LOL, you aint kidding! Like you said what is good on the street isn't always good on the track. Maybe I should do like Larry does and run my Q-Jet on the street and tune my AED for the track, but even at that, taking carbs off and sitting 'em on a shelf to dry out cant be good for 'em over and over
This is going to sound stupid, but Im glad I found my limit on total timing, all the while Im thinking " 11 to 1 comp and iron heads, no ping, WTH?????" I found the safe threshold on my combo, I was there the whole time @ 36 total, at 38/39 no go. Even with 39 total with 22 initial it had no issues cranking, but at least I know now
I Forgot to mention, on my second pass, after my auto shift 1-2 ('bout 6 grand) I don't wanna say it felt like it layed down, but it felt like it was picking up in acceleration, like when a Q-Jets secondary flaps begin to open, it was weird, but I for sure noticed it! Im going to read up on a power valves function, I don't understand how they work.
Jet changes in a Holley style carb like my Demon 850 take me about 15-20 minutes in the pits, I'm sure others are much faster, but I cover my fenders and take my time. I set up a carb toolbox, jets , bowl gaskets, etc. My most recent addition to the box is a palm ratchet for the secondary bowls screws. No more fighting with Allen wrench back there. I suggest you air down the DR'S, return to the line with the original carb setting. Let her rip just as before, even let it shift 1-2 by itself as before and you'll have a baseline. Return to line, off ya go again , this time shift 1-2 yourself. Compare slips, then richen your secondaries jets one or two sizes only and go again. Compare slips again. I write notes on the reverse of the slip , re: changes made, mistakes made, etc. for later when I really go over the slips at home. I'm relatively new to drag racing, 3 seasons counting this one, and I am always learning. Talk to other racers, test n tuners are usually points/bracket racers and are good sources of information as they know the track can and give you an educated answer on track conditions. Don't ask the guy in the Honda with no helmet, he don't know nuttin...JIM
Lotta people were happy to see another Buick at the track, they said they’d rather see a Buick than another Chevy. A Mustang guy next to me in the staging lanes stopped to talk, nice guy, his brother has a 70 GS clone with a “ Luminati” cam
Never add timing and take away fuel at the same tine........not a good mix.......a mixture thats too lean will ping also.....but with iron head....I would think your pushing it but I don't know sbb stuff that well. Your power valve all it does is add and take away fuel supply based on a vacuum.....think of it as an extra jet.....when cruising or anytime when vacuum is higher than rating on power valve its closed reducing the total volume of fuel.......under load or any time vacuum is below the rating it adds extra fuel. Its normally 6-8 jets worth of fuel......the idea is to run the fronts 6-8 sizes smaller so it close to square under load. If your 80 up front do well when driving normally I would up the rears Don't forget to read your plugs. Not only will the show rich/lean.......there is a timing line, heat of burn....you can see detonation on plugs
I only made two, I could have made three MAYBE. I decided after my second pass to stop. I figured I found out it doesn't like 20 lbs in the DR's from the first pass, it did better on 18 lbs on the second pass (still spun a bit) so I thought " leave the DR's at 18 lbs, but I cant change jetting right now and it doesn't like leaner, so Im calling it a day" I didn't see much sense in pushing the engine when it was already starving for fuel.
