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Re: misfire under load

To: "'Datsun-Roadsters@Autox. Team. Net'"
Subject: Re: misfire under load
From: racery@comcast.net
Date: Mon, 28 Mar 2005 20:18:05 +0000
Have you pulled the float bowl covers?

That sounds similar to 2 problems I've had in past, both fuel- delivery related.

One is junk in the fuel system- varnish in my case- that would plug the jets 
when the needles lifted.  It was pretty erratic- sometimes it would hardly get 
off idle, others it'd pull pretty well for a while

The other is fuel supply.  And it's 68 specific.  If you remove the 
thermostatic valve on the back carb, under the right conditions the fuel return 
can set up a siphon in the line (usually under 1/2 a tank)  The carbs then run 
dry, and everything the pump sends up the return line sucks right back.  I put 
a 1/16" restrictor in the reurn line to solve it.

Also happened when junk in the line would plug the fuel pump valves, now that I 
think about it.

But to figure out if it IS fuel related, run it up until it starts misbehaving, 
shut it off quickly,  and pull the float bowl covers.  Odds are, one will be 
dry.

If not,  off you go to electrical troubleshooting!

hth,
Toby


>  Hi All,
> 
> Been working on the white 68 (stock) R16 over the last few days and once
> again stuck.
> Car idles great, carbs sync'd up very nice and air fuel is also good.
> 
> Problem:
> 
> Pulls out of the garage and rev's up to about 3500 rpm's
> after shifting into 2nd rev's up to 3k and then starts to run on 2
> cylinders. Some times I can nurse it threw but sometimes not
> Advance is hooked up and is timed to 16 deg TDC
> 
> TIA for any help!! Be nice to drive the car!!
> Matt






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