPM grin up devil stirthepot
I'm a racer and I couldn't get any of the local street racers to play with it on the street or at the local 1/8 mile track whiney shruggy

Last edited by Cab_Burge; 06/27/21 02:18 AM.

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Re: street manners of a Comp XS268s in a 499 [Re: Cab_Burge] #2937182
06/27/21 08:28 AM
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there's pro's and con's to everything. this cam isn't a real 268 seat timing. the 268 is at .015" lobe lift, but lash is .016". divide .016" by rocker ratio and you'll find that seat timing is going to be running around .010" lobe lift. actual seat timing on the intake, and the same math can be applied to the exhaust, will be around 276 on the intake. actually this is good for 499". the 110lsa will probably close the intake valve too soon though. with comp's 4 degree of advance ground into the cam the intake valve will close at 64 degrees ABDC; too soon and i think too much cylinder pressure. try to come up with something that will close the intake valve at 70-74 degrees ABDC, the xs282 lobe, intake and exhaust, ground on 112lsa with 4 degrees of advance ground into will close the intake valve around 72 degrees ABDC. should be fairly smooth with a bunch of torque.

i'm using an engle k65 in my '65 coronet with a stock displacement 440. it's 280 degrees at .020" lobe lift, 238@.050" and is about max for what i do. actual seat timing is close to mid 290's and closing the intake valve at 75-77 degrees ABDC. the cam is fairly gentle, pump gas friendly, low maintenance and makes good mid-range torque in my application. would be a little gentler in 499".

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937211
06/27/21 09:57 AM
06/27/21 09:57 AM
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Originally Posted by Jeff_383
Well I have a 247/255 in there now. Lift is not a concern at 549/571. I can't stop it from bucking when trying to lug it around. I can get idle down to about 800.


Yeah that is a problem with a performance cam in a street car, especially with a manual trans and higher rear end gears. I've run into that problem before and it isn't any fun to drive a car that bucks when you try to drive slow over a speed bump or in a parking lot. Even with 500 cubic inches you need to keep the cam down in the 230 range at 050 to prevent that. The Chevy ZZ502 crate motor cam is 222/232 and it works great for street rods and muscle cars. It does give up some top end power but the torque curve is right where you need it for a street driver. A lot of people use too large of a cam in their street car and then they hate it.

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937216
06/27/21 10:05 AM
06/27/21 10:05 AM
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Originally Posted by Jeff_383
I can't stop it from bucking when trying to lug it around.

Then shift ! For the love of God , man..............shift !!!
laugh2 laugh2

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937219
06/27/21 10:10 AM
06/27/21 10:10 AM
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Originally Posted by Jeff_383
Well I have a 247/255 in there now. Lift is not a concern at 549/571. I can't stop it from bucking when trying to lug it around. I can get idle down to about 800.
you probably have some tune-up issues that if solved would help the situation. personally i hate big cams, especially hydraulics for street cars. majority of people don't know how to tune for them, and even if your tuning skills are good there's still limitations. the more that valve timing is increased the more the engine dislikes mufflers.

Re: street manners of a Comp XS268s in a 499 [Re: lewtot184] #2937231
06/27/21 10:33 AM
06/27/21 10:33 AM
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I've tried to adjust timing and carb to help it along. It's the best it's been, but not fun to drive. I do ha ve a lunati 702 hydraulic I could put in. This car is just for cruising, all torque. I've got some things to consider now with all your advice. I should probably just call one of the guys on here to grind me one that fits.

Last edited by Jeff_383; 06/27/21 11:21 AM.
Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937275
06/27/21 12:47 PM
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Yep, if it isn't fun to drive then you need to change the cam. I've worked on a few cars like that where the only option was to put a smaller cam in it. It is easy for people to get sucked into the whole "bigger is better" thing with cams. The bigger cams will make more peak power but if the car is a driver then it needs to be driveable even at low speeds. Call Porter Racing Heads and tell him how you drive the car and he'll get you what you need.

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937304
06/27/21 01:30 PM
06/27/21 01:30 PM
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Originally Posted by Jeff_383
I've tried to adjust timing and carb to help it along. It's the best it's been, but not fun to drive. I do ha ve a lunati 702 hydraulic I could put in. This car is just for cruising, all torque. I've got some things to consider now with all your advice. I should probably just call one of the guys on here to grind me one that fits.


Custom grind is the way to go for the best end result.

Re: street manners of a Comp XS268s in a 499 [Re: 4406bbl] #2937356
06/27/21 04:41 PM
06/27/21 04:41 PM
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What gear? A 230@050" roller is what was recommended to me here for my 512. With a 3.54 gear the car gets squirrelly off a 40 roll. Idles nice and doesn't spin past 5500. Couldn't be happier with it.

Last edited by MarkZ; 06/27/21 04:41 PM.

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Re: street manners of a Comp XS268s in a 499 [Re: MarkZ] #2937360
06/27/21 04:54 PM
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3.23's with a 28" tire. So pretty tall

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937361
06/27/21 05:03 PM
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EFI can help smooth out a big cam but even with EFI you'll want the cam to be down in the 230 range. The timing control in an EFI system allows you to put a lot of timing in at idle to smooth it out but then pull the timing as needed to keep from pinging. EFI also gives you better control over the AFR so you can easily dial in the idle mixture as well as off idle. But even EFI won't solve the bucking problem if the cam is too big for the combination. Modern cars solve it with variable cam timing but we don't have that option with the older engines.

Re: street manners of a Comp XS268s in a 499 [Re: Jeff_383] #2937404
06/27/21 06:24 PM
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Originally Posted by Jeff_383
3.23's with a 28" tire. So pretty tall
that's what i use with my k65 cam with a factory street hemi 10 3/4" converter. my '65 coronet weighs 3900lbs. very decent driver, but the converter is a little tight idling in gear. makes 14" of vacuum in neutral at 900rpm.

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