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240Znomad

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About 240Znomad

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    Orange, CA

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    240z

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  1. @Zed Head, thanks for the reply. I don't remember the type of valve seals but I did replace them sometime last year. I believe I got them from Motorsports Auto. Here's a bit of history on the car. The car had a new head (E88) installed back in the late 1980's. It was driven for about 20,000 miles before being garaged for the next 28 years (1989-2017). I never had any problems with sticking valves back, these recent incidents are the first I've had (I drove the car from 1979-1989 and put about 110,000 miles on it before putting it up in the garage). When I got it out of storage in 2017 the gas tank was dropped and re-furbished, all fluids replaced, all hoses replaced. When I got it running in 2017 I replaced the valve seals shortly afterward. Have you heard of valve seals being too tight and causing a valve to stick? If so, that is a possibility. I'm leaning toward the gas (or gas tank) being the issue just because it seems to be happening on the intake valves (2 times now, happening on 3 valves). It seems like it may be related to the gas gumming up the intake valve guides while sitting. That might explain why it seems to happen on the intakes only. I'm thinking of picking up some Marvel Mystery Oil and trying that in the gas/oil to see if it helps. Does anyone have any experience or comments about using something like that in the gas or oil. It seems from reading the forums that some have had good success using it.
  2. I just fired up the engine on my '71 240Z to do some carburetor adjustments (car had been sitting for a week), and had 2 valves (both intakes, #3 and #5) where the rockers nearly popped out of the lash pads. Here's a quick history: 1. I had a lash pad pop off about 6 months ago, see pictures above in this thread. 2. The car has since been sitting for the last few months (I have been working on the heater core and a few other items) and fired it up last Friday. Warmed it up and took it out for a drive to the gas station and drove a few miles. No problems. 3. The car sat all week. I went to fire it up today and before it even started up (ie. while cranking the engine over) I could hear some loud clicking. Finally fired up 10-15 seconds (after filling float bowls) and clicking was loud so I immediately shut it down and thought of the previous lash pad issue. 4. Removed the valve cover and saw that the lash pads were "****-eyed" and the rockers were off line on both the #3 and #5 intake valves. I loosened the nuts to lower the rockers and got everything back in place. Re-adjusted both valves (cold), put the valve cover back on and fired it back up. Everything sounds and runs ok. @Diseazd mentioned earlier in the thread about a possible issue with the gas tank liner (Red Kote) dissolving in the gas and gumming up the valve guides causing the valves to stick. This sure seems like a possible cause since it ran fine when I shut it down last week and was clicking immediately on cranking today. I did have the gas tank completely re-done at a local shop about a year and a half ago so I think I need to run down and talk to them about what they use to line the tank. Does anyone have any other ideas or things that I might check? I think I read someone mention valve seats possibly being an issue, and another mentioning possible weak springs. Has anyone tried an additive like Marvel Mystery Oil to clean carbon deposits or gumming on the valve guides? In the pictures below, the first two (015 and 016) are intake #3 and the second three pics (017 to 019) are intake #5. Any help would be greatly appreciated.
  3. Captain Obvious brings up a very good point. I was just recently helping a fellow board member tune/balance his carbs ('72 style carbs) and one of the issues he was having was that even with the idle screws completely backed out, his car was still idling hi (1000-1200 rpm). We discovered that his throttle linkage was "on" even when the throttle wasn't being used. In other words, his throttle linkage wasn't returning back "off" fully. We popped off the throttle linkage (the little plastic cap) and suddenly the throttle plates closed completely, the rpms dropped way down (to where the engine would barely idle) and we were able to begin using the idle adjust screws to begin balancing and setting up the carbs. I think he was able to remedy the problem by adjusting the throttle where it goes through the firewall and connects to the gas pedal. It might be something to check out as it does sound like your throttle plates are partially open even at idle.
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