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--have you gone through the carb, set the float, cleaned it up, and adjusted it?
I have not. I't would be my first time. not opposed of doing it.just never done and don't have the knowledge of how to fix it if it goes sideways.
A high idle is a sign your idle circuits aren't working and the idle has been turned up to compensate, or never adjusted correctly, or you have a vacuum leak.
I don't hear a vacuum leak, it shows 15 - 17 inches on the vacuum gauge. I assume the idle circuits are inside the carb?
--these trucks do run rich as OEM. That's one way to keep them from burning a hole in a piston under heavy loads. But they can be leaned out if over rich.
--Does this thing still have a governor? That's going to limit RPM and MPH.
I believe it does. Truck seems to struggle over 50 empty.
Idle circuits are controlled by screws at the base of the carb, usually in front, or by screws on the metering plate behind the float.
Once the float is off, you can blow out most of the circuits with a can of carb cleaner without removing the carb. Being carefull with spilled gas and small parts is key here.
A vacuum leak around the intake manifold, or with the PCV system may not be easy to hear. Use WD40 or carb cleaner and spray around the intake where it meets the head. Any change in idle will tell the tale. Ditto other vacuum connections such as PCV, brake booster etc.
You should be able to make 60 at about 3400 RPM. So if it can't make much over 50 either the engine is really tired or something else is going on.
I don't have the same carb on my 85 C600, but the same engine. Just rebuilt the carb last week. Best $60 ever. Pulled all the vacuum lines except the distributor and capped all the ports. Engine runs better than it has since I've owned it.
I still need new wires and plugs, plus a few other things. This engine will never be a powerhouse, but it is on the way to being usable around the farm.
No vacuum leak was found. carb cleaning sprayed all around the intake and carb. no leak at the vacuum brake booster either.
Carb rebuild kit was mailed today.
See that red hose at the rear of your intake manifold? The one that connects to your firewall-mounted brake booster check valve (and tees to the dash vacuum gauge, probably)?
On my '73 F600 361 (an entirely different engine), the equivalent hose is on a hose barb at the front of the intake, and tucked kinda under the rear of the distributor. I've been chasing vacuum leaks off and on since I bought it in Feb, and I've got it so it'll finally idle with the manual choke fully off -- though still very lean -- when I capped off that fitting, and found this:
You might think that's just cosmetic, but let me assure you that those cracks leak to the vacuum side, and because there are so many and so diffused . . . no noise. I had a devil of a time finding that one. It's about 30" on mine, probably a bit shorter on yours.
Also, that hose is supposed to be rated for vacuum. I had a minor argument with the NAPA parts counter dude last week, who tried to sell me some 1/2" fuel-rated line. "See, it has cord in it, that's what it's for.". I looked up the Eaton/Weatherhead spec on my phone right there at the counter, and it's rated for 400 PSI all right . . . but NO vacuum spec.
I ended up special ordering 3' of Gates H-1451, which is 15/32” ID and rated for brake booster duty. I haven't installed it yet*. If it fits on my 5.025" hose barb, it's going to fit tight. Right now, it's too hot to go work on the truck, so it's something I'll get to later this week (I pulled the 2300 2V carb off due to a vacuum leak at the base spacer, and parts of the carb are in the ultrasonic cleaner right now).
Imagine you are running downhill in a low gear, revs up. Heater hose will see that high manifold vacuum and collapse. Your booster is charged, though. You hit the brakes once, twice, three times, then the fourth time . . . no boost. The booster can't recharge, because the heater hose has collapsed.
Make sure that red hose isn't heater hose, OK?
---
* = I installed it today. Of the 3' I bought, I had around 4" left over! It fits the 1/2" barb & check valve and booster steel line perfectly. I used a bit of Tri-Flow (silicone & Teflon) lubricant on the ID of the hose to aid in pushing it on (the brake booster check valves are getting harder to find).
My current favorite band clamp hose clamps are Peroni. For this hose,
fit perfectly. They're all SS, so you must apply anti-sieze to the pinch bolt or it'll gall and you'll never remove it (or it will strip), but other than that they work really well and aren't too expensive, $3/ea. after tax, in 4-packs.
They come in a lot of sizes, and I have ones on my radiator hoses, too. But you must anti-sieze the threads.
Last edited by asavage; Oct 8, 2024 at 06:26 PM.
Reason: typo
Idle circuits are controlled by screws at the base of the carb, usually in front, or by screws on the metering plate behind the float.
