383 street cam help

[Pat Broome]

Acquired a 70 383HP going into a 72 Charger. Not torn down yet, but appears to be unmolested, still having a points distributor. Plan on a light rebuild (if there's such a thing). Preferably a bump over stock. Charger will be a cruiser 90% of the time, but a little Mopower when needed. My 1st pump gas, exhaust manifold build. Assuming the innards look good, plan on honing, reringing, bearings. Should I stick with the 906's with new seats, or use 452's or equivalent? What's a good cam for this rebuild, 4120235 Purple? Different head gasket to wiggle closer to 9.0? I believe the 70 engine is 9.5. I'm using a Performer RPM with either Eddie or Holley which is another question. I'm always wrenching on my 6bbl RR carbs, and I want this car's carb trouble free. This will be an automatic car, with either a 2.94 or 3.23. Thanks in advance guys!

 

[Don Frelier]

I've run a .455 Mopar cam in my Charger for 20+ years with 906 heads, HP manifolds and 3.23 gear. Tuned right it's very nice all around in a 383 idles pretty well has a good range of power and not extremely thirsty.
There are tons of opinions on this so get ready...
Let us know if you stick to the "light rebuild" it's a tough thing to do.
****Edits 3/15 *******
Sorry should have noted mine is 9.4:1 compression.
I was able to run it on 89 octane for the first 5 years or so but had to go to premium fuel as it got some carbon buildup.
Used to have a Carter Competition 625 CFM carb which was super easy to clean and tune.
I now run it on MSD Atomic EFI it's a beautiful thing.

 

[Don Frelier]

Also my heads have no hardened seats. I had them milled for the thicker perma torque gasket thickness and I was told my the machine shop that they were hard as hell. Old cast iron heat cycled. No problems with valves and I've got about 25,000 miles on them.
If you are looking low budget the smaller Summit Cam is a great deal and good quality I've heard they run nice in a 383.

 

[Bill Monk]

the stock 383 cam specs are:
Lift............. .431"/.431"
Duration...... 268*/268*
I like the Mopar purple cams. I have heard a lot of negative feedback on them but I like them. If you want something a bit hotter than stock but still very streetable, my opinion is to go with this one:
Lift............ .455/.455
Duration..... 272/272
As for the carb, you will get a lot of opinions on that as well but my choice would be the Holley Street Avenger (easy to tune) unless you can find a good Thermo Quad but you would have to go to a spread bore intake for that. I'm also hearing a lot of good things on the Edlebrock AVS 2 but I haven't used it myself. You can check it out here:
http://www.edelbrock.com/automotive/mc/carburetors/avs2.shtml
Whatever you decide, have fun!

 

[Bill Monk]

By the way, I don't think you would see any noticeable difference going with 452 heads instead of the 906 and I have never personally had much luck with just honing the cylinders, I would recommend at least having them checked

 

[big_shmoop]

I've been mulling over cam choices for my 383 as well and like the OP and I are after the same result.

the stock 383 cam specs are:
Lift............. .431"/.431"
Duration...... 268*/268*
I like the Mopar purple cams. I have heard a lot of negative feedback on them but I like them. If you want something a bit hotter than stock but still very streetable, my opinion is to go with this one:
Lift............ .455/.455
Duration..... 272/272
As for the carb, you will get a lot of opinions on that as well but my choice would be the Holley Street Avenger (easy to tune) unless you can find a good Thermo Quad but you would have to go to a spread bore intake for that. I'm also hearing a lot of good things on the Edlebrock AVS 2 but I haven't used it myself. You can check it out here:
http://www.edelbrock.com/automotive/mc/carburetors/avs2.shtml
Whatever you decide, have fun!

Bill, if you don't mind can I ask what it is you like about your recommend cam? Not being critical, just trying to get a little more info. It sounds like Don is referring to the same one you listed. I've currently been favoring the Hughes Whiplash but haven't decided yet.

