carb replacement 71 mustang

[micali]

Ok, so If I choose a holley what all do I need to put it on the car? Thanks

 Which Holley Carb? a Street Avenger is a good start, at least a 670 #80670.

 Not much. At least a 1/4" insulator for sure to stop heat transfer and maybe top and bottom gaskets if required. There is a Fel-Pro base gasket with a metal insert you will need on a 71 as it has a heat transfer passage and you will need block this off or it will burn the base of your brand new carb. Re-route the fuel line to the right side. You can use good rubber for now till you get it set up. Use Fuel injector line as it is ethanol ruesistant and buy proper fuel line clamps, "T" clamps, not freakin gear clamps that everybody uses!! NO glass fuel filter either. Just make sure everything is tight and rechecked before putting gas to it. Electric choke needs keyed power source, been talked about before.

If I forgot anything others will add I sure.

Good luck as keep us up on progress.

Thanks for the info. I was looking at the 4160 600cfm. What about a kick down adapter? Linkage issues? 

 

[Stanglover]

Ok, so If I choose a holley what all do I need to put it on the car? Thanks

 Which Holley Carb? a Street Avenger is a good start, at least a 670 #80670.

 Not much. At least a 1/4" insulator for sure to stop heat transfer and maybe top and bottom gaskets if required. There is a Fel-Pro base gasket with a metal insert you will need on a 71 as it has a heat transfer passage and you will need block this off or it will burn the base of your brand new carb. Re-route the fuel line to the right side. You can use good rubber for now till you get it set up. Use Fuel injector line as it is ethanol ruesistant and buy proper fuel line clamps, "T" clamps, not freakin gear clamps that everybody uses!! NO glass fuel filter either. Just make sure everything is tight and rechecked before putting gas to it. Electric choke needs keyed power source, been talked about before.

If I forgot anything others will add I sure.

Good luck as keep us up on progress.

Thanks for the info. I was looking at the 4160 600cfm. What about a kick down adapter? Linkage issues? 

   Kick down. you will need to buy p/n 20-91, spring and perch kit according to the installation instructions for Ford application. I'm pretty sure your dealer will have this on the shelf along with a host of other repair and tuning parts for these carbs. There are too many pages to copy here, but you can get this on Holley's website.

Without going back over all this, if you have a 351C, especially a 4 barrel, a 600 will not give you the performance you need. I went with a 670, but a 770 or a Quick Fuel 750 would have been a better choice. I'm told by guys here that 351C 4V's like lots of air and I think they're right. I also had some rich running issues at idle, but that may have been more the mild upgraded cam I have. A Street Avenger should run right out of the box, with minor set up, curb idle for example.

Hope this helps and good luck.

 

[4Vforever]

A 600 CFM carb is too low for a 4V engine and a 750 vacuum secondary either Holley or my personal favourite, a Quick Fuel 750 slayer series would be a way better choice. Not only will this improve the engines all round performance, but help with it fuel economy. As has been stated the standard 4V intake isn't a true square bore and a 1/2"-1" spacer would help get you around the need to modify the intakes throttle bores and help with any possible clearance issues with the throttle lever on the carb sticking to anything.

 

[Stanglover]

A 600 CFM carb is too low for a 4V engine and a 750 vacuum secondary either Holley or my personal favourite, a Quick Fuel 750 slayer series would be a way better choice. Not only will this improve the engines all round performance, but help with it fuel economy. As has been stated the standard 4V intake isn't a true square bore and a 1/2"-1" spacer would help get you around the need to modify the intakes throttle bores and help with any possible clearance issues with the throttle lever on the carb sticking to anything.

 True on the 1/2 to 1" insulating spacer for the reasons you mention. Although on my car when I bought it, it had just a 1/4" insulator and it worked fine. I did machine a fiber spacer 1" thick, with taper bores, for clearance and a bit more insulation from the heat in the cross over...... until I made and inserted block-off plates in the intake. I still use the 1" spacer as it's supposed to make a bit more torque. Hmmm!

+1 on the Quick Fuel 750. If I had to buy another carb, that would be my choice too.

 

[micali]

So your saying the 4300 was undersized from the factory. So how does going with a larger cfm help fuel economy? I was always told larger CFM means more fuel and that's bad on the wallet. I can get my hands on a 750 holley but I'm not sure what model. Ive been told it will need to be rebuilt. How hard is it to do that?

