My awesome Q-Jet isn't happy on top of my SP3, sorta like a 350 Q-Jet on a 455, yeah, it will idle ok, but WOT performance no. So Im back to a Holley carb, which one? Are all Holley mechanical sec. DP's? Stay with a 750? I don't care about a choke I don't care about bling, shiny, polished, anodized, etc, I want function, regular old style is fine with me Boosters, down leg, straight leg? Ultra HP Holleys, looked at those, whats the difference between that and non Ultra?
Knowing Buick engines like bigger carburetors, I would get a 850 DP. Maybe you could borrow one and try it? What you want is the Holley 4150 type carburetor. http://www.summitracing.com/parts/hly-0-4779c/overview/ http://www.summitracing.com/parts/hly-0-4781c/overview/ I like the fuel bowls with the nice big sight glasses to set fuel level. http://www.summitracing.com/parts/hly-134-71s/overview/
Quick Fuel or Proform will get you more for your money. Chris Skaling may still be offering the Quik Fuel at cost Im not sure. Customer service at QF is light years better than Holley also. I would definitely get an HP style no matter where its from. Pro-67201 is the Proform $600 Billet baseate,billet blocks, HP main Body, screw in air bleeds , sight window, welded shaft etc = the best buy out there. The 850 Mighty Demon is $650 and some people hate them but ive always liked them they are a little finicky and since Holley bought them they have no customer service basically
I like the HP series of carbs too they are more versatile to tune but I do not know what would be better here a Holley series or Quick fuel or the Proform series of carbs. The nice thing here you have all winter to gather info and pick the right one. but SHOULD it be a 750, 800 or a 850 that is the real question. The safe bet might be the 800 carb. This will let you go back to the DP intake if you ever want to. Check out class racer . com. I would go away from this site and look in other places where this style of intake (SP) is used and see what other people are using for carbs. Go out and see what other people are using for carbs before making a decision. Check out what people are using on a Olds engine or a Pontiac engine, People that race all the time see what they have to say. Carbs do not know what engine it is on. Everyone here will have an opinion so go out site the box. Find out what the problems are with the different carbs. I am sure Gary will have some math on this so take in that information too. Math always get you somewhere in the ball park. There are annular discharge carbs check those out see what their problems are as compared to a straight booster carb. But once you have a DP carb you can make changes at the track in about 10 minutes, jet changes, pump cams, shooters, all that stuff.
Annular carbs are good bit more for one thing. The 830 Holley is a hard running carb too. I myself would go with a 750 on your combo. It will be snappier on the bottom but still should keep the Vacuum at 0. One thing to keep in mind is there is more to carbs than just cfm race oriented carbs HP'sHP have an aggressive fuel curve, which SOMETIMES can make low rpm operation on mild engines kinda touchy, nothing that can't be tuned out with air bleeds, just something to consider.
With no disrespect to you Mark I don't think you have made the best of what you have tuning wise. How many runs do you have on the SP3/Qjet combo? 8-10? Isn't that SS car running a Qjet on a SP3 at near 11 flat. To step up to a holley carb with more tuning options may set your progress back even further. Thats why I (and others) keep pushing you too get the air/fuel meter.
Yes, certainly less expensive than a DP carburetor. Borrow a DP carburetor first just to see what difference it makes.
If your an Amazon Prime member, this one is hard to beat, with free 2 day shipping.. http://www.amazon.com/Holley-0-4779C-Mechanical-Secondary-Carburetor/dp/B00029J4GK That's the basic 4150 750 Holley DP carb, been around forever, and is the basis for most of the aftermarket stuff, which generally just has more bells and whistles, for more money. If you want to spend less money that that, and get more hands on right away, there should be about a zillion of these things on hand cheap on craigslist and ebay/racingjunk and at swap meets... get a used one, and a rebuild kit, go thru it, get aquainted with the the parts and where they are, and freshen it all up. They are a super-simple carb. If going used, stay away from anything modified.. no choke horn milling or funky metering blocks/fuel bowls.. Stay away from the shiny silver carbs, the have issues with ethanol fuel de-laminating the insides of the fuel bowls. JW
although I would add my 2c to others, and tell you to buy this, and install it in your car. http://www.amazon.com/AEM-30-4110-U..._UL160_SR160,160_&refRID=04QSXYJNWK1NW0MJ9QMW It will not only assist you greatly in tuning, it will alert you to issues with fuel delivery/carb/ignition right away, before you hurt something. What once was considered high end tech, is now pretty much every day stuff, and I believe that every HP vehicle should have one of these. It's good insurance. You would not guess at your oil pressure, and A/F ratios are just as important. JW
Same Holley I have on now. I added the electric choke, just cause I had one, plus 50cc pump, power valve, main jet, cam & squirter changes. I couldn't run my k&n filter top with the choke crap in the way. The larger 850 Demon ran well also, with same changes. It has the smoother venturi areas for undisturbed air flow, plus no choke horn in the way, which i prefer. Choke isn't absolutely necessary for me. Expect some warm up time with either style. You shouldn't make a quick, short trip just to get some. :beer
Have to agree. The 830 is a really good carb. They were designed for NASCAR as the standard cup car carburetor. I had one on my 455 and sold it to get a 950HP. Never should have sold it. You can often find good deals on them as so many race series are switching to FI.