Thanks.

 

[Bill Monk]

I've been mulling over cam choices for my 383 as well and like the OP and I are after the same result.



Bill, if you don't mind can I ask what it is you like about your recommend cam? Not being critical, just trying to get a little more info. It sounds like Don is referring to the same one you listed. I've currently been favoring the Hughes Whiplash but haven't decided yet.

Thanks.

Don't mind a bit! I have just used several of these cams over the years and been happy with them. I have also used comp cams but preferred the purple cam. I am running the 484/484, 284/284 purple cam in the roadrunner (440 6bbl) and I like it as well, keeps decent vacuum and I run it with a 4 speed & 3.55 ring in the dana. I suggested the 272 because of his statement that he wanted just "a bump over stock and cruiser 90% of the time". I am not a expert on cams and there are a lot of choices out there I have no experience with but I can tell you what I have run and what my experience is with them.
Decisions, decisions!

 

[black64]

I had a 383 with the 284/284 duration Lunati hydralic cam, 30 over on the bore ran the 750 eldebrock with performer intake. 906 heads with new seats, valves, springs etc. Had the head trued and block decked to clean and make sure surfaces were good and rotating assembly balanced. My compression with the new pistons was 10:1 measured. This engine performed very good on the street and was good in traffic. Once you make the decision on a rebuild it's hard to not rebuilt the heads and block and usually leads to machine shop work just to get it back to a good performing engine. This cam also liked a looser convertor and headers but it sounded great and performed great as well. Good luck on yours.

 

[wyrmrider]

I am not familiar with a 268 268 HP cam with that 431 lift where did you get your info
IMHO square cams need headers with stock Iron you need more exhaust and somewhere around 260I 270ex
do not directly compare MOPAR advertised duration with aftermarket

Mopar Performance offers #P4286677
Camshaft and Lifters...........$225
Lift....................... .455"/.455"
Duration................ 272*/272*
Duration @ .050".... 231*/231*
Overlap................. 48*
Lobe Separation..... 112*
RPM Range............ 1300 to 5700

see: https://www.forbbodiesonly.com/mopa...ormance-purple-shaft-why-all-the-hate.119361/
The P4120235AE is 284 284 484 -484 lift 108 needs 10:1 3000 rpm stall and at lest a 3.55 gear- I do not recommend with sub 3:1 gear!
It was said by lewtot184 that is a copy of the racer brown ssh25 - at least it's close .050 241/241
THis is the same at 50 as the new Comp HL 274 cam

This is the specs for the cam used in the 383-335 hp engine used in Road Runners and Super B's and the 440-375 hp engines...
the advertised spec is 268-284, lift .450-.464, 115 lobe separation.
The duration at .050 lift is 214 intake-225 exhaust. This cam was hotter than the stock 383 cam used during the same era,it had a mild lope at idle.
Same Camshafts
* 383/270 HP '2-Barrel'
* 383/300 HP 'Super Commando'
* 383/330 HP 'Super Commando'
The 1968 ~ 383/330 HP and 383/300 HP 'Super Commando' Camshaft
Lift............. 431"/.443"
Duration.... 256*/260* Duration
Overlap..... 32* Overlap
Valve Springs........ #134 lbs. Valve-Closed / #208 lbs. Valve-Open

The 1968 383/335 HP 'Road Runner' and 440/375 'Super Commando'
utilized the same Camshaft.
Lift............. 450"/.458"
Duration..... 268*/284*
Overlap....... 46*
Valve Spring Load-Rate....... #129 lbs. Valve-Closed / #250 lbs. Valve-Open

Valve Springs (I use Isky)
Compu-Cams.....#911-16...........{#122 lbs. Valve-Closed ~ #309 lbs. Valve-Open} (open depends on lift
or
Mopar Performance...#P3690933
Are nearly identical in Load-Rate Spring Pressure.
Both are designed for Hydraulic Camshafts with Lifts between .450" and .500"

