Carbon Build up From Race Fuel - Heads Valve Seats
July 21, 2008
Just wanted to know if anybody has problems running 120 Oct fuels with the heads? In particular the build up carbon on the valve seats causing leak down problems because the valves will not seat? Sunoco, VP, F & L Distributors - ST 118, Turco.
Know your running a PSI Roots ... it would help to know your static compression ratio and the boost your putting to the motor ... assuming something like static 8.5 to 9.0 and your boosting something like above 20 + percent ... under 30, 120 Octane seems alot ... octane stilts ignition ... perhaps your running too high an Octane ... Have you run VP C16 (117) consistently enough to get a 'read' on how it does?
Can't really be specific without actually seeing (being there) what you have going on ... can only give you some 'maybe's' .....
Talked about it a bit with Mike and:
C 16 has a spec. gravity of 0.735 ... Assume you used Torco 118 (MON 120) 'Orange' ... it has a spec. grgaity of 0.710 ....... this means to stay @ the same mixture of a/f you would have had to increase the amount of Torco in the cylinders by minimually 3.4 % ... if you did, fine ... if not, you were leaner ... How did the plugs look? If they looked on the normal to lean side, then you were lean and what your seeing on the valve seats may in fact not be carbon, but, aluminium (piston material/head) due to being lean and higher heat... if the plugs looked 'sooty'/rich then could well be carbon ..... ??? Can't tell 'from here'.
Not seeing things first hand, I won't venture on the solution of using the Torco (things like taking timing out, increasing tha amount of fuel, etc.) ... what I, personally would do is say 'screw' the Torco and go back to the C 16 ... If it ain't broken, don't try and 'fix' it ... just me.
Start pullin a little fuel bit by bit and watch that thing come alive. That rich almost seems to shove fuel deep in the plug making it load down like your at the end of your power. Baby steps are key. What carb are you using?
Originally Posted by gn7
It would be a balmy 85* in Steel's shop if he would move a little faster
that's a pretty big jump in s/g, as well as a lot of other fuel specs that are not easy to obtain. why change from what you were running?
if i were you (of course i'm not), i'd haul the entire fuel system to a certain shop in havasu, and get it all tuned up for the fuel you intend to run. and if ya need directions, i'll lead ya there and take you in the front door