Hello and thanks to anyone who reads ALL of this and offers suggestions :beer: Here is the question I posed at the end of all this: How much money should I budget for the Q-Jet to get built to the maximum potential? The Q-jet I have is a 800 cfm from a early 73 engine. PONDERY: I am considering what I should for carb action. I built the current set up for the track originally, but I am not living that life anymore. I want a fun cruiser with the street / strip readiness. I am slowly putting ther car back to orignal, adding some CLONE features and some custom mods. I miss the old throaty Q-Jet and wonder what I should do. o No: THE CURRENT SET UP on the 1970 Convertible: I am currently running the Holley 750 that I re-built on my BUILT 1970 455 SF engine. Some engine details...Offenhauser Aluminum intake (non-spreadbore), Malory Unilite,MSD 6AL, 1-7/8" Headers, 4000 switch pitch trans, 411's, POSTON 105A cam, +.030 Hyper alum pistons, cross-drilled and stroked crank. CID Yields 474 cubes. THE GOAL: Get the vert cloned to a GS / GSX (spoilers and other fancy options available in 1970, etc) GS hood and air cleaner will be added. I think the only correct fit is runnning the Q-Jet. Other carbs don't quite fit correctly????? o No: THE DILLEMA: 1) The adapter plate needed will raise the carb up about 1", not a big deal with the GS aircleaner set up, right? Shave the foam down accordingly? 2) PERFORMANCE???? Granted, I am not looking at track action for a living, but I am very used to the throttle response and performance of the HOLLEY. How much money should I budget for the Q-Jet to get built to the maximum potential? The Q-jet I have is a 800 cfm from a early 73 engine. Thanks for any advice. :boring:
I think the Q Jet will give you better throttle response. I went from a Holley 750 DP, which I had on the car for over 10 years, back to a Q jet. After very minor tuning, I couldn't be happier. I would, however, be concerned avout hood clearance with the adapter if you're using the stock air cleaner. With a 350" my AC rubbed the inside of the hood. I had to mill my spacer down to 3/4" which is not an option for adapters...
I don't know about the offenhouser intake. From what I understand the performer is the only aftermaket intake manifold that will work with the stock GS air cleaner set up. The factory manifold puts the carb closer to the rear of the manifold and the performer is the only aftermarket manifold that follows this converntion, the other manifolds put the carb in the center of the manifold. So with the offy, even if you shave the foam down to make the height correct, it won't line up with the holes in the hood. You can use any carb that you want, but for a stock look go with the Q-jet.
the damn adapter come to think of it, mu offenhauser is not set up with "holes" where the carb sits, they are more like widened oval openings. Maybe the Q-jet would fit?
No, it would not. The whole carb pad is moved forward. (OK, I may be wrong. The old B4B moved the carb forward to center it, so that it does not line up with the scoops with the ram air installed. Can't speak for the Offy.) Either way, a dual plane intake (Edelbrock Performer) is going to have MUCH better street manners, and will negate the need for an adapter. Anyhow, if you are really done with your "track days," I'd seriously change a bunch of things. Get mid 3 series gears. A Q-jet will have way better throttle response that ANY Holley. For a street car, either a 71-up 800 or an earlier 750 will be fine. Since you have the 73 800, go with it. Contact John Osborne, or another reputable Buick Q-jet guy to do a rebuild ($275 or so, depending on how much work it needs.) I'd probably also swap out to a more street-friendly converter. 4000 stall on the street is gonna get annoying. The best part--I bet with all of the above changes, if you do ever take it to the track, I would bet it won't loose a tenth! Buicks are low end motors. Numerically lower gears aren't gonna hurt. Buicks like big carbs. If you were still racing it regularly, you would hear a vast chorus of "not enough carb with the 750" anyway.
a couple more questions.... OK, I will measure the OFFY manifold's carb postition in relationship to the engine and compare it to a stock '73 set up I have. Was there a difference between carb location on the manifold between 70 and 73? I only have a stock 73 set up handy on the shop floor. Also, is there a site that lists carb numbers for Q-Jets? I have a carb that is from a 72-75? number 7043240-LA 0093. I think it is 73??? Thanks
No difference in carb location over the years. Measuring the 73 intake will give you the answer you need. That is a '73 Buick 455 carb, 800 cfm. (fourth digit is year, "240" is "usually" big block) Run with it!!!!
