You might just have found your own answer.
Richard
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| Timing issues (I think) https://www.slantsix.org/forum/viewtopic.php?t=53335 |
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| Author: | sdahmer [ Sun Sep 15, 2013 3:56 pm ] |
| Post subject: | Timing issues (I think) |
Hi everyone, I would realy appreciate any help with the following. Thanks! So I'm having issues setting my Idle. When I set it to 750 rpm (as per fender) and adjust the timing to 10 degrees along with air mixture it sounds fine, but in gear it drops to around 400 rpm. Vacuum gauge shows a 1-2 in hg flick at under 2k rpm. Also, when adjusting the timing i noticed something weird, the timing jumps. Not sure how much, can't see it with fan and stuff in the way. It stays on my 10 mark for about 12 seconds then dissapears for another twelve and repeats itself. This is at 750 in park with lights on. |
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| Author: | Fopar [ Sun Sep 15, 2013 4:29 pm ] |
| Post subject: | |
Just a guess your timing chain has worn to the point you need to change out cam gear and chain. What is the vaccum in inches while at idle? Richard |
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| Author: | Aggressive Ted [ Sun Sep 15, 2013 8:38 pm ] |
| Post subject: | |
Agreed! a wee bit of timing chain slop or a heck of a vacuum leak. Also if your distributor springs are weak it may be allowing the advance weights to flop around making the problem worse. I had a SL6 in that shape once right after I bought it......... |
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| Author: | sdahmer [ Sun Sep 15, 2013 11:16 pm ] |
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Thanks for the response guys. I replaced the timing gears and chain around 3k miles ago. The vac is at 18 in hg or so in park or neutral but in gear it drops to about 12. Whenever I put it in p or n it starts to idle fine. I was thinking something in the sistrubutor is causing this (took it off a junkyard volare). |
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| Author: | Fopar [ Sun Sep 15, 2013 11:30 pm ] |
| Post subject: | |
You might just have found your own answer. Richard |
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| Author: | sdahmer [ Wed Sep 18, 2013 11:55 am ] |
| Post subject: | |
I hope that's it, just got another distributor. I'll be throwing it in today so we'll see how it goes. |
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| Author: | DCFAB.US [ Fri Sep 27, 2013 11:28 pm ] |
| Post subject: | progress?? |
Just curious if you got it resolved? |
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| Author: | sdahmer [ Mon Sep 30, 2013 3:02 am ] |
| Post subject: | |
Well, I put a different distributor in and it's a BIT better. Turns out the vacuum advance canister was bad. Still having issues but at least I can set the timing now and idle without it stalling. Now my vacuum gauge reads 8-10 in Hg idling in drive, really rough idle, no loss of power though. Possibly a leak at the manifold or carb? Anyone think otherwise, such as a valve timing problem? (I lined up the timing chain sprockets using the dots and didn't degree the cam) Thanks! |
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| Author: | Reed [ Mon Sep 30, 2013 8:28 am ] |
| Post subject: | |
What is your base timing set to? When was the last time you adjusted the valves? Have you verified that the timing mark has not slipped? |
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| Author: | sdahmer [ Mon Sep 30, 2013 11:56 am ] |
| Post subject: | |
I havent adjusted the valves in a few months to be honest (maybe 3k miles ago). Thanks for bringing it up, I'll readjust them this weekend. Timing is at 10 degrees btdc, sounds best there and starts quicker. The timing mark was put there by me when I replaced the timing chain and head gasket, using a piston stop to find tdc on the compression stroke, and it hasn't moved from where I've put it besides when the vac advance canister failed. It's easy to check again so I'll do that along with the valve lash. Thanks again! |
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| Author: | Reed [ Mon Sep 30, 2013 12:52 pm ] |
| Post subject: | |
Did you verify that the rotor is pointing at the #1 plug tower when #1 is at TDC on the compression stroke and not TDC on the exhaust stroke? The timing mark will line up at TDC on both strokes, and a motor can run with the plugs firing at TDC on the exhaust stroke, albeit run poorly. |
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| Author: | sdahmer [ Tue Oct 01, 2013 1:27 pm ] |
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I either used my finger or compression gauge to find tdc on the compression stroke when I marked the damper. It's worth a check though since it's easy enough. I just have to wait for the weekend since I can't work at it at home (complaining apartment neighbors). My gf's dad is nice enough to let me keep my project dart and work on my cars in his driveway. |
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| Author: | sdahmer [ Thu Oct 10, 2013 2:05 pm ] |
| Post subject: | |
I didn't get a chance to work on it over the weekend but I figured I could check the valve lash cold since my neighbors can't hear that and wouldn't complain, and if the valves were too tight cold then they were definitly tight hot. Sure enough, some of them were. I think all the parts replacement, tuning, and driving I've done had affected it. Anyway, started RIGHT up showing 16 in. Hg before any tuning, rpms increased as well and it is idling much better. I'll redo the lash, mixture, timing, and idle speed when I go over to my gf's place (good warmup drive and no complaining neighbors). On a side note, is it possible to have a vacuum leak at the charcoal canister? I applied vaccum at the dist port on the canister and it didn't hold. Thanks for all the help! |
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| Author: | wjajr [ Fri Oct 11, 2013 7:26 am ] |
| Post subject: | |
Quote: On a side note, is it possible to have a vacuum leak at the charcoal canister? I applied vacuum at the distributor port on the canister and it didn't hold.
Charcoal canister is part to fuel tank vent and fuel vapor recovery system hence air is drawn from tank and carburetor fuel bowl when engine is off to be stored in canister then to carburetor to burn vapors once engine starts; a controlled vacuum leak so to speak. So yes, that vacuum circuit won’t hold a vacuum. However that said, its connecting tubing can become dry, cracked, and cause excess vacuum to bleed off which will lean up your idle mixture, but be insignificant enough not to upset A/F mixture at larger throttle openings. If you smell fuel when is engine off there is a leak in recovery system somewhere. There should be some sort of air throttle foot valve device(s) somewhere along recovery vacuum plumbing to meter air and fume flow along its path. You have to check vacuum line diagram posted under hood that correct plumbing routing and related devices are installed as they should be. If no diagram survived, a general routing diagram should be in a 1972 FSM. Cars sold in California had different more complicated emission controls than rest of the country, and often predicted what would be used for the other 49 states a few years into the future. Quote: It stays on my 10 mark for about 12 seconds then disappears for another twelve and repeats itself.
Depending which way timing is moving (advance or retard) this could be caused by weak or broken governor springs internal to distributor, and or sticky governor weights, and or incorrect vacuum supply at carburetor (not ported), and or vacuum leak in advance plumbing or somewhere else. |
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| Author: | sdahmer [ Fri Oct 11, 2013 2:38 pm ] |
| Post subject: | |
After intalling the new reman distributor the timing issue was fixed along with a leak free vac adv canister. Thanks a lot for that canister info. I was just worried it was leaking since it wouldn't hold, adding to my valve adjustment issue. I'm just glad it's not the intake gasket, I find that repair somewhat annoying. I will be readjusting the valves HOT tomotrow, hopefully improving it further. The increase in vaccum and idle quality prove that it's the valve lash that was causing the issue. So, to anyone experiencing these symptoms, I reccomend a valve adjustment before further troubleshooting. |
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