Well, I now that i got a few other problems out of the way I begin try to play with jetting I was tring to get color on the plugs and couldn't not do it I have a holly 4150 1000cfm pro series carb i got start out with 87 jets in the front and 88 back the mph was 124.5 i went you to 89 in the front and removed power valve and 98 in the back mph was 126.7 so that was working......but when i pulled a plug they still looked brand new. I talk to the tech line at holly today and he said with race gas and a msd the plug will not get any color to them he said jet to mph ...but when i show a plug to a fellow racer he had a maginfine glass and found a few silver spots! That i was tolded that is denanation Now i run 36 total timing (ran out of time at the track to change it) but is that to much?I have j.e. flat tops 0 deck height with stage 2 heads so that is like 12.7:1 CR I run 110 cam2 fuel or is it still to lean? or should i run like a 116 fuel??I got some chassis dyno time soon so any ideas would be great Thanks Mike
I would reset the timing to 32 for now or even 30. The specks on the plugs could very well be detonation. Make a pass to get a base line and then go ahead and jet up 2 more sizes on the fronts and make another pass. I rather be too rich to start with then to lean. If you have a rich/lean indicator or an exhaust gas temp. unit would be nice also. If it was way lean then I think it would be popping in high gear. Just my .02 worth.
Engine is lean. The color on the plugs will show up with race gas and an MSD if you get enough fuel. Try the lean is mean rich is quick method. Jet up until the 60' or ET drop or quit going faster at least. Rich makes low end power but will not rev like lean will. When you get too rich it will fall on its face before the shift and act like the valves floated. The silver on the plugs is not detonation but melted piston chunks from running too hot which means lean. Moving the timing back from 36 to 32 will more than likely kill the bottom end and I would not recomend that without a trans brake. I run the same pistom compression type with iron heads and run more timing than you with 110 fuel with no sign of problems. I would bet that your car would really pick up with a dominator on it that 4150 is not optimum by any means. I would bet somewhere in the 90+ jet range front and back with powervalves is going to be your best spot without working on boosters or air bleeds.
melted piston chunks hmmmmm....That doesNt sound Good.......Now does that mean that there is damage yet???I ran the same set up last year and the pistons all looked perfect after 110 passes but i never noticed the spots and on the plugs before
I wouldn't think that there is any damage yet. I ran into this same problem on my first engine. We called the specks "Fly Turds" and they looked purple as well. Once I got the engine tuned and changed plugs I never had a problem. As long as you fix the problem now you shouldn't have a problem later.
Don't get too excited about the spots, this is just an early warning sign that doesn't cause too much damage. The small size of the spots reflects the size of the particles coming off the pistons, big spots are bad. If this was running fine last year without these deposits with no major change find out why the problem started. If there were no changes you have a problem somewhere that you need to find. Make sure everything on the carb is clean, look closely at the air bleeds it doesn't take much to plug them up at least partially. Check all of the gaskets including the base to body gasket on the carb, this is one that is usually overlooked. If you have removable air bleeds check with a carb expert to see what can be done there to help pull more fuel without increasing the jets. The problem with running the biggest jet available in the summer is you have no where to go in the spring and fall with better air. If you have some dyno time coming up see if they can run brake specific fuel consumption reading through the entire RPM range this will tell you how the carb is actually working and give the carb guys a starting point to work on. Most box stock Holleys will start out decent at low RPM start turning lean mid range and end up rich up top air bleed sizes will fix this. If you are running a forward facing scoop that works you will want to be a bit rich at upper RPM will on the dyno to make up for the extra air charge at MPH with the scoop. I have a pro stock scoop on mine that really works well, motor is very rich at upper RPM on the dyno but actually starts to lean out at speed which is exactly what you want to see. Rich at leave gives good torque and lean at speed gives more horsepower, but if you go too far either way you will lose power. I can see the difference on the plugs when I take out the sealed air box. Motor will not rev high at 1-2 shift but will scream out the back door at 130MPH with the scoop working.
After talking to some local guys They were asking maybe a colder plug would help also, right now i'm using r45xls plug is that too hot?
:eek2: Wow, I'd say so, I would think with your compression you would need a 43 or 42 heat range. The XLS plug, is that the extended reach plugs?? Make sure none of the threads extend into the combustion chamber, they can cause detonation when they heat up. I know the Stage2 heads use different plugs. I seem to recall alot of guys use NGK's in the 6 or 7 heat range.
You definitely need colder plugs with that comp ratio. I like the NGK race plugs. I'd trying riching it up 2 more jet sizes in the front and the back to see if the mph picks any more and keep going until it drops or levels out. On the plugs..... They are always white. If you look down inside you'll should see some color toward the base of the porceline. Another sign of being lean with no detonation is a purplish heat discoloration on the tip of the electrode which mean your combustion chamber temp is too high.
My local parts supply couldn't fing that part# I called t/a and dave said the plug# was bp7es that sound right?
Mike Have your local parts store look up stock #4554....... Those will be the R5671A-8 which is what I run gapped at .040 OR...... Check out www.oldsperformanceproducts.com Tell Andy that I sent you,He has good pricing on the NGK race plugs. PS I just found an invoice from my local parts store,Looks like the R5671A-7's are stock# 4091 if you want the ones the next heat range hotter. They should be able to find them by the stock #. My local store sells them cheaper than Summit or Jegs....They shouldn't be more that a few cents +/- $2.00 each.