 

[Bill Monk]

I am not familiar with a 268 268 HP cam with that 431 lift where did you get your info
IMHO square cams need headers with stock Iron you need more exhaust and somewhere around 260I 270ex
do not directly compare MOPAR advertised duration with aftermarket

Mopar Performance offers #P4286677
Camshaft and Lifters...........$225
Lift....................... .455"/.455"
Duration................ 272*/272*
Duration @ .050".... 231*/231*
Overlap................. 48*
Lobe Separation..... 112*
RPM Range............ 1300 to 5700

see: https://www.forbbodiesonly.com/mopa...ormance-purple-shaft-why-all-the-hate.119361/
The P4120235AE is 284 284 484 -484 lift 108 needs 10:1 3000 rpm stall and at lest a 3.55 gear- I do not recommend with sub 3:1 gear!
It was said by lewtot184 that is a copy of the racer brown ssh25 - at least it's close .050 241/241
THis is the same at 50 as the new Comp HL 274 cam

This is the specs for the cam used in the 383-335 hp engine used in Road Runners and Super B's and the 440-375 hp engines...
the advertised spec is 268-284, lift .450-.464, 115 lobe separation.
The duration at .050 lift is 214 intake-225 exhaust. This cam was hotter than the stock 383 cam used during the same era,it had a mild lope at idle.
Same Camshafts
* 383/270 HP '2-Barrel'
* 383/300 HP 'Super Commando'
* 383/330 HP 'Super Commando'
The 1968 ~ 383/330 HP and 383/300 HP 'Super Commando' Camshaft
Lift............. 431"/.443"
Duration.... 256*/260* Duration
Overlap..... 32* Overlap
Valve Springs........ #134 lbs. Valve-Closed / #208 lbs. Valve-Open

The 1968 383/335 HP 'Road Runner' and 440/375 'Super Commando'
utilized the same Camshaft.
Lift............. 450"/.458"
Duration..... 268*/284*
Overlap....... 46*
Valve Spring Load-Rate....... #129 lbs. Valve-Closed / #250 lbs. Valve-Open

Valve Springs (I use Isky)
Compu-Cams.....#911-16...........{#122 lbs. Valve-Closed ~ #309 lbs. Valve-Open} (open depends on lift
or
Mopar Performance...#P3690933
Are nearly identical in Load-Rate Spring Pressure.
Both are designed for Hydraulic Camshafts with Lifts between .450" and .500"

My bad, you are correct on the roadrunner/super bee cam specs, I pulled my info from the wrong place, the cam I referred would be correct for the 63, 64, 65 383 HP.

 

[rumblefish360]

The first move up from the factory HP cams would be that Purple 272/.455 cam. It would work very well with well prepped cylinder heads and a bowl porting. As well as the equipment you listed. You’ll need a higher stall converter to help the package and use the 3.23 gears though I’d suggest 3.55’s.

 

[65-440]

383, .030 over, comp XE268H , Holley street avenger 770 , 727, 3.23 gear. Drive it all the time, multiple days a week, decent gas mileage, car pulls very good too ..

 

[wyrmrider]

OK I see where you got your info the 268-268 is the 64-65 cam THANKS TO 440 CUDA
https://www.forbbodiesonly.com/moparforum/threads/factory-canshaft-specifications.74740/

383 High Performance'

Lift............. .431"/.431"
Duration...... 268*/268*
Overlap....... 48*

Found in the;
* 383/330 HP ............ {1963/1964/1965}
* 426/365 HP ............ {1964/1965}

Regarded as a 'Mild Camshaft' by the Sales Literature.
Safe idle, and low RPM Horsepower with good Mid-Range Torque.

