quick fuel

[jpaz]

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_systems/carburetors/quick_fuel/street/ss-series/parts/SS-735-VS

 

[TommyK]

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_systems/carburetors/quick_fuel/street/ss-series/parts/SS-735-VS

I think that is a great choice.

 

[Fabrice]

for 100 xtra you could have an EFI...

https://www.summitracing.com/int/parts/sum-240500/overview/

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

 

[red351]

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...

 

[Stanglover]

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.

 

[red351]

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...

 

[Stanglover]

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.

 

[c9zx]

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

 

[clevelandcoupe]

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

 

[jpaz]

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.

 

[rotorr22]

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...

While I've yet to use one on a Cleveland (I'm going to soon), I have used both the 4100's as well as Summit's "improved version" on Windsor applications with good success. The large annular boosters provide very good throttle response, quick starts and I like the fact that I can replace jets without fuel spilling all over the intake. The down side is that I've given up some HP vs. other carbs I've tried of similar flow ratings. On the street, the trade off was worth it as I find them pretty easy to dial in. I've never used one with a real lumpy cam, however.

 

[EBSTANG]

I have approximately 2,500 miles on my new QFT BD-750 that I installed on my 408 Cleveland since last spring. Never looked back.

 

[Omie01]

I ordered a Pro-Systems 780XP, and filled out the spec sheet for my build. In 2 weeks I had a carburetor that has no issues at all, works perfectly for my car, and was only $100 more than the equivalent holley from summit. Just for S&G's I tried 2 other DP carbs and actually lost a LOT of power. I just can't say enough good about this carb. It does have the primaries drilled as well, and has their base plate, and Venom metering plates, so maybe that tells you that Holley does not make good ones of those. I know they have been a little sketchy in the past, but they built me one heck of a carb!! It ran great right out of the box. Just set my timing and air-fuel and have been good to go since. Just my .02. Good Luck!!

 

[jpaz]

Lots of great info guys, thank's so much! I will update when I figure out which carb I get and will post results. I'm looking at the QF SS 735 or the Slayer 750 with vacuum secondaries and electric choke.

Ya Omie01, there is a place that I can order one up and they said it could be set up for my application. Problem is I don't know what cam I have so I don't think much can be done to it before it's installed on my car. They did say though for as long as I own the carb they would help with tuning if needed. I'm gonna check them out.

Thank's again guys!

 

[Stanglover]

Some very interesting reading indeed. I am somewhat surprised at the number who have had issues with the Holley SA. Yes, I had more than a few frustrations getting mine to run, but run it does. For me, when I first ran into this problem right after my engine was rebuilt and that custom Holley no longer working as it did, the obvious thing to do at that time was buy a new carb. The only one available to me over the counter, was the 670 SA. I think that little extra lift on the new cam was the reason it just needed more air. Right out of the box, the SA ran waaaay better, no more fuel smell ( which it did not have as much before the rebuild), but it was also obvious it needed a bit of tweaking.

To be honest, I did have friends say "why didn't you buy a Quick Fuel?", but at the time I got what I could get. Would I change to another better brand, Yes, if spending the extra cash justifies it.

Geoff.

 

[jpaz]

Yes Geoff, I am basically frustrated with my SA. It was a big improvement over the stock 4300d that was on it, but after realizing how this carb really is, I'm over it. I feel like I beating a dead horse, lol.

I would like to thank you for all the helpful information you have provided regarding this subject. I know you went through a lot of BS to get your carb right. I hope it keeps on truckin!

 

[boilermaster]

Well Fellas,

Lets just see what is going on here.

We expect to install a universal carb on (''stanglover big valve big air engine'') and expect it to work like EFI , that ain't going to happen unless we do like (omie01) and do the spec sheet thing or have the extra cubes like (ebstang).

The carbs our Clevelands like are generally in the 700-780 cfm range and a UNIVERSAL carb in that cfm range is going to be calibrated as such.

700-780 universal carbs are generally for much larger engines than ours, therefore the AIR is generally close to being right, but the fuel is almost always not.

When tuning a universal carb in the 700 to 800 cfm range , be prepared to tune each and every circuit in that carb to make it custom fit your application.

I have done just that with my 750 sa carb and it preforms flawlessly throughout the entire rpm range.

The only way to do this with any certainty is to use a wideband O2 monitor!.

Now I am going to a 408 stroker and plan to use the same exact carb, yoooou guessed it, I will have to tune each and every circuit again.

If you want it to run like EFI , tune it like EFI.

Boilermaster

 

[jpaz]

All I'm saying is how can I give anyone a spec sheet when I don't know what they are? The only thing I know about the cam it is it is larger than stock. So ya any new carb I get has to be tuned through every circuit. Would I still benefit with a carb being set up for me without know any cam specs?

I'm sure an 02 meter would be very useful, but for now I'm plug reading.

 

[Stanglover]

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.

 John, I forgot to reiterate that it's not only degrees of advance, it's also spring tension and freeplay on the weights so that the timing comes in at the correct "curve". On mine, I found that a Mr.Gasket 925D spring on one side and the factory heavy spring on the other set with a slight looseness on the pegs, worked best. My timing come in smooth and all in at just below 3000 rpm, no vacuum. I also resized a slot to achieve 20 degrees on the crank, i.e. a 10L slot width. This is just from MY experience, others may have other opinions.

Geoff.