Mart, don't get me thinkin' of another carb:shock: LOL I am a bit disappointed, but I did so much jackin' around with my timing, fueling, sec.adjustment for the street, I probably screwed myself, now I take it to the track, and I gotta go the other way with everything.
you need to figure out how you lost 10 mph sure there is no vac leak, have you read it lately. I don't think port matching it to the heads slowed you down any it probably needs a ton of gas to fill the giant hole in the engine. Holley makes this so much easier to do. Maybe they won't run the gamblers race next weekend and you will get more runs in but 4 was pretty good before 1 pm.
Might be a lifter issue.maybe valve springs?cooler air should have brang in a few tenths quicker et. But try shifting a few hundred rpm sooner out of first. Check your oil for fuel. You mentioned float bowl going dry.
Match up your timeslips from when you ran the Holley as compared to the Q-Jet as compared to running the SP3 look at the middle of the runs, the 330 ft 60 ft and the 1000ft along with mph and see where the change is happening at. Cars do not run faster on the street as compared to the track they just feel faster on the street. The air was probably better today since it was cold and that is why you had to loosen up the secondary spring. Write down the temp for today and what the humidity was along with the dew point. The track is your dyno session. you should have been shifting out of first at 6200 and 2nd. Taking it down to 5800 aint going to help you any the thing is designed to go past 6 grand. That is why is called a SP. put the Holley back on for next weekend and put a nice lite spring in the secondaries. If it don't rain I may make the trip in my car. what time do they start 10 am?
Well, ........... if you're sick of messing with carbs, if you sell the 2 you have and saving the cash for not buying another one and not buying an A/F gauge you can step up to a self learning EFI setup that with optimize the A/F ratios by itself with one of these; http://fitechefi.com/default.asp.pg-GoEFISystem4-InjectorKit If you don't like the look of this one here is the rest of their line of products; http://fitechefi.com/default.asp.pg-Products This might be the better choice for the X-Mas list rather than the A/F gauge, not much more $$$ anyway. GL Derek
Yeah the 10 mph loss is a puzzleruzzled: I have a vacuum gauge in the car, no vacuum leaks, gauge reads 7" at idle in gear, hangs at zero at WOT Readings haven't changed from the intake switch, or carb switch (Holley to Q-Jet) I have #43 rods and #73 jets in the primary side I have "CC" rods on the secondary side. With the Stage 1 intake I had the air doors adjusted so loose, they would almost flop open if you breathed on 'em! With the SP3, I have 'em much tighter, even tho I did lessen the tension yesterday and the engine seemed to respond, but they are still tighter when compared to my best time with the Stage 1 I may be screwing myself:af: I think your on to something about there being a "big hole" needing to be filled:Brow: OMG the SP3 is a fuel whore:eek2:
CC secondary rods are extremely rich. Combined with a tight air flap spring that forces more secondary fuel pull, you might be overfueling the secondaries, losing power. Make one change at a time. Small steps.
I bucked up and bought these items right from Amazon, and it's really the only way to go if you can swing it. I have five cars, and I can switch the sensor and gauge to any of them and just clamp the O2 sensor to the tailpipe. It takes minutes to hook it up, and I know if I'm in the ballpark with my carb tune. From there, it's just a matter of finding out what each car likes for driveability. It's SUCH a time saver. http://www.amazon.com/Innovate-Moto...qid=1446382298&sr=8-1&keywords=innovate+mtx-l http://www.amazon.com/Innovate-Moto...=8-11&keywords=innovate+cable#customerReviews http://www.amazon.com/Innovate-Moto..._UL160_SR160,160_&refRID=0GPY3SEF04931RVH41NJ
Go with solid lifters. You have the roller rockers so the big $ part is taken care of. I went with the EDM lifters on my 455 and don't ever have to worry about what the lifters are doing. They make less noise than the Rhoades lifters I used to run, not that you can hear anything over the blower anyway.
