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Re: Tune-up help please
Posted by: MattNall ()
Date: May 15, 2019 07:26AM

Sounds good... do the compression test.

If you find a low cylinder Back it's rockers off 1/4 turn and retest.


Then we will investigate the need for advanced initial timing.

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Tune-up help please
Posted by: TahoeRon ()
Date: May 15, 2019 08:41AM

I too had problems getting my idle down and smooth. Stalling and hot starting were also problem. There were two things that helped me: First, I reduced the fuel pressure by taking a turn off the pump spring. Next, I replaced the after market needle valves with the ones OEM ones specifically for my 63. There was a Corsa article about the effect of the needle valve opening and the effective float level. Anyway, all's well now.
======
Ron

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Re: Tune-up help please
Posted by: joelsplace ()
Date: May 15, 2019 09:49AM

Where did you find the correct needle valves?

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...

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Re: Tune-up help please
Posted by: TahoeRon ()
Date: May 15, 2019 05:11PM

I bought the needle valves on ebay. A pair of them cost me about $14. They were NOS in the little plastic tubes. The early needle valves have a smaller opening than the late models with the float assist spring. My rebuild kits only gave me the larger size.
====
Ron

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Re: Tune-up help please
Posted by: Peeeot ()
Date: May 15, 2019 08:21PM

Compression test complete!
1 144
2 148
3 157
4 167
5 158
6 151

What's interesting is that the spread is almost exactly the same as my previous compression test prior to purchase (and poster earlier in this thread), but the individual cylinder readings are not the same. Spark plugs were very clean, just a little color on the ring and at the base of the insulator. Insulator tip and ground electrode were both pretty spotless on all 6 plugs. The lifter tick, while never completely gone, is inaudible while driving and sometimes quieter than my leaky exhaust at idle.

With a few more miles driven, I'd say the current float setting is too low. The transition from idle to main fuel circuit is not as smooth as it was at the higher float setting. I will shoot for 6-7/32" next time.

One other thing: after adjusting mixture screws for leanest best idle, I seated them both and counted turns. One carb was 1.75; the other, 3 turns. The tips appeared to have the same taper. Not sure whether this should be a clue.

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Re: Tune-up help please
Posted by: MattNall ()
Date: May 15, 2019 08:39PM

Raise it! 1/8 "!!

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Tune-up help please
Posted by: Peeeot ()
Date: May 16, 2019 03:40AM

So, I know nothing of this engine’s history beyond that is was supposedly rebuilt sometime before the previous owner bought it. I also have almost no experience with high performance camshafts. Is it possible that my idling problems have to do with an aggressive cam? Maybe it just needs a higher idle speed to idle reliably?

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Re: Tune-up help please
Posted by: MattNall ()
Date: May 16, 2019 07:08AM

Can you post a video of it idling?

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Tune-up help please
Posted by: Peeeot ()
Date: May 16, 2019 07:46AM

If I can post direct from my phone, then yes. I don’t have any video hosting accounts.

I set my floats at 3/16” this morning and the off-idle transition smoothed right out. I drove the car to work for the first time, everything was great including smooth strong highway cruising. As soon as I got off the highway, it stalled. Started right up, then as I drove away from the light it felt like I was in 3rd gear, then it started to pull like normal, except with some intermittent hiccups that felt like misfire. Stalled at next light, this time much harder to start, but I got it going. Stalled again as soon as I let off the gas to coast through a turn, so I coasted the rest of the way to my parking spot! Popped the hood and found that fuel was actively dribbling into the intake.

So before, it stalled with no fuel dribble that I could see. Now it seems like heat soak fuel dribble is drowning it out. I haven’t checked fuel pressure yet—guess that’s the next item.

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Re: Tune-up help please
Posted by: MattNall ()
Date: May 16, 2019 08:02AM

Fuel pressure is too high!!

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Tune-up help please
Posted by: Peeeot ()
Date: May 17, 2019 06:57AM

I feel like I’m playing whack-a-mole with problems and symptoms here.

Observed major flooding at one carburetor this morning which prompted me to check the fuel filters, which I foolishly neglected when cleaning up the carburetors. Someone had installed the springs INSIDE the filters (wire mesh type)rendering them mostly ineffectual. I thought I had found the source of the problem there: intermittent crud in needle causing intermittent high fuel levels, dribble, etc.

Put everything back together and engine runs rough for a while, probably clearing out all the extra gas from flooding, then slows down to idle at about 500 rpm, much lower than before and with no alteration to speed screws or mixture. So I try changing mixture: no increase in speed. So I start turning in speed screws: no increase to speed! Before long, I couldn’t sustain an idle at all. I’m guessing the idle jets are clogged.

Super frustrating.

