Knock and Idle issues

[86Woodgrain]

Well at least we've narrowed things down and can confirm it's timing related. I am not super familiar with how all of those switches and lines work on your 82, I will have to look at a diagram. I was able to get my 86 running nicer by replacing all the vacuum lines and rebuilding the carb, and fixing the wrong vacuum lines.

Edit: See this thread and in particular the second to last post: https://forums.amceaglesden.com/index.php?topic=44263.0;all

Update:Was almost ready to give up on this problem when I finally found the problem. It was something that I overlooked. The problem was caused by a partly restricted vacuum line to the distributor advance. I had vacuum, but it was weak and unstable. This was causing my timing to be all over the place. I assumed it was good because I replaced it about a year ago. After replacing the line and resetting timing, no more pinging and it is running like it did before. I believe that this has been my original problem before the timing chain & gears were replaced.

I truly think your problem is vacuum related, if the base timing is correct.

Also, I have an AC Delco EGR valve in the box that I may not need. It's part # 17066176 it literally fits, I put it on but it didn't fix my EGR problem so I put the old one back on. It works but I only had it installed for like 15 minutes run time. The spring pressure is a little lighter than the stock old one when I manually press but visually it's the same size & shape and fits. If you're interested let me know and if I'm sure I don't need it I will sell it. I need to track down a new CTO, which is actually my EGR problem!! Not the valve...

p.s. I sub you on YouTube and usually comment. I have a couple of Eagle vids on my channel (InternetDude)

[Taylor]

Kennedy American has the CTO switch.

[86Woodgrain]

Kennedy American has the CTO switch.

Too late, I did some Googling and wound up buying a Standard PVS91 off eBay. The stock one appears to be 115 F turn on, and this one is 120 F turn on so it'll be good. I found one at TeamGrandWagoneer I think it was that claims the OEM part number but it's aftermarket but they hide the real part #. It looked identical to the one I bought for less on eBay.

[MIPS]

Okay I sat down and tried graphing out the vacuum advance curve in case I was not adjusted and overshooting.



Okay so for the period before the computer started taking over timing (I forgot to unplug the spark retard cable) it remained in the margin long enough for me to say we're "close enough".

Following your suggestion that there's a restriction I did a few tests to see if I had run new tubing that was too narrow. Ultimately I determined there was no restriction from using a slightly smaller diameter, but there was a delay.



I screwed up. Either I didn't notice an error from the previous owner or I didn't correct plumbing while testing the CTO and the lines for hot and cold are reversed. When cold the advance gets unobstructed vacuum, but when hot it was getting a reverse delay which is the opposite of what all the routing diagrams for the '82 258's wanted. I switched it back around and went out for a test drive. Seems good now unless it moved the problem to cold starts. I'll find out tomorrow.

[86Woodgrain]

Woohoo great update! If this fixes it you should probably put the timing back where it should be (15)??

[MIPS]

Yeah, TSM states 15 degrees.

Alright so I believe I have now sorted out the carb issues entirely after a week of driving. Both of my venturi cluster screws had started to come loose, I had the adjustment screws for the fast idle idle and sol-vac switched around and the previously mentioned loose throttle arm. I fixed the latter by drilling out the dimple and locktiting in a nut and screw.



And yeah, the knock issue was the delay pod was installed on the wrong side of the CTO. Cold start it seems pretty happy on and off the fast idle cam and the knock is pretty much gone. I'll still add the EKE to deal with the altitude and ethanol issues down on the coast but that seems to be it.