Aftermarket wise for my 66 401 nailhead in my GS? What is the highest cfm that I can run safely and this is a stock rebuild. Oh yea is there single aluminum aftermarket intake that will bolt up to this 401 also,that factory intake works great just interested to know, thanks.
This is going to come as no surprise but............Quadrajet! Find a spreadbore intake on E-Bay, call Ken at Everyday Performance to build you a hybrid M4M and throw it all together. You'll not regret it...
I used to love flooring the q-it's and hearing it open up... But I am in love with my 950 quick fuel with annular boosters with a half inch open carb spacer. Really wakes up when put to the floor
Well I'm gonna keep my stock square bore intake that the factory Carter carb was on which I think was 600 cfm's. So can I go up to a 750 or stick with a 600 cfm,on a stock rebuild with original h.p. being 340. Tech on the phone other day said I shouldn't go any higher than 600 cfm,i wanna get this right the first time,im not worried about economical gas mileage here either but I also don't wanna go to big an the motor dose not breath right an make it actually loose h.p. Thanks
It's not about CFM's so much as how the engine draws the venturii and boosters. So far you have good advice in here. Keep in mind a phone tech is giving very generic and safe advice NOT particular to your engine type or combo.
I have a 750 Edelbrock I'm looking to sell. The original carb is a 630. I put a 750 QJ on my '65 and it really woke it up. I already had the Intake for it. I used the Edelbrock for Two Weeks and that's it. I bought it from summit brand new. I had it on my 300 and it was way too big. Let me know if you're interested. Jim
In my humble danish opinion, 600cfm is just too little.. I have a 750 edelbrock on my otherwise stock 65' 401" and it could take a bigger one, no problem.. That carb and recurved dist. really worked magic..
The best thing to do with a carburetor is to throw it in the nearest dumpster and go with one of these: http://fitechefi.com/default.asp.pg-Products And never look back!!! Your choice of shiny or black powder coated, for just under 1k, install it and run it because its self learning and will set the A/F ratios automagically!! It will bolt right on to your square bore intake and will give you better fuel economy than a Q-jet when you don't have a heavy foot. It will also look like there is a carb under the air cleaner as well. GL Derek
Yeah, EFI would be the BEST setup! The 'dual' setups would look awesome on a Nailhead!!! There isn't a aluminum 4 bbl intake available yet, but EELCO is working on one, hope he makes it to production. The factory intakes are the same except for the '66 Q-jet version. You can improve the performance of the stock manifold, see this thread: http://www.v8buick.com/showthread.php?225437-Doc-s-dual-plane-mod-and-port-matching-stky I like 2x4's and the Q-jets. Will be trying some 750 cfm AFB's in the future.
Thanks wkillgs and definitely doc, really makes being part of this site worth while finding stuff out like that mod intake,really cool idea. By the way what is the correct and best red paint for my 66 gs rebuild? Make it shine
I don't know where it is, but I put up a thread a while ago on AFB vs. Q-Jet back to back, and 750 vs. 800 Qjet back to back. I like Q-Jets, but I think what was more important was CFM. Nailheads seem to like big carbs, just be careful not to find one that acts like a faucet....a big AFB might work well, vacuum secondary Holley (?) just something that senses the need for secondary kick in rather than dumps open.
I have some cans of Krylon 2114 Buick Engine Red that will match up correctly. One can should do an entire Engine. Let me know if you want a can. Jim
Umm, I've had little trouble getting 7.0-8.2 liter displacements into the 28-30 mpg range with Q jets. Having one in decent shape is a different matter. Saying that the cfm is what made the comparo work better is like saying "the blue one is better". There were other differences that could have helped. (I also have better luck with the bigger ones) The primaries are very tiny on Q jets, sometimes the combo needs a slightly larger throat but it isn't because it's "on a Nailhead" or any other generic situation. Timing curve, rod ratio, combustion dynamics, valve seat and port work, cam timing events and the Delta P between cylinder demand and what the intake tract can supply, ALL change the intensity of the draw on the boosters. Even larger primary carbs might be favored on engines with higher cruise rpms, such as with deeper gears or freeway speeds. Knowing that you really can't make comparisons because of the hundreds of variables, the questions shift to "How much commitment or skill do you have to tune it?" "What is a good starting point for my combo?" "How good do you really need it to be?" All the comments are valuable so far! The only specific I can add is that the Edelbrock's at best are "OK". I've read that the 750 is a copy of a flawed OEM design. The text written made perfect sense, anyways. I have successfully used them on a couple of motorhomes that I was able to triple the mileage, not saying much as they were horse s*** to begin with Least hassle? Drop it off with a pro and write the check. Skilled Diy with least tuning difficulties? EFI You know your attributes and priorities better...
I'm not sure what exactly 8ad-f85 is talking about, but I did get an honest 21 mpg out of my Nailhead on a M4M Q-Jet - once. I was pretty impressed with that.
I haven't used it but I haven't been able to find a bad review on it either, seems like the people that have one like it a lot. I think they're sold out right now and if you order one it would be on back order for a while is what I heard too. It is priced really temping because some of the high end carburetors can be in that price range and if I had the $ right now I would get one to try and if I liked it maybe get a couple more before the price goes up. Maybe Santa Claus will be good to me this year instead of passing me up again. LOL If Santa comes through for me I'll start a thread for when I install it. Derek
As far as I can gather, the Quad was only the 425 on Wildcat and Riviera, all others still used a 4GC if not the Carter AFB, which is why they're so rare. The 66 Quad was a one year only affair, the 67 Quad used on the new Buick Big Blocks would probably fit, but in 68 they used an entirely different throttle plate, so it won't fit on the 66 or 67 manifold. The 68 and later quads are the better ones, but...yeah, they don't quite fit.
Q-jet was standard on the '66 425 and optional on the '66 Skylark GS 401.... There was a mid-year (Feb '66) option rated at 340 hp which included the Q-jet, earlier 2x4 cam and distributor. Only 132 car had the option.