Camshaft names
* Plymouth 383 Golden Commando ~ {1963}
* Plymouth 383 Super Commando ~ {1964/1965}
* Plymouth 426 Commando
* Dodge 426-S
* 426 Mild
* 426 Street Wedge

383 Standard'

Lift............ .425"/.437"
Duration..... 256*/260*
Overlap...... 32*

Found in the;
* 383/325 HP ................{1966/1967}
* 383/270 HP '2-Barrel' .. {1967}
* 383/280 HP A-Body ..... {1967}
* 383/290 HP '2-Barrel' .. {1968 thru 1970}
* 383/300 HP A-Body .... {1968}
* 383/330 HP ................ {1968 thru 1970 'B-Body}
* 440/350 HP ............... {1966 thru 1970}

Advertised by Mopar as the 'Much Torque Camshaft'.

Camshaft names;
* Plymouth 383 Super Commando ~ {1967}
* Plymouth 383 Commando {A-Body} ~ {1967}
* Dodge 383 4-Barrel ~ {1967}
* Dodge 383 4-Barrel {A-Body} ~ {1967}

Note; The 1968 383/300 HP Camshaft for the A-Body was supposed to have;
Lift............. 425"/.437"
Duration..... 264*/268*
Overlap...... 40*

(IMHO because of the different exhaust in the A Body)

 

[lewtot184]

one thing to keep in mind is that 383's are very easy to screw up with too much cam. I've used, and am still using, the mopar 272/.455. easy on parts, good idle and low end. I built a 383 last summer using a cheapo summit 6400 and that turned out well. the comp cams 268/276 magnum replacement would work. a lot of choices.

 

[wyrmrider]

YOu can compare these factory figures with Direct Connection and Mopar Performace - you have to have some experience to compare them with aftermarket
Take a deep breath and let's see what your real compression ratio turns out to be
http://www.hotrod.com/articles/mopp-0209-383-engine-restore/ shows how a big cam- here the 284 comp HL KILLS your drive-ability (given the axle ratio and converter)
https://www.forbbodiesonly.com/moparforum/threads/original-roadrunner-camshaft-is-it-lame.21025/
says
The 383/335hp 0.450"/0.468" lift 268*/284* duration, respectively intake/exhaust "Roadrunner & Super Bee" part # is 2843564
Roadrunner & Super Bee "only"..... the 69-1/2 440 6pac & 6bbl is 3512033 the difference is the taper ground into the lobe and less curvature on the lifters (both are long gone)

 

[Mopars & Missiles]

I haven't seen anyone mention the "power brake" issue yet, and you didn't say whether your car has power brakes or not.

But be careful when going to a more aggressive cam if you DO have power brakes. Its easy to overdo the duration and end up with less manifold vacuum than what you need for proper power brake operation. You really need about 14-15" vacuum minimum at idle for the PB's.

Just something else to consider................

 

[oldbee]

AND, I keep going to Hughes Engines site with faster lobe rates to take advantage of Mopar’s bigger dia. lifters. Ya see, it just never stops with the wondering.

 

[oldbee]

I keep wondering why not+ .030” on exh lift with extra 20*duration on same to account for small(er) exh valves. I’m no expert & could be totally wrong. With HP manifolds. The hard part for me is I have no idea of comp.ratio, put motor together 30yrs ago, with stock TRW flattop pistons & no idea of heads. It’s been a long time!!

 

[lewtot184]

howard's has a cam that at first glance may seem like a road runner clone but I think could be better. the #720031-12 has .050" and lift numbers similar to the factory cam but when looking at the lobe master it has more area under the curve and a 112LSA vs 115LSA. should have a fatter torque curve without giving anything up on top.

 

[oldbee]

howard's has a cam that at first glance may seem like a road runner clone but I think could be better. the #720031-12 has .050" and lift numbers similar to the factory cam but when looking at the lobe master it has more area under the curve and a 112LSA vs 115LSA. should have a fatter torque curve without giving anything up on top.

That’s what we’re giving up— no real R&D because of low volumn of sales.