Anyone have any idea what Holley carb (new) would be best for a 534? The Holley website suggests a vacuum secondary 570, but the calculator only asks the cubic inches and rpm of the engine. I'm wondering if a 534 being the beast that it is has different needs than a "normal" motor. Its got a vacuum secondary 3310-2 750 on it now and runs poorly, starts hard, and uses a disgraceful amount of fuel. Time to throw some money at it and buy my way out of a recurring headache. Hopefully one of you guys has the answer!!
Regards,
Mike Haworth

 

I think the 750 cfm is way too big. I took off a 370 cfm vacuum secondary Holley from a 477 (which I modified to use on a 260 small block). This carb had the idle circuit on the secondaries, an accelerator pump on both sides and of course the governor.

Is there any particular reason you want a new carburetor and not a good used one?

 

Thx again Beanscoot! Been a while since I visited this forum. I talked to the factory techs at Holley. The guy described the symtoms exactly and seemed sure that a 570 street avenger would make a huge difference. Youre right, a 750 was way too big, ie: too much flow for that motor. My mech ability is too limited to try and tweak or diagnose a carb that may have been modified and isnt performing quite right, so in order to save future headaches I went ahead and bought the new 570 which came with a really great dvd on adjustment. I get a week vacation Feb. 5 and will be rebuilding the fuel system from tank to intake. Hoping for the best!! will post results.
Regards,
MIke

 

Hi Mike,
The new carburetor should save you a lot of trouble. I have to correct my last post. Where I wrote "an accelerator pump on both sides" I should have said "a power valve on both sides". Of course there's only one accelerator pump but two power valves in these old governed carburetors.
Even if you aren't too experienced with carburetors, I would think you could do alright in rebuilding one if you just take lots of care. Most problems are simple ones, like dirt in a main jet, a torn or hardened power valve etc. Supposedly these old SD carbs use different gaskets, but I seem to recall that I got a couple from the stock at the local speed shop years ago when I repaired mine.
I just replace the gaskets that get torn and parts that are faulty, I don't bother with the expensive kits since the needle and seat assemblies and such seem to last forever for me. I rub never-seize on the bowl gaskets to help keep them from sticking and shredding next time the bowls or metering blocks are removed.

 

I'm hoping it works out good.. Supposed to have "next generation" power valves. -whatever that means. At least parts are readily available. Its supposed to be wet tested at the factory, and you just set the float level and idle and away you go. LOL We'll see.. it did come with a really great dvd for troubleshooting and adjustment, and is all polished and shiny!!! HAHA. If this works I may have to get some more sexy looking parts to dress up the old bitch!

 

Hey this seems to be continuing in two posts...

 

Hi, I was wondering how that new carb worked out for you, I have a similar situation as you did, and would like to just get a new one and be done with it, I have a 534 in a grain truck. Any info would be appreciated

 

Well, eventually I got the whole fuel system rebuilt right down to a newly fabricated 150 gal aluminum tank, and bolted on as many new parts as I could buy. She ran better, but still crappy by my standards so I took the damn thing to a heavy truck mechanic familiar with Fords for a checkup. He ran down a faulty voltage regulator that was part of the problem, but called me a couple of days later saying that he had tried several new jets, but just didnt think there was any way he could get the 570 to work. Its just too small. No matter what he tried, it had a really nasty "whistle" when the throttle first cracked open, and was starving the motor for fuel. He ended up rebuilding the 750 double pumper that was on it before and now she runs like a scalded cat. Its really frustrating that I could not use the new carb, as I bought it on the advice of the Holley factory tech! But, in conclusion... REGARDLESS what Holley may tell you about which is the right carb for a 534SD, my experience has been that a 750 is the SMALLEST you should run. I plan to buy a new 750 double and replace the older one eventually, and I'm on to a guy here that has a performance shop that supposedly can work miracles on old truck heads, so thats my next step to try and squeeze everything I can out of my motor without a radical re-build or replacement.
Regards,
Mike

 

Thanks for the reply 57fitz, since I don't run the truck at rpm's over 3000 it actually says the 570 would work for me too, the first time I ran the Holley carb finder it recomended the 0-1850 (4160) 600 cfm, so I tought I would prob. order one. I guess I will rethink that. My truck runs good and starts good but once it gets warmed up it idle's too fast, which makes it hard to engage the pto and get it into gear. I think it is also flooding itself a little. The carb has been rebuilt recently, that's why I want to replace and not dig a deeper hole. The thing backfires when you shut it off unless you can slow the engine down by engaging the clutch a little with truck in gear to drag the engine down a little.
how about the Holley 0-3310 750 cfm for a choice of a new one? I was hoping a smaller carb would work since the truck is ran mostly at lower rpm's. I know it's going to drink lot's of gas, I just want it to idle and shut down better. Thanks again for the input!

 

yknow, I used to keep my 534 under 3K too but after I drove it some I find that it doesnt hit its powerband till about 3,300. Between 33 and 36 it seems really happy and pulls hills like a champ. Im not sure what all had been done to it before I got it, so I cant be sure if its all original. Guess if I blow it up I'll upgrage to a beefed up 460!!!! I got a friend that says he can build one to 600+ hp pretty cheap. Keep me posted on what carb you end up using. BTW,, are ya sure the high rpm thing cant be adjusted out with the carb thats on there? A new one is always nice, and the installation dvd is pretty good, but when it comes to finessing a carb to run like it should I had to defer the work to a higher power. Easier for me to work a little extra and pay someone else to do it fast!!

 

Hey Mike, I ordered the 65-1850 carb, it look the most like the one on there, came today, but I have a problem, did your old truck have a mechanical governor? mine does, it's linked to the carb, the new one doesn't have any shaft for it, and I'm not sure what to do about it. I'm going to do a search and see if I can find anything. FUN! Thanks, Dave

 

I have to disagree that the 570 cfm carburetor is "too small to work". The smaller carb will work better than a larger carb at low to mid rpm, actually until the demand of the engine is over 570 cfm.
There may have been other problems with that carburetor, but not smallness. As an experiment, disconnect the secondary throttle linkage from your 750 and see how it performs on only 375 cfm.

 

Hey Spinach,
Yeah, mine did have a mechanical governor... disconnected now. The motor will over-rev if you let it. I will be the first to admit that I dont know a whole lot about carbs, and Bean is most likely a whole lot better to ask about this than me. I'm just going on what the mechanic who actually did the work told me. He was a heavy truck mechanic for 20+ years. Maybe he was just tryin to jack up the bill by talking me into a rebuild on my 750, I dont know. He did try to re-jet the 570 a couple of times and couldnt get it to work. There was a nasty whistle in the carb when you first cracked the throttle, and absolutely no torque. I came down to the shop and checked that out myself. The rebuilt 750 is really doing an impressive job.. 70mph with no issues, and good pick-up off the line. As I am not a mechanic, and the motor is running great for the first time in 2 years, I dont think I'll do any experiments!! Yknow, let sleeping dogs lie and all that. I have no idea how to incorporate the old governor system with a new carb. I just keep an eye on the tach!!

 

Well I think you are right in leaving well enough alone now.

Adapting a governor to the 750 cfm carburetor would be extremely difficult, as the throttle shafts on the governed carbs have different ends, and quite possibly are longer to attach the linkages. A lot of parts would have to be adapted to fit.

If one really wanted to govern an engine nowadays an aftermarket electronic ignition system with rev limiter would be easier.

 

that whistling you described is a vacuum leak. I am running a 600 cfm holley, and it runs just fine