im currently building an 18RG with a 88230 head with 9.7-1 comp pistons.
i have 2 sets of cams too choose from
one set had a big lift of 11mm and the other set a lift of 9.5mm but with a very long duration compared to the 11mm lift cams.
Which would be better?? bigger lift shorter duration??
or longer duration shorter lift??
im using either 40mm solexs or 45mm webbers
What should i do?? Can any1 tell me the advantages & disadvantages of both pairs of cams??
11mm lift isn't excessive on an 18RG but you would want to check spring bind and piston/valve clearance.
I ran 282 inlet and 292 exhaust total duration and 10.5mm lift on the street running 45mm webbers with the same pistons you are running. Head was shaved a poofteenth so comp ratio was more like 10:1. i used Nissan double valve springs rated at 80lbs seat pressure.
It would ping sometimes on super but loved avgas. Ran a solid 112rwkw at 5000rpm the day it was dynoed...ignition was breaking down after that. Easy 180-200hp flywheel depending on timing and fuel used.
I WAS RUNNING A SET OF CAMS 49/79 INTAKE AND 51/81 EXAHUST ON 9.7 WITH 45MM WEBBERS AND IT WENT VERY WELL WE MADE 220HP OF COURSE YOU NEED SOME HEAD WORK BUT THE MORE OVER LAP YOU HAVE THE MORE TOP END YOU GET BUT YOU LOOSE BOTTOM END. IF ITS AN EVERY DAY CAR KEEP THE DURATION DOWN BECAUSE THEY BECOME A PIG TO DRIVE IN TRAFFIC BUT BY ALL MEANS GIVE THE CAM SOME LIFT.
Tue, 19 April 2005 13:38
