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TR6 hard starting

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pdplot

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How long should it take to start a cold engine? Mine cranks for at least 30 seconds before it fires. Worse in cold weather, especially with 20W-50 oil and an aging battery. Once it's run, it starts instantly. These Stromberg/SU carbs don't have an accelerator pump which might speed the process. Would a replacement hi-speed starter help?
 
Sure sounds like something is wrong. Have you checked that the choke is moving fully on both carbs? Are the float bowls going dry? Ignition in top condition? If you have a later TR6 (sorry, I forget), does the ballast bypass circuit work? How's the compression and valve lash?

A gear drive starter might help; but IMO it's better to fix the underlying problem. It should start easier than that with the stock starter, etc. This time of year in CT, you might consider dropping back to 10W40 oil.
 
1971 TR6. No ballast bypass. Choke is fine, in fact pushing in to the 1/2 position, the idle speed remains the same. I think car actually runs a shade rich but without an exhaust analyzer, it's hard to tell by looking. In summer,it will idle (almost) normally a few seconds after pushing in the choke. Float bowls? How can I check? Stock ignition seems fine. Is it possible to check the intensity of the spark(if that makes any difference). I could change the oil but it won't make a great deal of difference except in the first few seconds since in past years, I was running 10W-40 with no discernible difference. The only car that started worse was my son's Fiat Spider. You had to crank for about 60 seconds.
 
Check the pressure on the fuel lines before the cold start. Your pump one way valve may be letting the pressure off and you have to get it back up to speed before it will start.

Wayne
 
You might check the volume of fuel the pump is pushing by disconnecting the fuel line at one of the carbs.

I agree with Randall, find the cause. Especially since the starter life span in those days was considered to be about 8 hours accumulated during all the starts.
 
I have the same type problem with my tr3A, only worse. In cool weather I must use starting fluid for the 1st start.
after she's warm, she starts right up, & runs great.
funny thing is she got harder to start after I had a professional tune up, with some expensive ndk platinum plugs etc.

switching back to champion L87y to see if that helps.
Guy
 
I'll check the fuel line at the carbs for strong flow - something like my prostate used to be - but no more.
 
Apologies if this is known and practiced, but when using the 'choke', don't put your foot on the accelerator pedal when engaging the starter...if you have ZS or SU carbs that is.
 
Thanks for the no gas pedal/choke tip.
I've been pumping away. Might have caused my own problem.
 
Marvin Gruber said:
Sounds like fuel leaking down, once the bowls are full, engine will crank.

marv
Click to expand...
I agree with Marv, the mechanical pump does have a disadvantage over the electric SU that fills the carbs before you turn the car over, mine exhibits this behavior a little bit too, but not too bad, if you have an original pump with a hand primer try pumping it up before you start from cold next time and see what happens, if it starts right up you have identified the problem and can start working on the solution.
 
When starting, I never pump the gas pedal or floor it nor do I push in the clutch because of wear on the thrust washers. This does add a little more drag on the starter. I've tried mechanical priming the fuel pump too but it didn't seem to work. Maybe I quit pumping too soon. I've thought about adding a Facet or SU pump but I wonder if that would cure the problem if the mechanical pump stays in place. One thing I forgot to add. It doesn't start all at once but begins to catch and stumble before finally kicking in. Hot starting is no problem.
 
pdplt, Sounds more and more like a fuel starvation issue. Does it fire right up if you spray starting fluid in the air filter. Not run, just catch until the fluid run out.

Wayne
 
How about the contact between the fast idle cam and the head of the throttle stop's adjustment screw ?

The 'heel' of the fast idle cam should just touch the adjustment screw with the engine still at idle speed.
From that point on pulling the choke knob further will both increase the fuel and open the throttle disk the appropriate amount thereby increasing the idle speed
You should end up with 11-1200 rpms when the dash knob is fully extended.

Also make sure the fast Idle cam maintains contact with the head of the adjustment screw as the choke is increased.
I've seen a few fast idle cams that have gotten bent..As the choke is pulled, the cam looses contact with the throttle stop and the throttle disc closes back up to the regular idle position.
 
Great suggestions. I'll buy some starting fluid and give it a shot. And - I'll check out the fast idle cam. I think I adjusted it a few years ago - who remembers?
 
Ok. Just came in from the cold garage. Starting fluid (about 3 years old but never used) brought an instant start. Idle cam on rear carb just touching screw. Idle cam on front carb almost 1/4 inch away from screw but seems to be ok when choke is pulled out. The front cam was slightly off center so I bent it back with a large screwdriver so that it now hits the screw in the center. When choke knob is halfway out, idle speed is 2400 rpm. Normal idle only returns when knob is pushed all the way in. BTW, both adjustment screws are all the way out to the end. No way to back out the front screw any further if in fact it should also touch the cam.
 
I may not have made myself as clear as I could have. In the normal idle position with no choke, the fast idle cam does not touch the head of the screw and in fact may be 1/4 inch away.
It is only after it contacts the head of the screw as shown in the picture, does the throttle disc begin to open as you continue to pull the choke knob on the dash.
You may have read this before because I find myself writing it pretty often, but no amount of carb adjustments will compensate for components that need replacing.
And from that description, something is wrong with at least one of your carbs that has required you to exhaust the adjustability of the chokes.
 
I set the fast idle speed according to the manual using a 5/16 drill bit. Both cams are about a 1/4" away from their stops with choke pushed in. Fast idle speed is now about 1400 rpm which is fine by me. Will it start better? I'll know tomorrow morning after a cold night in the garage. I don't think my fiddling will make any difference. Am I correct in saying that these carbs do not have a real choke as we know it from conventional carbs but pulling out the "mixture control knob" simply increases the idle speed so the cold engine won't stall. IMO, these variable choke carbs are simple and when properly set up and not messed around with too often, they work very well.
 
There are 6 or 7 adjustments depending upon the version and if properly made the carb does work well, but there are parts, particularly the 'rubbery' ones that dry out and wear out.
As far as the choke and how it functions, basically as you pull the choke cable a hollow disc that is filled with gasoline from the float chamber rotates.

The short tube supplies gas to the hollow disc

The gas enters the hollow disc thru the opening in the body of the carb at 5 o'clock and exits the hollow disc and into the throat of the carb thru the slotted hole in the body of the carb at 10 o'clock.

Look back at the picture of the hollow disc and you'll see 4 tiny holes of different sizes. Gas enters the hollow disc thru it's slotted hole.
As the disc is rotated via the choke cable, one by one, those tiny holes are exposed to the slotted hole in the carb allowing more fuel to exit the hollow disc thru those tiny holes
As I described earlier pulling the choke cable also brings the fast idle cam into contact with the throttle stop lever and thereby opens the throttle (at full choke) to 11 -1300 rpms when adjusted properly.

..............
This picture shows the hollow disc on the right, it's shaft where the fast idle cam resides with the choke cable attached and it also shows compression spring around the shaft that keeps the hollow disc in firm contact with the carb.
The starter box (housing) is shown on the left.
 
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