I don't know, but now that the intake is no longer a restriction 355 CID might want less CFM? Unless you have a cam like Mart does or setup like the SS guys 650 to 700 CFM may be a whole lot easier to tune and run better than a 750 to 850 CFM carb? The Q-jet could be to big now, that makes sense on how it slowed you down? The SP3 is a game changer so with a new game there will be a new set of rules. That is one hell of a deal for the A/F gauge JW posted. With one of those and about 5 or 6 different borrowed carbs, 650, 700, 750, 800, 830, 850 you would be able to get the A/F ratios dialed in pretty quick to see what the optimum carb would be for your combo. :idea2: Derek
Wow, LOTS of good info, much appreciated!! Jim, Im going to pull the trigger on that A/F meter, you guys talked me into it:laugh: Derek, your right on the money, the SP3 IS a game changer, Im new to the game as it is, and I throw the SP3 into the mix, Im back to square 2 so to speak! You made me laugh about having 5 or 6 carbs on hand to try, but all I have right now is my 750 Vac. sec. carb which I bolted on this afternoon, gonna give it a run next Sat. if the track is open. I Want to see the difference between a spreadbore and square bore on the SP3. It might be an apples to spinach comparison, but interesting none the less:laugh:
Mark I wish you good luck, but the Holley vacuum secondary carburetors are the worst on a 455, just ask JW about that. Maybe they will do better on a 350, not sure. Isn't there anyone who could lend you a good DP. I'd give you my AED 1000 if I was closer:laugh: It would be way too big though.
I'll tell you what, for less than 200 bucks this is worth it. I am thinking of getting one myself now that I have seen it we have prime so free shipping. Darn good idea. You know, I would go to a swap meet and look for a used Holley 750 dbl pumper and get a rebuild kit and try it. That way you are not out a lot of money or look on E-Bay, Heck, someone here might be selling a carb and you can get it from a club member here you can trust. Get one with a 4 corner idle system and it will be easier to tune the idle in. I am still concerned that you lost almost 10 mph with install of the intake. I can't believe port matching it would have made you lose that much power. There has to be an answer here for that. That would be insane if it did come down to the carb causing that much power loss. It probably a combination of things. I do still think it has to do with the higher rpm range needed to get the heavy car going with this intake, The fuel is dropping out of the airstream and the engine is waiting for gas to get it moving. This all takes time and power from the engine to get it going. This is going to be a new ball game with this intake so plan accordingly. Demko did hit 79 in the 1/8 so it should have gained at least 18 mph in the 2nd half of the track. Take some pictures of the timeslips of the 3 carbs you ran and post them so we can analyze them. you guys have to remember the SS car that runs 11's has a high gear ratio is a lot lighter of a car and a high stall so it does not need a big pump shot to get going. Big difference between a heavy car starting off the line at 3300 -3500 rpm as opposed to a car that is lighter and is at 4500 -5000 rpm in that SS car on the launch. Demko has a lot lower gear ratio plus a lot of weight, probably about 3800 w/driver. I would bet the SS car comes in under 3000 with driver. Where is that math guy at
That would be up to you, more power to you if you can but it seems when you go you only get 4 or 5 runs in, you'd probably need at least 2 runs per carb to get a fair comparision that is if all goes well on the 2 each runs. Did you see the part I posted? http://www.ebay.com/itm/Quick-Fuel-...ash=item2c966e6dad:g:8zsAAOSwo6lWKomK&vxp=mtr I think this part would be VERY helpful with any carb it can be used on. Derek
Again you hit the nail on the head Derek... I myself have said this very thing quite early in the other post, but my idea was poo-poo'ed since everyone's basing their knowledge off the 455, and we can't do that with the 350! I'd say 750 Holley DP is the most you'd want to run, not 800's or 830's or 850's, or... Velocity is the issue here, not CFM. I suggested a 650 CFM Holley DP, and I'm sticking to it. It may turn out wrong, but that's cool. I like having different input, it keeps things interesting! Let's find out what works and see who was right. :grin: P.S.--out of time so no further input, sorry. Gary