 

[4Vforever]

So your saying the 4300 was undersized from the factory. So how does going with a larger cfm help fuel economy?  I was always told larger CFM means more fuel and that's bad on the wallet. I can get my hands on a 750 holley but I'm not sure what model. Ive been told it will need to be rebuilt. How hard is it to do that?

Absolutely the 4300 at 605 CFM was well and truly undersized for a 4V Cleveland. One thought on the reason for such a small carb was so people couldn't over rev the engine as I haven't seen or speaking with those that had these engines from new could not get them to rev past 5800 RPM and 6000 RPM would be absolute maximum and a smaller carb on the engine is cheaper and easier than fitting rev limiters to every car fitted with a 4V engine. The small carb looked after the engine for warranty purposes by allowing it to rev too high, hence why Ford sold so many 780 Holleys for these engines back in the day to those wanting to unleash the potential from a 4V. If the carb wasn't too small on the closed chambered 4V engines, then why did the Ford engineers go for a 4300D rated at 715 CFM on all open chambered 4V engines. 

The old it's bigger so it's got to use more fuel is just a myth. If the carb meters the fuel better and makes a better mixture, which in turn makes better power across the board with less fuel delivery needed. The 4300 was designed back in the 60's when fuel was cheap and economy wasn't an important factor when purchasing a performance car, whereas modern carbs take not just power, but some sort of economy as well. I have a good friend of mine with a really nice car collection of all makes and engine sizes, the only modified engine is in his Impala which makes just under 600 HP. He swears it's the most economical car out of the lot, a 406 SBC with a modded 850 is more economical than 60's/70's vehicles that are all standard, everything from station wagons to muscle cars to luxury barges that are kept well serviced and looked after better than himself. Since I replaced the valve springs and tuned it, not only does it go heaps better and harder, but the fuel usage is better again. The reason why I only use a dyno as a baseline when the engine is fresh and not as a tuning tool, as a dyno is only as suitable as the conditions at the premises and not where the car actually is being used.

Holley carbs are a very basic carb to build and a very straight forward. As long as the throttle shafts aren't worn, then a kit and a can of carby cleaner and compressed air is basically all that's needed to rebuild one. If the shafts are worn either have them bushed or buy a new throttle plate. Unless the carb is cheap or even better free, then buy a new one with warranty, as other problems like a casting fault in the metering block can ruin your day after doing the rebuild. Trust me chased those problems too many times over the years, thank god for billet metering blocks and throttle plates.

 

[micali]

So your saying the 4300 was undersized from the factory. So how does going with a larger cfm help fuel economy?  I was always told larger CFM means more fuel and that's bad on the wallet. I can get my hands on a 750 holley but I'm not sure what model. Ive been told it will need to be rebuilt. How hard is it to do that?

Absolutely the 4300 at 605 CFM was well and truly undersized for a 4V Cleveland. One thought on the reason for such a small carb was so people couldn't over rev the engine as I haven't seen or speaking with those that had these engines from new could not get them to rev past 5800 RPM and 6000 RPM would be absolute maximum and a smaller carb on the engine is cheaper and easier than fitting rev limiters to every car fitted with a 4V engine. The small carb looked after the engine for warranty purposes by allowing it to rev too high, hence why Ford sold so many 780 Holleys for these engines back in the day to those wanting to unleash the potential from a 4V. If the carb wasn't too small on the closed chambered 4V engines, then why did the Ford engineers go for a 4300D rated at 715 CFM on all open chambered 4V engines. 

The old it's bigger so it's got to use more fuel is just a myth. If the carb meters the fuel better and makes a better mixture, which in turn makes better power across the board with less fuel delivery needed. The 4300 was designed back in the 60's when fuel was cheap and economy wasn't an important factor when purchasing a performance car, whereas modern carbs take not just power, but some sort of economy as well. I have a good friend of mine with a really nice car collection of all makes and engine sizes, the only modified engine is in his Impala which makes just under 600 HP. He swears it's the most economical car out of the lot, a 406 SBC with a modded 850 is more economical than 60's/70's vehicles that are all standard, everything from station wagons to muscle cars to luxury barges that are kept well serviced and looked after better than himself. Since I replaced the valve springs and tuned it, not only does it go heaps better and harder, but the fuel usage is better again. The reason why I only use a dyno as a baseline when the engine is fresh and not as a tuning tool, as a dyno is only as suitable as the conditions at the premises and not where the car actually is being used.

