AWilson

I also posted this under the "Getting Frustrated" thread.

I have changed back to the 383. I think thats the final decision,,,,like the last final decision, and the one before that.

I have been reviewing the mind boggling amount of cams between Crane and Comp. My idea is to pick some out, see what you guys say, then see what Crane and Comp tell me. Then make a decision. It will be interesting.

Selection considerations:
Street performance car. I want the best performance I can get without sacrificing too much drive ability. I guess that means the idle can't be too rough. I need the power and torque at lower rpms as most driving is under 3000.
The stock 291 heads will be opened up to 2.03/1.6.
383 cid
about 9.5:1 Cr
3.7 rear end, M21 trans. (But may switch to a Richmond)
Hydraulic lifter, no rollers because it seems that most of the extra power you get from them comes in the higher RPM's which is not where I will be as a street engine. But I want hydraulic so I won't be making adjustments.

It seems like keeping the duration low relative to the lift. is better for torque and low end power.
Headers?
Here are my Cam selections:
Comp:
11-242-3
12-242-2
Crane:
133941
133801
114142
113941

Feel free to offer your thoughts. I will advise what the mfg's recommend next week.

dgruenke

Personally, I went with the Crane 113941 (Powermax 272). I am building a 383 with 9.25 CR.

The 133801 and 133941 are big block cams.

thecorvette

The Comp Cams 12-242-2 (XE268H) seems to have a good following. It would probably work well with your compression ratio.

63mako

The 383 will run a size bigger cam than the manufacturer suggests. They rate them for use in a 350. 383 needs more cam. Those heads don't flow well on the exhaust side either. Likes a little more duration on the exhaust. Look at the Comp Cams XE274H

73, Dark Blue 454

I'm no fan of the XE line of cams,..waaay too many reports of failures and noise.

And I'm no fan of dual pattren cams if you have headers and good exhaust. Here's some good reading:

http://www.camaros.net/forums/showth...attern+cabbage

How about Comp's 270H?...(Magnum series)...would work great, especially since you don't have much interest in the dark side of 5500 RPM. This cam would pull hard from 2000-5000 RPM and have the vacuum to run the brakes, headlights, etc.

63mako

Read the article you posted. It states the exact reason I suggested a dual pattern cam. The Stock heads he is using are going to be opened up on the intake and have small exhaust ports with restricted flow on the exhaust side compared to modern heads. This is what dual pattern cams were designed for, stock type heads with stock exhaust. The original poster is building a 383 with stock 68 heads and trying to maintain factory apperance in the engine compartment. The dual pattern will let him maintain a stock look and give him better flow on the exhaust side which will be needed with his build and head choice. The XE has a working range of 1500 to 6000 RPM. The magnum has a working range of 1500 to 5800 RPM. The lift is .010 different. The big difference is the duration on the exhaust lobe. You can drop the working RPM range about 500 RPM with a 383 vs a 350. He is running a close ratio 4 spd.trans with 3.70 gears so the additional duration will still be streetable. JMHO.

AWilson

Thats what I thought too. A cam noted as a slightly rough idle on a 350 will not be a rough idle on a 383.

69vettester

274H range would be great for a 383 , 9.5CR. It will Idle smooth, so would a 276H. Both are considered moderate cams installed in a 383. Or the comparable cams By Crane.

Felpro makes some reliable thin Gaskets to insure your CR doesnt Drop to less than 9.5 to 1. under .030 thick for example may gain you a hair CR and get it close to ideal quench.

Yeah Lots of options avalable!!..the 383 is such a fine engine ,GM went on to make a stock performance 383 block.

Oh yeah, You might research in another post reasons to use or not use Roller assemblies with your engine. expense is the only Negative factor I know of. Another "final" decision Might be in the works .

Glensgages

BKbroiler has a 12-second 9.7:1 383CID/SBC, with vortec-style heads, XE262H cam, and 3.73 gears

http://forums.corvetteforum.com/show....php?t=1746763

His signature:

'77 - 383, 9.7:1CR, forged pistons, Vortec heads, CCXE262 cam, Lars Qjet, Dynomax headers, 2.5" duals, 3000 stall converter, TH350, 3.73:1 rear, painted in my friend's garage, 12.90 sec, 105.22 mph, 1.85 sec 60 ft, (street tires) best so far.


He might be able to shed light on this subject.

DRIVESHAFT

Lunati Voodoo 60102 or 60103

dgruenke

Some of the larger cams (like the 274) may be perfect for a usual 383, but it moves the power band further outside of the range that he will be using. If the engine will not see RPM's about 5,000-5,500, why sacrifice low end torque for high RPM horsepower that will never be tapped?

jackson

As a point of reference:
Virtually all chevy V8 (both OE production and current GMPP hi-po crate; both sbc & BBC) have some sort of dual pattern cam. From L48 to late LSx to BBC572. Not every single one but virtually all chevy V8 included; exceptions are very few.

