Probably end up 14.5-15 to 1 Not sure exactly what it'll be yet.
I'll take 15.5-1 if I can get it without compromising too much.
Here is the 113 if you dont already have the specs.
randy331 wrote: ↑Sun Nov 12, 2017 11:17 amNew pullin truck engine to replace Tommy Boy
4.155 bore x 3.875 stroke SBC
Targeting 7200-7300 for peak HP rpm ( that's where the head/induction looks like it's sized for) GMPP vortec bowtie heads
Wanting it to hang on as good as possible past peak HP rpm
2.08 in 1.58 ex valves
1.7 in 1.6 Jesel shafts
Dart SHP Pro block so it's big block cam journal and .904 lifters
lookin at Comp cams lobe # 1839 for intake and # 1960 for the EX. ??
Those lobes look ok for pullin truck engine ??
What were you thinking for lobe separation?
Thanks for the reply.Old School wrote: ↑Sun Nov 12, 2017 12:49 pm
My inexperience with pull engines doesn't lend much credibility to my thoughts but....
The lobes should be a good compromise between power and relialibility. A 272 intake lobe will give a 65/66 intake closing point on a 112 lobe separation advanced 2/3 degrees. That's not to say that's where it should be but a starting point. The 286 exhaust should keep the power from falling off the cliff. My first instinct would be 112LS but again just a starting point. Someone with more experience will have a better recommendation. Based on the lobes the cam should peak in the 7300/7500 area if the induction can support the flow needed.
Will the 1.7 rockers, larger cam core and the .904 lifters add a little duration to the .050 and up? Still you've got to start somewhere.
How much power do you hope to make at peak? Average power between 7000-7800? The average will be worth more than the peak.
Looking forward to your build and results.. best of luck Billy
PS Don't tell the lobes they are going in a pulling engine, that way they will not have a preconceived idea of what they should do.
That would be cool, you guys tend to produce above average power with parts that the average speedtalker can afford and would be a much greater benefit to the majority of the readers here.Maybe I should start a new thread for this build ?
Bet there wouldn't be much difference in that cam vs the other one once both are moved around for best position.
Steve. I'm not seeing the 1720 intake lobe. Which lobe series is that?