'74 2056 + dual 40's, mallory + blue coil internally ballasted.

So, because I just can't get the carbs right, I had a mechanic do it. The car ran great for about 300 miles and then started missing. I have gone through ignition, tested or swapped with known working replacements and the miss remains. I tested the mallory according to the instructions here: unilite module testing. It passed all those checks.
I did a fuel flow test to the carbs. flow at under 1lb is a little shy to the 3&4 side, but at 2, where I run the regulator normally it's effectively even flow. I pressurized the system and got 3lb's max (my return line is calibrated for that). Both carbs seem to be feeding fuel appropriately.

I can unplug wires 1&2, and the car still idles @<300rpm. Unplugging either 3 or 4 causes the engine to die.

Here's the weird part: I can almost get the idle correct by holding the plug wires on 1 & 2 about a quarter inch from the tops of the plugs. That is to say that the idle comes up momentarily, and waivers depending on if ignition gets through the plug in time.

I've replaced more plugs in the last year than I'd care to admit, and I broke my CSOB plug wrench or else I would have a report on those too. I can't see how they'd go bad though.

Ignition or fuel?

TIA for the help!

Paul
952.451.5205

Sounds like the carburator is out of sync at idle, try turning up the idle screw in
on the carb on cylinder 1&2 if that smooth out your problem the carbs are out of
sync get a Uni-sync and set the flow rate the same on both sides of the carbs
at idle.

Actually, before I started messing with the carbs I ran to the flaps and paid too much for a so-so plug socket. I just swapped the 1&2 plugs for some older ones in the used bucket.

Problem solved. Although, it brings up something I have come to notice:

Everytime I chose to change the plugs, the 1&2 look wet and black, as opposed to 3&4, which look dry and grey at the tips of the nodes.
?~ Am I fouling the 1&2 sides on a regular basis, and am I not solving an air/fuel ratio issue by buying a pro to sync my carbs...

Sounds like your running rich on 1&2, that would foul your plugs. What do 3&4

look like?

3&4 look gud. This is a long-standing issue with this car. 1&2 look wet, 3&4 look good.
I think I've been getting "the treatment" from my carb guy...

I'm taking a wild assed guess, but, 3&4 are the hotter running cylinders, it's possible that the extra heat is making that side burn better and the colder side rich.

Again, a wild assed guess

do you own the synconometer that has the numbered scale as opposed to the ball in a tube type? if you do i'll continue...

k

it's at the top of the list now, rhodyguy.

I'm going back to my guy and ask him about this. It's something he should fix gratis I'd hope.

Paul

Check your plug wires and your coil wire.

If you need a unisyn carb gauge I have a few laying around stop by and pick it up if you need it.
I am willing to bet it's the wires though, if the carbs were tuned not long ago they still should be.

Thanks, Chappy. I swapped everything except mallory with known-good items, mostly off Dave-O's car (which runs great). I think ignition is o.k. and the rich carb is causing fouling (something I noticed 2 years ago, but I can't get an ear from anyone about that...)

Hey, do you know Greg Smith @ Smith Imports? He's right in town down Shady Oak from you. He is who sync'd them. I think he should make it right.

Paul

If you ever need any help, there's plenty of room at my garage.

Thanks, Kelly.
How are you? Is the car getting it's new paint yet?
Hopefully we'll get some type of gathering this year, eh?
Paul

No paint yet. I want to finish this season, so it will go in late Oct this year. There's a concours on May 20th at 1000 at the plymouth radison. The Nord Stern PCA is hosting the "Inter-Marque Spring Kick Off". I'll be there, so if any of you guys are in the area swing by.

I haven't joined Nord Stern but I'll come by, if you don't think they'll ask me to get out!

It's open to the public I believe, you just have to join to show a car.

Greg Smith knows what he is doing, been around a long time is a good friend of Rick Moe(Nurburing).

Yep, I think he does know a fair amount. I just spoke with him. We agree that either the carb is allowing unburned gas into the cylinder or the ignition isn't strong enough to fully ignite the mix. he gave me a few things to check:
Double check resistance in the 1&2 wires, if good then
Install new needle and seat in that carb and check float level.
Then maybe go to a hotter plug... but then we'd want to add head temp gauges to monitor.

I checked the floats for leaks a couple months ago, and they passed.

Anything else?

Paul

No, but your still welcome to the extra carb syncer I have if you want it.

I was once told (and I'm not sure if this is correct or not), that you should have equal length hoses into both carburetors. in other words, you should split your line to a T and feed both carbs from there with equal length hoses. MIght be a relatively simple and inexpensive solution to your trouble.

I need to do that very thing. I just recently got rid of the single priogressive carb and replaced it with dual 40IDFs. My fuel hose tees at the right carb with a much longer hose going over to the left carb.

The car stutters at steady throttle. When starting the car imediately after I rebuilt the carbs last week, it wanted to run but couldn't quite get it done. I checked the carbs for fuel squiting, first the right and then the left. The right carb float bowl had filled up and was squirting fuel, while the left carb was not. And this was after trying a good deal. I would have thought that the left carb float bowl was full. I primed the left carb and she fired right up.

The moral? The car still sputters a bit at steady throttle. Not as bad, but it still needs something. One of my first thoughts was to replace all of the fuel line and make T in the middle of the two carbs with equal length lines to the individual carbs. It may be helpful, and it may not, but it's going to be done reagrdless. YMMV...

Here's my example, fuel Y block right in the middle on the fire wall

Mine are really close to the same length. I have a trick brass splitter that's positioned just off-center.
I noticed the 1&2 carb do get a little more pressure at low regulator load (between .5lbs-a bit over 1lb, but that's not where I run it), it's the longer line by maybe 2", not the shorter.
I don't think the architecture of the splitter would fail to distribute fuel pretty equally. That part was made by a pro race mechanic, Chappy your guy Bob Johnson.

Paul

Kelly, mine's not as attractive but functionally identical. I still have the return line from the FI setup. The return is internally restricted to bleed off up to 2lbs excess fuel pressure, but *might* on a good day return .5lbs. It's really restricted...

Anyway, that car has a lot of acrylic on it. I especially notice the rain tray... Vcool. I've thought about trying to get some plexi molded similar to stock, but tight to the lid like that one.

pfb