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quick fuel
#1
Hey guys, I'm thinking about this carb for my 72 Mach 1 Q code. I currently have a 770 Street Avenger on now, but not real happy with it. I've had it for about 3 years now, and I'm still having the same troubles as others. I just can't seem to get it dialed in right. I thought I had it running decent, but it's way to lean. I'm getting tired of messing with it, and you can see that it's cheaply made. It's already leaking from the throttle plate and the butterfly shaft.
My 351 is the original Q Code block that has been rebuilt by the PO, so I don't really know exactlly what had been done. I do know it does have a larger than stock cam, but I have no details for it other than it's a non roller rocker set up. I have a Blue Thunder dual plane intake on it, C6 auto trans with 3.50 Trutrack rear end. This carb looks like it is a better made piece and more tunable. Any feedback would be greatly appreciated, Thanks https://www.holley.com/products/fuel_sys.../SS-735-VS

run_horse Run Horse Run!
John 72 Q Code
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#2
(03-12-2018, 10:14 AM)jpaz Wrote: Hey guys, I'm thinking about this carb for my 72 Mach 1 Q code. I currently have a 770 Street Avenger on now, but not real happy with it. I've had it for about 3 years now, and I'm still having the same troubles as others. I just can't seem to get it dialed in right. I thought I had it running decent, but it's way to lean. I'm getting tired of messing with it, and you can see that it's cheaply made. It's already leaking from the throttle plate and the butterfly shaft.
My 351 is the original Q Code block that has been rebuilt by the PO, so I don't really know exactlly what had been done. I do know it does have a larger than stock cam, but I have no details for it other than it's a non roller rocker set up. I have a Blue Thunder dual plane intake on it, C6 auto trans with 3.50 Trutrack rear end. This carb looks like it is a better made piece and more tunable. Any feedback would be greatly appreciated, Thanks https://www.holley.com/products/fuel_sys.../SS-735-VS

I think that is a great choice.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
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#3
for 100 xtra you could have an EFI...
https://www.summitracing.com/int/parts/s.../overview/

Prolly 250 more for a fuel pump + tubing/hoses/details.

73 modified Grandé 351C. Almost done. 
71 429CJ. In progress
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#4
Let us know if the Quick fuel works out. I've been running 770 SA on one car, and yes its very sensitive to change, and the 670 SA I just gave up on. Never been happy with the SA series. Been going to maybe try Summits copy of 4100 show box carb. The money I got tied up in both SA carbs with the mods has never been money well spent...
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#5
I don't know what your problems are with the Holley SA carbs, I currently run a 670SA on my 71 M code, Melling MTF2 flat tappet cam, factory intake, 1" fiber spacer, Autolite 24 plugs, manual trans. My engine is about 10:1 comp ratio, in other words pretty much stock and it runs like Jack the Bear. The only problem I had was it ran RICH at idle and a bit rich on hard acceleration. TIMING is huge in getting an engine to run right from my mega experience. If you're running more than 34-36 deg. with an initial of 14-16 deg. mechanical timing with about 6 deg. of vacuum on top, again from my own findings, it'll never run right. I spent most of last summer working with all of it. The only thing MY engine needed was to increase the idle air volume. This was done by a tuning tech. He achieved this by drilling a 3/32" hole in the front half of the primary throttle plates. The trouble is with these big valve engines, they need that bit more air. Opening up the transfer slot by adjusting the curb idle screw only worsens the problem, which is what I had done trying to get the idle right.
If anything I could step up to a 750 QF Slayer, but that may have to wait. Recently I contacted Summit Racing's tech guys for information on QF versus Holley versus the Summit 6208 ( I think?!) I copied the email scan on here. If I knew how to link them, I would, but I could recopy them again. There was some pretty interesting conclusions.
The only thing I see I don't like on that QF carb linked, is it does not have the quick change vacuum secondary spring cap.
Again, I realize all these motors are different beast and behave very differently one to another. I'm just relaying what I found needed to be done to get the best out of my motor.
Geoff.
Found the scans. Go to Klinton994's post of 02/09/18, Carb Selection, post #7. Summit tech's response and suggestions.
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#6
My DP 650 holley has never been a problem on my 72, but the two SA always a problem. The 67 has the same engine everything and yes limited 34 deg total timing , The 670SA HAS been drilled and 50cc pump added for the late stumble different power valves, a lot of different squirters, cams profiles you name it. If it ran good that day, the next day...NO...The 770 was much better after some tuning mods but the DP 650 has been totally trouble free since I set it up. I been messing with Holleys and Clevelands for 40 plus years. That 670SA is just for parts now. ITS The only carb I wasted so much time and money on and just would never run the same for 2 days in a row. Last fall I changed the 67 to a BT intake and been waiting for spring too tune the 770SA for the now new stumble problem. HOPEFULLY but I'm done with SA series for next carb if needed...
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#7
(03-12-2018, 06:20 PM)red351 Wrote: My DP 650 holley has never been a problem on my 72, but the two SA always a problem. The 67 has the same engine everything and yes limited 34 deg total timing ,  The 670SA HAS been drilled and 50cc pump added for the late stumble different power valves, a lot of different squirters, cams profiles you name it. If it ran good that day, the next day...NO...The 770 was much better after some tuning mods but the DP 650 has been totally trouble free since I set it up. I been messing with Holleys and Clevelands for 40 plus years. That 670SA is just for parts now. ITS The only carb I wasted so much time and money on and just would never run the same for 2 days in a row. Last fall I changed the 67 to a BT intake and been  waiting for spring too tune the 770SA for the now new stumble problem. HOPEFULLY     but I'm done with SA series for next carb if needed...

