misfire

[69tr]

I got the wiring back together and took the TR out for a ride. I had replaced the speedometer cable & wanted check it out. (any excuse for a ride) The car runs pretty well but it misses occasionaly at highway speeds. It seems like a random event but happens often enough to keep my attention. I still don't have the timing set by the book. Right now it is at 12 degrees BTDC. Maybe I just need to play around with the timing to see if things improve? I have not done anything to the carberators yet. Any suggestions?

 

[vettedog72]

You might want to try setting the timing back and see if it makes a difference. The motor will idle slower when the timing is retarded so you may need to set the idle up.

 

[Guest]

[ QUOTE ]
I have not done anything to the carberators yet. Any suggestions?

[/ QUOTE ]

If you are running at 12 degrees, you might want to back down to around 8 BTDC. That said, you are running centrifugal advance and not vacuum advance, make sure all your vacuum ports on the carbs are blocked off. Speaking of carbs, when you say you have done nothing...not even checked the oil? Might want to top off each pot with some 20wt oil.
Have you considered changing the fuel filter? Is everything on this car original? Time to start looking at things like fuel lines, both steel and rubber joints. Wouldn't hurt to clean/replace these things in a 37-year-old car. And on, and on, and on....


Bill


(wait a sec. you haven't got rid of that electronic ignition yet???)

 

[Banjo]

Could be the coil starting to break down under a full load. Or if you were running points I would suggest the condenser or point gap. It could be a bad distributor cap or wire (plug or coil) or quite possible the carbs being on the verge of being starved for fuel when there is a large demand. Check the filter, float settings, and pump output.

 

[69tr]

I did check the oil in the carbs. They were low & I filled them. I have since advanced the timing a little more & the car runs better. When I retarded the timing the car did not have any power & tried to backfire. The carbs were supposedly rebuilt by the previous owner. I guess I am hard headed (they say that about us hillbillies), but I still think the problem is in the timing. I picked up a vacum gauge today & checked the vacum on the vacum advance. There was no vacum at all, even when I reved the engine. I had vacum to the brake booster, but none from the vacum port on the carb. I appreciate all the input. I plan to go through the complete tune up procedure soon. I will be out of town for a few days so I won't get to tinker with it for a while.


Yeah, I still have the electronic ignition. Refer to "hard headed" above

Thanks, Pete

 

[Guest]

Pretty hard to have no vacuum on your carb unless the DPO made his own gaskets and blocked off a vacuum channel internally or something. I have even seem where some have jambed something to the vacuum port on the carb instead of just sticking a rubber nibble over it. You can't stick your finger over the vacuum hole on one carb and remove/replace the finger with the engine running and feel the engine stumble? You are setting the timing with a strobe with the engine running, right? What's your points set a......oh, geez, I forgot. I always look at the usual suspects -- plug colour, gap, timing, compression, coil, wires, etc. Basic tuneup stuff. Usually something simple.


Bill

 

[Banjo]

there are two holes on the underside of the carbs. one is a vacuume port, and one is a blanked hole. I bet the DPO threaded the vacuume nipple into the wrong one. Or the right one is plugged up. that can happen too.
Your vacuume drops to almost nothing during acceleration, that's normal, but at idle and de-cel you should have a pretty good reading.

 

[69tr]

I had some time today, so I checked the vacum port on the other carb. That port did have vacum when I reved the engine. I plugged the first port and hooked the vacum line to the second port. I did not get to check the timing, but when I drove the car I did not notice the misfire.
When I get back home I am going to set the timing again by the specs to see how it does. I probably need to check and lube the distributer before I go much further.