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Username Post: The BEST TBI Cam        (Topic#132643)
2ToneGMC 
Member
Posts: 16

Reg: 05-09-06
05-29-06 01:05 PM - Post#943508    

I have a 1988 TBI 350 and I was wondering what the best cam would be. It already has L98 heads, Edelbrock intake, CFM tech throttle body, TB spacer, 14 psi fuel pressure, headers with dual exhaust, and an open air filter. I am currently running the 3702 Edelbrock cam and I am looking for an upgrade.

 
65_Impala 
Very Senior Member
Posts: 2406

Reg: 12-29-02
Re: The BEST TBI Cam
05-29-06 03:08 PM - Post#943509    
    In response to 2ToneGMC

Is that block set-up for a GM roller cam? If so, then I would use something like a LT1 cam (or it's other variations). A roller cam like this have a much better valve lift profile and would make good power without adding so much duration it kills the streetability.

You really didn't say what the application is or what you're expecting from the motor.

Peter

 
2ToneGMC 
Member
Posts: 16

Reg: 05-09-06
Re: The BEST TBI Cam
05-29-06 04:28 PM - Post#943510    
    In response to 65_Impala

The block is the older GM block, 4 bolt main, two piece rear main seal. I don't tow anything with the truck, and I only drive it on the weekend. I wsnt to have good streetability but also have good power through 5,000 rpm.

 
Thadd 
"12th Year" Gold Supporting Member
Posts: 11139
Thadd
Age: 75
Loc: Rolling Hills, Ca,
Reg: 12-30-01
Re: The BEST TBI Cam
05-30-06 02:13 PM - Post#943511    
    In response to 2ToneGMC

Most cam manufacuters grind a "CompuCam". TBI (and other FI) engines can not handle a big overlap(when both valve are open at the same time), so the compucam (and blower cams) are ground on a big lobe center (114-118º) to minimize overlap and not confuse the computer. I honestly think that a stock TBI cam would probably out perform your Edelbrock.
Pick a manufacturer and select one of their cams ground specifically for a TBI...You will love it
Proud member of the BABY BLUE T-SHIRT BROTHERHOOD


 
racereno 
Junior Contributor
Posts: 285

Loc: Smoky Mtns. NC
Reg: 03-10-02
Re: The BEST TBI Cam
05-30-06 05:00 PM - Post#943512    
    In response to Thadd

Thadd mkes a good point, the factory computer (ECM) isn't real flexible. That's why cam cos have "Computer Grinds". If you need a lot more see the DynamicEFI link.


As others have said, cam companies grind what they think you need. I have the Crane recommended CompuCam for a pretty much stock 305 TBI with a Edelbrock Performer TBI intake and nothing more than a Flowmaster muffler. What I see is a decent torque increase at around 2500 RPM and up to 4500RPM. That's with the factory gear of about 2.73 or so and it's a good daily driver. If you're not doing alot of other stuff to the stock setup then you'll probably be pretty happy. If you want to look into something a little racier to make the TBI system more efficient on anything from a stocker all the way up to popular strokers then I'd recommend the ultimate TBI ECM setup here: Dynamic EFI.

 
65_Impala 
Very Senior Member
Posts: 2406

Reg: 12-29-02
Re: The BEST TBI Cam
05-31-06 04:45 PM - Post#943513    
    In response to 2ToneGMC

In that case, I'd look for a cam with no more than about 118 degrees duration and the most lift you can get, which is likely around 0.45". At this level, custom tuning will need to be done directly on the engine since it's very unlikely anything mail-order will work. There are a few good mail-order guys around but it's hard with a really modified engine.

If you're running an auto you also need a higher stall converter. If it's a 700R4 then a S-10 or Vette converter makes a cheap higher stall unit, usually around 2400rpm.

Peter

 
1983G20Van 
Super Senior Member
Posts: 3223

Loc: Bedford, Texas, USA
Reg: 11-13-02
Re: The BEST TBI Cam
05-31-06 06:25 PM - Post#943514    
    In response to 65_Impala

I may sound crazy, but as long as you have a pretty steady vacuum signal you can use as much cam as you want with TBI. My 305 only made 6-7 in/hg of vacuum in Drive @ 700 RPM with the A/C on. In park/neutral with the A/C off and idling at 700 it made roughly 12-13 in/hg of vacuum. I ran it using the stock 1227747 ECM, with DIY chip tuning. It was not that difficult to make it run, drive, and idle great. The L82 cam ( 291/287 advertised, 224/224 @ .050, .450/.461(.480/.490 with my 1.6:1s), 115 LSA, 114 ICL, advanced 4*) in the 305 sounded awesome as well. With the 3.73 gears, 700r4, and 2,800 rpm stall torque converter it was no slug either.



PS-65 MAP is 10.8 in/hg vacuum @ 700 rpm (transmission in Drive)
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


 
65_Impala 
Very Senior Member
Posts: 2406

Reg: 12-29-02
Re: The BEST TBI Cam
06-01-06 03:36 PM - Post#943515    
    In response to 1983G20Van

Yes, something like that cam would be good. I meant to say around 218 degrees duration. I've tuned an engine with 228 degrees and 0.480" lift with 112 LSA and it wasn't that hard but less duration and more LSA would be easier. It also wants a fair bit of rpm's to begin really making power.

Peter

 
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