yes the stock valves have too thin a margin to do a chamber side cut.. an oversize valve cut down in diameter would work.. you leave the chamber side cut sharp as that reduces reverse flow back past the intake valve... the exhaust valve likes as wide a margin as possible as far as flow is concerned, only problem that makes for a heavy valve so it is a trade off..i have never done it and i would bet it cause exhaust valve failure on a turbo but i have seen exhaust valves with a "ditch" cut into the back of the valve to reduce reversion,,,basically making a dam against reverse flow...Thanks, Now I see. Thats going to take some trick machining to keep enough margin to maintain valve strength. Maybe oversize valves cut down? I'll have to do some measuring and thinking....
Did you adjust both of the cams symmetrically?I have tried degreeing of cams (slotted sprockets), about 6-8° less overlap and 5° higher spark advance, but was not content with the results, the EGT was still far...
okay, then it is waste of time and not worth of risk to loose a slotted gear.that was quite a while ago, yes I did them symmetrically, EGT went down just 50°C, the typical engine characteristic remained more or less unchanged, I did't dyno it
with the slotted sprocket you can degree the cams in and then pull them out and pull out one bolt and machine a small aluminum spacer to fit in the slot to keep the sprocket from slipping and reinstall the bolt... we used to do this but it was a lot of work... the last time i degreed the cams is didn`t and have had no problem with slippage but it does cause me a little worry every time the motor goes to high rpm`s...okay, then it is waste of time and not worth of risk to loose a slotted gear.
btw. mr silversurfer, mine did smoke tyre easily w/o any clutch teasing with 4th (30T) when boost came, ....but just for a while while -then pangfftopic:
sideways67 said:This is my opinion on turbo cams with the v rod. Use stock intake 1130 or stock 1250 cams with 114 lobe centers, use the same intake cams on the exhaust side at 112 0r 114 centerlines.Using the intake will require you use the exhaust gear and slot, also of course removable of the compression releases. While this may not be the absolute ultimate in cam selection its damn close. I believe you could chase different profiles for the rest of your life and not improve to much over this setup I could be wrong just MO Tim
PS I would like to share more with the forum but won't until we set the record.
Jan, you say you installed the cams without degreeing. Did you use stock sprockets on both intake and exhaust? Sounds interesting!I tested 1130cc cams (4xintake) without degreeing. Didn't dyno it, but it felt like more torque in low and mid range (front wheel seemed to lift more easily) and less pronounced "stampede" from 5k upwards.