TBI Whipple Cam Selection

[Cadride]

When tuning TBI and EBL Flash are there any cam combinations that don’t work good together? I know some cams are specific to EFI, TBI and such and wanted to make sure that the new cam that I go with doesn’t conflict with the TBI and EBL systems; since I will probably have a custom cam made. My engine is a 355 with Whipple Supercharger and many modifications.

[EagleMark]

Split duration cam with exhaust being higher at max 224 @.050 duration and a high Lobe separation angle, ie.. less overlap. 113+

[1project2many]

SC cam should have reduced overlap anyway. Keeping both valves open with forced induction is a great way to blow fuel and air into a hot manifold and muffler. Bang!

[Cadride]

Thanks for the input. Mark I am trying to learn; can you explain to me, why you state: max 224 @.050 duration, lobe separation angle max 113 (I assume) and no split duration.

Current Cam and suggested by Comp Cams with old vortec heads
08-503-8, 224/230 @ .050, .509/.517 Lift, 112 LSA, 108 Intake Centerline

Cam Suggested by Lunati with new AFR 195 heads
Part# 20080721, 221/229 @.050 .515/.530 Lift, 112 LSA, 110 ICL
Or step up in cam
Custom Grind, 227/231 @ .050, 114 LSA, 110 ICL

All of these cams somewhat conflict with your recommendations or come close. By no means am I saying you are wrong, I think that most cam grinders don’t deal with TBI due to small market. I am hoping that I can learn and explain to them, why I may not be able to tune my engine very well with their cam.

[Cadride]

Little about my build: Redline 6000 rpm, EBL Flash computer, 355, Flat top pistons, 6" rods, 2.3 Whipple @ 10psi boost, AFR Eliminator 195 heads 76cc combustion, Static 9:1 CR, with current cam Dynamic 7:1 CR, Dynamic under boost 11.7:1 CR, Edelbrock Performer intake, Roller cam and rockers, 750 cfm 454 TBI bored to 54mm ports, Longtube headers 2 1/2 duals. In a 1994 C1500, 2wd, EXT, 4600lbs, 4l60E, 2500 stall, 3:73 gears. I also will need to be able to pass emissions.

On the dyno last year the engine only made 315 rwhp, but pulled 425 rwtq. This could be cause of many reasons: 9:54 CR, Vortec Heads, Cam didn't work with TBI computer, bad tune. Didn't have EBL installed and there were issues on dyno requiring to pull before engine was tuned.

[EagleMark]

The 113 lobe separation was minimum and duration were maximum. Reason I recommended this was idle and RPM power range ie no overlap issues at idle low RPM.

Both the cams you have and chose have an operating range from 1800 RPM up... at least you have a 2500 RPM stall convertor. so both I could tune to a TBI and it would drive good because of the converter, without it would suck off idle/dead zone...

Now you have to wait for 1project2many who is an actual engine builder to tell you how they will react to boost?

[EagleMark]

The 113 lobe separation was minimum and duration were maximum. Reason I recommended this was idle and RPM power range ie no overlap issues at idle low RPM.

Both the cams you have and chose have an operating range from 1800 RPM up... at least you have a 2500 RPM stall convertor. so both I could tune to a TBI and it would drive good because of the converter, without it would suck off idle/dead zone...

Now you have to wait for 1project2many who is an actual engine builder to tell you how they will react to boost?

[Cadride]

Nice to have tuner and engine builder on the thread

Thanks for the info Mark. The cam that is in it right now idled out pretty nice, but you are right about the dead spot. If you were planning for the hesitation off the line it wasn't horrible, but if you stomped it from a light you wouldn't go anywhere; that was also with a stock converter. The tuner that I was working with got the hesitation down, but never got rid of it. Sounds like, probably wouldn't be able to.

1project2many what cam would you suggest not being stuck to one that I posted or do you have a cam grinder that you would recommend?


I had one person recommend that with a TBI you shouldn't run over 210 duration; saying that is one of the reasons that my power dropped off quickly after 5000. I don't know what his expertise are to say he is right or wrong.