Hey guys,
I have an '88 Chevy fulltime with TBI 350/465/205/14/44. The engine is a stock unit rebuilt by me 10 k miles ago. I recently had a buddy give me a comp cams extreme 4x4 268 camshaft. Looking on compcam website these shafts were made for carbureted motors. I did a bit of a comparison between the extreme 4x4 line and one of their cams meant for a fuel injection application and the biggest difference seemed to be lobe separation angle for a similarly ground shaft. My question to yall: what will happen? Will the knock sensor throw my timing out of whack? Any of you ran into this before and made it work? Thanks for reading.
Good question. On a stock tuned computer you need to keep the duration short and the lobe seperation angle wide. Something quite close to stock. Now, with TBI you can just swap your prom out for a custom tuned prom for about $250. I would not have it any other way. You can go to Howell and play 20 questions with them and they will make you a custom prom so you can run your Chevy TBI on what ever you want. On a 350 cubic inch V8 I would definately run ~208/214 @.050" lift and a 108, maybe 110 degree lobe separation angle. That is what I have for my 351 W .040" over, it was selected by Schneider Cams for me and I have found this grind referenced on forums discussing the 350 Chevy. I think that the stock cam makes for a narrower torque curve, but a long duration cam over 275 degrees seat to seat will really make the torque curve narrow. I believe that this grind makes a wide torque curve.
Since you are running Chevy TBI, go to Howell and get a custom prom, and run what you want to run.
Since you have the Competition Cams 268 hydraulic already, run that. That cam is almost what I have. It will make a nice wide torque curve. Now go to Howell and get a Custom Prom so you can run that cam and you are good to go.
A buddy of mine is running one in his 93 1 ton with a 6 inch lift and 35s with 4.10s and he gets 15-17 mpg on the highway unloaded driving like my grandmother. We just built a carbed 350 with flat tops and a 268 with matching springs. We are taking it to get dyno'd next week and ill report back with the numbers.
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