Holley carbs are a very basic carb to build and a very straight forward. As long as the throttle shafts aren't worn, then a kit and a can of carby cleaner and compressed air is basically all that's needed to rebuild one. If the shafts are worn either have them bushed or buy a new throttle plate. Unless the carb is cheap or even better free, then buy a new one with warranty, as other problems like a casting fault in the metering block can ruin your day after doing the rebuild. Trust me chased those problems too many times over the years, thank god for billet metering blocks and throttle plates.

Thanks for the info. You may have convinced me to go with a Holley.I can get a free 750 holley that will need to be rebuilt .I have a guy that can rebuild it for $100. I just went throrogh my car parts and found a Holley 4160 but thats a 600CFM. I've read were others have went the smaller route and gave done fine. I think the 750 will be the way to go.

 

[Stanglover]

I think our friend from Australia hit it pretty much right on. He definitely knows his stuff by all accounts. Let's not forget too, that in the late 60's early 70's, before a lot of you were even thought of, the freakin' EPA was starting to screw up all our fun with emissions controls and running a smaller carb would make it a bit easier to reach standards. The thought was less fuel, less pollution, and more economy as gas was getting "expensive". Not necessarily the case as we now know.

As for the carb you can get for free, grab it! It can be rebuilt and either kept for back up or sold for a profit.

4Vforever talked about rebuilding a Holley carb being easy, which it is, unless there is a casting issue with the metering block. I had such a carb on my car when I got it. It was a (new)  Holley 670, but it never ran right. I eventually sold it and bought a new 670, but in hind sight I should have kept it as it only needed a replacement primary metering block for about 80 bucks.

 Go with NEW if nothing else for warranty.

 

[4Vforever]

Well if you can get the 750 for free then grab it. As for the rebuild, give it a go as they are a very simple carb to build and you can check everything anyway, especially any excess play in the throttle shafts which can play havoc trying to tune it. There's plenty of advice not just here to help you if need be, but would be plenty on the net also. Heaps of people do the 600 CFM carb thing and it's fine if you just drive it, but if you like giving it a workout every once in a while, then the 600 will come up short. When I replaced the 600 Edelbrock carb when it crapped itself with a new 750 vac sec Holley (nobody had a QF in the country at the time) the difference was more than just noticeable performance, but in fuel usage as well. The economy from my vert from when I first got to now is night and day, but took a few parts and some tuning to get it where it is now. Going to interesting the difference between the engine in it now and the 398 I'm building now. Just doing my part to help with "climate change"

 

[micali]

So the guy didn't want to part ways with the Holey 750 after all. I found a Demon 750 for a good price locally, how will it due on this car?

 

[turtle5353]

So the guy didn't want to part ways with the Holey 750 after all. I found a Demon 750 for a good price locally, how will it due on this car?

I have never really heard anything good about the Demon carbs. Especially the early ones. They had a ton of trouble when machining them, not getting them clean of the shavings and getting shavings lodged in the metering blocks.  I personally have never owned one...just going by stories I have heard and bench racing with buddies.

 

[micali]

So the guy didn't want to part ways with the Holey 750 after all. I found a Demon 750 for a good price locally, how will it due on this car?

I have never really heard anything good about the Demon carbs. Especially the early ones. They had a ton of trouble when machining them, not getting them clean of the shavings and getting shavings lodged in the metering blocks.  I personally have never owned one...just going by stories I have heard and bench racing with buddies.

What carb are you running?

 

[turtle5353]

So the guy didn't want to part ways with the Holey 750 after all. I found a Demon 750 for a good price locally, how will it due on this car?

I have never really heard anything good about the Demon carbs. Especially the early ones. They had a ton of trouble when machining them, not getting them clean of the shavings and getting shavings lodged in the metering blocks.  I personally have never owned one...just going by stories I have heard and bench racing with buddies.

What carb are you running?

I am running a quick fuel 850 on mine now.