Good AM,

My name is Jason and I reside in Wake Forest, NC. I recently acquired a '64 Triumph TR4 that a previous builder setup with a 22R and 5-speed transmission. While she starts/runs fine when cold, things go south when she gets warmed up. Aside from the 22R, which appears to be installed from a mid-to-late 80's 4Runner, here is some additional info:

-Weber 40 DCOE 151 Side Draft carburetors with mesh air filter screens
-Cannon Side Draft intake manifold
-LC Engineering Pro Electronic Distributor w/out vacuum advance
-F.A.S.T. E6 Digital CD Ignition
-F.A.S.T. E92 E-Core Ignition Coil
-Edelbrock micro fuel pump
-New metal gas tank w/ new sending unit
-New Painless wiring harness
-New battery relocated to trunk w/ new power cables
-New aluminum radiator w/ new electronic fan
-New LC Engineering performance header

I recently installed a new set of NGK plugs, MSD spark plug wires, along with a Monza exhaust. At this time, she starts up and appears fine when cold. When she gets warm, the idle gets rough, the carbs stop popping, and the exhaust backfires. There are absolutely no emissions, vacuum, or electronic sensors. She's as basic as it gets which makes it more frustrating. Please let me know should anyone have any guidance on where I should focus next.

Thank you,

Jason

 

I wish I could help you but, I don't know much about this stuff. Sounds like a carb choke or fuel delivery problem. You mention there's no electronics but, your fuel pump is electronic when the original engine came with a mechanical pump. Something to think about.

 

Thank you Baller. You are correct that the fuel pump has been migrated to electric. In fact, one of the first things I noticed was that there was too much fuel pressure to the carbs. After installing the fuel pressure regulator, I reduced this from 6 to 2.5 psi which I was told the Weber carbs prefer. I'll do some research on the choke assemblies to ensure nothing is sticking.

Thanks again,

Jason

 

Cool setup. I would do a hot compression test, then valve adjustment. Maybe one exhaust valve is overtightened and begins to leak as it warms up to temp. Also, a vac gauge reading could help with the diagnosis.

 

What Melrose 4r said AND......what about that ignition setup? What is it? You can pull one plug wire at a time to look for change or not on each cylinder. At least you can determine if it's ignition related. Smart move on the fuel regulator.

I have a 52 Ford Flathead with points that would be fine until warmed up. Was a bad coil.

Very cool by the way. Good luck and let us know what you find out.


EDIT: I JUST saw your list of mods. Maybe contact FAST or LCE about troubleshooting the ignition?

 

To add, I had an MSD ignition setup on two 22RE's. No noticeable improvement over stock that I or my son could tell. Both failed in a few months. Went back to stock, Worked well and was reliable with OEM ignition.

I don't know why you would need a high output programable ignition on a normally asperated, carbureted, fairly stock engine. If it ends up being your ignition needing expensive parts, can you just put a stock distributor back in? Points or even electronic conversion like Pertronix if you don't like points. I haven't had to mess with the points in my 52 in over 7 years so far.

 

Appreciate the continued guidance! I've reached out to LCE to see if they have any suggestions. One thing I'm not certain about is the correct timing specs for this setup. I'm thinking it's set at 5' but I don't know if that's correct with what I have. I've been reading that timing could result in some of the symptoms I'm experiencing. I'm also finding that if she's running too lean, this might explain why it's fine when cold as the choke is engaged.

 

First off, this is rad.

We bump the timing up to 10-12* for a small power gain.

Does it have compression? How do the plugs look? Valves adjusted correctly? Carbs in sync?

Maybe a good idea to get a add on wide band 02 setup to read the fuel mixture to rule that out.

Could you stab a good ole vac advance distributor on it to see if it makes a difference?

I see too, you have an open vac port on the valve cover. Could some of the problem.

 

I ran 45DCOE's previously and have the same LCE distributor. Your timing at idle with that setup should be more like 10-12 degrees.

For everyone - DCOE's do not have ports for vac advance, that's why LCE sells a recurved dizzzy without the vac advance.

Is the poor running happening after you disengage the manual choke, or just once it warms up?
I found that I only really needed the manual choke in the winter, and even then only 1/3 - 1/2 of the full pull to get it to idle well and warm up in very cold conditions.
Have you checked sync on the carbs? Dialed in your idle mix? The DCOE's are pretty cool and this is a really cool application for them in this old Triumph, but those carbs are somewhat finnicky and really need to be dialed in to run right.
I often had to play with the mix/tune between hot months and cold months, but we get a pretty broad temp swing here.

 

Appreciate the continued guidance. She starts to run poor after she gets warmed up. I need very little choke to get her started and everything sounds great for the first 5-10 minutes. I have reset both carbs per Weber's guidance and they appear to be in sync. Of course I'm basing this on sound since I have no equipment to verify. I'm going to go back to the timing since I'm confident it's closer to 5'. I'll set it closer to 10-12' to see what happens.

Thanks again,

Jason

 

I had no clue there was an open port on the valve cover. Should this simply be plugged or do I install some type of breather?

 

Plug it!

