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Username Post: L31 Camshaft choice? (for max torque)        (Topic#164101)
Senior Member
Posts: 637

Loc: Dawsonville Georgia
Reg: 05-11-01
07-08-07 07:38 AM - Post#1203195    

I'm researching a new camshaft for my 1999 350 vortec engine (L31) (in a suburban).

It's been suggested I run a Comp Cams tripower extreme (TPX254HR) 254/264, .477/.471 lift

... I'm also looking at the GMPP HT383 camshaft.

The comp cams looks a little more aggressive and is supposed to be used with a fast-flash gizmo to optimize the injection to work with the cam, whereas the HT383 seems to compliment the larger cubes of a 383 (which I don't have).

My 350 has a free flowing induction and free flowing exhaust (true duals, stock manifolds). 105000 miles.

I'm after torque, for towing.

Anyone have any 1st hand experience with either of the above 2 cams, or a different opinion? My engine runs fine and tows alright now... I'm just doing my homework.


Low priced Genuine GM Auto Parts
Senior Member
Posts: 629

Reg: 01-03-03
07-08-07 03:56 PM - Post#1203500    
    In response to MadMike

Your stock cam is probably best for low end torque. Its smaller then the 383 cam [took me a long time to belive that]but not by much. I highly doubt you'll see anything using it compared to stock. Have you considerd a stock LT1 cam? Its 201/207@.050, should make peak torque in the 3000-3300rpm range.
- - - - - - - - -
78 c10: 11:1 388,M20,5/5" drop.-playtoy
98 gmc sierra: 5/6" drop, 17" eagle alloy's, flowmaster 50 series.-daily driver
06 CBR600F4i- freakin rocket ship

Senior Member
Posts: 637

Loc: Dawsonville Georgia
Reg: 05-11-01
07-08-07 05:01 PM - Post#1203535    
    In response to bored&stroked

I got the specs on the other cams:

Camshaft-Part # 14097395 Billet Steel Hydraulic Roller Camshaft. (i.e. HT383E)
Intake Lift- .431" Intake Duration @ .050" 196
Exhaust lift- .451" Exhaust Duration @ .050" 206
Lobe Centerline-109

Stock L31
Intake Lift- .414"
Exhaust Lift-.428"
Intake Duration @.050"- 191
Exhaust Duration @ .050-196
Lobe Centerline-111

Comparing stock against the HT383... doesn't look like much. The tripower extreme may be worth checking into.... or I should just shelve the whole idea.

I may just look into adding 33 cubic inches to what I already got (along with the cam).

Posts: 27804

Reg: 01-06-02
07-08-07 06:12 PM - Post#1203580    
    In response to MadMike

Your true duals are hurting your low end torque, I had true duals on my '96 4dr Tahoe and it killed the off idle response and hurt torque below 3599 rpm. I went to a Magnaflow straight through 2 into one with 3" outlet and mine felt like I had 50 more horsepower at the bottom end.

DON'T mess with Old Men, we didn't get old by being, STUPID!!!

"The veneer of civilization is very thin!" (Arlo)

Posts: 27804

Reg: 01-06-02
07-09-07 06:48 PM - Post#1204446    
    In response to Randy_W

Of course I meant '3500 rpm'.

DON'T mess with Old Men, we didn't get old by being, STUPID!!!

"The veneer of civilization is very thin!" (Arlo)

Super Senior Member
Posts: 3223

Loc: Bedford, Texas, USA
Reg: 11-13-02
07-09-07 07:06 PM - Post#1204467    
    In response to Randy_W

The Ramjet/HT383 camshaft is actually the GM Marine 350 TBI camsahft. That engine makes 285-320 HP @ 4,600-5,000 rpm depending on the heads and 365-370 ft/lbs of torque @ 3,200.
1983 G20 Van, 350 TPI, Ported 906 Vortecs, Edelbrock 3817 Base, ASM oversize runners. Reed Custom Roller cam, 700r4, 12 bolt with 3.08 gears, Doug Thorley Tri-Y headers, true duals

Low priced Genuine GM Auto Parts
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