Max cam lift in stock 383 bottom end

[charger500guy]

Does anybody know the maximum lift you can get by with when choosing a new cam to pu tin a 70 383 with a stock bottom end? I want to put in a cam that will be 520/524 lift with my new 1.6 RR's. Bottom end is stock, but headwork , intake, exhaust, etc is all ready to go! Thanks, Clint

[bbaspense]

Do you really need that much lift? If it is a stock bottom end with stock pistons you would probably make more power with a 484 or 509 cam.

Anyways, you will have to probably torque the heads on and check the valve to piston clearance. Don't guess, make sure you can accurately check the clearance so that you don't have a disaster.

More cam doesn't necessarily mean more power.

Jason
indychamp@hotmail.com

[charger500guy]

Actually, I have done some research on the cam choice, although it sounds like a lot of lift, it is a short duration (230/236 at 0.050), and will perfectly complement my headwork, etc. I am aware that "bigger isn't usually better" with cams. I just wondered if anybody knew how much available ceiling room I had, so I could do a quick cam swap without yanking the heads. Thanks for the reply, though.

[JVMopar]

I'm wondering the same thing.

[HOLESHOT]

PISTON TO VALVE CLEARENCES VARY FROM ENGINE TO ENGINE,BASED ON DECK HEIGHT AT BUILD,HEAD GASKET THICKNESS,PISTON DOME AND VALVE RECESS AREA OF PISTON USED.IF ITS A STOCK ENGINE YOU MIGHT GET AWAY WITH 520 LIFT AFTER THAT ITS DICY,SUGGEST YOU GO 1.5/1.55 ROCKER RATIO WHICH LOADS THE GUIDES LESS IN A STREET MOTOR ANY WAYS.

[PRO]

The biggest cam Ive run on a stock 383 was a 504/528,it was a 68 383 2 bbl motor originally and I had the stock pistons.I know of a 383 4bbl(RR) that ran a .528 mp cam w/o any interference but your talking about .554/.559 with 1.6 rockers,you had better take the time to check it,who knows if your heads have ever been redone? or milled or what your actual deck heigth is,or what head gasket thickness you have,or if your valve springs will bind,or what pistons you have,a wrong move here and youll have nothing but a screwed up mess,personally I doubt youll have enough valve spring to cover the added lift,you may or maynot have enough piston to valve clearance(.100 for a 4 spd car or .080 for an auto)plus I doubt used valve springs are up to the job....PRO...

[451Mopar]

When I built my 383, the piston to valve clearance was on the tight side, but I had the replacement forged flat-tops (no valve reliefs) and the heads were milled 0.040".
I was using a slightly smaller Crower cam, I think it was 0.489" lift?

[charger500guy]

PRO, I already considered the added lift for the figures I posted. The advertised lift is .488/.491, so the lift I am concerned about is with my 1.6 RR's, which would bring it to 520/524" lift. And I purchased valvesprings to match the 520/524 lift. The heads have been milled about .030 and I used Fel-Pro Permatorque head gaskets. Does that change your answers any?

[PRO]

Well it does change my answer some,the lift will probably be ok if it is truly an original piston/head/deck thickness combo but still your taking a dangerous chance to some degree,you dont want a bunch of bent valves just because you didnt check things out,You can check your piston to valve clearance even if the heads are already on,simply bring a piston to TDC then lock the crank in place at the flywheel,a piece of stock that engages with a flywheel tooth and bolts to the bellhousing,then apply air pressure to the hole and remove a valve spring and measure how far down it goes,it must go .600 on int and .604 on exh if an auto or .620/.624 if a 4 spd,even if you have to buy a few tools and borrow an air compresser its worth the hassle,in reality your only .008 closer to the piston than you were before you milled the head .030,the Felpro gasket is .042 compressed and the original was .020 so Id have no prob just dropping it in and running it with less than .500 lift, but since you have 1.6 rockers Id still check it.By the way the best cam I ever had in any 383 was a 480/292,I retarded it 6* and it pulled from 3000-6800,theres nothing like a BB mopar at 6800 r's burning rubber thru your nieghborhood at midnight!!!I guess it would really depend if you though the motor was original internally too,well if you dont check it and decide to go for it I sure hoe your a little bit on the lucky side.....Good Luck........PRO....

[This message has been edited by PRO (edited February 09, 2001).]

PRO- If I understand your latest reply correctly? With a unrestored stock engine, you can replace cam to a .500" lift without any problems with piston/valve tapdance? I ask cause I have a 66-383, that have never been opened up and would like to do a cam upgrade but not real sure where to start. The heads havent been shaved either.