ok, thanks Great help folks, thanks for the input. As for the rear-end gears, the 411's are not he cruisers, howvere, that moroso brut strength really puts it to the pavement andf the 411's really surprise any car and street bike I have met up with at a light :laugh: :TU: . I am thinking about picking up another carrier for 3 series gears, but, I want it to be aftermarket for super duty strength that I require. Any ideas o No:
What's the rear end? Chevy 12 bolt? 8.2? BOP 8.5? Whatever it is, I bet you will still crush the street opposition with a mid 3 series gear. What do you run for tires? I can't believe you can leave a light on any street tire with a 4.11. I ran 3.90s for a while in a legit street-strip car and was MUCH happpier when I went to a lower-numerically gear, both on the track and on the street. NO loss of ET at all on the track. Stock converter, though...
the set up Chevy 12 bolt, 30 splines sommer axles, moroso brute strength. Rims and tire that have both tried are 275-60-15 and 295-50-15. They are both the BF Goodrich drag T/A's which have been pretty reliable traction. With the 4000 switch pitch, it takes quite a touch not to melt them right off the bat. Did I mention that 5.0 Muskrats are a great snack... :laugh: I don't understand why the little imports think because I rumble at the ligth and they are cute that they need to race ou: Rarely worth the speeding ticket. I ahve run all series of gear ratios, 3.42 are pretty good, but, the 411's have always done the job. The motr spins to 7K. I generally shift at 6500. :bglasses:
Reminiscing--maybe a good kill story post, 10 years ago? I built the CRAP out of this engine in 1992 for the track GS I had. One day, I pulled the engine and put it in a custom hand made show car I had, a 68 camino / GS. Neat car. Anyway, the engine was damn near as it is today as far as mods, but it did not have the 6AL or aluminum intake on it and other goodies. It must have been 1995???, the year the TA Firebird 350 hit the scene. I commuted the misserable 411's from Seattle to Bellevue every day on that damn thing. I thought I was sure to ruin it since it had fully grooved bearings etc. built for 1/4 mile. and the gears maybe saved it keeping the rrrr's up ther o No: Abyway, I happen to get side by each with the new RED TA firebird on the high way in rush hour morning traffic. Really not a lt of room to open up the top end of that TA, but, we sparred back and forth for several miles, and I figured I would pop the engine for sure, rrrs' up at 5-6 for a couple miles on the drag engine :3gears: Then I saw the opening between some cars and usually would not do this, but I was committed...... He did too. We both burried it and I just smoked that TA away in my mirror, top end of the 474 cubic inch BUICK just letting that TA have it. I missed my exit but my heart was pounding out of my chest. He finnally cauight up and gave a big thumbs up. He realized he had spent several grand oin a brand new TA and just got whipped, on the HIGHWAY!!!! those were the days... That enbgine still runs today, just like it did in 1992. There is something to be said about balanced below NASCAR Spec and rods within a 1/2 gram :laugh:
the offy was close The offenhauser matches up to stock carb setback, BUT, does not have correct (wide enough) spread bores :af: I was considering boring the aluminum out, but, I am thinking maybe just finding a performer?
Qj I'm sitting down here on the boat at Eagle Harbor on Bainbridge Is. If you need a QJ done, I can fill that order. Can be recolored (acid etched the original olive green color) and rebushed or whatever level you want. PM me back as I'll be here for about 4 days. I would also suggest using a newer manifold, such as the Edelbrock Performer if you want to run the factory air cleaner set-up. I'm not real familiar with the older Offy intakes, but wasn't aware they made a square bolt pattern, I thought all the single carb Offy's were spreadbores. If you want to bring the car down, we can take a look at it and go from there.
My wife WON a rebuilt correct number job (QJ)(800cfm) for my 72GS455($275 delivered)----it RUNS great--starts EVERY time with one push to the floor to set the automatic choke,the guy that rebuilt it (CARBDOCTOR--on Ebay) put Stage One jets in it also---performs great---my engine is original with 92000 miles and it really makes my car run great.I think for non racing applications you can't do better then the QJ! :TU: Good luck Pete--My rear is a 3:42--good compromise--IMHO