1. Virtually all have longer EX duration than IN.
2. Vast majority of (1) also have more EX lift than IN.
3. Nearly all have both (1 & 2).

-edit-
In same vein but 383 specific:
GMPP recently released a derivative of the venerable iron vortec head HT383 ... the newer HT383E is same except for addition of a reluctor wheel inside timing cover to accommodate crank sensor (for ECM). GM touts HT383E as dropin, plug&play replacement for 350R motors in 96-00 pickups etc; to use with OE vortec fuel injection but with no reprogramming of OE ECM. Both HT383 & HT383E use same hyd roller cam GM P/N 14097395 ... .431"I/.451"E, 196°I/206°E dur @ 0.050", 105° ICL + 114° ECL / 2 ≈109° LSA

Link to article detailing vortec 350R -to- HT383E swap http://www.maxchevy.com/tech/2007/ii_1-swap-1.html

BTW, that's actually a marine cam and not very big either ... but it works in a heavy / torque-dependant STREET vehicle.

cardo0

Crane 114142, 113941 or Comp 12-242-2 all fairly close but the Comp will have less overlap.
Those others u listed were for BB's

Good luck,
cardo0

ratbike88

I have to agree with the post about Comp Cams XE line being too noisy.

I have an XE268 in a 350 and that thing has had a loud tick since day 1. I have tried everything. Made sure there were no exhaust leaks, new rocker arms, new pushrods, different length pushrods, new lifters, different valve covers. This cam is just plain noisy. I would recommend you listen to a few XE cams and decide for yourself. For me, I will never put another XE cam in my engine. YMMV

KyleDallas

Might as well cam it for low rpm use because stock heads on a 383 are
going to run out of steam by 5500rpm.... they are too restrictive.

Bare Sportsman II's are $600 a pair...200cc ports and 240 cfm of airflow
beat your stock heads 167cc's and 200cfm... you'll struggle to make
400hp with the stock heads...and should sail right past 450hp with
II's and the right cam.

Im for you and for making power.... Get some World Sportsman II's if
$$ is an issue... they flow enough CFM's to feed a 383, stock heads
don't flow the CFM's nessasary to take advantage of the extra cubes...

Good luck even if you stay with the stock heads... if you do, cam it
for low R's..

AWilson

Yes this is important to consider when making recommendations because If I ever go to the track it may be once or twice just to see what it can do. The vast majority of my driving time will be afterwork and weekends in the summer time for an hour or two goofing around town doing things I shouldn't be doing like tearing up my tires and heating up my brakes. . I just want to steal away some satisfying play time.

And remember these are stock 68 327/350 hp 291 heads except for the 2.02/1.6 valve upgrade.

AWilson

KyleDallas, Thanks but to be clear, I am going to open up the stock heads to 2.02/1.6. I know it won't be as good as modern heads but I figure it should give more than what I am looking for. I intent to cam it for low R's as I doubt I will be seeing too much of the 5000 numbers on the street. So I am looking for low cam RPM numbers from the forum members. I think I picked low RPM cams and am looking for confirmation and advice.

BKbroiler

Since Glensgages invited me into this, I will add my 2 cents. The Comp XE262H cam in my engine is quiet and provides plenty of low rpm power. (Use oil with high zinc content). My car is an automatic, but with the 383, that cam works from just above idle to about 5,400. Thats with headers, 2.5 pipes and Magnaflow mufflers. With more restrictive exhaust, the usable peak rpm was lower on my car. I've run a few 12.9s with it, at 104 -105mph. Your mph might be higher with the 4 speed, but you will roast the tires on the line. Plenty of vacuum too.

Scott Marzahl

If you are going to cut those '291s for 2.02 valves, make sure the shop doing it has the cutter to unshroud that intake valve like they did from the factory or they will flow less than 1.94s do. Either that or it is a hand grinding job. Also, have the shop use a bowl hog cutter on them and open the bowls up.

Here is a link to a photo that shows a typical GM unshrouded intake valve.

http://forums.corvetteforum.com/show...t=intake+valve

73, Dark Blue 454

Not to belabor the topic, but if Davd Vizard and Ed Isknedeiran tell me (above) to use a single pattern cam for more power if I have a good exhaust system, I'll take their word over some sales guy at Comp.

Also, if you read that a cam makes "great HP from 1500 to 6000 RPM", you're being suckered. Not even rollers are this versatile, much less a flat tap.

Figure on about 3000 useable HP with a hydraulic.

Lastly, do search at these two sites, "nosiy XE cam":

You'll get a 121 hits here: www.camaros.net
...and 161 hits here: www.chevelles.com

It's my opinion (worth what you're paying) that Comp's XE line is poorly designed and tested.