360 roller cam - safe to retard a few degrees?

Posted By: Montclaire

360 roller cam - safe to retard a few degrees? - 04/01/19 07:42 PM

Hello, I have a stock 1989 LA 360 roller motor. Compression is listed as 8:1, HP is 190@4000, torque is 285@1600. Cam is pn P5249663- hyd roller with 250/264 duration, .385/.401 lift, and 108 CL. Heads are stock 308s. I've read some complaints that these motors could be prone to over scavenging, resulting in cherry-red manifolds. I'm planning to run a cooler plug, would I also be safe retarding the cam a few degrees? Application is a 1973 Charger with a 727 and CR20 converter (roughly 2400-2600 stall behind a 360). Haven't settled on rear gears yet, maybe 3.55s for the 8.25 axle. This is strictly a street build.

Thanks

Posted By: MR_P_BODY

Re: 360 roller cam - safe to retard a few degrees? - 04/01/19 09:56 PM

Whats the reason you want to retard the cam.. is this a running
engine

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/01/19 11:59 PM

It's a Jasper rebuild out of a B250 van. The seller said it had about 1500 miles on the clock when pulled and the internals were spotless so I believe him. I am guessing Jasper installed the cam straight up for one, and a 73 B-body isn't your mother's Dart. Secondly I thought that retarding it a couple degrees would help minimize any detonation from scavenging and extend my top end on what is really probably a grind for towing.

I don't have the motor in the car but from what I have been reading they top out way before 5k. Torque is peaking at 1600, well before the stall on the converter. So my thought process was to retard it a few degrees and move my top end past 5000 while timing the torque curve to match the converter and avoid the detonation. Am I on the right track?

Posted By: madscientist

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 12:59 AM

Originally Posted by Montclaire

It's a Jasper rebuild out of a B250 van. The seller said it had about 1500 miles on the clock when pulled and the internals were spotless so I believe him. I am guessing Jasper installed the cam straight up for one, and a 73 B-body isn't your mother's Dart. Secondly I thought that retarding it a couple degrees would help minimize any detonation from scavenging and extend my top end on what is really probably a grind for towing.

I don't have the motor in the car but from what I have been reading they top out way before 5k. Torque is peaking at 1600, well before the stall on the converter. So my thought process was to retard it a few degrees and move my top end past 5000 while timing the torque curve to match the converter and avoid the detonation. Am I on the right track?

Don't just move the cam. I'd bet everything you have that jasper didn't degree the cam so right now, until YOU degree it, you have no idea where that cams at. It could be 8 degrees retarded already and you want to back it up.

You need to degree it yourself and VERIFY where it's at and then make a decision.

You need to do it right, not just guess.

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 01:14 AM

Yes, that's the plan. I'm just not sure how much I should retard it once I figure out where zero is, or if that will accomplish what I am trying to do.

Posted By: madscientist

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 01:39 AM

Originally Posted by Montclaire

Yes, that's the plan. I'm just not sure how much I should retard it once I figure out where zero is, or if that will accomplish what I am trying to do.

I guess my question is what are you going to do if the cam is already retarded???

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 01:57 AM

Haha, I really don't know. The same cam was used in the first magnum crate motors, although with a 1.6 ratio and not the 1.5 on the LA. I guess I would try to figure out how the factory installed the cam originally (it was truck or van only for the tbi 360) vs how they installed it on the crate motors, assuming I can even find that out. Would they specifically design a cam for truck/van application and not grind it how they want it straight up?

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 01:08 PM

Nobody? I figured this would be an easy one.

Posted By: MR_P_BODY

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 02:04 PM

You can move the cam but you better know where you are
starting at first so degree it first.. with that low of compression
it shouldnt be a problem but you will be losing the bottom
end torque and that car is heavy so you need it

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 02:46 PM

Don't know if this helps any:

Quote

The specs given for the Magnum 5.9 in the 1995 Dodge FS Manual seem to be incorrect, and actually for the last pre-Magnum V8 in 1992 that did also have a roller cam by then. The 'Magnum Engines' book by author Larry Shepard seems to repeat this mistake because it copies the 1995 FSM word for word.

