383 Cam Suggestion

[71ChevyCheyenne]

Hey guys,

Been planning on building a 383 stroker for awhile now and have the parts coming to assemble my short block next week. This is my first engine build so I’m looking for a few more opinions on what would be your suggestion for a cam in my truck. Here are my specs.

383 shortblock
9.5:1 compression
Vortec heads with ls6 springs to allow .500” lift
Dual plane intake manifold

It is a 2 piece rear main so I’m going to go with a hydraulic flat tappet cam.

Truck is a manual with 4.11 posi rear but will probably change to 3.73 or 3.42.

I am (like everyone) looking for a nice lopey exhaust sound, but don’t mind sacrificing it for great low end torque and driveabilty, which is my main priority because this will hopefully be a daily driver. Been looking at the comp xe268h.

Any info would be greatly appreciated!
-Nick

[Coley]

Usually you can have to give up one for the other.
The 'lopey' sound comes from the engine running inefficiently at low speed because of its long duration characteristics.
This means, with the engine running inefficiently at low speed...it won't generate much power until the revs come up.
Usually for more torque, which is what these 4000+ lb vehicles need....you want a cam that emphasizes more lift...than duration.
You are going to get about 100 opinions on this based on everyone's personal preferences.
As a result you have to choose if you intend on using the engine a lot over 4000rpm?......and 95% of people don't.
Or, if you figure most of your foot work will be in the 1500-4000 rpm range....which is where most vehicles and drivers live....despite their desire to be 6000rpm guys.

My two bits.
coley

[Mike C]

Good points above. I would go with the Comp 270 Magnum. With gear you could go up to the 280 cam as well, but peak power moves over 6000 rpm.

I am not a fan of the faster ramps on the XE cams as I think they are not as good for long term reliability. They are harder on valve springs and lifters IMO. I don't think small blocks need split duration cams.

But to smooth the idle out (power brakes?) and a spread duration exhaust look at the Comp 280AH which is a marine cam.

I have the Crane 266 in my Jimmy which is the same size as the Comp 260 and it's a little small I would think for your 383. (I have a 331 in my truck.).

[Rickysnickers]

I really don't have a suggestion as far as cam specs go, but I would look into a roller cam if I were building a new engine.

[Ironangel]

Originally Posted by Mike C

Good points above.

I am not a fan of the faster ramps on the XE cams as I think they are not as good for long term reliability. They are harder on valve springs and lifters IMO. I don't think small blocks need split duration cams.

+1 on the Comp Extreme Energy cams, they're oriented more toward the roller motors and like Mike describes, they're hard on lifters, springs, etc. I've had (still have) excellent luck in the Lunati Voodoo series cam & lifter sets. They have that mild lope at idle and pull like a train from idle up to 5500 rpm. With your set up I'd run this, http://www.lunatipower.com/Product.aspx?id=2324&gid=287 My 350 is a stock internal motor used for towing a 7000lb tandem trailer so I went with the 256/262 PN10120701, that motor is still pulling strong with a Turbo 350-373 gear on 31" tires...Your set up would compliment the next size up very nicely. ~Ghostrider~

[Snake72]

My 383 is very similar to yours, 9.5 compression, stock heads freshened up with enlarged SS valves, running stock intake and Qjet with manifolds for factory appearance. Still have to plumb and wire truck so I haven't had it running yet. My engine builder used the cam below, he uses them in most all 383's he builds. He says enough vacuum for power brakes, decent chop at idle and good low to mid end cam. I'm running comp magnum roller tip rockers, 1.52 I believe. Wish I could give you a video clip of it running and a better report, hopefully soon!

http://www.claysmithcams.com/h-274-8...ppet-camshaft/

[Swar]

I went with a comp cam for my 350, .462 intake, .469 exhaust. Can't remember the duration, I'd have to check the paperwork, but it has a nice lope to it. I also have Edelbrock vortec heads, 10.2 compression. Been running strong since 2007. Can be driven daily and has always started, even in sub zero temps. This was also my first engine build, so I guess I did it right.

[cla511]

95% of us are going to run below 4000 99.9% of the time. I like the loppy sound too but you just give up so much bottom end torque to get it. I like zoom much better and that takes torque.

I have a 400 SBC (large bore 383) in my 86 K20 Burban. with this cam

http://www.compperformancegroupstore...ory_Code=HFTHE

It will launch for the 7000 pound behemoth that it is. Great acceleration. And a pleasure to drive daily. I have no doubt this more would propel my 72 just as fast as the 402 that's in her. Which is a lot faster than she will stay on the road.

I like the high energy cams since they have equal intake and exhaust duration. The longer ext duration extends your torque range but bleeds off low end torque. My opinion is that torque is king.

[Coley]

Originally Posted by cla511

95% of us are going to run below 4000 99.9% of the time. I like the loppy sound too but you just give up so much bottom end torque to get it. I like zoom much better and that takes torque.

The longer ext duration extends your torque range but bleeds off low end torque. My opinion is that torque is king.

...good points.

