Hello-
I read that the 1986 IROC was detuned that year because of a cam change from 1985. The question is, if I could get my hands on a 1985 IROC cam, what effect/ramifications would that have on my 1986 IROC if installed? Thanks,
Dave

 

Don't waste the time and money to swap over a stock, non-roller camshaft into that 1986. I know the peanut cam is tiny, but the HO cam is not that much bigger.

Something along the lines of the Crane Truck Power cam will work well in an otherwise stock LB9 305 TPI. The TPI engine builds the bulk of its power from idle-4,600 rpm, so it is only logical to pick a cam that works in that same power-band. You also don't want too much duration or overlap. I prefer small duration cams with tight lobe seperation angles. That will beef up your torque even more than it already is.

I have actually swapped a Crane 113904 into a stock LB9 305 with GREAT results.

http://www.cranecams.com/index.php?s...04&lvl=2&prt=5

You would want to add some good valve springs and a new timing set at the same time.

Take some time to clean up the lower manifold and plenum with some port work as well.

As for the car I put the cam into, it was a 1986 LB9 305 TA, pulled something like 155 RWHP @ 4,000 rpm stock. We added a full exhaust system, ported the lower manifold, cleaned up the plenum, and massaged the stock runners only to find 155 RWHP @ 3,800 rpm, but we added 30 ft/lbs of torque down low. When we changed the cam, we picked up another 40 RWHP, to 195 RWHP @ 4,600.