TR2/3/3A The Newest Bug to Fix...Now with Video!

[pdplot]

Question - are you running Pertronix or stock ignition? I had a similar problem years ago with Crane ignition. It would suddenly run poorly on a hot day and I could barely make it home. Cooled off, it ran fine again. I sent it to Crane in Jacksonville, they tested it, said it was perfect and sent it back to me. I reinstalled and the same thing happened - but only when it got hot. I swapped it out for the old points & condenser and never had that trouble again. If you haven't done so, reinstall the stock points and see what happens. If that doesn't cure the problem - i'm tapped out.

 

[M_Pied_Lourd]

Yeah,I thought the pertronix might be acting up so I pulled it out and put my points dizzy back in...no change.

Cheers
Tush

 

[pdplot]

Give it an Italian tuneup. Take it out on the highway, up to the redline in every gear, bring it back in after at least 5 mile run and see what happens. You might have a sticking valve or who knows what. Woreds for me when I'd get a plug or two fouling.

 

[TexasKnucklehead]

Very interesting.... but puzzling.

I think you have proven your issue is temperature related. My guess is the fuel is getting too warm because as soon as the warmer air gets to the carbs, the issue starts.

If you look at my attached picture you may notice a few things different. (1) My fuel line does not run the same as yours. The bowl cap on the front carb is rotated such that the fuel line enters from the front, with the only bends in the fuel line being under the radiator neck, and the other side of the rubber mount. That means it comes thru that rubber lined mounting block straight across the front of the engine, until it has to bend for the in-line fuel filter. It might not seem like much, but when idling, not much fuel is being used, so the longer it sits above or next to a heat source, the hotter it will be. Your fuel line must be directly above the header. I'm not sure who has deviated from the stock configuration. -Actually I know I have, because of those H6Ss instead of the HS6s. (2) I have a home-made heat shield under my H6S's. My thought was that I was trying to save the plastic jet from the heat, but also think the purpose of a heat shield is to divert heat away from the bowls. My shield is not insulated, but I drove in temperatures over 100F and have never had the issue you are seeing. I have only a single insulator block, the shield bolts to the same holes as the air filters -it can be a pain but provided a great place to add in cruise control linkage.

Anyway, these differences may or may not have anything to do with your issue, but I thought I'd point it out. I'm eager to know what you find.
Jer

 

[M_Pied_Lourd]

Thanks Jer,

Something to consider to be sure. I like your intake manifold better as that cross branch sits higher. My intake almost touches the header wrap there.

Took some temperatures tonight...posting video in a few minutes.

Cheers
Tush

 

[M_Pied_Lourd]

Ok...some temperature checks....

https://youtu.be/kvT_rkjZXBk

Cheers
Tush

 

[mgedit]

Watching your video suggested something. What cam are you running? The info that came with my car gave valve clearances different from stock. Not sure if that might account for behaviour you are getting, but one more possible variable ... as if you wanted another. Cheers, Mike

 

[M_Pied_Lourd]

Hi Mike,

According to the PO, it is still running the stock cam so I set the intake/exhaust to .010 as per the manual.

Cheers
Tush

 

[TexasKnucklehead]

Something doesn't add up properly. Correct me if I'm wrong, but in the first 'in-garage heated test run' video, you show the dash temperature gauge rising up until the electric fan turned on, and then the dash temperature gauge showing the temperature decreasing as the fan cooled it back down to normal. But in your latest video with a 'data sheet' showing various temperatures at 185 and 195 (determined by fan-off and fan-on) you show the head temperature constant at 185/185. The temperature probe for the dash gauge is on the engine side of the thermostat and should be showing the temperature of the head. Why would the dash gauge show values above the thermostat value (and in-line with the probe for control of the radiator fan) ? And also, why does the charted head temperature measurements not follow the dash gauge measurements ?


Perhaps the fan should turn on much sooner and keep the temperature of fluid entering the head lower than the thermostat setting.

 

[M_Pied_Lourd]

I took temperatures on top of the thermostat housing not at the side where the probe goes in for the guage. Having said that, I have always suspected that the thermostat guage reads off a little bit, possibly 10 degrees . The fan is supposed to come on at 185... I suspect that my guage shows 195 when that happens. The thermostat I have installed is a 165 f and I try to guage when this opens by holding the rad hose below the bypass hose.
Regardless of this, I have tried running the fan on over ride right from start up and it makes no difference. Still does the same thing. I was hoping to eliminate the fan shocking the carbs or fuel lines etc with that first blast of warm air when it is on auto mode.
Cheers
Tush

 

[TexasKnucklehead]

165? That seems a bit low, even for Canada.

I have a 180 in mine (in Texas). (I verified it started to open at 180 in a pan of heated water with an oven temperature probe and it fully opened by 190.) My electric fan is preset to come on at 185 and off at 165. The probe is installed into the highest fin possible on the left side of the radiator (my thinking it would be the hottest spot). The temperature of my radiator is not setting the running temperature of the engine -but I believe yours is. Once your thermostat opens, the temperature is regulated by your fan. I don't think that's a good idea.

