CHCH_gtst

sounds more like cam timing problem, retarded inlet cam maybe?

possibly broken shaft had similar problem, found the shaft in the sensor was broken but would catch and turn every now and then.

i know for a fact that the rb20 and 26 are different, weve got both these heads at work at the moment, and ill have a 25 on my bench tommorow so ill do some measuring.

didnt cost me anything as i work at a engine reconditioning shop. The ports r not enlarged much at all, just reshaped, i removed the portion of the guide that protrudes into the port, not sure if this will make much difference itself but made it alot easier to shape the roof. I tried to square up the port floors as good heads like 4g63 and ej20 seem to have really wide flat floors around the short side radius to improve low lift flow. The seats are done on a sunnen vgs, it makes the job so easy.They have a 70 degree throuting angle, 45 seat 30 then 15 all with radius. I machined the seat so as its situated on the valve right on the margin so i could bore the inserts out as mucch as possible without going to bigger valves. Ive got a mate who works at kelford cams in christchuch, he ground up some magic sticks for me, havent got the exact specs on me but i compared them to some gtr cams at work and mine have got 40thou more lift. Got new springs as well, they give me 70 pound seat pressure, and wont coil bind like the standard ones.

more

pics

pics of the head ive just finished