Pacific coast Datsun Posted March 31, 2009 Report Share Posted March 31, 2009 Ok got a small issue possibly & have a few ?'s. I have flat top 38mm SU's on my 620...the engine has'nt been started since last oct [08]. Last week i went to fire it up so i primed the fuel pump [manual]...manually choked the carbs [pull cable] & after a few tries no luck. Removed the air cleaners, pushed up on the "needle" under each carb & shot a bit of starter fluid in each, fired right up but died after the fluid evaporated. Am i missing something / is there anything else i need to do on SU's that have sat un-used for awhile? BTW ive let it sit for weeks at a time before & after the 3rd try the motor would fire right up so now im a bit puzzled. Quote Link to comment
dat620 Posted March 31, 2009 Report Share Posted March 31, 2009 not that it may be connected, but in 76 i had a triumph spitfire car that had twin su's, and after sitting for a while, i would have to lube the sliders so to say, they have a seperate fill spot, i believe that they take brake fluid or the same as clutch cylinder fluid, just a thought, mine would be like half full after sitting for a few weeks, no leaks ever found, had it to the dealer several times, fluid just got used i guess, ck it out..:) tom Quote Link to comment
Skib Posted March 31, 2009 Report Share Posted March 31, 2009 check that the needle and floats are adjusted and that the needles dont have any old gas clogging them up. the knob on the top is a dip stick for the piston oil, Id check that to while your at it, they only take a tiny bit of oil and any extra will seep past the piston and burn off. Quote Link to comment
72dyme Posted March 31, 2009 Report Share Posted March 31, 2009 Just a general question, what type and how much oil do you use for the su's? Quote Link to comment
Skib Posted March 31, 2009 Report Share Posted March 31, 2009 Iv always just used motor oil, its usually less than the bottle cap full. when you pull the cap off theres a dipstick attached to it. Quote Link to comment
Wharf Rat Posted March 31, 2009 Report Share Posted March 31, 2009 Odd that she won't fire up, sounds like they are not getting fuel or the choke isn't working at all. The cable didn't happen to slide through the cable end? It maybe stuck float valves, but unlikely they both would do that at the same time. Hold the gas peddle down just a touch this will give you a little richer mix when cranking. Good luck :) As for the oil these carbs love Marvel Mystery Oil and if you overfill don't worry they seek there on level and the extra our old engines topends love it. And it smells nice too :) Quote Link to comment
Wharf Rat Posted March 31, 2009 Report Share Posted March 31, 2009 Just saw how long they sat for and maybe they do have stuck float valves give them a little tap with a plastic hammer were the fuel line connects this might knock some sense into them :D I also should have said when checking the oil level in these carbs the plunger or the thingie at the end of the rod is the damper valve like in a shock so after you unscrew it pull it out and then push it back in, if you feel resistance then it's ok if not fill with M+M. Like I said before it does no harm to overfill them anyway but you can tell if they were low this way. Quote Link to comment
Pacific coast Datsun Posted April 1, 2009 Author Report Share Posted April 1, 2009 TY guys for the advice. Will try all things mentioned & report back. Quote Link to comment
Pacific coast Datsun Posted March 31, 2010 Author Report Share Posted March 31, 2010 Guys i need your help again. Similar issue, truck has been sitting for many months without running... removed & hand primed the fuel pump & verified fuel getting to the carbs...... shot 2 quick squirts of starter fluid in each carb........ turn key but she wont even fire. Verified good battery [1200 cca i use for the HB hydraulics] removed, cleaned, checked gap on spark plugs. I know it's time to check spark but i need an extra set of hands & eyes. Could it be that the HEI module & or the coil went bad from sitting ? Quote Link to comment
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