Carb Advice

[gregaba]

It looks like the artic fronts are about over here and I can get back in the shop.
I was looking for Carbs today and am at a loss at what to buy.
I have 10 or 12 used Hollys in the shop I can rebuild and one new Summit brand 780 CFM.
The Hollys are all vacumn secondarys [? sp] but I have eleminated all vacumn from the engine except for the dist.
What I am building is a 428 30 over with accutech flat top's Ford D cam, Jays adaptor,  trick flow Track heat single plane intake, Edlebrock heads, harland sharp rockers with POP stands with a mild port and 2.19 in. and 1.73 exhaust's.
As i don't have the engine together yet [hopeing for next month] we have guessed the CR at about 11.2 to one. I won't know about that untill I can get it together. 
It will have a 6R80 behind it with the torque converter stall and rear end ratio still open.
It is going into a 63 Galaxie that will probally weigh about 3800 when I get new insulation,carpet's.headliner etc installed.
I was looking at 1050's but think these may be to big for my build.
All comments greatly appricated.
Thanks
Greg

[Rory428]

Not sure what you mean by "Eliminated all vacuum" from the engine is supposed to mean, but the vacuum secondary system is completely self contained in the carb, no need for any vacuum source from anywhere else. If one of the carbs you have is a Holley 780 vacuum unit, I would use that. Ran the 780s on my very low 10, high 9 second 428s and 427/454 for decades. Great working carbs.

[frnkeore]

For all around street use, the 780 Holley VS would be great but, as a drag engine, with good rpm off the line, I think the 850 cfm, 4781 Holley DP with your manifold and the "D" cam would like each other more.

[Lowrider]

Can't add any advice for your carbs. I'm interested in how it will run with the "D" cam in it. Had one in a 63 Galaxie years ago. Car was a rocket ship. Meanest sounding (and performing) cam I ever ran. Do you plan on driving it on the street?

[Rory428]

For all around street use, the 780 Holley VS would be great but, as a drag engine, with good rpm off the line, I think the 850 cfm, 4781 Holley DP with your manifold and the "D" cam would like each other more.

Possibly, but on my 428 drag engine, with a big solid flat tappet cam, I tried 800 & 850 DPs, a 950 3 barrel, 830 annular, 950HP, and a 1050 Dominator (with an adapter), and none of those ran any faster than my sorted out 780 vacuum 3310-1. Both with the transbraked automatic (5200RPM launch at WOT), or the 4 speed, launching at 6000-6200 RPM.Also tried 5 different intake manifolds (OFFY PortOSonic, Edelbrock F427 (ported), Victor, modified Streetmaster, and a port matched, divider cut down Sidewinder, and on my car, with my combos, nothing beat the Sidewinder /780 setup, EXCEPT when I tried a buddys Tunnel Wedge with 660s, which was worth 1 1/2 tenths and 2 MPH, back when there was the C6 behind the 428.

[gregaba]

Thanks for the quick answers.
When I said I eliminated the vacuum I ment that I will have the only vacuum line going to the dist. I will have no other vacuum needs for the engine.
The car will be 98% street driven with a little stoplight racing. It will go to the strip 8 or 9 times a year but it is a 180 mile round trip and they don't start racing untill late afternoon so I wouldn't get home untill 2 or 3 in the morning.
It looks like I  might need to rebuild one of the 780's I have on the shelf or order another one with mechancial secondaries.
This has really went a long way from my first plans for it ie a stock rebuild with a small cam but when I start on something I don't seem to have enough will power to stay on course.
Greg

[My427stang]

Just to be clear, engine vacuum has nothing to do with the secondaries, not the kind of vacuum you see on a gauge

In the primaries there is a tiny hole and hood that the air rushes over and creates vacuum which pulls on then secondary diaphragm.  If there is air flowing down your primaries, and the secondary throttle arm is out of the way, they open.

You may prefer mechanical secondaries, but having vacuum "needs" has no bearing on that airflow in the primaries.  They are called called vacuum secondaries but really no bearing on engine vacuum

Now if you like and want a double pumper, 2 accelerator pumps and mechanical secondaries, fine.  I'd likely go with a modern 950 from QFT

[Falcon67]

At this point, not sure why you're even using the vacuum advance.  With that much hardware, I'd be using a locked advance and a start retard in the ignition box.  Agree - the 750~780 vacuum carbs are all around decent performers.  I've used them on 300~500HP engines vs 650 and 750 DPs and usually see the same MPH at the strip, which is a pretty good indicator that they are making the same power.  Also same - if you want a DP then either a 750 DP or a 950.  "950" used to be a 750 body on a 850 base in the Holley line. The engine will be more sensitive to a DP, which is why there are so many choices in the DP carb line. 

[gregaba]

Thanks for the explination on how the secondiars work.
When we were racing late models Monty Mc Carthy [RIP] would do the carbs while I would build the long block so I am not into carb's much.
When the EFI units came out I switched to EFI either Accel and later FAST and now Holly Sniper.
Later I want to order a megasquirt system and play with that.
As to the dist I am mostly going to run this on the street and wanted at least 4 or 5 GPM. I have run locked out dist's on the street before and it did cost a little more to run.
I was going to run a Sniper system on the engine to start but looking at the cam choice I made I didn't think it would make enough vacuum for the system.
Later on if I decide the D cam is to much I will go to one of the EFI systems and run a locked out dist and let the computer run the car.
Thanks for the responses.
Greg
 

[RustyCrankshaft]

I think you could make the Sniper work, but it would take some time to sort out. A better choice would be to run a Terminator, MSIII, BigStuff, something you can run set up AlphaN to work with that cam. A little work up front but probably better in the long run. Sniper would be easer to set up but likely wouldn't ever be quite dialed in.

[66FAIRLANE]

My previous 390 build idled at 7" of vacuum and the Sniper still behaved itself at idle in closed loop.

[Falcon67]

LOL - I don't drive mine much on the street even though it's tagged, but I could care less what MPG the thing gets.  The speedo hasn't been connected since probably 1979 so couldn't check it even if I wanted.   If I put the 750 alcohol carb on it, it's use 2~3 gallons just getting warmed up.

[gregaba]

I went ahead and ordered an 850 yesterday along with a rebuild kit's for the 650-750 and 780 I have in the shop.
As far as the EFI unit when I get it broke in I can check my vacuum and make a decision on weather to switch or not.
At least I have some choices.
I am still planning on running CNG as a fuel, I just have to get with the manufacture and make a decision on the type of unit I want to run.
Greg