Post by dando127 on Nov 12, 2021 6:22:17 GMT
70Oly399
at the last race my 335 ran pretty good through the first heat, a little boggy out of the corners. In the final it made 2 laps and started to pop and lose power. I could back th low jet out and it would get better but finally died. at the end of the race I backed the low jet out about 6 turns and it started and I rode it to the pits. I figured the low jet was plugged so I took it all apart and cleaned everything. Put it back together and it started on the second pull. I let it set a couple days and it started on the second pull so I could do some hot laps in my field. I took it out and it went great no bog at all was pulling hard. After 5 or 6 laps it started to pop and died again and I couldn't get it to hit at all. Its got good spark, an inline and spin on filter and a clean plastic tank. what am I missing?
wdchuck
Ooooh, Oooooh, pick me! Pick me!......Really though that's a tough one, but here's a shot in the dark- Had a similar experience with my 292- mine turned out to be dangling wires. Just a shot in the dark. Give me a call- we have no more excuses not to race, (I think) and my dad will be coming with a sled too.
Hermit
Make sure your fuel lines have the insulator beneath the muffler and engine. The dreaded heat can cause trouble, but watch the lines very closely when this is happening. If the inlet line has any intermittent bubbles you need to check the flow. Also if there are excessive bubble sin the return line it indicates insufficient inlet levels of fuel. When you start it cold just sit and run the throttle a little and observe the fuel pattern, so when it acts up you'll have a comparison. If all these items check out you could have bad seal sucking air, or how are the rings etc, compression?
70Oly399
I'll take a closer look at the fuel patterns. Th lines do have the insulator under the muffler and engine. I'm afraid it could be just a tired engine. Its never been apart that I know of and I was hoping to make it through this year and do a rebuild this summer. Chuck I'll give ya a call this week.
70Oly399
well I checked some things out tonight. It started on the second pull like always. There were tons of bubbles in the supply line and the return line looked like foam. Its a 70 and when I switched it to the elan tank I used the plastic tank fitting. The lines in the tank fit real loose onto the nipples, so I'm gonna go with a steel fitting and new lines in the tank. Also the white insulator tubing on the lines is black and melted under the muffler, so I guess I'm gonna re-route the lines. It was late so I didn't run it enough to make it quit, just on the stand in the garage. I'll run it around outside tonight and let you know if that fixed it.
Yukon Jack
Getting rid of the air in the inlet line should solve the problem. If it's sucking air and running lean, it'll be overheating. The coil on my '68 shuts down when too hot (backfires, quits, and won't start again until cool)
Vintage Elan Guy
The dreaded vapor lock strikes again.
You are probably experiencing vapor lock. When the heat of the engine gets to the fuel lines and the body of the carb, the gas begins to turn to a vapor and then you are done until it cools enough to turn back to liquid again.
One of the biggest problems ever with Tillotson carbs.
Next time, try laying some snow on the carb body and see if that cures it,
Yukon Jack
Ah yes, I re-read the original post and see that you said there was still spark after it quit. I agree -sounds like vapour lock.
(Mine won't spark when hot)
70Oly399
I think I got it worked out now. pre-laced the pickup line inside the tank and the bubbles went away. Also routed the lines away from the muffler, down on the running board then up under the recoil to the carb. Racing tomorrow will let everyone know how she does.
at the last race my 335 ran pretty good through the first heat, a little boggy out of the corners. In the final it made 2 laps and started to pop and lose power. I could back th low jet out and it would get better but finally died. at the end of the race I backed the low jet out about 6 turns and it started and I rode it to the pits. I figured the low jet was plugged so I took it all apart and cleaned everything. Put it back together and it started on the second pull. I let it set a couple days and it started on the second pull so I could do some hot laps in my field. I took it out and it went great no bog at all was pulling hard. After 5 or 6 laps it started to pop and died again and I couldn't get it to hit at all. Its got good spark, an inline and spin on filter and a clean plastic tank. what am I missing?
wdchuck
Ooooh, Oooooh, pick me! Pick me!......Really though that's a tough one, but here's a shot in the dark- Had a similar experience with my 292- mine turned out to be dangling wires. Just a shot in the dark. Give me a call- we have no more excuses not to race, (I think) and my dad will be coming with a sled too.
Hermit
Make sure your fuel lines have the insulator beneath the muffler and engine. The dreaded heat can cause trouble, but watch the lines very closely when this is happening. If the inlet line has any intermittent bubbles you need to check the flow. Also if there are excessive bubble sin the return line it indicates insufficient inlet levels of fuel. When you start it cold just sit and run the throttle a little and observe the fuel pattern, so when it acts up you'll have a comparison. If all these items check out you could have bad seal sucking air, or how are the rings etc, compression?
70Oly399
I'll take a closer look at the fuel patterns. Th lines do have the insulator under the muffler and engine. I'm afraid it could be just a tired engine. Its never been apart that I know of and I was hoping to make it through this year and do a rebuild this summer. Chuck I'll give ya a call this week.
70Oly399
well I checked some things out tonight. It started on the second pull like always. There were tons of bubbles in the supply line and the return line looked like foam. Its a 70 and when I switched it to the elan tank I used the plastic tank fitting. The lines in the tank fit real loose onto the nipples, so I'm gonna go with a steel fitting and new lines in the tank. Also the white insulator tubing on the lines is black and melted under the muffler, so I guess I'm gonna re-route the lines. It was late so I didn't run it enough to make it quit, just on the stand in the garage. I'll run it around outside tonight and let you know if that fixed it.
Yukon Jack
Getting rid of the air in the inlet line should solve the problem. If it's sucking air and running lean, it'll be overheating. The coil on my '68 shuts down when too hot (backfires, quits, and won't start again until cool)
Vintage Elan Guy
The dreaded vapor lock strikes again.
You are probably experiencing vapor lock. When the heat of the engine gets to the fuel lines and the body of the carb, the gas begins to turn to a vapor and then you are done until it cools enough to turn back to liquid again.
One of the biggest problems ever with Tillotson carbs.
Next time, try laying some snow on the carb body and see if that cures it,
Yukon Jack
Ah yes, I re-read the original post and see that you said there was still spark after it quit. I agree -sounds like vapour lock.
(Mine won't spark when hot)
70Oly399
I think I got it worked out now. pre-laced the pickup line inside the tank and the bubbles went away. Also routed the lines away from the muffler, down on the running board then up under the recoil to the carb. Racing tomorrow will let everyone know how she does.