As for the 'desire' for the lumpity lump sound....I simply installed a wire that shorts out one spark plug whenever I enter a parking lot or cruise in....thus creating a rough idle and making me look very cool and my truck fast and mean.
When I leave, I re-engage that plug wire to get my 8 cylinders back.
(lol....just kidding of course)

All good
Coley

[TXgearhead67]

For the money it’s a no brainer to run a roller cam. By the time you put a hydraulic cam with lifters and springs your only $400 or so short of a roller. The benefits of a roller is worth that to me. Especially in a daily. If your going carb I like the comp mutha thumpa. Just my thoughts.

[Swar]

For the record I have not noticed any "low end torque loss" with a lumpy idle cam, however I have noticed "traction loss" and "significant tread wear". And have surprised other, more expensive cars when the light turns green.

[PTC002]

I put an ISKY #201271 which is their 270-Maga Cam......

Been driving a few months. My wife wanted the rough idle and I wanted the low end torque. The machine shop that did the machine work recommended this cam as he is not a fan of Comp Cams. So far it idles rough and seems to perform well....still working on a hesitation when the secondary opens on the carb. This is the cam the engine builder puts in every 383 he builds. Since I wanted more low end torque (I have a 400) he thought I would like this. So far I am quite pleased with the cam. (Engine guy builds all the engines for the Bounty Hunter, Iron Outlaw, Scarlet Bandit monster trucks).

SBC 400
AFR 195 heads
Air gap dual plane intake (1 inch 4 hole spacer)
9.7:1 compression
Comp Cams 1.52 roller tip rockers
Edelbrock 650 carb.
DUI HEI ingnition
3.07 posi rear end and 700r4.

The smaller carb will give you better throttle response and you only loose any power above 5500 rpm which I doubt I will ever see on the street.

Good Luck!

[71ChevyCheyenne]

Wow thanks for all the responses guys.

I knew it was going to be tough deciding what cam to choose, but I never thought it would be this hard! I’ve decided, I don’t really care too much about the lopey sound that I’d want to sacrifice performance to get it (although I like Coleys idea of shorting a plug ). I don’t have a roller block and I don’t really want to pay a lot of money for a retrofit roller, so I guess I’m going to have to keep looking for a low end torque hydraulic flat tappet cam.

I’ll try and post the results when I choose one and get it in the truck!

[Mike C]

I think you will be happy with the Comp 270 why I mention it again. It has 2 deg more LSA than the Isky. You have 383 ci and 9.5:1 compression. You have gear too. Next size down is the Comp 268 which is a good choice for a 350 ci motor.

The Comp 260 is next size down which is same as the 266 Crane in my JImmy (210 @ .050) and I only have a 331" motor and it is quite peppy down low.

Regardless of manufacturer, 212-218 at .050 would be a smaller cam in a 383. The 220 for the 270 would act like a 215 or so in a 350 ci motor.

[harpo231]

Comp 270 is what my 383 700R 3:73 has...my builder also recommended

http://67-72chevytrucks.com/vboard/a...1&d=1518300152

[KQQL IT]

12-443-8 Comp hyd roller.
Ran a 2500 converter with a 3.08 gear on 28 inch tire.
a riot to drive. Would boil the tires until you lifted.
And had a nice lope and plenty of torque

[71ChevyCheyenne]

I found a machine shop near me that can make my vortecs able to run more lift, so I think I've decided I'm going to run the Lunati 60103 cam. What do you guys think about this cam?

Update on the build: My rotating assembly came and I've started to clearance for the longer stroke.

[Mike C]

That’s a bigger cam than the Comp I recommended. Once again, my motor is smaller but the Cam Dynamics 284/228 at .050 was too much cam for my Jimmy. I’d stay in 220 deg at .050 for driveability and 110 LSA which the Lunati has.

[Mollzyie]

Originally Posted by Swar

For the record I have not noticed any "low end torque loss" with a lumpy idle cam, however I have noticed "traction loss" and "significant tread wear". And have surprised other, more expensive cars when the light turns green.

Lmfao 😆

[Mollzyie]

Lots of good info in this thread .... op good luck w your build . I'm sure whatever u end up doing is gonna be kick ass .

[Swar]

Originally Posted by Mollzyie

Lmfao 😆

Thought you might like that.

Originally Posted by 71ChevyCheyenne

I found a machine shop near me that can make my vortecs able to run more lift, so I think I've decided I'm going to run the Lunati 60103 cam. What do you guys think about this cam?

Update on the build: My rotating assembly came and I've started to clearance for the longer stroke.

I like the sound of that, but that's pretty high lift, definitely gonna bark.

I did a quick video of mine awhile back you can use for reference. .462 intake .469 exhaust.

https://www.youtube.com/watch?v=DuJhZExCtJA

[Average Joe]

Originally Posted by 71ChevyCheyenne

I found a machine shop near me that can make my vortecs able to run more lift, so I think I've decided I'm going to run the Lunati 60103 cam. What do you guys think about this cam?

Update on the build: My rotating assembly came and I've started to clearance for the longer stroke.

Vortecs flow best under .5 lift. I would capitolize on that. They are a great factory cylinder head that offers great torque. Personally I would build toward that.

Yes it would be a good idea to modify the heads for additional lift. I had my guides machined down after having problems with a .454 lift cam in my Nova.