I don't really know much about carbs either, but I do know most people will tell you that the fact that it's a 4350 IS the problem. An upgrade is probably in order as the stock carbs were horribly inefficient.
Motorcraft 4350 carb grief
So...I just got done rebuilding a 460 for my '78 E350 Pathfinder 4X4 conversion. About the only thing I didn't replace is the original intake and carb. Once I got the new engine running and got the cam broke in I turned my attention to the carb. The carb that was originally on the motor was broken so I was able to source another 4350 that had a "remanufactured" tag on it but basically I don't know anything about it.
I got the carb on and am struggling to get a decent cold idle. I still need to wire up a lead for the electronic choke and hopefully get that working and I'm not sure what to do with the throttle solenoid (don't have a lead for that either). I'm pretty ignorant with all the available external adjustments.
The biggest problem is that it seems to run OK when it's warm except when I corner at idle or low RPMs. If I'm giving it gas it's fine but otherwise it really bogs down and wants to stall, like the floats are set too high. Any suggestions? Any idea how far out the idle mixture/idle limiter screws should be set out from full-in? Thanks!
I got the carb on and am struggling to get a decent cold idle. I still need to wire up a lead for the electronic choke and hopefully get that working and I'm not sure what to do with the throttle solenoid (don't have a lead for that either). I'm pretty ignorant with all the available external adjustments.
The biggest problem is that it seems to run OK when it's warm except when I corner at idle or low RPMs. If I'm giving it gas it's fine but otherwise it really bogs down and wants to stall, like the floats are set too high. Any suggestions? Any idea how far out the idle mixture/idle limiter screws should be set out from full-in? Thanks!
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In a perfect world I'd just replace the carb with a new one but I'm afraid it's not that simple. The Motorcraft spreadbore pattern is different than a Quadrajet pattern and adapters to bolt on a squarebore on the spreadbore intake aren't very easy to find either. If I was rich I'd just buy a new Edelbrock intake and bolt on a Holley but that's not going to happen any time soon either. I'm sorta at the point I need to get this working at least in the short term.
Last night I looked at the old carb I took off and counted how many turns the idle air bleed screws were turned out and compared that to the carb I put on. The old ones were about 4.5 turns, the new carb was about 2.5 turns. I tried 1.5 to start (old Chevy standby) and it'd barely run. Then I tried 4.5 and it seemed to idle pretty good. I took a quick run around town and it was much better. This morning it even started right up, idled OK and I drove to work so maybe I'm on the right track...
Last night I looked at the old carb I took off and counted how many turns the idle air bleed screws were turned out and compared that to the carb I put on. The old ones were about 4.5 turns, the new carb was about 2.5 turns. I tried 1.5 to start (old Chevy standby) and it'd barely run. Then I tried 4.5 and it seemed to idle pretty good. I took a quick run around town and it was much better. This morning it even started right up, idled OK and I drove to work so maybe I'm on the right track...
Yet more beta... I drove the van around a bit today and it idled and ran pretty darn well until it didn't. At one stop light it seemed to load up and wanted to stall but accelerated fine and seemed OK until I stopped at a stop sign and it flat died. It wouldn't re-start and I got it pushed out of the way. After I thought about it a bit I took the biggest screwdriver I have and beat the sh!t out of the bowl and started it right up. Conclusion? The needle valve is gummy. I'm planning on getting a fresh can of carb cleaner, pulling off the filter and spraying the crap out of the carb and hopefully keeping it free. It's 80% there and I'm trying really hard to not give up on it.
Sounds like an overhaul is due! I know times are tight and these damn vehicles can be trying but stick with it, it will be worth it when you get it done. Try Northern Auto Parts for the rebuild kit they have great prices. You have 2 carbs so you can tear one apart to familiarize yourself with the internals before you rebuild the keeper.
