Great Lakes 4x4. The largest offroad forum in the Midwest - View Single Post - Blown motor What would you do?
View Single Post
Old March 6th, 2013, 11:23 AM   #20
Iggy
Senior Member
 
Iggy's Avatar
 
Join Date: 01-02-12
Location: Traverse City, MI
Posts: 131
iTrader: (7)
Mentioned: 0 Post(s)
Default

The cam in the 260 hp crate motor is the same stock cam that came in the 350's and 400's for years (the one in the 290 hp crate motor is totally not computer friendly). The TBI cam by comparison is terible. While the standard small block cam has 193* intake duration, the TBI cam has 179* intake duration. In comparison an RV cam has 204* intake duration. The reason the TBI cam has such low intake numbers is because the heads flow is terrible, so by keeping the cam duration low the seat of the pants feel is great, but the real power is not there.

I ran that set up in a 1989 K1500 and was very happy with it. Great acceleration and drivability, and averaged over 20 mpg on hwy, never had a cel. You could also feel there was at least an additional 1000 rpm usable range becasue the heads breathed better. The 260 hp GM claims is a Gross Rating (think 1960's) and not a Net Rating including all accessories like motors were rated since the early 1970's. I have also tried to run an RV cam in a TBI and you are correct - it did not like it. Part of the reason is the lobe seperation, if you increase the lobe seperation of an RV cam to 114* it would run fine. The TBI cam is ground on a 110* LSA and the general small block cam is on 112LSA - As you increase the intake duration you also need to increase the LSA to keep the computer happy. LS motors cams are ground with a 122* LSA for that reason.
Iggy is offline   Reply With Quote
 
Page generated in 0.07573 seconds with 20 queries