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Re: 290 HP 350 anyone used before?
Quote:
Originally Posted by 68c10owner
For 25 years I was told you needed to match the cam with the compression until a few weeks ago when I had a discussion with Chris Straub. He is the one who told me you don't cam for compression, you cam for the desired RPM range.
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Both statements are correct. However, if you are replacing the cam in an existing engine, and have to live with the CR, then you MUST take that into consideration when selecting a new cam. Otherwise, you MAY pick up some RPMs and horsepower, but you WILL kill torque and throttle response. This is especially true for an engine that already has VERY low compression, like both Goodwrench engines. In fact, they have been measured at closer to 7.8:1 than the advertised 8.5:1. You may want to Google "Goodwrench 350 actual compression".
Quote:
Originally Posted by 68c10owner
The last point in the cycle is the intake closing. This occurs slightly after Bottom Dead Center, and the quicker it closes, the more cylinder pressure the engine will develop.
Seems it's closed a little sooner than you think.
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Well, "slightly" is a relative term. And it's very easy to know EXACTLY when the intake valve closes. Looking at CompCam's 268H, which has been very popular over the years, you will see the Intake Closing Angle at .006" tappet rise is 60 degrees ABDC (After Bottom Dead Center). I don't know about you, but I wouldn't call 60 degrees a "slight" part of 180 degrees. And this cam at 268/268, 218/218 has less duration than the one GM puts in the 290hp crate engine!
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Mike
1969 C10 LWB -- owned for 36 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes.
1982 C10 SWB -- converted from 250-six to roller cam 350, Vortec heads -- sold
1981 C10 Silverado LWB, 305, TH350C -- sold, but wish I still had it!
1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming.
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!
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