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> Still a miss at 4,000 RPM..., Backfiring at WOT, even with all new ignition components
r_towle
post May 29 2013, 08:13 PM
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This is a 1.7 liter motor?
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904svo
post May 29 2013, 08:13 PM
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Have you check your linkage to make sure both carburetors have the same travel?
What you describing is what happens when one carburetor is opening more than the other. To check this measure the distance from the throttle shaft to where the ball joint is connected they should be the same.
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r_towle
post May 29 2013, 08:15 PM
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(IMG:style_emoticons/default/agree.gif)

I asked in the other thread, post a pic of the linkage, or a few
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r_towle
post May 29 2013, 08:15 PM
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With those specs on a 1.7 you are not starved for fuel.
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ThePaintedMan
post May 29 2013, 08:27 PM
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Ack! So many questions, which really makes me happy... I'm just having a hard time keeping up.

Yes, I agree that my jetting settings should be more than adequate for a 1.7, based off of Tomlinson's Weber Manual tables.... that is, assuming it actually is a 1.7 and not some rebuilt monster (IMG:style_emoticons/default/smile.gif) In my dreams, right?

The linkage is a Tangerine Racing cable setup, which I am really happy with. From every indication I have, it is synched... it's really hard NOT to have them synched with this setup actually. I need to re-synch again tomorrow since I adjusted the valves today, but before I did the valves today, they were synched both at idle and at 3,000 RPMs.
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r_towle
post May 29 2013, 08:31 PM
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Yup, that setup stays synced.

Hmmm

Did someone rebuild that motor at some point?
Starting to wonder about the valve timing....
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ThePaintedMan
post May 29 2013, 08:36 PM
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QUOTE(r_towle @ May 29 2013, 10:31 PM) *

Yup, that setup stays synced.

Hmmm

Did someone rebuild that motor at some point?
Starting to wonder about the valve timing....


I dunno. I cannot recall ever really trying to push the car hard enough in the first year that I owned it and got it back on the road to even cause these symptoms to appear. It could be that it's been like this all along, but ever since I was getting it ready for the DE, the backfiring has been the bane of my existence.

Rich, here's something interesting I noted today. The valve lash adjustment screws on the passenger side of the engine look pretty well adjusted in. As in, there are only a few threads left on them to allow me to continue to tighten them up. The drivers side seems to have closer to 4-5 threads showing on most of them. Not sure what that indicates, if it indicates anything.
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r_towle
post May 29 2013, 08:47 PM
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May I suggest a slightly different way of adjusting your valves.
Pin the opposite valve wide open, then adjust the valve directly opposite that wide open valve.

Then you know you are on the bottom of the lobe.

If your ignition is correct, you have no manifold leaks, your linkage is setup, then it's back to the valve that may be opening to early for the intake stroke.

I have never built a motor with the valve gear off by one tooth, but this may be the result.

Try this.
Go for a run once hot....take it down the street and come back towards the house in a low gear, as its backfiring.......run it like that for about 100 feet then shut it off.
Do not let off the gas.
Kill the motor at the higher rpm,s on the main circuit, not on the idle circuit.

Then pull the plugs and rad them
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r_towle
post May 29 2013, 08:48 PM
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Alternate would be to pull the oil pump and see if you have a stock cam gear, but even that could be put in wrong...
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messix
post May 29 2013, 09:50 PM
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now that it is pulling good until the higher rpm i'm going with worn out/or broken valve springs.

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type2man
post May 29 2013, 10:38 PM
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I think I mentioned this before but have you tried swapping out the cap, rotor and wires. It seems to me like something is arcing and higher rpm. With the carb setup you have, you should have no problem revving unless there is a spark problem or even a distributor problem.
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URY914
post May 30 2013, 05:01 AM
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Check your tire pressure.
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URY914
post May 30 2013, 05:01 AM
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Clean your windshield.
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URY914
post May 30 2013, 05:02 AM
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Move your seat all the way back.
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URY914
post May 30 2013, 05:03 AM
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Do your back-up lights work?
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URY914
post May 30 2013, 05:03 AM
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Check your heaterbox valves.
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URY914
post May 30 2013, 05:04 AM
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Change your underwear.
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URY914
post May 30 2013, 05:12 AM
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Try more brand in your diet.
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ThePaintedMan
post May 30 2013, 06:33 AM
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Don't forget the blinker fluid Paul!
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carr914
post May 30 2013, 07:40 AM
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How are your Muffler Bearings?
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