The care and feeding of DeLorean carburetors

[sean]

Switch to K-Jet and your carb problems go away!

Wilson for the win!

[stevedmc]

Switch to K-Jet and your carb problems go away!

What are you talking about? That little Motorcraft 2100 is way more reliable than K-Jet and possibly more reliable than EFI.

[sean]

While this is a carb thread, the bickering can be taken here if you really need to continue the "mine is better" exchanges:
http://dmctalk.org/showthread.php?95...t-Carb-tangets

[Ashyukun]

Sorry for the long lead in getting back to this thread, but it's been a nice enough week that I've been able to bike instead of drive much of it, and I've also been very occupied otherwise.

However, last night on my way to practice (have to drive, can't safely carry all my gear on my bike...) I think I found what the problem actually is. I had largely discounted it being an electrical problem just on how it felt- the way it felt and sounded, it seemed far more likely that the problem was that the engine wasn't breathing properly than something electrical. I had assumed the issue was on the much more complex (comparatively) 'front-end' of the system with the carb- but when the engine started behaving even worse than before on the drive to practice last night and I pulled over and took a look at the engine to try and figure it out, I found that the back half of the catalytic converter was glowing red hot.

So, it seems far more likely that the cat is clogging intermittently and causing the engine to not be able to 'exhale' properly. The annoying thing with this is that I HAVE everything necessary to fix this (read: Hervey's headers/muffler setup)- it's just that I've been completely unable to find a shop or person with the equipment to do exhaust work that will do the work- either because most shops won't touch if if you're removing a system with a cat in it and putting back one without or because the 'smaller' places are scared of damaging something on the car and won't touch it.

[content22207]

John Marconi is still running a single converter with his conversion. Of course he is HEI as well, which arguably gives him more complete combustion than stock ignition.

Bill Robertson
#5939

I've been completely unable to find a shop or person with the equipment to do exhaust work that will do the work- either because most shops won't touch if if you're removing a system with a cat in it and putting back one without or because the 'smaller' places are scared of damaging something on the car and won't touch it.

Buy a couple of $20 converters off eBay and have a shop install them in lieu of the mufflers. If anyone asks, tell them you are going to modify the muffler at home to fit the new system. Converters are about as quiet as mufflers, so the drive home won't be unpleasant at all.

Bill Robertson
#5939

[Ashyukun]

*sigh* Well, I'm kind of back to square one on this.

I had the car at a shop taking a look at the exhaust and whether they'd be willing to take a crack at it (no- they're scared of breaking the manifold studs), and through his looking at it said that he was pretty certain that the the problem wasn't a clogged cat- meaning that the issue was on the other end of the system with the carb.

I'm not wholly convinced that there isn't something weird with the ignition/electrical system- but I did take a closer look at the carb to check something I had noticed before and set up to see if it continued- and there is fuel coating the shaft that the throttle plates are on outside of the body of the carb, and down onto the linkages that attach to it (lower part of the throttle linkage, lower part of the choke linkages). I'm 99.9% certain that's not normal. It's not leaking from the fuel line connection, and appears to be coming from the shaft itself.

I'm not wholly certain there isn't also something of an issue with the electrical side of things- there's an odd issue with the washer fluid pump/switch and the wiper switch that I need to resolve, but I don't see how it would be causing ignition problems- but these problems first manifested both times when I had the wipers running in the rain, and I need to resolve them anyway, so...

[Farrar]

I have a different fuel leak -- I will take pictures and post them here in case anyone has any ideas.

Farrar

[Ashyukun]

OK, got some pictures this evening. They're not the best, but will at least let me point out where I'm seeing the fuel. Don't bother noting, "Hey, it looks like your bowl cover is loose!", I know, I was checking that everything was working properly with the float (and pulling the gasket so I can get a new one).

The RHS, where the fuel was most noticeable, is annotated- the other side it was difficult to get a good shot of the other side of the throttle plate linkage...
Carb_fuel_RHS2.jpg

[sean]

How old is this carb setup and was it new when you installed? There seems to be a lot of surface rust on the fasteners and brackets.

[Ashyukun]

How old is this carb setup and was it new when you installed? There seems to be a lot of surface rust on the fasteners and brackets.

The carb is, I believe, a reman. Bill ran it for a little while on his car after the manifold was first finished to tune it since mine was the first of the newer dual-plane manifolds. I got it about 15 months or so ago (a month or so before DCS). My car has lived outside much of the time though, since my RX-7 has much of that time been immobile and in the garage.