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Re: Tune-up help please
Posted by: MattNall ()
Date: May 17, 2019 07:34AM

It sure is! But part of the game of not letting a '60's engine beat you!

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Tune-up help please
Posted by: Peeeot ()
Date: May 17, 2019 11:02AM

Thanks Matt, I appreciate the encouragement.

So before all the flooding, I was taking a closer look at the ignition circuit and found 8.5V at the coil + terminal with points closed. Spec is <6.5V. Could this be a contributing factor?

Coil primary resistance was 2.1 ohms and secondary 10140. Both are higher than specified. Resistor wire (new) was 1.5 ohms, below 1.8 spec. Voltage drop from point terminal inside distributor to ground was 0.1-0.4V, depending on how I moved the breaker plate. Seems like the spring loaded pivot point isn’t the best ground.

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Re: Tune-up help please
Posted by: MattNall ()
Date: May 17, 2019 02:43PM

There you are... change coils.... must be 1.3 ohms or less!

BUT flooding is mechanical.... didn't you say earlier you cut ONE coil of the FP spring? Cut another.... 2 is more normal.... you want 3-4 psi.

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo




Edited 2 time(s). Last edit at 05/17/2019 02:45PM by MattNall.

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Re: Tune-up help please
Posted by: Peeeot ()
Date: May 17, 2019 07:44PM

Ok, I will plan to replace the coil soon.

Another poster had commented about cutting the FP spring. I still haven't verified my pressure due to needing a helper to crank the engine while I hold the gauge. But my flooding was caused by trash getting around the filters which were not installed correctly. I verified that there was trash in the idle jet of one carburetor as well. I was seeing manifold vacuum around 15" at 900 rpm after cleaning the trash out, but still had problems with stalling. Hopefully the new coil will be the cure there.

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Re: Tune-up help please
Posted by: MattNall ()
Date: May 17, 2019 09:15PM

Make one of these... you test pressure while the engine is running!

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Tune-up help please
Posted by: Peeeot ()
Date: May 18, 2019 09:05AM

New coil has correct resistance and now I get 5.1 volts with points closed and key on—everything just as it should be. No change in symptoms at all.

Start engine cold, it runs till choke opens enough to get to last step of fast idle cam, then rpms slowly drop below 600 until it quits. If I move the throttle once to get a squirt of fuel, it starts right up around 650 rpm, then slows below 500 to a stall. Every time exactly like that. So I think there is still a problem with the idle circuit of the carbs because it is fine when the main cluster is flowing fuel and it needs that squirt from the accel pump to crank. I’m going to remove them, thoroughly clean them, then try again.

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Re: Tune-up help please
Posted by: Peeeot ()
Date: May 18, 2019 12:16PM

Carbs have been cleaned. Though I didn’t find any clear blockages like before, I was able to idle the engine again. Manifold vacuum is steadier and stronger, now seeing 15-16”. However, the engine did eventually quit. Idling below 850-950 rpm just isnt stable over time. Even at 850 rpm, the speed screws are backed off far enough that the screw springs are not under any tension.

Took it for a test drive and it was wonderful not to have to restart the engine at any point in the drive!

I think that trash in the fuel resulting from the incorrectly installed filters was the ultimate culprit here. Time will tell...

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Re: Tune-up help please
Posted by: joelsplace ()
Date: May 18, 2019 12:29PM

I'm confused about the terminology. You are saying you have the throttle stop screws almost all the way out? Or did you mean the mixture screws?
If it's the throttle screws then you have an air leak and that is why you are having idle issues. The carburetors can't control unmetered air.
I just scanned the whole thread and didn't see any mention of the rubber hoses connecting the balance tube. Have you checked them?

Joel
Northlake, TX
4 Ultravans, Lost count at 100 Corvairs...




Edited 1 time(s). Last edit at 05/18/2019 12:33PM by joelsplace.

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Re: Tune-up help please
Posted by: JimBrandberg ()
Date: May 18, 2019 01:00PM

I'm going back to earlier posts on this topic.

Regarding the flooding and fuel pressure. Thee's lots of mechanical fuel pumps these days putting out too much pressure, I've seen up to 9#s, 4 is better but Rochesters can usually handle more, some are fussier than others. Excessive pressure can overcome the inlet needle and seat.

Regarding inlet needle and seat sizes, I believe there was originally a smaller EM size and larger LM size. The Clarks ones are bigger still. I bought 20 of the LM size from Grant Young, I usually buy individual components as needed rather than kits. Some folks think it makes a difference and some folks think it doesn't. I don't know the orifice sizes off the top of my head, it's something like .080 - .100, I really shouldn't guess. It's probably in the Bob Helt book.

A quantity of raw gas into the venturi will goof up the idle for a few seconds or more.

I wish I could say what your problem is. I guess all I've done is add more information.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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