Ede 800 AVS2 or Holley 870 Street Avenger on 364 nailhead?

Any update on this... looking at a AVS2 800 for my Nailhead

 

Update: I got the 800 avs2, did the doc mod, 2 in aluminum carb spacer (add plenum volume), etc. She ran far better then the show quality rebuilt factory 4gc. Every aspect of how it ran went up a couple notches. Only gripe is I noticed fuel making its way in the crankcase. I think it had to do with the electric pump I was using. It was only a mockup to run it and will be sorted out when in the finished 58. Needless to say BUY a 800 AVS2. You will notice the change!

 

Bump! There's some great info in this thread.
I saw a post on Facebook yesterday by an 'expert' claiming a 800avs is worth 50 hp on a 401/425. I could believe 20 hp over an original AFB, but not 50 hp. I see so much wrong info posted there, it just burns me up.
I like it here better!

 

Must be the J. C. Whitney Facebook page with that kind of expertise. Probably said they picked up 5 mpg too. Going from a 401 to a 425 you're lucky to pick up 25 HP. I might have to ask Tom Wagner if he has considered swapping his TQ out for an original carb just to see what happens.

 

That's typical of the information provided by that "expert" and if questioned even the slightest bit folks will chastise you for not accepting the wisdom of the Guru. Apparently when it comes to building a Nailhead all the known standards do not apply.

 

True. You and I are experienced enough to know bad information when we see it, many of the FB followers do not.
I take Tom T at his word, as well as Rhett, Joe, and (used to have a Nailhed) Mike who was one of the firs GS guys I ever met back in 1982.

 

I picked up 2 tenths which is probably 20 TO 25 horsepower on two different 401 stock engines. But only with an air cleaner change had to take the stock pancake air cleaner off and put an open air 14 x 3 air cleaner on. On my 425 Buick which was a high 12 second car I had the 750 avs and changed to an 800 AVS only to lose throttle response and low midrange power and just being about the same at high RPMs. On a 401 an 800 would really kill power most likely

 

My blue car didn't like the stock pancake air cleaner either. There was a noticeable improvement when I switched to an open element air cleaner. I think it was at least 2 tenths. It was 1993(?) when I did the testing at the GS Nats.

Any opinions on whether a 800 AVS2 would beat a 2x4 setup? My '66 Q-jet gained 2 tenths over a pair of 500's (13.42. vs 13.64).
Jim tells me the new TA alum intake is working very well on Stark's car. Hope we get some details.

 

The 800 may offer better performance than the factory dual quad but the eye appeal is no contest. Easy way to tell if you don't have enough carburetor cfm capability is to hook up a vacuum gauge and check what the manifold vacuum reads when throttle is wide open.

 

So.... greater than 0 vacuum= too small of a carb(s)?

 

That's my understanding. It means engine wants more air than carburetor can provide

 

on my 446 .030 over 440 Chrysler Newport i went from a 750 edelbrock to 800 avs2 edelbrock much better off the line throttle responds. they run very rich at cruise had to change from 65 x 52 metering rod to a 73 x 52 rod which comes out to 12% leaner. only went about a tenth faster because it helped my 60 ft time. don't think the extra 50 cfm made a difference.

 

why the small 500 carbs? thought they came from the factory with 600 cfm. what air cleaners were you running? really you need the eelco 2 x4 stock 2 x4 does not flow well. need flow numbers on the ta-intake that might be the best one to run. now that i think about it I picked up a total of 3 tenths with the carb and air cleaner i could see how it will help the 425 more than the 401

 

Less than 1" vacuum is what you're looking for.

 

I put those 2x 500cfm AFB's on my car back in 1982, I was 21 and didn't know any better, figured 1000 cfm was enough.
I replaced the stock 2x4 air cleaner with a Ford 427 style open element style air cleaner, it's worked well.
I do have a bunch of parts I want to try out, an Edel 2x4 intake and bigger carbs. But I haven't been to the track since Englishtown closed, I mostly do cruise nights and local car shows these days. And spending more time on getting other cars back together instead of making my blue car better. I do expect to to take it to the Morgantown, Pa BCA meet in June.

 

I would imagine changing from progressive linkage to simultaneous linkage on factory dual 4 would help performance a bit.

 

tried that. changed it right back it was terrible. it was on the eelco intake not the stock one though.

 

going with the bigger carb and air cleaner kept the 401 pulling to 4800 rpms before dropping off when the stock was all done at 4400 rpms. works out good by taking out one spring from the governor with a 2-speed 300 tranny that shifts at 4400 from the factory which now will bring the shift point to 4800 rpms.

 

" On a 401 an 800 would really kill power most likely "
That's interesting. A certain Nailhead spare parts / rebuild firm praises the 800 cfm AVS2 as a carb option for a 364. I wonder how the 650 cfm AVS2 carb would go on a stock 401 --- if fuel economy was a priority over Hp ? I currently have a later Quadrajet 800 cfm on my 401, but it drinks juice.

 

I recently installed a 650 AVS2 on my '63 Riviera 401, and it has plenty of power. Perhaps an 800 would make more, but I don't drive very fast and I didn't want to (potentially) have to grind the intake manifold for butterfly clearance.