Ok, the headers starting to glow means that exhaust temperature is going through the roof. That would track with the engine going lean. Do the spark plugs look like it's going lean? It's also odd that adjusting the mixture screws doesn't change how it runs. I think I would first go through the carbs to make sure they don't have trash in them or anything, and then look at re-jetting them richer.

 

Also keep looking for a vac leak or plugged exhaust system. It runs good when cold, probably on the choke but the idle circuit is very lean, why? Headers should not turn red idling.
Idle mix screws won’t control much if there is a vac leak.

 

My next step is to pull the plugs again to see what they say. I'm determining that previous Weber tuning guidance is incorrect for the 40 DCOE setup. Initially, I was told that the mixture screws should not be more than 1-2 turns out. I found recent guidance that it should be closer to 2.5-3 turns out. This would explain the lean issue if they were starving for fuel. I'm also going to increase the fuel pressure as it sounds like it should be more for a dual carb setup. Lastly, I can open up the carbs and make sure nothing is in there. I do have a brand new fuel filter directly next to the electronic fuel pump so I'm hopeful this is capturing any debris. I'm confident I've ruled out motor and ignition issues and the timing should be correct at 12'. I'm going to focus my attention on the carbs and keep my fingers crossed.

 

There does not appear to be any sign of vacuum/vacuum lines anywhere on this car. Is there anything I should look for to confirm that some type of vacuum port was not plugged? For example, the Webers and distributor do not support any type of vacuum connection. Lastly, there is an open port on the valve cover but it is not vacuum. I do plan to install a breather so this is just not blowing into the engine compartment.

Thank you!

 

If ethanol gas sat in the carbs for too long it will plug up the carbs.

You can find vacuum leaks by spraying carb cleaner or WD-40 and such at the base gaskets or intake gaskets. Anywhere that's supposed to be sealed for the intake. The idle will change if you spray it near a leak and it gets sucked in.

Were all the header tubes glowing red or just certain ones?

The PCV valve is attached to the valve cover so there is supposed to be vacuum in there. If the PCV valve is bad you will have a giant vacuum leak.

You never said if this was a problem when you bought the car or if it started after mods.

Sounds like you're heading the right direction at least. Good luck.

 

My memory is a bit fuzzy, but I believe that I was running 1.5 psi to dual 45DCOE's. I'll check my Weber tuning manual tonight.
Initial idle circuit setting should be out 2.5 turns from closed.
Can you get the syncrometer in there if you remove the air horns? Even just checking between cyl 2 and 3 to make sure the 2 carbs are close to synced is hugely important and really the first step in this process. Out of sync will absolutely make it backfire, pop, and sputter.

Idle adjust:
1) choke off, idle around 800 rpm, all idle screws at 2.5 out from closed, carbs synced.
2) slowly open idle screw on cyl#1 until you reach max rpm's with that screw, close a little bit and make sure you're right on the edge of rich.
3) bring idle back down to 800rpm (desired final idle) with the throttle blade idle adjust screw.
4) repeat step 2 and 3 for each barrel in order.
5) Go back to barrel #1 and check that it's still correct (likely minor adjust) and make a pass through all 4 again.

After all that, opening up the throttle a bit (1500 rpm's ish) by pulling where the cable does, and checking sync again holding those rpm's is important. the carbs sit on the idle screws for the individual carbs, but if the arms don't open the throttle plates the same amount when you start giving it gas it will stumble and/or backfire.

 

I ran dual breathers on my valve cover like you're planning, it's fine.
The only Vac port these have is the one on the manifold on the backside of #4 runner. I had that run to the brake booster but it looks like you have that plugged so it should be fine.
Checking for vac leaks around the carb bases and the manifold to head interface is a solid plan.

 

Thank you!

 

Thank you for confirming I can simply install a second breather. Also, confirmed the manifold is plugged and not leaking. I have confirmed that all carb and intake mounting locations is tight. This was not the case when I first purchased.

 

Thank you for the above and I will focus on this next. I will also see about removing the velocity stacks as they are currently preventing the use of meter. Good idea!

 

Given the new head internals what about the theory of tight valves closing up as engine heats up? Seems like it has been mentioned...that might be the first thing I'd investigate, maybe just check them cold to get a sense. I believe lean condition / tight exhaust valves / burnt valves can become related symptoms...an wideband AFR gauge has helped me avoid leaning out my 32/36, might be a good idea to tune your setup.

 

Made some great progress today. I started with the mixture screws at 3 turns out. This was a full turn out from what I had before. After starting, I noticed she was still popping a little and the header started to heat up again. I then turned out the screws another full turn. The header stopped glowing and the motor started to idle without issue. I let her warm up for a little then gave increased the throttle a few times. I had some minor popping in the carbs so I decided to increase the fuel pressure. The fuel pressure was set at 2.5psi and ended at 4psi. In the end, she idled in the garage for over 30-minutes without issue. The header had no signs of overheating and she sounded great.

It appears the main issue was running lean. I have no clue if the carb jets are correct but she is running now. I shut her down and she fired right up again without issue. I'm confident there is no issue with the internals or ignition. When I went to check the timing, it was no longer at 12'. I attempted to adjust to 12' and immediately noticed the header started to heat up again. I put it back and the car continued to run great. At this time, I'm going to leave it to a professional to complete the tune. I can't thank everyone enough for their continued guidance.

Thank you!

 

I hope you get it dialed in. It's a cool car.

 

Doesn't make any difference. The original spec on the mechanical fuel pump is 2-4 PSI @ about 30 GPH. The electric (not electronic) Edelbrock pump he's running is rated at 37 GPH max, & 4-7 PSI, but he's got a fuel pressure regulator on it to control the PSI.
If the electric pump was supplying more fuel than the stock mechanical pump, & absent the fuel pressure regulator, he would have been experiencing a rich condition, not a lean one.
Plus, the original SU carbs had smaller bores than the DCOE's he's running now, 38mm vs 40mm respectively. Bigger bores = more fuel.

 

Copied and pasted from above, like most of this users posts, not sure if we’re going for post count but it messes up the thread flow on quite a few threads and makes them make no sense….

 

sorry late in the game...
I build TRs for a living and have the W58 supra gearbox in my TR4. if you have a truck engine and steel case gearbox your gearing for the TR will be a bit low... is your gearbox case allum or steel? is car a 4A with IRS? if it is we need to talk... the frame will fail at the diff.
Good... keep going richer and check the plugs. check the valve clearances and double check the timing.
If you have any TR questions drop me an email; Id love to help. spitfire4@1147cc.com