TR6 TR6 distributor advance and retard hook up

[smaceng]

So I have this 1970 TR6 which I am raising from the dead. I've got it started and it runs (sort of) after setting the way off valve lash. Next I will do a tuneup and set the timing by light at 10 deg. B.T.D.C. What should I do about the distributor retard/advance lines? Nothing is hooked up now. It has the temperature vacuum advance valve on the upper radiator hose, but no vacuum ports on the carbs. It is my understanding that there should be ports on the carbs for the advance and retard distributor lines, but nothing on mine. Should I get rid of the temperature vacuum valve? Is there a way to use either the brake servo vacuum line, or the crankcase ventilation line for the distributor advance? Any help would be appreciated. BTW, no tags on the carbs for identification.
Scott in CA

 

[trrdster2000]

Doesn't sound like you have the parts for the hookup. There would be a couple of small vacuum control valves under the carbs, right below the choke stops that kept the idle from coming down too fast. Just get that junk off the car, if California will let you. The trick if to use just the advance side and disconnect the rear portion, with the hose coming off the bottom of one of the carbs. I replace mine with a old vacuum advance unit, which worked really well.

Wayne

 

[smaceng]

Having read up on this it seems like I need to have my front carb drilled for port vacuum. How is this done? Is this done by sending it out? To whom? Then I should just connect the front (advance) valve on the distributor to this new ported vacuum port.
I should eliminate the temperature vacuum valve on the top radiator hose, and just don't have anything connected to the retard distributor valve. I can also set the timing by having 32 degrees of maximum advance at 3K rpm.
Is that about right? Do I need to change to another advance distributor valve? In CA there are no smog tests for cars 1975 and older. 1976 TRs have to be smogged.
Thx, Scott in CA

 

[poolboy]

Carbs for a 70 model TR6 would have a 1/4" nipple on the bottom of the rear carb for the distributor's Vacuum Retard. That module is mounted on the cockpit side of the dizzy.
The vacuum source for the distributor's Vacuum Advance would have been a 1/4" nipple on the top of the front carb. That module is mounted on the radiator side of the distributor.
But it wasn't until 72 that there was a Thermostatic Vacuum Switch in the top radiator hose. When it sensed the coolant temp reach about 200*F it blocked the vacuum to the distributor's retard module. At idle it's effect would have been noticed by an increase in the rpms by about 200.
You can not use vacuum directly from the manifold for a Vacuum Advance. In fact the only place you can source the vacuum for Vacuum Advance is in a very specific location in the carb's throat relative to the carb's throttle disc position.
If it's not already there, someone who knows what they are doing should be able to get it placed right.

:wink-new: Looks like I was typing while you were doing your reading up on the situation...

 

[trrdster2000]

Scott, what Poolboy said is right, I just didn't remember the whole story. I think you have had a engine transplant, the finger thermo thingy was on the later cars and it sounds like your carbs are that year. Just tends to make things difficult.

Wayne

 

[TR3driver]

Having read up on this it seems like I need to have my front carb drilled for port vacuum. How is this done? Is this done by sending it out? To whom?

Good question! You might ask Joe Curto if he can do it, or it might be simpler to just source the right carb for your engine. They show up on eBay from time to time (for wildly varying prices).

Somewhere I've got some photos showing where the port goes, but it's going to be a really tricky setup. The critical point is where the port opens into the carb throat, it needs to be positioned so that when the throttle plate is at idle position the port is on the intake side of the plate; but at cruise throttle the port is on the manifold side of the plate. Looks like a job for a vertical mill with an adjustable angle plate, and even then I'll probably mess up the first one.

Another possibility, depending on how adventuresome you are, would be to setup a small mechanical vacuum valve so that it would only pass vacuum with the throttle not closed. Similar (but opposite) to the retard setup used on TR250 & 69 TR6. Then you could use manifold vacuum for the advance.

Yet another option is to just leave it disconnected. The advance was eliminated in 72 anyway. The presence of the TVS and absence of the advance port makes me think that at least part of your car is not from 1970. Maybe an engine swap (plus the TVS), or maybe something happened with the paperwork. Not having the advance will lose 1 or 2 mpg, but not really affect anything else. It doesn't work at full throttle anyway, so no effect on max power.

 

[smaceng]

Thanks all for the help!
I like Randall's idea about not doing anything.....not only can I move this task to the back burner....we can move it into the back yard where maybe it will get forgotten! Just to give you an idea about the fact that I have bigger fish to fry, take a careful look at the picture of the trailing arm and rear suspension. See anything unusual? I was so stunned that I had to take the opposite side wheel off and compare sides to make sure this TR wasn't from another planet!



The next picture is what I took, no took is the wrong word, sawzaled out! About 4" in diameter and 4" long. The whole car is like this! If you tell me this is a TR part, I'm in big trouble!
Scott in CA