• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

383 street cam help

let's get the compression first
several now have Mopar lifter optimized grinds
Crane 2843564 Blueprinted Magnum Cam 272-292 @.004 which is about 268 286 at .006
I'll repeat that when we tested for Chrysler back when Racer Brown was still around and the Purple shafts were new
If you went one size bigger than the Magnum cam (27x) 60 foot times dropped with stock exhaust, compression, magnum converter gears
the 260 cam makes more grunt torque
the 268 Direct connection cam is BIGGER than the 268 magnum cam
if you end up with 9:1 or lower or even 9.5 [email protected] 256 @.005 [email protected] .205 lobe lift asymetrical essentially regular duration with Magnum Lift and
however the stock cams are really lazy (low intensity) so even at less seat duration the modern ones (not the DCMP) have more area under the curve
for example
http://www.compcams.com/Technical/Catalogs/CamLobeMasterCatalog.pdf pdf page 18 catalog page 16
Take a look at the Extreme 4x4 Hydrallics looks like they can work with 1.6 rockers use for the intake
look how a modern lobe can get .488 lift with only 266 @.006 221 @050
what you care about more is the duration @200 more is better) and the seat duration (less is better) MOPARS do NOT like overlap- especially with stock HP manifolds
you are not getting real exhaust pull like you do with headders Stick Magnum has too much overlap cuz it's so lazy do not even think of using in a low compression motor with stock gears- it's ok when it's really reved up but to drive it on the street is just makes heat and sucks gas
Check out (some of the grinds found will be getting old) Howards, Ultradine, Lunati, and Engle , crower
 
Like Lew said, the 383 is very finicky. You'll want to know for sure your compression ratio. There are no 10:1 replacement pistons. The closest you'll find are the 2315's. If there there are aftermarket pistons in it, it could be 7.5:1. If that's the case, consider a smaller combustion chamber head.

The MP 272° cam is a nice choice. Despite what you might read on the internet, it has 221° @ 0.050". My 4200# Charger ran high 12s at nearly 109 mph with that cam, factory manifolds, and 2 1/4" mufflers w/ 3.23 gear, 12" factory converter and P 235 BFG street tire. I think Lew went 13.0s at 108 with that cam and manifolds.
 
Thanks to Everyone who chimed in. Its power disc brakes, will have fresh 727, undecided on converter. I thought the factory numbers were lower, but looks like the 272/455 sounds like the way to go. Using 68-70 HP ex manifolds. I'll stick with the 3.23 ratio. Will I lose that much with the factory rockers, or does it pay for a true ,1.5/1.6 adjustable? Think I'll send the block in for good measure.
 
Pat Broome said:
Thanks to Everyone who chimed in. Its power disc brakes, will have fresh 727, undecided on converter. I thought the factory numbers were lower, but looks like the 272/455 sounds like the way to go. Using 68-70 HP ex manifolds. I'll stick with the 3.23 ratio. Will I lose that much with the factory rockers, or does it pay for a true ,1.5/1.6 adjustable? Think I'll send the block in for good measure.
Click to expand...
don't worry about the factory rockers. the 1.38:1 stuff is B.S. the 272 will set up nicely with stock valve guide height and will work with stock magnum springs and seals. the only issue I can find with magnum springs is that I don't believe they are being reproduced anymore. the crane 99839 spring is a good substitute, fits stock retainers; but might need a little shimming to get to the recommended 1.80" installed height.
 
the 272 is an over achiever. couple it with 2315 pistons and some pocket work on the heads and you'll be surprised. earlier I recommended the comp cams 268/276. I used this cam in my 440 for a little bit, but the 272 went 3mph quicker in the 1/4 mile. I don't like any of those comp cams 268 grinds in a 440 but I think they'd be fine in a 383, but the 272 is a simpler more reliable cam.
 
IMO, a move away from the stock rocker arm when money allows is a good move. The roller rocker ensures a true ratio of 1.5 or 1.6. They themselfs do not add HP or torque but ratherly I sure your going to get all that your supposed to get.

I myself would move to a 1.6 rocker. I’m sure you he head will have good flow to that level. That would be .485.

FWIW, a nicely prepped head bowl ported would be excellent.
 
i've found 1.5 adjustable rockers to be very close or right at 1.6. I checked the 272 I have with crane 1.5 ductiles and they measured around 1.6; 1.6 ductiles were 1.65. this would require taking a good look at retainer to guide distance and a stock magnum spring will coil bind at these lifts. the crane 99839 spring is far more lift friendly and stock retainers are more lift friendly.
 
I don’t call them Chevy cams but I do call them slow *** ramp cams.
They will still increase the power. The idea of taking advantage of the 904 lifted on mild mills is over rated. Yes it makes more power but not to the tune of what many say is worth it vs. how it acts.

Not every build requires the fastest rate ramp cam available.
 
rumblefish360 said:
I don’t call them Chevy cams but I do call them slow *** ramp cams.
They will still increase the power. The idea of taking advantage of the 904 lifted on mild mills is over rated. Yes it makes more power but not to the tune of what many say is worth it vs. how it acts.

Not every build requires the fastest rate ramp cam available.
Click to expand...
i'm pretty much over .904 tappet hype. we can thank hughs for this. the first ".904" tappet cams he sold were engles "904" profiles. while I like engle stuff they still weren't as fast as comp XE or HL profiles. there's a difference between wanting to drive your car a lot or race it a lot. wiping a cam is worst than crapping the bed; expensive mess to clean up!
 