When I first got on the road, my gauge was reading about 10 degrees high. After I was sure the thermostat opened at the proper place, and after adding a voltage regulator, I calibrated my gauge -but I have the early TR4 electric meter, not the stock capillary tube. Still, for the first few hundred miles, I tried to drive on cooler days, and the gauge often showed much hotter than I wanted to see -never pegged, but it got up there.


Having said all that, it's a slow, cool, rainy day here in Houston. I just came back from the garage after running a similar test as you. I turned on the floor fan out of habit. Since it's only 81F, I pulled the choke and started a timer at 4:04pm as I watched the temperature meter(s) and let her idle at 900RPMs. I have a probe on a meter touching the front carb bowl (started at 28C (or 82F)). After 3 minutes, I pushed the choke in to high idle with the dash temp gauge showing under 110F. At 4:08, I pushed the choke all the way in as the dash gauge moved towards 110F (the first mark) -the carb reading 34C (93F). I have a small hole in the thermostat which may make seeing the actual dip of the thermostat opening harder to see. Anyway, I was fiddling with my phone camera when the electric fan came on the first time at 4:22 and turned off before I could switch modes on my phone to the stop watch. The fan turned on again at 4:24 with my stop watch showing 19:10 (min:sec since start up) and off again at 19:20 with the dash showing temp of 185F and the carb bowl at 47C (117F). So, it took almost 20 minutes to turn on the fans (185), but only 10 seconds to turn them off (165) but my dash gauge never went past the "mid range" of 185.


I'm not sure if any of this helps, but it is information. I have 20,000 miles on my engine, so I think it's broke in, and I'm pretty sure it's timed well too. But I also still have the original style radiator with a crank hole in the center. In the 30 minutes it took me to write this report, the car cooled down to 100F (dash gauge and fuel bowl) with just the box fan blowing in the garage, and restarting was a snap.

 

[M_Pied_Lourd]

Excellent! Thanks for doing that. You mentioned you turned on the floor fan. Is that by chance aiming at the grill and into the rad?

20 minutes before the fan turns on I would say is excellent....and turning it off almost instantaneously is a dream.

Having said that, your carb bowl temps are not far off from mine either. Curious.

I'm just about to go out and do a power hour. I'll report back later.

Cheers
Tush

 

[TexasKnucklehead]

My garage has a pair of doors for the cars to enter on the front, and a small regular entry (32") door on the rear. The floor fan sits in front of the rear open door, blowing outside air into/through the garage -somewhat pointed at the grill of the TR3, because that's where I am. But SWMBO's car is blocking most of the air, and her car was home today.

I wish I'd have noticed your 20 degree difference when hot between the front and rear carb bowls -I'd have measured the rear carb bowl too. Sorry, maybe tomorrow... I don't have one of those IR guns, but I could probably get one if you'd like more measurements. My meter probe must actually contact the surface to get a reading. It's not annoying enough that it only reads in Celsius. 117 is close to 120, but far from 140.

How do you know your fuel mixture and timing are correct?

 

[M_Pied_Lourd]

Thanks,

Timing I have set to 8 degrees btdc. Done with a timing light with a variable advance dial. Mixture was checked doing the air valve lift test according to the book. I've pretty much done everything in between just to test...from lean to fat and back again...can't really get a good read on the plugs based on its running condition...needs a good run to be able to do that...

Took the SU's off tonight. Going back to the webers and see how we do. I think they are a little more tolerant of heat,air for the following reasons;

The have a split manifold (1 per each carb) and don't have that center branch that is sitting over that 500 F header...
I think they sit at a little higher angle than the SU's and therefore are farther away on the bottom from the header.
They sit a little farther out than the SUs and the velocity stacks I think will be a little further out from the electric fan air flow.

But, they have their own running issue...major flat spot on acceleration....but, that might have been attributed to a weak fuel pump.

We shall see!

Thanks for taking the time to research and respond. I appreciate it.

Cheers
Tush

 

[TexasKnucklehead]

8 sounds a little low. The TR manual distributor mechanical advance timing chart shows about 6 cam degrees at cam speed of 500, which equates to 12 crank degrees at 1,000 rpm. So adding the static 4 yields 16 degrees. I painted a colored dot on my crank pulley at 4 and 16 because I found the timing light advance mechanism was off significantly. So I'm positive my idle timing is set to 16. I also marked different colored spots at 24, 26 and 28 degrees to verify the advance at differing RPMs.

I use a color tune on #1 and #4 plugs to see the sweet spot. I had no luck with that piston drop test. I'm sure it works for those that use it, but it confused me. With the color tune, it is very obvious the mixture is within a flat of optimal (at idle). I'm told webers are much more difficult to set up properly.

Good luck, let us know what you find.

 

[karls59tr]

Just as an aside. I have a 4" hole cut into the radiator shroud and a duct that runs up to the carbs for better cooling there. I have also wrapped the fuel hose to the carbs with header wrap.

 

[M_Pied_Lourd]

Thanks Karl.

I was following a thread on one of the other forums where a couple of guys did the ducting as well.

Cheers
Tush

 

[M_Pied_Lourd]

Ok...

New update. https://youtu.be/QgQWncy1kMM

Jer, also put the Pertronix dizzy back in and am now at 16 degrees btdc at 900 rpm idle...

Cheers
Tush

 

[mgedit]

Looks look. Hope that solves the issue. Cheers, Mike

 

[poolboy]