Valve / Piston Clearance in 383

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Pana.Mopar

Pana.Mopar

Duster Down Under
Joined
Apr 25, 2008
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Location
Sydney, Australia
Hi All,

I'm running flat tops in my 383 and 516 heads with 2.14/1.80 valves, Comp Cams Valve Springs and Roller Rockers and Mopar Purple 484 cam. Want to upgrade cam to newer profile and bigger cam but not sure on valve/piston clearance and also going to port and polish heads as well.. Anyone had much experience with cams in 383's or should I do the PlayDoh trick for clearance check...?
 
Always play-do/clay check for clearance just to be sure you installed it right.

What pistons are in there now?
Did you mill the deck or heads?
 
Pistons are Speed Pro Flat Tops is it's a near zero deck height. I don't think the heads were milled. Just cleaned up slightly.
 
Yes.....

Check the clearance with some clay and be absolutley sure the proper installed valve spring height is checked and double checked.


Same basic setup on HP 383 with older 5.09 mopar cam. Used brand new recommended hemi springs and got some minor contact on one piston because I did not verify what the machine shop gave me back. First good run the valves floated a bit and this was the reason. Tear down a few shims on the springs installed wrong and all was well. So double check others work.
 
To be honest, after doing some research I think I might leave the Mopar Purple 484 cam in it (P4120235). I quite like it. Just looking at either doing some work on the 516 cast iron heads or getting a pair of 440 Source Stealth alloys. Current engine spec is:

383, bored 30 thou, flat tops, comp 10.1
Mopar Purple 484 Cam
516 heads, cleaned up, hardened valve seats, stainless 2.14/1.80 valves, dual springs
Edelbrock TM6 single plane intake
Holley 4779 Double Pumper
727, 3000 stall, 4.10 sure grip.

Just want to get some power out of it.
 
There's a related discussion going on in another thread here in the big block section about 383s and compression. Unless you're going to zero deck with those flat tops, and the 516 heads are ~76cc or less, it's going to be a bit of doing to actually hit 10:1 compression. It can be done for sure, but you have to choose the right pistons (zero deck), a tight head gasket, and compact chambers.

The 516 heads *should* be about 76-80cc dressed with new valves and seats, so it might not be far away from your goal, but realistically, you won't "need" 10:1 to make good power with the right cam/induction/exhaust. And I certainly wouldn't steer you away from the stealth heads...but if you do go that route, you'd do well to have them checked by your machine shop for valve sealing and spring installed height...there've been a few folks on here who've posted comments stating their machine work wasn't all that stellar out of the box.

Just food for thought...

EDIT: sorry, just read through the post again; you already have this together and you're asserting it has 10:1 CR-cheers, and I'm sure that 484 will work just fine matched up with the right parts
 
Hi txstang84, Yeah, the combo is already together. The slugs are at zero deck. I was going to put a bigger cam in it but to be honest I'm quite happy with the 484. The 516's have big valves and a little bit of a clean up but I definitely think it needs more in the heads..
 
Hey Pana! I'm betting that will work out for you pretty well once you get the dizzy curved up right and dialed in.
 
All I've read on the 516s suggest they are around the 80cc mark. I have two sets. I guess I need to CC them.
 
That sounds consistent with the articles I've read...curious to hear your findings. I'm also curious to know how much the volume is reduced by larger valves and new seats.
 
Just an update - Took the Duster out racing a couple of weeks ago on an extremely hot day around 35 degrees (around 95-100 degrees for those in Nth America) and it ran a 13.79 at 103 mph (2.109 60ft). I was a little disappointed as thought it would run a little quicker than that but the weather didn't help at all. I reckon it's got a low 13 in it with good weather. My shifter cable was causing me grief too and it ended up snapping later on. First time I've ever raced the car as well. Really want to get the car into the 12's. Any advice on what I should do here? Cam and heads?
 
As a base cam recommendation, MoPars 292 Hyd. cam and then bowl port the heads with a gasket match.
Do you have?
sub frame connectors
S/S springs
Pinion snubber
About a 27-28 inch tire
Shift kit in the trans. And wha size exhaust pipe are you running?
 
I would say you have more power in that combo. I have a 383, .030 over with trw flat tops, no valve reliefs around .020 in the hole. Using stock 516 heads with the small valves, holley street dominator intake, holley 750 double pumper and the mopar 284/484 cam installed straight up. With this combo my dart had been 13.20 with a 1.91 sixty foot. Oh yeah, and this motor was using water and my compression was down on cylinders 7 and 8.
 
What chassis work been done ,mate? The 103 is damn close. Give us a breakdown. Rumble fish dead on in recommendations.
 
rumblefish360 said:
As a base cam recommendation, MoPars 292 Hyd. cam and then bowl port the heads with a gasket match.
Do you have?
sub frame connectors
S/S springs
Pinion snubber
About a 27-28 inch tire
Shift kit in the trans. And wha size exhaust pipe are you running?
Click to expand...

Hi Rumblefish,

Ive just got chassis connectors. Ran M/T ET Street radials 255/60/15. Stock springs and no snubber. No shift kit either. Im running twin 2.5 but I have cut outs.
 
If it's the .484 and the heads have bigger valves, it might be alittle slow at low rpm. The .484 is a pretty large camshaft and you'll need to gear the car a little. The MPH says it's making steam for 12s.
 
Something's not right if you have 4.10s. Was the cam degreed when it was isntalled?
 
Thanks so much for the replies guys. Here's the specs to make it all a little easier...

383 - Bored 30 over
Speed Pro Flat Tops (No Valve Reliefs)
Balanced Bottom End
Mopar Purple 484 cam (hydraulic)
516 heads - (Unported) - 2.14 / 1.80 valves - Roller Rockers
Eddy TM6 Single Plane intake
Holley (4779) 750 Double Pumper
Schumacher Tri-Y's
Dual 2.5" with Cutouts after X-Pipe
MSD Streetfire ignition

Subframe Connectors
Stock Springs
TFlite 727 - 3,000 stall - Shift Kit????
8.25 Diff - 4.10 Sure Grip (No Snubber)
M/T ET Street 255/60/15's

00005590_f_zps2a915efd.jpg
 
First thing you need to do is get the front suspension checked and an alignment... That leave looks horrid.
Was the cam degreed? How were the heads with those valves?
 
moper said:
First thing you need to do is get the front suspension checked and an alignment... That leave looks horrid.
Was the cam degreed? How were the heads with those valves?
Click to expand...

Yeah, wheel alignment needs to be done.

I would assume the cam was degreed in when engine builder did the bottom end.
 
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