I believe you and thanks- any more data ?
and yes the intake has a lot more area than the very lazy Magnum (which does rpm and wear well)
good example on why not to use MOPAR advertised durations and compare them with .006- like comp
the 256 @006 cam I use also has over .300 lobe lift and about the same at .050
20 degrees shorter duration - lets say evenly split between opening and closing means that I can get the valve shut 10 degrees earlier ABDC
(all depending on where they are installed)
but why it works good on the lower compression engines without giving up much when reved up (and obviously not for a 10:1 motor)
which one works best depends on compression, etc
The Magnum cam dies on low compression 400's even at highway speeds with stock gears- you have to hit kickdown to get a 440 cordoba to accelerate
The Magnum 268 is over 270 @.006 so I try and go less on less than OEM Magnum compression and make it up with better ramps and rocker ratio
thanks again
 
lewtot184 said:
i'm pretty much over .904 tappet hype. we can thank hughs for this. the first ".904" tappet cams he sold were engles "904" profiles. while I like engle stuff they still weren't as fast as comp XE or HL profiles. there's a difference between wanting to drive your car a lot or race it a lot. wiping a cam is worst than crapping the bed; expensive mess to clean up!
Click to expand...
Well, yes! That is a mess! LMAO!
IM9, the hype on the “TKing advantage “ of the .904 lifted hype is justified but not in every build. Every build is different. There is a time and place for said cams.
wyrmrider said:
I believe you and thanks- any more data ?
and yes the intake has a lot more area than the very lazy Magnum (which does rpm and wear well)
good example on why not to use MOPAR advertised durations and compare them with .006- like comp
the 256 @006 cam I use also has over .300 lobe lift and about the same at .050
20 degrees shorter duration - lets say evenly split between opening and closing means that I can get the valve shut 10 degrees earlier ABDC
(all depending on where they are installed)
but why it works good on the lower compression engines without giving up much when reved up (and obviously not for a 10:1 motor)
which one works best depends on compression, etc
The Magnum cam dies on low compression 400's even at highway speeds with stock gears- you have to hit kickdown to get a 440 cordoba to accelerate
The Magnum 268 is over 270 @.006 so I try and go less on less than OEM Magnum compression and make it up with better ramps and rocker ratio
thanks again
Click to expand...
Wooo, spec’d data, love it. Can you match it to others of similar grind/intake intentioned cams?
 
looking at the lewtot184 Data on the 272 Purple shaft
Comp 275/.525 [email protected] [email protected]", [email protected]", .350 lobe lift similar seat duration
Purple 272/.455 data ; [email protected]", [email protected]", [email protected]", .301 lobe lift.
Comp 5904 .488 [email protected] [email protected]" [email protected]",. .325 lobe lift similar @.050 note the same lift as the Purple 284
Comp 5901 .467 [email protected] [email protected]" 130@200", ..317 lobe lift similar @.200

pretty easy to see that the comp 275HL is quite a big bigger than the older 272 purple shaft
and you can get profiles that breath as well as the 272 purple with quite a bit shorter seat duration I like to have 20 degrees to play with any chance I get
IMHO much more important for lower compression engines that high compression
but you can build more low and midrange with any engine build with careful cam selection
Engle cams were great too we used them in the AMC Matador and Javelin Trans Am program both FT and roller Ive used the HYD grinds-they wear well look in the AMC listings to find more MOPAR lifter size grinds and there are many more not in the catalog- same with Crower
 
cams mentioned above
oldies but goodies- not too long ago comp did not have any MOPAR cams
Comp XE262H-10
[email protected] [email protected] 130@200 .308 lobe lift
Comp 5903 .904 lobe
[email protected] [email protected] 134@200 .321 lobe lift
3106 Low Lift HR not much reason to go Comp HR in short duration is there- durability?
[email protected] [email protected] [email protected] .300 lobe lift
3118 High Lift HR
260 @.006 [email protected] [email protected] .333
Mike Jones Inverse radius flank HR
[email protected] [email protected] [email protected] .340 lobe lift

COMP CL21-237 looks like Comp used an "Extreme Energy" exhaust lobe for the heaver Chrysler valve train- nice touch
280H [email protected] [email protected] 130@200 .320 lobe lift ok not a chevy but a universal .842 oldie but goodie
6882 [email protected] [email protected] [email protected] .316 lobe lift . 904 Purple Plus
5820 [email protected] [email protected] [email protected] .331 lobe lift .904 Thumper
5962 [email protected] [email protected] [email protected] .356 lobe lift newer .904 HL
I'll take an additional 20 degrees at .200 with the same seat timing anytime
 
a comp275hl with a 1.6 rocker (rated at 1.5) took about 20 very expensive minutes to cure me from the .904 lifter thing.
 
I noticed from forum writings that often guys complain about a loud valve train. While that doesn’t bother me on one car, it would on another car. Depends on what I’m doing and with what. When I’m rippin a 1/4 at W.O.T., I’m not so concerned. In the cruiser, I don’t wanna year it.
 
You must log in or register to reply here.

Similar threads

TorRed
Help Me Complete My 383 Engine Build
2
Replies
22
Views
4K
1KoolBee
1KoolBee
TorRed
Kind of 'stock' 383 build questions?
2
Replies
35
Views
4K
Geoff 2
G
S
1970 rebuilt 70 383 Mechanical or electric fuel pump feedback help.
Replies
6
Views
2K
1STMP
1STMP
Boosted66
  • Locked
FOR SALE 1966 Plymouth Satellite, 383, Factory 4 speed
Replies
0
Views
3K
Boosted66
Boosted66
70chall440
Help me pick a cam - 426 Hemi
Replies
12
Views
4K
Runcharger
Runcharger
Auto Transport Service
Back
Top