Couldn't have been tested on a 350 Buick. Why would any carb manufacturer recommend a smaller cfm carb than the factory engineers designed it for?
If you read through this thread, https://www.v8buick.com/index.php?threads/anybody-running-an-sp3-with-a-quadrajet.329027/ I think there was 1 or 2 guys that got the Q-jet to work.
I knew nothing about buick performance until 2 months ago. Just figured it was a good carb. I dont think I'd even try the 800cfm at this point. I'm discouraged. Big time
I did read it last night. that was actually the thread I was referring to earlier. Jclstrike ended up getting his quadrajet close. Still struggles in 3rd and 4th gear though. 3 or 4 other guys on the thread run the double pumper and sp3...blyons, gs Johnny (b4 the blower) , mark, and not sure if fox's den has one or not.
What makes you so sure? The lower gear sets are pretty expensive, https://www.tciauto.com/th350-2-75-low-gear-planetary.html http://www.atiracing.com/products/gears/lowgears.htm https://www.bteracing.com/products/BTE347500 https://www.jegs.com/i/TCI/890/327500/10002/-1
Okay, but a place that builds custom transmissions would probably put one in by request for an additional expense. Seems smarter than buying a $500 gear set for a 50 year old transmission. I could rebuild my 50 year old transmission but I really don't have any interest in doing that.
Anyone that rebuilds transmissions can do that, for an extra cost. Get your transmission built locally. You might get a better price. Have you called around?
Yes he does....And Mart, walts72, Phil Green (txgs), along with many others. Kevin, (storm1), is still going to try and run a qjet on an SP3. Still waiting for results on how that goes. I tried to tell him... he said something about stock air cleaner, stock looking, etc.
I have not yet. I have an interesting Theory though I've attached a picture of my stock air cleaner. Something like this would drastically reduce the air flow going into the carburetor I would think. Would an air cleaner like this possibly eliminate my bog?
Thanks for the video Larry that was great made my day!! Been wanting to see that one for a while now. I win that lottery I will sure rent a track for a week and we can all go nuts. Do 3 tracks What else you gonna do with all that cash!
I tell you what, I’m no carburetor expert so I sent my quadrajet to ken@everydayperformance I gave him my engine specs and he rebuilt and tuned my carb on a running 350. I pulled it out of the box and bolted it on my intake, perfect, no tuning needed. No bogging or flat spots at all....... just a thought.
Well I read thru some of this and I ran this 350 for a very long time all the way back to 1983 and I can tell you I have 4 different carbs sitting on the shelf right now. The 750 dbl pump is the one on the car now. Nobody ever mentioned the Thermoquad bet that bad boy would not bog I ran one of those on a stock intake, baked the crap out of the tires. I ran a 650 Holley spread bore (Q-Jet replacement) on a stock intake that ran good I needed more help on getting the pump shot correct but this was 1984 so I was stupid then still got that carb. I ran a 650 Holley with vac secondary on a stock intake with the open adapter, ran ok but got the spread bore later on and seemed to be faster. Then I bought a 750 Carter AFB ran on the stock intake not too bad was running a 14.80 with a 373 gear stock engine basically with my 268 comp cam and headers It ran fastest with the Thermoquad but the float must have been too high or that crap Royal Purple ooil I had in there but anyways the engine started knocking and had to go home. So now I get the motor rebuilt in 1994 with all the best I could get at the time. Used the New Carter AFB I bought from Poston in 1990 or so. Dyno could only get the engine to 365 HP and the owner at race shop thought he could get more power out of a Holley I went to Summit and bought a 750 Holley dbl pumper and the engine went to 395 HP at 5900-6100 Forget that stupid low gear in your 350 trans that aint gonna do diddly. You put in a 342 gear at least and get the JW convertor like suggested that will be the ticket. I run a Pro Torque lock up convertor 3000 stall and it cost me 800 bucks so the JW convertor for your car will work Get a 2500 stall at least, the engine will not have to be at 2500 to keep rolling down the road it will probably be at 1500 or so. I ran a 3500 stall with a 373 gear and was at 3000 rpm at 55-60 mph. So your not going to be at stall rating when cruising but when you stomp it 2500+ comes up quick. The best is a 2004R with a 373-430 gear 3500 stall and a roller motor that can spin to 6500. If they had this in 1994 I would do it in a heartbeat based on what I know today. I can tell you this much the 350 does not start to pull until past 3000 rpm. The Q-Jet may be working on the cars with the SP3 because the have a High ratio gear and the car gets up and going on the convertor so it really does not need that big shot of gas to get going. With the real low gears 256 the engine need a longer pump shot for the big opening in the carb and has to be longer on the shot untill the engine gets to the rpm where it starts to pul on the secondary system of the carb. The bog is the carb not in its secondary system and needs a longer shot of gas before it can get going. Hope all this **** makes sense. G out
No, that will make things worse. You will lose HP. Your problems stem from a mismatch of parts. It may be possible to tune the carburetor to work on the SP3, or it might not be. I don't know for sure. The DP's additional squirters definitely make it easier. Your problems stem from the combination of the single plane intake, your rear gears, stock converter, and the camshaft. The single pane intake begins to shine from 4500 RPM and up. Your rear gears, and tight converter are delaying the engine from getting up into the RPM range it needs for peak performance. The camshaft loses some low end power to make more upstairs. It is likely that your HP peak is in the low 5000's Lets look at your gearing. In high gear, you are at 2.56 final drive. In 2nd gear, you are at 1.52 X 2.56 = 3.89. Let's look at engine RPM when you are hitting your wall at 90 MPH. RPM with no converter slip is 336/tire height X gearing X MPH. Assuming stock tire height of 26.6" In 2nd gear at 90 MPH, 336/26.6 X 3.89 X 90 = 4422 RPM. Then when you shift into 3rd gear, 336/26.6 X 2.56 X 90 = 2910 RPM. The combination of parts is killing your power. Try leaving it in 1st or 2nd gear and revving the engine out. Don't over rev it. 1st gear will be like 2.52 X 2.56 = 6.45, and second as mentioned will be like 3.89. Try some acceleration runs from 0 -60 MPH in 1st gear only. 60 MPH should be close to 5000 RPM. Try leaving it in 2nd gear past 90 and see how that feels.
Larry is right I ran 1st and 2nd gear in the quarter and that was it for the 256 gear That is funny though mine would go 100 mph in 2nd gear and I had that 71 with no compression and the engine would not go until it hit 3 grand either No stall all stock in those days I think I was going 85 in the quarter at the time and 15.90
I could do a better burnout with my stock 2 barrel then I can now. After rebuild I have a better cam, intake, headers, carb, higher compression, and valves that seal. I'm not too concerned with where my intake makes MAX power. According to TA I the s/p loses nothing on the low end. Will the proper carb setup at least get me back to my low end performance I had before rebuild? There is nothing else really I can do to this carb to increase the pump shot. I could go to a SMALLER nozzle maybe. That would extend the duration of the shot. The .043 let's it all out faster then an .035 might. I also have the stiffer accelerator pump spring installed that quickened the shot
I have no doubt that the SP3 intake is a great intake, but it will not work when you hamstring it, and that is what you have done. Gears and converter is what you need. THEN change the carburetor. Changing your carburetor to whatever now, will not get you back your low end.
