The Isky with 1.6 rockers and the comp with 1.52 rockers will have pretty similar valve lift curves. The Isky comes off the seat a little quicker, but the Comp will have a few more degrees duration above 0.200" tappet lift. The Comp with a slightly wider LSA and more exhaust duration might pull slightly harder above 5,000 rpm. I think their characteristics will be so close, it would not be worth the effort or expense to change from one to the other.
If a person were to spend about an hour swapping relevant parameters from BLG's bin to Old Truck Guy's, I think it would run and drive pretty good on the first try.
I worked on a 97 C1500 5.7 truck Thursday evening. Installed BBK shorty headers into 2.5" Jegs offroad head pipes and matching catback exhaust. Then swapped on a set of Jegs 1.6:1 full roller rockers. A Volant cold air intake and March underdrive pulleys. The truck already had a built 4L60E and 3.90 gears with a Grizzly locker. Runs around on heavy 20" wheels. Truck also already has a larger 454 radiator and 34" Tahoe Efans. I had previously swapped an 0411 into this truck and HP Tuned it. Was seeing about 200 gms/sec airflow. Now seeing 260 gms/sec and the truck is a completely different truck power wise. Next up is a hotter cam.
95 GMC K2500, 4l80e, 4.10 gears, 355 L05 4-bolt block, ARP rod bolts, Speed-Pro H423DCP-30 pistons, moly rings, 217 heads, vortec cam, TBI mods, cop car injectors, headers, 2 1/2" Y-pipe and 3" single exhaust with high flow muffler and cat.
I might have found an explanation. Since I began tuning this engine a year and a half ago I've fought knock retard. Looking back at my latest log it was pulling timing at WOT and the max the engine ever saw was about 13 degrees. This is with 92 octane fuel. I decided to take a risk and disable knock retard. I kept the spark table pretty conservative with about 5 degrees at 400 rpm and 20 degrees at 4,000 rpm WOT. Went for another run and my 0-60 times increased... due to violent wheelspin off the line. So I compared 40-60 mph times and the increased timing dropped a full 0.5 second. Yes, knock counts were climbing the whole time but at this point I don't care. If it blows up I'll need to get off my behind and put the new engine together.
Earlier in the week I took a trip to the west side of the state over two mountain passes and honestly the truck has never run this good since I bought it in 1999. More power everywhere and ultra smooth. I had the laptop connected for the trip over and even driving conservatively it picked up 11,000 knock counts in the first 150 miles. They really start to climb at about 2/3 to 3/4 throttle and 2,500 rpm, but the engine is only seeing 20-22 degrees of timing. As I stated earlier, at this point I'm done worrying about it.
roadknee, I got a 4.3 v6 that is worn out and it developes a lot of knock counts and I hate it.i put a set of fine wire bosch plugs in it and it help the knock counts.stock engine almost stock timming table the ac delco plugs would look blue as if thay were glowing at 70mph cruise on the ground side of the plug. the old 288 don't retard timming with the bin I have. it might be the bosch plugs are a little shorter than the ac plugs, it didn't cure my knocks but it helped using them fine wired plugs.
go with a hotter plug. i had a similar problem my knock counts would be maxed out within a 30 minute drive. went from a r44lts to a r42lts plug (ac delco) and knock counts dropped to the teens. i like ac delco plugs only. apparently proper torque on the knock sensor is crucial as well. I think it's 13 ft.lbs. you can also add a brass elbow (90 or 45 degree) to "lessen" or TUNE the knock signal.
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