Im going back to the factory jetting in the AED. I looked at my notes I've been keeping for awhile since all this started ( man does it help!) and saw my A/F at cruise was near the same as leaner jetting, and still not overly rich at WOT. Checking my notes was an eye opener! This Wed. weather permitting Im going to give it another try. One of the younger kids at work with a Mustang GT wants to go, but said hes afraid to run it, I give him credit for admitting it. One of the other painters wants to go and take his Impala with a 496 with huge horsepower, and bigger aftermarket 5 spoke wheels, its a nice car, like a mid to late 60's Impala, but I think hes a big talker, poser, he said hes gotta get tires for the rear before he goes first His son has an 8 second blown Camaro too....….…. Never made a pass yet, but its an 8 second car d
That's a spread in the front rear that is more normally seen with a pv....80/82 is drastically leaners than 82/92
Do a damn John Force burnout and those DR's won't spin Watch that Bruce Kent video in the bench section for details. lol I am not spinning with them and I run over 20 lbs. or very seldom, last year I spun about 3 feet and still ran 12.32on the bottle I cannot see why or how you guys are running 36+ degrees of timing I can't get past 32 and I am supposed to have a 10.6 compression. I run at 28* with the 75 shot of nitrous. if you are hearing the pinging you are way over on timing I would go to 34 max. You want to try that big timing you better have colder plugs in there. lean, mean, = boom Maybe this is how mine has lasted 25+ years now. I run the NGK plugs non projected plug and they burn fine. I think I am using YR 5. you need to have the tools ready at the track to change the jets within 5 min in the pits. go to your original jets and only change one jet size all the way around up or down Usually the primaries stay within 1 jet size up or down depending how it runs cruising. then do the back jets for power. How fast did the car run this time on the low jets Think about this for a moment, You are supposed to have the timing all in by what 2200 rpm? so as you are driving down the highway to the track at 2500rpm+ you are driving at on the highway the engine is at 36+ degrees of timing while you have the vac up on the high side and now you have the carb lean and mean. still has to be close to pinging at that point. Or am I not thinking correctly on this statement Since I know this is not as bad as if you had the engine floored.
I would return that carb back to the AED jetting... 8 steps more in the rear is common when you omit the secondary power valve. An 850 from Holley is jetted 80 square with power valves front and rear, if I recall correctly. Jetting requirements are based on the venturi type and size of the carb vs the throttle plate size.. and rarely will you be changing more than a couple jet sizes. Put that carb on a 600 HP big block, and it simply flows more air, the a/f ratio stays relatively the same. The idea that when you put an 850 on a 350, you have to jet it down, is really not true. The 35o will just flow less air, and with it, less fuel... Jetting is much more dependent on the specifics of the carb.. down-leg vs annular or skirted boosters, throttle plate size, power valve usage ect. Jetting typically is only done to match air conditions, once a baseline tune is established. That's what we do on the dyno... establish the correct baseline tune, customers will then rarely change the jets more than a size or two for weather changes. JW
Dont do a big Jon Force burnout with DR that actual makes the work worse. Mickey specifically says little no burnout for these tires. just a short burnout before you pull into the beams is perfect for them.
My prosystem carb had an acceptable range +/- to adjust within.....if needed to be outside those numbers Patrick wanted to talk because clearly something else needed changed
What are you doing at 39*? You might want something that will watch out for you..... Good thing you've backed it down... https://www.ebay.com/itm/123877066400
Yep, I’m going back to factory jetting, I’m glad I’m keeping notes, cause I never would have remembered why exactly I changed the jets. I do remember bolting it on and firing it up, I really made no adjustments, took it for a ride, it ran flawlessly I was wondering why everyone says “850 is too big for a 350, it’s going to run rich” well I got sucked into that wives tale What you said makes sense about the jetting being set up depending on carb set up, I didn’t know that about no power valve in the rear needs fatter jets. By me monkeying with jets, I probably had that poor carb all confused
We you see a spread that large in jetting normally it means a pv is in the primary....when it opens up below your 4.5" vacuum sett the power valve opens adding extra fuel acting like larger jets
So Ben if I’m understanding this correctly, with 82’s and a power valve in the primary, and 90’s and no power valve in the secondary’s, when I go to WOT (near zero vacuum) the primary side is actually going richer than the 82 jets would normally make it because the power valve is adding fuel? When at cruise and say 17” vacuum, the power valve is closed, and it’s just sucking from the 82 jets for “supposedly” better economy? Why do racers like to remove the power valves altogether, easier tuning??