Wow! I can't claim anywhere near your experience, but what you say about SA's is nothing short of surprising. I will say though, that when I got my car in 08, it had a 670 SA on it. Apart from a fuel leak from the acceleration pump, it ran, but with a lot of roughness. Not long after I got the car, I had a carb specialist build be a custom 4V Holley 650. That ran like a charm until the engine rebuild, then not so much. A friend who builds stock car engines, rebuilt the 670 only to find the real problem. The primary metering block was bad, the right side idle screw could be turned in till it disappeared!! Take it right out and it made zero difference. The conclusion, bad metering block right from the factory. I sold it for parts, but should have kept it just in case.
OK back to why I'm surprised you're having issues with SA's. Not only myself, but I personally know 2 guys who love them. One has one on his drag toy, a 72 Chevy Nova. Another friend has one on his 78 Z28 Camaro and he occasionally drags it too. OK they're Chevy's not Fords, so that could explain it !!
Anyway, back to the Quick Fuel 750 Slayer that the Summit guy recommends. I think that is what I'd go for and they're cheaper than Holley's. For now, mine is running well and strong, no issues up to 6 grand!
Geoff.
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#8
I've never met a Street Avenger carb that I liked. The factory calibration doesn't match anything I or my friends have built. In general, the QF carbs offer more adjustability for the same or less money. Having said that, the adjustability isn't usable if you don't understand when and why to adjust what. To learn requires a lot of time and effort, and occasionally some money. The Summit "shoebox" also has good adjustability at a reasonable cost. The slayer is a good, inexpensive, adjustable carb. The Edelbrock works OK for stock or near stock engines, if max power is not needed but, has a wonky adapter for kick down and has minimal adjustability. Just my opinions. Chuck
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#9
I agree with Chuck on the street avenger carb. I had one on my Model A when I first put it together and the motor was basically stock. It ran well sometimes and not......
I also found that once I updated the motor and the jetting and other adjustments were needed, it just wouldn't run well on a consistent basis. I upgraded to a 650 quick fuel and never looked back....
Thanks, Jay
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#10
Thank's for all the great feedback guys! Ya Stanglover I have followed what you have done, but not getting your results. Initial timing 15 with total being 35 and I didn't bother with the vac advance. Just seems no matter what I do I can't find a consistent combo. I'll mess around a bit more but I think I'm ready for a change.
I know I can't just slap on a carb and it will be good to go, for sure needs to be tuned  for each different engine, but this looks like it could be a dead end. I get the same, some days it runs good and other days not so much.
I really think I'm gonna give this QF a try.

run_horse Run Horse Run!
John 72 Q Code
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