Those (maybe incorrect) specs are:

Exhaust Valve
Closes ATC 23
Opens BBC 61
Duration 264

Intake Valve
Closes ABC 80
Opens BTC 13
Duration 274
Overlap 36.5

Valve lift 0.410 inches

The major difference is in how late the intake valve closes at 80 degrees After Bottom Center.

The above 264/274 cam is supposedly what was put in the first 360 Magnum 'Crate Engine' from MP according to Al Kirchenbaum in his Hot Rod Magazine article titled 'Magnum Manifesto' in Aug 1998. The Hot Rod article says the cam used was the stock cam from a pre-magnum 1992 model 360 V8 with TBI.

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 04:28 PM

I sent an email to Jasper, and to my surprise I got an actual phone call from them. They said on that motor the cam would have been installed on TDC. So it could still be off but at least I know they didn't intentionally retard/advance it.

Posted By: madscientist

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 05:30 PM

Originally Posted by Montclaire

I sent an email to Jasper, and to my surprise I got an actual phone call from them. They said on that motor the cam would have been installed on TDC. So it could still be off but at least I know they didn't intentionally retard/advance it.

I have no idea what that even means. How do you install the cam on "TDC"?? I've never heard that.

I use the intake centerline method and degree the cam at whatever the card calls for and tune from there. That means if the card says install the cam on a 110 intake centerline, the intake valve is at max lift 110 degrees AFTER top dead center.

Ain't no way you can install it at TDC as that makes no sense. Call him back and remind him he is out of his gourd. Tell him you either want an intake center line number of where the intake opens at .050 lifter rise. Either will do.

Maybe I can make a phone call and get you the number you need.

Posted By: madscientist

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 05:33 PM

Wait wait wait...I just read the OP and you say the cam is ground with a 108 LSA. That means if it's typical Chrysler it installs at 106. You may be able to install it at 104 if you want more bottom end.

I've never seen any DC/MP cam that wanted to be retarded past its LSA. I'm not sure about your cam. It if is ground on a 108 LSA as you say, I'd degree the cam to see where it is. If it's not 106 or 104 I'd put it there and try it. I've seen very few cams that liked to be retarded past the LSA. I've seen a few, but those were oddball combos.

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 06:06 PM

I've seen the centerline listed as 108 and 110. I think the 110 comes from the magnum crate literature so take that with a grain of salt (EDIT- from the 2000 mopar catalog). Overlap is 37.

Posted By: MR_P_BODY

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 06:50 PM

First off.. forget about the overlap.. you have no idea if it will turn
your manifolds red or not.. you still have no idea where that cam
is installed till YOU check it.. get that data then go from there.. big
deal if you read that somewhere.. I havent ever seen a 360 turn
red IF it was tuned right and I seen a ton of them at Chrysler and
beat on them hard when testing

Posted By: WO23Coronet

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 07:05 PM

If your numbers are right from the snippet you added from the HR article, this cam has 273 intake duration and 264 exhaust duration, which seems odd the intake has more duration that the exhaust. I know the 308 heads exhaust ports flow almost as much as the intake but that still seems off, usually heads with a strong exhaust port seem to get a cam that has equal intake and exhaust numbers. Going by those numbers you have a 116ish degree LSA, which is a far cry from 108 and seems more likely (factory cams all seem to have an LSA around this mark). If anything you should degree that cam in around the 108 mark, be a lot peppier.

Posted By: Cab_Burge

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 07:15 PM

SB Mopar motors do not like the cams retarded, NEVER

Any time you retard the ignition timing it will end up burning unburnt fuel in the exhaust turning the manifolds and pipes red

Retarding the cam will open the vales later allowing any unburnt fuel to go into the exhaust with loss of power also

It has been mention and stated by several other posters on here to make sure and check the cam timing before moving it

Do NOT ASSUME that Jasper got the cam timing close, NEVER ASSUME any thing on motor parts, especially cheap rebuilder parts

On your deal make sure and check both the intake and exhaust lobe separation angles to make sure exactly what the cam core lobe separation angles are before changing it

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 07:29 PM

I at least want to open it to see what kind of timing chain they put on it, I might just throw on a tensioner from a 3.9 and call it a day. The motor ran when it was pulled and it's not a performance build but I figured it wouldn't hurt to make sure the cam was phased properly.