Thanks for the encouragement, I appreciate it. A quick question: do you know whether the the needle valve has any rubber on it; i.e. is there hope of getting it clean without having to tear it apart?Sounds like an overhaul is due! I know times are tight and these damn vehicles can be trying but stick with it, it will be worth it when you get it done. Try Northern Auto Parts for the rebuild kit they have great prices. You have 2 carbs so you can tear one apart to familiarize yourself with the internals before you rebuild the keeper.
It has been several years since I messed with one so I can't remember for sure. Hopefully someone who has played with one recently can shine some light on it.
a rebuild kit will come with a new needle and seat and you can get one at oreilly auto parts for 30 dollars... and yes the needle does have a rubber tip
Bummer to hear the needle has a rubber tip... I think I found the real root of the problem though and I don't think it's the carb now. I got the carb good and flushed out and soaked with carb cleaner through the plug on the front of the body above the fuel filter. I hooked everything back up and drove it around and it runs like a top. I decided to put the air cleaner and engine cover back on and drive it around; it was mid-to-high 80's here today. I drove it for 15-20 minutes and along a smooth calm stretch about 25 mph it stalled. I pulled it over and whacked the bowl and it would try to catch and die. I thought about it and decided the fuel was boiling.
Now the x-factor: an electric fuel pump mounted between the front of the block and the steering pump bracket. Long story short; we didn't know we needed to put the accentric on the front of the cam to drive the fuel pump when we rebuilt the motor so it got an electric pump. It acted up earlier when I had the pump mounted on the front of the block (oops, duh). I figured if I space it out a couple of inches and fab a heat shield it'd help. I guess not. I'm in the process of moving it to the driver's side inner fender where the ignition box was. I'll follow up following more testing.
Now the x-factor: an electric fuel pump mounted between the front of the block and the steering pump bracket. Long story short; we didn't know we needed to put the accentric on the front of the cam to drive the fuel pump when we rebuilt the motor so it got an electric pump. It acted up earlier when I had the pump mounted on the front of the block (oops, duh). I figured if I space it out a couple of inches and fab a heat shield it'd help. I guess not. I'm in the process of moving it to the driver's side inner fender where the ignition box was. I'll follow up following more testing.
OK, finally got the problem "system" identified. I took it for a test drive with the new pump location and it died again. I managed to struggle it home and quickly pulled the fuel line off the carb and turned on the ingition...fuel just intermittently sputtered out the line. So, it seems to be heat related and fuel pump related. I'm going to swap in another electric pump I know is good and if it works then I might have just cooked the other pump. I'm debating on just breaking down and tearing the front off the motor and installing the accentric and a new mechanical pump.
Funny, for all the "Found On Road Dead" jokes I've heard lately the problem looks like it's one of the few non-Ford parts.
Funny, for all the "Found On Road Dead" jokes I've heard lately the problem looks like it's one of the few non-Ford parts.
Any reason your leaving the fuel pump under the hood? I'm about to put on an electric fuel pump on our 78 Quadravan and I was planning on putting it in the frame rail just in front of the tank selection valve which is just in front of the mid tank.
Underhood temps on the vans is quite high plus from what I've "read" the electric fuel pump like to "push" the fuel, not pull it anyway.
~Mark
Underhood temps on the vans is quite high plus from what I've "read" the electric fuel pump like to "push" the fuel, not pull it anyway.
~Mark
Mark, it's still under the hood mainly because of convenience. It'd be a bit more complicated to mount it on the frame rail what with the hard line under there too. I'm going to get the eccentric mounted on the front of the cam and install the mechanical pump ASAP anyway so that should be one more thing out of the equation.Any reason your leaving the fuel pump under the hood? I'm about to put on an electric fuel pump on our 78 Quadravan and I was planning on putting it in the frame rail just in front of the tank selection valve which is just in front of the mid tank.
Underhood temps on the vans is quite high plus from what I've "read" the electric fuel pump like to "push" the fuel, not pull it anyway.
