508 or 509 Purple Shaft cam

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csx452

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I've been trying to find the specs on the Mopar Performance Purple Shaft Cam for a smallblock. I found specs on a 508 cam but I thought they made a 509 for the smallblock and I can't find anything out there on it. Can anyone help me out here?
Thanks,
Frank
 
I see a 508 there but not a 509. My 360 has what I believe to be a 509 cam in it. My mechanic did some measurements and that's what he came up with. Don't know anyone with a cam doctor around here to find out for sure though. I want to degree the cam properly when the engine goes back together. I thought about just getting a new cam and bearings but money is just too tight now so I'm just regasketing the engine to get rid of the annoying oil seepage. It ran like a bear but since it's apart, why not make sure it's correct?
 
csx452 said:
I've been trying to find the specs on the Mopar Performance Purple Shaft Cam for a smallblock. I found specs on a 508 cam but I thought they made a 509 for the smallblock and I can't find anything out there on it. Can anyone help me out here?
Thanks,
Frank
Click to expand...

509 was big block. 508 was small block. most people mistakenly refer to the 508 as a 509.
 
Were there 2 different 508 cams? I kinda remember reading on here or maybe somewhere else that there was a Direct Connection cam and a Mopar Performance cam and one of them wasn't as good as the other.
 
Thanks for the replies so far. Good info from everyone. I do appreciate it.
Frank
 
the 284/484 cam came with a 108 LSA and a 112 LSA...

the 112 idles better....dont remember if the 508(9) did also
 
Yes at one time there was two. The 292 - 108 version might not out anymore. They were coming out with one with better vaccum. But i have seen one. and i dont remember the centerline on it. More than 112 i think. When i put my last 340 together thats what i ran into. So i used the comp cam 508. Split dur 292/299. I like it .
 
My car didn't idle well but it also had an M1 single plane intake. It went from idle to screaming like turning on a switch. I'd really like to figure out just what it is that I have. Is there any way to figure it out besides a cam doctor?
 
I have a air gap with a 750 holley. This is the second motor for my car. but the first motor did what you are saying. it had a 508 purple. i disconnected the vaccum advance it halp some with the rpm problem. It did it coming to a stop mostly. had to smack the gas petal in neutral to get the dam thing to come down. You could pull a valve cover and measure with a 1 inch indicator on the bottom of the rocker and it might get you close.
 
Last catalog had 484 and 508 was to have a better vac. They were calling more street friendly. Ill see if i can find it.
 
Just got back from the shop and the 9th Edition of the Mopar Engine book listed a small block 509 cam. It didn't list a 508. Now I'm really confused.
 
csx452 said:
Just got back from the shop and the 9th Edition of the Mopar Engine book listed a small block 509 cam. It didn't list a 508. Now I'm really confused.
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The book has a misprint. My God, what difference does it make? You're worrying about a .001" of an inch difference, do you realize that? ONE THOUSANDTH of an inch. You've already been told by more than one reputable person that the .509 was the big block grind and the .508 was the small block. It's a great cam but it's REALLY big for a hydraulic. You need at least 10.5:1 compression for it to run properly and give the power it was designed to give. It has 248.5* of duration @ .050" lift ground on a 108 LSA so don't expect a vacuum signal worth snot and expect a VERY rough idle. It will need a 3000-3500 converter and at the VERY least 3.91 gears and prefferably 4.10 or 4.30. It is a race bred hydraulic cam and runs that way, but it's a damn goodun.
 
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for some people .001 can make the difference.......lol
 
StrokerScamp said:
The book has a misprint. My God, what difference does it make? You're worrying about a .001" on an inch difference, do you realize that? ONE THOUSANDTH of an inch. You've already been told by more than one reputable person that the .509 was the big block grind and the .508 was the small block. It's a great cam but it's REALLY big for a hydraulic. You need at least 10.5:1 compression for it to run properly and give the power it was designed to give. It has 248.5* of duration @ .050" lift ground on a 108 LSA so don't expect a vacuum signal worth snot and expect a VERY rough idle. It will need a 3000-3500 converter and at the VERY least 3.91 gears and prefferably 4.10 or 4.30. It is a race bred hydraulic cam and runs that way, but it's a damn goodun.
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Yes, it is a damn goodun and I was running 410s before pulling the engine. I'm not worried about .001". I just want to be able to properly degree the cam. I do appreciate the info I've gotten on here and I come here for advice because of the reputable people on here.
 
csx452 said:
Yes, it is a damn goodun and I was running 410s before pulling the engine. I'm not worried about .001". I just want to be able to properly degree the cam. I do appreciate the info I've gotten on here and I come here for advice because of the reputable people on here.
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Just go by the part number. It is P4120233. .508/.508 248.5* @ .050 on a 108 LSA with 76* overlap. I think the MP Performance book even has all of the valve timing events as well, but you can degree it regardless. Just keep in mind that huge amount of overlap. That is what bleeds off cylinder pressure. That's the reason you should run 10.5 minimum compression.
 
StrokerScamp said:
Just go by the part number. It is P4120233. .508/.508 248.5* @ .050 on a 108 LSA with 76* overlap. I think the MP Performance book even has all of the valve timing events as well, but you can degree it regardless. Just keep in mind that huge amount of overlap. That is what bleeds off cylinder pressure. That's the reason you should run 10.5 minimum compression.
Click to expand...

Cool!!! Thanks. I'm not sure what the compression ratio is, but since it ran so well before I'm assuming it was at least 10.5 to 1. I was running 410s but I think I may go with 391s. I think anything less would be useless.
 
Well, just to add a little confusion to the pot I have a .509 purple shaft and it says it's for an A engine, is that not a smallblock? Now I'm confused.

Duration 280
Overlap 68
Centerline 106

Part# 4529969
 
I know I'm a little late to this but I spent 30 years working at Mopar dealerships, even running a Mopar speed shop out of one. Anyway from Mopar there was a mechanical camshaft designed for oval track that was a .509 lift. The specs that momoparnut described are correct. Part # was P4529969. However it was not very common. More than likely you have the 508 hydraulic cam part# P4120233. Rusty Rat Rod's spec's are right on and he is correct; it is a big hydraulic. I ran one in my old Dart engine. Power does not come on until 3000 rpm, no vacuum at idle. Listen to his recommendations; he knows what he's talking about. There where misprints on the 508 and 509 numbers in the book; it is a .508 lift. For trivia as well: the spec's on Mopar Performance Purple Shaft cams are the same whether they're for a small block or a big block. You'd have to ask Larry Shepard about that.
 
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