Our FT 2300s are unique in that the idle mix adjust screw ports on the metering blocks are both plugged with brass slugs, and -- if you pull the plugs -- are un-threaded.
Instead, the passages transfer to screws in the base plate . . . on the firewall side. Threw me for a while, until I read around and found a couple of references w/pics.
If you Google (etc.) for "adjust Holley 2300 idle mix", all you'll find is directions for the metering block screws.
My screws were non-functional, due to five (so far) vacuum leaks. Eg, someone plumbed the brake booster check valve tee to the floor-mounted windscreen washer pump [rolleyes]. And other fun-to-find leaks. I'm gettin' there.
Valueflex.. multi purpose line... No vacuum specs.
The Weatherhead line they tried to sell me was also coded "multi-purpose" on the jacket. I rejected it . . . I think some of those NAPA counter people are beginning to recognize me when I come in the door now. It's annoying as ***** that I have to tell them what they sell; they're always telling me, "we don't sell that", then I go home, find it on their website, verify that store's inventory, print it off, then go back and tell them, "nice try".
This is what I got (I read the Gates number off the 50' box they ordered in to sell me 3', but that number is not on the hose itself):
Only three of the special reduced hex nuts were installed at the carb base when I bought this truck. I know why: you have to remove the governor linkage cover (four screws) and the governor assy. (three screws) in order to gain clearance to that nut, and the PO probably went, "phbbt" and figured three nuts were enough . . . er, no. I think I mentioned around five vacuum leaks I've found so far?
Those 351089-S8 nuts are $20 shipped from four suppliers I checked -- the nuts are cheap enough, but everybody wants $10-12 shipping, and I refuse to patronize businesses that can't figure out how to set up their online storefront for real-world shipping charges -- this is $2 max to ship, add a buck for the envelope. You're not charging me a "handling" fee to put four nuts in an envelope, print a packing slip, and slap a label on it, nope.
So, it got a 1/2" hex 5/16-24 nut instead. Fits fine. I'd like the correct nut, but . . . not paying for and rewarding that kinda slovenly. Yours, being a '79. has the electric governor, so IDK if you have a similar clearance issue, but on the vac. governor, it has to be loosened enough to swing out of the way to get a wrench or socket on that passenger front nut.
I have ordered carb rebuild kit Walker 15524 which covers my '73's D3HF-CA & LIST 6548, and which will be arriving tomorrow.
I really can't fault the PO who cut this gasket, IDK if I could have done better, but I heard noise using my "heater hose stethoscope" at the rear of the carb, so I pulled it:
However, the base gasket was soooo wrong:
So, since it's off, I had to at least pull the bowl . . . ugh. A little water damage, probably from old ethanol phase separation:
I tried a couple of things, but what I ended up with was using an ultrasonic cleaner, Branson 5510 that I bought via eBay around 2003 for about $320 IIRC, but I had never actually used, and a 2% solution of white vinegar (50/50 tap water and conventional 5% vinegar from Costco). 20 minutes + 50°C, then rinse. NO scrubbing at all:
Neither the Jobmaster degreaser (2 hours + hot) nor the vinegar solution removed all the gasket material. But the white junk is gone.
With the idle needles removed, I used aerosol CRC Clean-R-Carb in all the passages in the main body, and located the fuel transfer passages. They sprayed out fairly clean, though two other passages did contain visible junk on the jet stream. I'll be separating the throttle body (base) from the main body when the kit arrives; I don't like to over-disassemble too early. I want to replace that last gasket, though.
I can't really give you any Holley tips, as this is the first I've touched in perhaps 30 years, and I wasn't a Holley guru back then, either. Generically, every orifice should be chased. Mine is relatively clean, and I'm content with spraying the aerosol and watching the fountain out the other end, kinda like half-assed injector spray pattern testing. Make certain your gaskets fit and that you don't leave any out (my vacuum governor was missing a o-ring or gasket between it and the main body, for example).
I think I may have found the vain of my problems.. two things.. one the ICM was getting very hot and oozing. I have replaced it.. but also found the horseshoe (? whatever the C shaped clip is that goes to the coil) is lose.
Is there a way to tighten these up or just cut and splice a repair unit on?
carb kit I received was in the right box, but the contents was for a 4 barrel. Still waiting for the correct kit.
Those two things (ICM hot + coil connections seem wrong) might point to the wrong coil installed, too. If its primary impedance is lower than OEM, it'll draw too much current and overload the ICM's output transistor. Just guesses here, though. If it looks like it's an OEM coil, disregard.