 

You really need to have one of these:
1) Set timing around 10°-12° and allow to warm up. close choke and make sure both choke levers on the backs of the carbs are actually to full closed position.
2) Check/adjust sync on each barrel
3) Set idle mix for each barrel (follow instructions, but tighten down a little and slowly open up till you find max idle speed for that barrel. likely 2 passes through each bringing overall idle down to desired after each adjustment)
4) Re check sync just to make sure after adjustments

 

I had this same set up on a Celica I once had and did have almost the same problem.. Pretty much the tuning advice of "Bingle" is spot on but a couple more things.

I was always suspicious of the manifold in that it may effect the cooling of the engine as it blocked off the coolant passage between #1 and #2 cylinders, and promoted carb heating. I machined some much thicker heat insulators out of 1/2" phenolic board, (the same stuff printed circuit boards are made of) between the carbs and the manifold and this made a world of difference.

I also got vacuum advance to work but you need to build a vacuum manifold plumbed to each runner with a check valve. You need a check that opens with very minimal pressure/vacuum and is a pneumatic ball check...that's the hardest piece to find. It was years ago but if I recall right they were either Parker or Eaton. I could then plumb the power brakes and PVC system into it. The manifold was simply a piece of 3/4" hydraulic tubing with appropriate fittings silver soldered on. You need to"check" in the direction from carb to manifold as in manifold vacuum will open the check. I don't know how long term durable this system is as I only had the car about 2 years.

 

If in fact it is running lean, the 2.5 PSI isn't enough. Every source I can find on The Google sez DCOE's run great at 3 to 3.5 PSI. Many say 3.5 PSI is correct for a DCOE 40, & a few say 4 PSI. So perhaps the 2.5 PSI is starving them lean?
That's about a 28.5% difference between 2.5 & 3.5.
I'm more familiar with the Weber 32/36 but one thing about all Weber's that I've heard thru the years is that they are all fuel pressure sensitive, & basically need to be precisely "dialed in" for them to work well.

 

Good AM. I wanted to pass along some updates after receiving various guidance from forum members. I was able to set the timing to 12'. In addition, I performed a compression test and all cylinders are at 150psi. When I removed the plugs, I cleaned them up before reinstalling. Once reinstalled, she fired right up and everything sounded great for about 5-minutes. At this time, the carbs started popping and the exhaust was backfiring. I did increase the fuel pressure but this did not appear to improve the running issues. While I've reset the carbs to the Weber specs, I was not able to utilize the carb sync tool because the velocity stacks are too close to the fender. Any further guidance on what I should check next? I was thinking about removing the valve cover, just to take a look at things, but I'm thinking the compression figures would have identified a larger concern.

Thank you,

Jason

 

It wouldn't hurt to at least verify valve clearance. You're right about the compression being a good indicator they're ok though. Unless any are at zero lash and get tight as it gets hot. Unlikely but worth a check.

Does the fuel pressure maintain at the time it starts running bad?

Any vacuum leaks? The engine looks pretty basic. They're aren't any components that open or close as it warms up are there? Does battery voltage drop at the time it starts to run bad? Like if an electric fan kicks on.

Did you gat any troubleshooting information for the ignition? I had a points ignition that did this. I could start and run normal and it would stumble and die before I got a block from my house. After sitting it would start and run again. It was my coil. Failed when it warmed up a bit. Tested fine cold.

Any theft deterrent on the car that you weren't told about maybe? I had a Jacobs ignition years ago that had the option built into the box. I mounted a tiny switch and I had a few seconds to hit the switch. If I forgot, it would run long enough to pull out into the street and start losing power and die like it ran out of fuel. If yours runs 5 minutes probably not. Grasping at straws at this point.

 

Sorry, I reread your first post and saw that you have no "extra" stuff on your very basic engine.

I would think that you could verify a lean condition by adding a little choke when it starts running bad. Sounds like you verified that.

If your carburetor float settings are correct and the fuel pressure isn't overriding the needle and seats I would think no flooding issue. You'd have black smoke if it was rich.

It runs good until warmed up.

Back firing and popping do seem more like a lean condition or ignition related. If your carbs are set well enough to start and run, AND SOUND GOOD until it gets up to temp, it seems more ignition related to me. Based on what I'm reading anyway. You adjusted the carbs, fuel pressure and timing without a change in the problem. It still started and sounded good until warmed up.

Did it run good before anything you changed? Or was it like this since you got it?

Did you try pulling one plug wire at a time when it's running rough?

Does F.A.S.T. offer any help with troubleshooting their ignition?

Good luck and please post up what you find. This has to be frustrating for you.

 

Today I decided to remove the valve cover just to be certain nothing was going on. To my surprise, it looks like everything was recently replaced. I’ve attached a photo so please let me know your thoughts. While I didn’t confirm the valve clearances, all valves are opening/closing without issue. Same behavior that motor starts/runs great until warm. While she was warming up, I started increasing fuel pressure to see if there was any noticeable improvement. I also adjusted the mixture screws with no success. At one point, the carbs started popping and the exhaust backfiring. While she continued to run, I then noticed the header started glowing orange. At this time I shut her down. Lastly, I did confirm that all spark plugs are getting spark. I inadvertently removed the coil plug and it nearly dropped my butt on the floor. Wow! Doesn’t mean there still isn’t an ignition issue but the coil
works. 🥴

 

Appreciate your help!