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> Part throttle backfire...
quadracerx
post Jan 8 2010, 09:46 PM
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Work is progressing nicely but slow...

Got all the electrical stuff worked out finally..lights, gauges, front heater, new radio, etc...and I couldnt have done it without everyones help....

I drove my car for the first time....only about 15 minutes...it was great..except I found out its got a part throttle miss and backfire...sometimes its through the exhaust and sometimes the carbs...So confused (IMG:style_emoticons/default/confused24.gif)

Idles fine....revs good...just misses at part throttle 2-4000 if you hold it.....Weber carbs...new cap, rotor, wires, etc...so Im stumped now...

Think I might need a carb guru...anybody in the Tacoma Seattle area?

Thanks again for all your help you guys....your awesome...

Steve
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underthetire
post Jan 8 2010, 10:47 PM
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Possible dizzy advance plate sticking. Did you put a couple drops of oil on the felt under the rotor? I don't know much about carbs. I'm a FI guy. Just something to check.
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quadracerx
post Jan 8 2010, 11:13 PM
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Thanks...

Since you said that....i forgot to mention that my buddy who actually got it running said he "recurved" the distributor....So maybe thats why its missing? So Im sure its cleaned and stuff...but maybe the "recurve" messed it up...? Now I wish I had a spare distributor.....are they all the same? My car is a 76 I do have a 73 1.7....

Thanks again for your help and input...Anybody in the area wanna come check it out?

Steve
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underthetire
post Jan 8 2010, 11:34 PM
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Probably close enough. Since you don't have the FI, it's just a std dizzy now. Easy swap out to try.
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McMark
post Jan 8 2010, 11:45 PM
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Which distributor to use when running carbs is a constant issue. The stock distributor still won't be correct. It might be better, but it won't be perfect.

The Mallory is a good option, but can be pretty pricey when trying to get going 'on the cheap'. You can get used ones on TheSamba, even the old dual point Mallorys can be upgraded to electronic internals.
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ME733
post Jan 9 2010, 10:49 AM
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(IMG:style_emoticons/default/popcorn[1].gif) ...well I,m glad you mentioned the recurved distributor. My quesstimate is this....if the distributor was recurved, (this is properly done on a distributor testing machine)...He SHOULD HAVE THE PAPERWORK showing the "NEW" curve. Compair that to the" before curve", or a stock distributor of the same designation./curves are in repair books. Based on the symptons of your running engine, the advance mechanism is intermittantly sticking, probably at too much advance.(backfire out the carb).BUT this is if the valves are adjusted... AND the backfire out the tailpipe is due to a probable missfire. Check the distributor shaft. It must not 'wiggle at all... check the rotor for tightness, and the cap is proberly centered, check the point gap, and wear pad. check for loose wires/connections in the distributor., and wiring to it, Make sure your GROUND cables (to the engine and chassis)are on , and tight. Make sure the IGNITION wires are tight on the spark plugs , and the dist. cap.(an end can be pulled off in the cap). this will get you started...good hunting. (IMG:style_emoticons/default/popcorn[1].gif) murray
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jmill
post Jan 9 2010, 12:38 PM
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Dizzy is a good bet if it was messed with. Keep in mind that it could also be carb transition issues. Low float level and jet sizing lead to similar problems.
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quadracerx
post Jan 9 2010, 07:06 PM
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Ok...so more work done today....re-assembled console...and pulled plugs...they look black....not oil fouled black..fuel fouled black...and they all look that way to some degree....so Im gonna put some new plugs in it again....and see....if that doesnt do it....its swap distributor time....

Thanks again for all your help and input...

Steve
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quadracerx
post Jan 10 2010, 10:53 PM
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Progress update.....

Sometimes I feel like an idiot...(OK I AM AN IDIOT) I replaced the plugs, it made almost no difference...I then took the cap off again....and when I put it back on the distributor moved (IMG:style_emoticons/default/WTF.gif) Ok so thats the idiot part....so I then go to time it by ear....first shot still lazy and backfires under load....but I noticed that although it seemed to like it...it also died once on me and was very hard starting....(too much advance...) so I go back home and play with it again....no more hard starting and now it runs AWESOME.... (IMG:style_emoticons/default/cheer.gif) (IMG:style_emoticons/default/aktion035.gif)

So thanks again....for everyones help...now on to bleeding the brakes and or adjusting the brake pedal throw....and then its time to just drive the damn thing....Real maiden voyage upcoming....

YOU GUYS ARE AWESOME...

Steve
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yeahmag
post Jan 11 2010, 12:28 AM
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GET A TIMING LIGHT!
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