View Full Version : help with ATC 70 PLEASE
elcamino12sec
03-04-2008, 09:01 PM
Hello all, new to the forum and my first post. I have an 1985 atc 70 I bought to fix up. It sat for 8 years in a basement before I bought it and know nothing of its history. After cleaning the carb and three pulls it started right up with no smoke. After I found the motor does not smoke I figured its worth putting money into. I bought a carb kit with new jets, needle, slide, float, seat, bowl and pretty much everything except the carb body is new. I also replaced the points and condenser and have it properly set at .012. At the moment the motor starts and idles great, I could not be happier. However once there is a load and in the high rpm's the motor will cut out and die. It sounds like its not getting fuel, so I sprayed starting fluid in the carb when it starts cutting out and it did nothing, so I ruled out the possibility of it being fuel related. I checked the points again and they were spot on. However, since I have adjusted the points so many times I have found that the wider the gap is with the points better it runs, but never can get it to rev full rpm at WOT with out it dieing. I checked the coil with a mulitmeter and it checked out ok. The exhaust is not clogged and the airfilter is new. The valve clearance it correct and I dont know what else to do. This thing is killing me, Im about to give up. Please give me some advice before I take a sledge hammer to it!!!!!!
TravEX
03-04-2008, 09:26 PM
When it cut out like that, reach down and put the choke 'on' (lever up is 'on', down is 'off'). make sure the air filter is good and clean too. If running the choke on helps, you need to up the main a size or so. Any air leaks around the rubber boot between the carb and airbox? Check for other leaks too, just spray carb cleaner around the carb and boots when it's idling. Good luck! Any pics of the ride?
And, WELCOME!!!!!!!!!!!!!
TravEX
03-04-2008, 09:31 PM
O, and sometimes the carb kits may have a different brand of jets that could be slightly different in size than the stock one.
One of my 70's does that after I put a clamp on (open) air filter. I went up a jet size when I did it, just not big enough. I gotta re-jet it.
elcamino12sec
03-04-2008, 10:16 PM
It looks pretty bare sice Im still working on it at the moment. i will post some pics when the project is done though.
TravEX
03-04-2008, 10:24 PM
You gotta drag El Camino? My uncle used to have a 87 camino drag car, completely streetable, all metal, all throttle, ran 12.30's. Good sleeper car except for the wrinkled ET streets out back.
FPMXer
03-04-2008, 10:35 PM
Did you change the plug? What does it look like? Compression test? What is the PSI reading? Does the carb's petcock have the diaphram and was it changed? My cousins long ago had a 70 and it had the same symptoms until we changed the diaphram.
elcamino12sec
03-05-2008, 12:30 AM
Mine is a 78, first year of the last body style, same et streets too. I have built everything including the trasmission, its killing me that I cant figure out what is wrong with this atc. Its a lawn mower with three wheels for gods sake!
sandpuppi101
03-05-2008, 07:27 AM
I would take another look at your point's.Your .012 is the minimum gap on your point's,I usually go .016 which is top of spec,and which allow's for wear.When they get to .012 you can see they are wore on an angle,and that's when I pitch the point's.I know you said you installed new point's ,just set them fatt.I have worked on many ,many 70's where I was for sure it was a carb issue an it was almost alway's ,Point's..
dizasterzrfun69
03-05-2008, 08:18 AM
After cleaning the carb and three pulls it started right up with no smoke. After I found the motor does not smoke I figured its worth putting money into. I bought a carb kit with new jets, needle, slide, float, seat, bowl and pretty much everything except the carb body is new.
"if it aint broke dont fix it"
Hair Bear Bunch
03-05-2008, 02:50 PM
Is the condenser ok?
elcamino12sec
03-05-2008, 07:21 PM
conderser is new, along with the points, spark plug and everything in the carb.
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