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Need FSM 1971, 383 Magnum Cam specs

Posted By: varunner

Need FSM 1971, 383 Magnum Cam specs - 12/29/14 03:11 PM

Does anyone have a FSM or any other "offical" oem specs on this cam ? I'm planning on running stock eliminator next yr with a 1970 383 challenger. According to NHRA,the cam specs are different on the 383 magnum from 70 to 71. I have the FSM for 70. What I have is below on cam lift. NHRA hp rating for these 2 engines are only 1 hp apart. So running my car as a 1971 may be a better choice, but I'd have to buy a grill/tail lights at roughly $1000. So I need to verify cam specs and make sure there isn't a typo in the nhra docs.


1970
FSM: lift = .450/.458
NHRA: lift = .455/.470

1971
FSM: lift = ?
NHRA: lift = .467/.483


thanks
Posted By: Big Wedge

Re: Need FSM 1971, 383 Magnum Cam specs - 12/29/14 03:34 PM

Hi. My 1971 Service Manual calls for .458" on the 383 Hi. Perf engine.

Garth
Posted By: scatpacktom

Re: Need FSM 1971, 383 Magnum Cam specs - 12/29/14 04:11 PM

You only need to concern yourself with what NHRA thinks it is. You need to access the NHRA Blueprint specs on the NHRA website. That is what the people you will be racing have done
Posted By: varunner

Re: Need FSM 1971, 383 Magnum Cam specs - 12/29/14 04:44 PM

Garth, Is that the lift on both intake and exhaust ?
Posted By: varunner

Re: Need FSM 1971, 383 Magnum Cam specs - 12/29/14 04:49 PM

The numbers I already posted were directly from NHRA's site.... If there's a typo in their documentation, I want to let them know......if it's in my favor of course.......so to do that I need rock solid OEM numbers. I don't know what's better than the FSM.
Posted By: Big Wedge

Re: Need FSM 1971, 383 Magnum Cam specs - 12/29/14 07:23 PM

Quote:

Garth, Is that the lift on both intake and exhaust ?




Sorry, my mistake. The intake lift is listed at .450" and the exhaust is listed at .458".

I scanned the 2 pages related to the camshaft for you.

Garth

Attached picture 8377228-Scan4.jpg
Posted By: Big Wedge

Re: Need FSM 1971, 383 Magnum Cam specs - 12/29/14 07:24 PM

Quote:

Garth, Is that the lift on both intake and exhaust ?




Sorry, my mistake. The intake lift is listed at .450" and the exhaust is listed at .458".

I scanned the 2 pages related to the camshaft for you. This is the first.

Garth

Attached picture 8377230-Scan4.jpg
Posted By: Big Wedge

Re: Need FSM 1971, 383 Magnum Cam specs - 12/29/14 07:26 PM

here is the second page

Garth

Attached picture 8377231-Scan5.jpg
Posted By: varunner

Re: Need FSM 1971, 383 Magnum Cam specs - 12/29/14 08:15 PM

Garth,

Thanks for the scans. Pretty interesting actually. As most would have guessed, the FSM shows both 70 and 71 magnum cams having the same lift. NHRA shows the 71 with more lift........
Posted By: RUNCHARGER

Re: Need FSM 1971, 383 Magnum Cam specs - 12/30/14 04:05 AM

Best double check the pistons specs as well. I thought a 71 383 was low compression.

Sheldon
Posted By: JohnRR

Re: Need FSM 1971, 383 Magnum Cam specs - 12/30/14 07:24 AM

Quote:

Best double check the pistons specs as well. I thought a 71 383 was low compression.

Sheldon




lower piston to deck height. 79.5 cc min chamber.
Posted By: varunner

Re: Need FSM 1971, 383 Magnum Cam specs - 12/30/14 04:15 PM

True. Less compression, but more room to play with the cam on the 71
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