TR6 TR6 Distributor cap issue

[ahfan]

'74 TR6 - 650 miles since complete rebuild. Ran greqt untill yesterday. All of a sudden lost power like running on 2 cylinders. After several minutes, ran normal then did it again later. Now, does it on start-up. New SU carbs are adjusted fine and getting gas, fuel lines clean and no vent issues. Took the distributor cap off and 4 of the 6 contacts are REALLY badly scored. The rotor tip was scored too. The shaft has no play in it and the cap fits tight with no movement. I dod not remember ever removing the cat after the rebuild but can't rule it out so I don't know if maybe it was not on right. So the question is, obviously it will affect the engine but would it cause the power issue described? I've ordered a new rotor and cap. By the way, it has Pertronix ignotion.

 

[Sarastro]

Sound like you might not have had the right cap, or the rotor wasn't pushed on all the way. So, those problems should be fixed. It's possible that they caused your power loss, but I think it's likely that something else is going on. While you wait for the parts, make sure that all the other wiring is clean and tight. Check the ignition wires with an ohmmeter; connect it and bend the cables a bit, near the connections. When I hear about sudden cutting out, I almost always expect it to be electrical.

 

[ahfan]

Thanks, it was rebuilt by a Triumph guy who works in nothing but these cars so I'm fairly confident that everything wise is good but I'll take your advice and check anyway. Not too sure how to check the wires as you suggested but I'll pay around with it. Thanks for the help.

 

[ahfan]

Thanks, it was rebuilt by a Triumph guy who works in nothing but these cars so I'm fairly confident that everything wise is good but I'll take your advice and check anyway. Not too sure how to check the wires as you suggested but I'll pay around with it. Thanks for the help.

darn typos but I'm sure you'll know what I said.

 

[Sarastro]

The scoring on the rotor and cap concerns me. The rotor should not touch the contacts in the cap, but have a small gap. If the rotor is not pushed all the way on, it can contact. Usually it collides with the contact, breaking both the cap and rotor, but it's at least theoretically possible for it just to scrape. It's important to make sure it is pushed on all the way.

Also, in any car, there are a number of rotors that are not exactly right, but close enough for you to think so. I have a 123Ignition distributor in my Porsche, and one of the suggested rotors, I found, does not fit. Others don't really work well--I think the rotor-to-cap gap is too great. And so on.

To clarify my earlier remark--I'm concerned that there may be an intermittent break in an ignition wire. One way to find those is to hook up an ohmmeter to a wire, and wiggle the connections to see if anything changes. Resistor wires come in various types, and some of those are notorious for having internal breaks.