Good point Ken, I might try the combo of "CE" rods and a VERY loose air door. That combo screamed with the Stage 1 I actually have a book that Im noting all my changes, so I have some reference, it really works LOL! Can you explain what you mean when you say "combined with a tight air flap spring that forces more secondary fuel pull" Damn, I wish there was a track a mile away, I'd be there all day:TU:
You may wanna look at the fuel pump. Sounds like its took a dump on you to show tgat much hp loss , fiddling with the Qjet isn't gonna get you 10mph back let alone the potential improvement the SP3 should show. My money is fuel psi put a gauge on it and run it up to 50mph then lay into it that should load it enough to see what its doing. But only way you basically dont pick up any mph from the 1/8 to 1/4 is fuel related, I mean the car had to trap at least 72 or so to tbe 1/8 rite?. All NA cars should pick up at the very LEAST 20mph from the 660 if not you have a little bit more than a tuning adjustment to be made
Got a GPS, time it out on a road somewhere going thru first and second and see what the mph is. go do it now before you change anything. Make a change and go back to your road where you can time it out. Do the same distance with first and second that way you are only going about 80 lol. When you get to top of second gear and hit 3rd gear that is the distance you want to run. What is the stall and gearing? I forgot re fresh me. Check the plugs out You better go get a book on that Q-Jet. That is why I do not like that carb. can't do crap with it. they didn't call it a Quadrabog for nothing back in the day it is for a stocker not a performance car with a bad *** intake. Now you have the intake cut for the Q-Jet and can't go back. You have those two little primaries trying to feed that big hole and now you are waiting for those two big flaps to open to feed that big *** hole in the back of the engine. I got it. I heard it somewhere with the carb sitting foreword in the engine the whole back end is starving for gas. You know the Holley Dbl Pump would not have that problem and Without the Q-Jet cut outs the distribution would be the same, even, all the way around the intake. Put a 2 inch spacer on top of that and have a tunnel ram. Maybe a Wilson 4 into open spacer with my K&N Flow control air cleaner. and a 950 carb That's what I am talking about. G.F.
Simple shim from edelbrock allows you to use both spreadbore and square bore cost about $9. I'll be the first to say id have a 750 dp on it but the qjet can supply that engine more than fine. There are just to many BBB's running SP1s and qjets successfully to say otherwise. And I.promise the fuel demand from a 500hp BBB propelling a 4000lb car to high 11's far exceeds what a 375 hp 350 requires
excellent idea with the book, tracking data. think of the air flaps like a choke setup. The engine wants to pull volume. It doesn't care if it's air or fuel or both. When you tighten the air flap spring you are delaying and slowing the opening of the flaps, restricting air and increasing pressure drop, pulling more fuel for any given secondary rod set. How much of an effect is determined by how tight you wind the spring. Spring setting is one piece of the puzzle. I personally prefer a 1/2 or 3/4 turn setting on the spring (just enough to keep air flaps from flapping at wot) and then using primary pull off release rate to tune out a bog, since it's controlled by engine vacuum. I feel it's a smoother release. a heavily preloaded spring opens flaps late and winds itself tighter as flaps open once the flaps reach wot position and get pinned there the spring won't have that effect. CC RODS not only have a very small power tip, but an aggressive ramp up as well.
I have tested 750 QJ and holley 750 dp on 454 chevy between rounds with exact ets. This was a 70 nova . If setup right both will run the same. 750 cfm is 750 cfm. Car ran 6.25 1/8 . If you cannot make you qj work get a holly and make it work. either way they net adjusted to make work with your combo. PS the car owner could not believe my qj was as fast as his holly! Dan
Best 1/8 mile mph is 76.67 that was run #4 New Airtex pump this past May, who knows maybe its weak. Maybe that's why I have to crank it so long to get fuel to the carb after it sits for a few days.
Wow, Thanks Ken, VERY interesting explanation on the secondary side operation! Seems its a fuel issue Im having.
Hey Dan, Im sure I can get the Q-Jet to work fine with the help of this board:laugh: I know my combo isn't taxing the Q-Jet at all.
I don't think it's any different than slowing a primary pull off too much. Same effect. I agree with the above post that said carb adjustment won't account for the large difference in times you've seen. but it's something to consider. You're wise to keep records and data. That is your best guide in tuning. I just thought CC RODS seemed awful rich.
