L18 Performance Woes

[ServeEm]

As stated in my previous post I recently purchased my first dime. She's a '71 510 with an L18, weber 32/36. When I picked her up for the first week she ran strong w/o any hesitation. This performace deteorated shortly after that.

 

She would start to hesitate and backfire through the carb. The issues would be intermit. and would mostly occur while she was cold. Since then I replaced the cap, rotor, wires, plugs and condenser. After replacements she ran great again, so I warm her up in the driveway and go for a ride. Right through the 1st intersection she starts hesitating again and backfires through the tailpipe and wants to die. I feather the gas to get to a parking lot and she dies.

 

From here she will not hold an idle with the choke open. But with the choke closed she idles at a really high rpm, (maybe 4500-5000rpm). While running at this high speed, there isn't any uneven idling, backfiring or knocking. I checked my point gap when I got home with it being fine. She still remains in the same condition, will not hold an idle unless choke is closed and she idles at high rpms. I tried to adjust the mixture with no change in idle. I'm not well versed in carbs, I understand mixture adjustments but nothing more. I looked into the carb and the accl pump works squirting an even amount. The choke and throttle linkages are complete and operate fine. I am at a loss and would greatly appreciate any guidance.

[]2eDeYe]

Check for vaccum leaks...Your intake may have come loose.

[Bleach]

intake manifold at the head or the carb attachment to the base plate... or possibly the base plate to the manifold. You'll need to remove the carb to check the base plate to manifold bolts.

[Pacific coast Datsun]

Timing may be off...float level in the carb. may be off...dist. shaft may be moving [back & forth] causing the spark to be intermittent...bad fuel filter. Just a few of my ideas. Check this site for baseline settings for the Weber.....set it as they suggest & go from there...

http://www.racetep.com/weber.html

BTW your avatar is....interesting LoL.

[banzai510(hainz)]

Does this weber have a eleltric wire to the side of the carb. It might have a idle cut off selinoid. Or the idle jet is plugged. Unscew it and clean it out.

 

1st photo show item B this is the idle jet. pull out and clean.

If you have photo #2 this is what a idle cut off selinoid look like. Make sure the wire is on when the switchable 12volt when Key is in the ON position. .This lets the gas go in at idle.

 

item A with the tension screw is the mixture. Once get motor running turn it in/out till it runs smooth. Then time motor again and hopefully its OK.

 

 

also make sure your acell pump on the carb is working good. Look in the main barral and cycle the carb. and see if gas is squirting in there!!!!!!! If a nice steady stream its OK.

 

get a Pertronix ignition conversion or a Matchbox distributor. Dont Be cheap!!!!!!!! Get rid of points and Dont LOOK BACK!!!!!!!!!

[ServeEm]

Thanks guys for your quick responses. I was talking today with my co worker and he was also thinking that it could be a vacuum leak(s). Could've happened when she backfired. If that's the solution I should then be able to time it.

 

I do plan on getting a pertronix ignitor kit here real soon.

 

BTW A while back ago I ran across this pic and had to use it for my avatar. I certainly don't look like him :D

 

 

Thanks again!

[Bleach]

I look just like my avitar

[hang_510]

Does this weber have a eleCltric wire to the side of the carb. It might have a idle cut off selinoid. Or the idle jet is plugged. Unscew it and clean it out.

 

i ended up cuting the tip of the cut off solenoid as it was defective (and clogged) rather than replacing (cheaper!). TEP recommendation too.

solved the idle issues i had w/mine.

[banzai510(hainz)]

Vaccum leaks???

yes it could be. just tighten the intake bolts upper and lower and the carb to adapter. But DO NOT over tighten snug is FINE.

 

But really how much vacuum hoses are on a 510? The vacuum advance? and mine will still hold a idle with a Weber DGV with the hose off.

Then the PVC valve. nothing really more.

 

If idle jet is clogged change out fuel filterASAP otherwise it will be dirty again and plugg up(I know this one on my 521 truck). Most common on the trucks since the gas tank is outside and rusts/dirt gets in from the filler hose in the wheel well.

 

 

Make sure the dist is mounted solid. the 10mm bolt isnt loose. Yes the distributor shaft should be pretty solid ,no sise to side play where it would open the point s on its own but hightly unlikey.

Condensor is good?

 

 

its most like your idle circut is plugged cause when using the choke your drawing gas in from the main jet. Thats why i think its the idle jet is plugged or the 12wire is OFF if you have a selinoid.

 

Let me know. But do exactly as my privios post. adj and time it

[Guest DatsuNoob]

my truck was doing the exact same thing when I first bought it and drove it home from Rochester. It would only run with the choke completely closed(manual). I drove home with one hand on the wheel and one pulled back on the choke knob, acceleration and top speed were terrible. Never figured out exactly wht it was since it was a hitachi carb and I really didn't care. Only cared enough to pull it, piss on it, and replace it with a weber that Hainz still swears to this day is the wrong one:D Wish I could be of more help, but to me it makes sense that if the motor is only running well choked out, it's already drawing air from an unwanted source(vac leak).

[DatDoug]

Also make sure u have a good ground from Dist. and from motor to chassis

[banzai510(hainz)]

also just to let u know I hqd a 510 where the main jet had a tiny rock in it. at idle it would run ok but transition into the main jet it would cut out.

I poulled the choke and ran home that way(ran on the second barrel and accell pump from the main barrel)

 

 

 

Datsun Noob

 

get rid of that gas smell???????? Hook up those hoses and PCV valave. It might help get rid of the stink

[ServeEm]

Well I feel like an ass. I found the vacuum leak which was a lead into the intake manifold under the carb. I believe that was used for smog which was plugged before. This whole time I was looking all around and in the carb that I didn't bother with the intake. Anyways I plugged it up and she running like a dream again. Timed and adjusted the mixture so now onto taking out the points.

[DatDoug]

You fixed it tho, Right? Thats all that matters. You got a good response from your fellow Datters. This is a %$#@&%* cool site!

[Bleach]

I agree! Lets have a BBQ

[Guest DatsuNoob]

mmmmmmm BBQ, you dont gotta tell me twice :D

[ServeEm]

Yea right away I knew this place was great. Thanks again for all your input guys! BBQs are my favorite passtime.

[Bleach]

mmmmmmm BBQ, you dont gotta tell me twice :D

We're having a Puyallup BBQ in about 3 weeks. Rebekah and I are planning it. I'll be bringing my new lady friend. :cool:

[SHADY280]

bbq huh?

[]2eDeYe]

Is this BBQ gonna be instead of Pauls or as well as?

[Bleach]

2eDeYe;14570'']Is this BBQ gonna be instead of Pauls or as well as?

actually, this one would be a non-Datsun related event so I shouldn't be discussing it on the forum. sorry

DatsuNoob and I were friends before he had a Datsun.

 

What is the deal with Paul's BBQ? I assumed it would be canceled due to his current health conditions. Any word from him?

[71-521]

Yea, I'm not going to be able to host the bbq....

it under events on the calender and here are well:

http://www.nwde.org/extras/forum/forum_posts.asp?TID=4703&PID=55523#55523

tried to get someone else to host it but no replies...

so here we go:

10-2 at Titlow Beach here in Tacoma on the 18th...

no host BYOF and be there or be square!