Posted By: WO23Coronet

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 07:36 PM

Put a degree wheel on it, set up a dial indicator and piston stop and see exactly what it has and where its at, that's 1/2 the fun with messing with engines! I've never done it but guys claim even on a 318-2, advancing the cam a few degrees really helps.

Posted By: MR_P_BODY

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 07:42 PM

I advance all my SB cams.. I have been from 99* to 108* on some
but NEVER retarted... 99* had great torque but ran out of RPMs..
I tend to stay just a couple degrees advanced
EDIT
When you start talking 114 LSA your getting into blower and turbo
stuff and it bleeds off too much pressure for NA stuff

Posted By: WO23Coronet

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 07:49 PM

Originally Posted by MR_P_BODY

I advance all my SB cams.. I have been from 99* to 108* on some
but NEVER retarted... 99* had great torque but ran out of RPMs..
I tend to stay just a couple degrees advanced

Can you explain why advancing the cam is always referenced to the LSA? What is the relation between them? I know its an easy reference (it's 4 degrees advanced etc) but wouldn't it be more important to be concerned on the opening point of the intake for installation purposes rather than how far apart the exhaust and intake lobes are? If a cam with a 106 LSA runs well/makes more power at a 102/104 ICL, why wouldn't a cam with the same lobe specs but a 114 LSA also like being installed at 102/104 ICL? Or would it, and the old "install it X degrees advanced" has become so entrenched as common knowledge/settled science/popular opinion its what guys automatically spout?

Posted By: MR_P_BODY

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 08:25 PM

Originally Posted by WO23Coronet

Originally Posted by MR_P_BODY

I advance all my SB cams.. I have been from 99* to 108* on some
but NEVER retarted... 99* had great torque but ran out of RPMs..
I tend to stay just a couple degrees advanced

Can you explain why advancing the cam is always referenced to the LSA? What is the relation between them? I know its an easy reference (it's 4 degrees advanced etc) but wouldn't it be more important to be concerned on the opening point of the intake for installation purposes rather than how far apart the exhaust and intake lobes are? If a cam with a 106 LSA runs well/makes more power at a 102/104 ICL, why wouldn't a cam with the same lobe specs but a 114 LSA also like being installed at 102/104 ICL? Or would it, and the old "install it X degrees advanced" has become so entrenched as common knowledge/settled science/popular opinion its what guys automatically spout?

I was using a known LSA cam based on what the card said checking
with the wheel.. with advancing the cam I,m moving both the intake
and exhaust points.. otherwise I need a new cam so moving it works
for me

Posted By: JAKE68

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 09:34 PM

You said you wanted to check to see if jasper phased the cam right. I can tell you that I have been to their plant and everything is installed dot to dot. So if they where off 1 tooth it would have been a tured.. they only use stock profile cams and if it was a roller motor they would have most likely used the original cam ft cams get replaced. If you retard that cam you would be very disappointed in the performance. If you go and waist your time and go and check the degree of that stock cam for what ever purpose you might as well put something in there that would make a difference in performance. By the way jasper dose not use junk parts. For a stock production reman motor they are the premier remanufacture

Posted By: madscientist

Re: 360 roller cam - safe to retard a few degrees? - 04/02/19 11:17 PM

Originally Posted by JAKE68

You said you wanted to check to see if jasper phased the cam right. I can tell you that I have been to their plant and everything is installed dot to dot. So if they where off 1 tooth it would have been a tured.. they only use stock profile cams and if it was a roller motor they would have most likely used the original cam ft cams get replaced. If you retard that cam you would be very disappointed in the performance. If you go and waist your time and go and check the degree of that stock cam for what ever purpose you might as well put something in there that would make a difference in performance. By the way jasper dose not use junk parts. For a stock production reman motor they are the premier remanufacture

Dot to dot means nothing. Never has, never will.

Posted By: Montclaire

Re: 360 roller cam - safe to retard a few degrees? - 04/03/19 12:16 AM

Originally Posted by madscientist

Dot to dot means nothing. Never has, never will.

That's what their guy meant by "installed at TDC." Meaning no degree wheel, they rotate up to TDC and slam her home. Which is plenty enough to tell me I need to start at square one. As for the cam itself, I would go with a different grind but then I am looking at new springs since the stockers are marginal. All of that adds up and it's just not in the budget for now. If it moved a Ram truck, it'll move a 73 Charger.