~Mark
As an update, I went the rounds thinking the problem was fuel-supply related and tried the other pump and eliminated the electric pump I have in it, checked the hard lines and switch valve, and replaced every millimeter of rubber fuel line underneath. Eventually I came back to the carb. and decided it was the needle valve and seat. I got a kit for the carb and rebuilt it last Monday. I put it back on Tuesday and drove it back and forth for a few days and it started right up in the mornings and overall ran like a champ...until it died on me the other day and I had to leave it overnight a few blocks from home... I got it started the next day and limped it home with it running really rich and dieing a few more times. As a last resort I plan on resetting the float height (I left it alone when I put in the kit). If that doesn't work I'm taking it to a mechanic I know. I really hope it doesn't come to that but I have absolutely no faith in it at this point
.One other off-the-wall question: should this have auto. trans. kickdown linkage? When I got it last year it never seemed to have any kickdown linkage hooked up but the carb looks like it has provisions for it? Just another joy of buying a heavily molested vehicle I guess.
Stock, that c6 should have the kickdown cable. Our Quadravan also has the 460 and c6 and luckily it still had the kickdown cable. I had to buy some adapter thing to put on the edelbrock carb we stuck on there.
BTW, Fuel pump on the block may not work as well as you think. I know that was factory but I am currently running a cheap mechanical fuel pump which works great Except if I let the truck idle. Leave it idle, say at a light, then try to accelerate and it will fuel starve. But thats not the real issue with the mechanical pump.
Its practically impossible to get that fuel line run up to and from the mechanical fuel pump and keep it cool. I tried wrapping the lines with insulation and it didn't seem to help. If I run it hard (say towing) and then park it, it can get vapor lock (so far that has only happened on the really hot days, like 105F).
~Mark
BTW, Fuel pump on the block may not work as well as you think. I know that was factory but I am currently running a cheap mechanical fuel pump which works great Except if I let the truck idle. Leave it idle, say at a light, then try to accelerate and it will fuel starve. But thats not the real issue with the mechanical pump.
Its practically impossible to get that fuel line run up to and from the mechanical fuel pump and keep it cool. I tried wrapping the lines with insulation and it didn't seem to help. If I run it hard (say towing) and then park it, it can get vapor lock (so far that has only happened on the really hot days, like 105F).
~Mark
Mark, are you the guy with the "Lego Motor"; if so, you're a huge inspiration. I don't suppose you have a picture of how the kickdown cable is connected? I bought a premium factory pump so I thought that'd be the way to go. At this point I'm drawing at straws so I'll reset the float level then it's going to the mechanic if it kicks the bucket again. I've actually had zen-like patience with this thing because it's so cool and I have a vision of what it's going to be when I'm all done. I'm starting to near my limit though...good thing I'm still under $2k into it.
Yup, thats me.. Good 'ol lego motors..Mark, are you the guy with the "Lego Motor"; if so, you're a huge inspiration. I don't suppose you have a picture of how the kickdown cable is connected? I bought a premium factory pump so I thought that'd be the way to go. At this point I'm drawing at straws so I'll reset the float level then it's going to the mechanic if it kicks the bucket again. I've actually had zen-like patience with this thing because it's so cool and I have a vision of what it's going to be when I'm all done. I'm starting to near my limit though...good thing I'm still under $2k into it.
I don't have a pic of the kickdown but I can get one. Which end do you need? I'm assuming the carb end? If so, I can get it this weekend. I'm going to change that universal spread bore to square bore adapter with one that actually matches the intake I have (got the adapter for $5 at the swap meet). When I have the doghouse and air cleaner off I'll take some pics.
Under $2k is good. I started at $1100, then rebuilt the motor and of course just kept doing things. Since its my tow rig it has to be right.. I'd venture to guess I'm still under $4k but not by much but I've learned quite a bit.
~Mark
Yeah, a pic at the carb end should get me started. There's a motorhome with a 460/C6 in it at the local junkyard I'll go check out tomorrow and see if I can figure that out. Funny, I bought mine for $1100 then discovered the cracked block and started traveling down the money road. I'm sure by the time I'm done I'll have lots more in it but still lots less than a decent used Sportsmobile.
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