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78 620, L20B foreign matter in combustion chamber.


Atikin9000

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I never use power tools to clean either surface. Take the time to do it with manual power and save the time doing a head gasket 3 months from now.

 

Don't use those things (either plastic or scotch brite discs) on any gasket surface. A good gasket scraper can get all the tough bits off. I will use a wire wheel, but that's only after I have the gasket removed, and even then, never on a head gasket surface.

 

Also consider, some of these older type gaskets have a high level of asbestos in them and taking that off with a wire wheel, or anything else that creates flying tiny particles, can leave you wheezing for a day or two. I wish I knew that when I was a kid...

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Well on the first comment the shims aren't a big deal if done right....

As long as the cam slids in and out of all towers smoothly your ok....

And as far as the cam location that does look a little off.... there should be a front to back dimension for how much play is allowed.. that can be checked.... is everything tight on the head?

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Well on the first comment the shims aren't a big deal if done right....

As long as the cam slids in and out of all towers smoothly your ok....

And as far as the cam location that does look a little off.... there should be a front to back dimension for how much play is allowed.. that can be checked.... is everything tight on the head?

 

 

Everything aside from the cam sprocket.

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Maybe the cam thrust plate is missing? Otherwise it looks centered on the lobes ok.

 

Sprocket looks worn, never seen one that bad.

 

Cam lobe wear, if any, is lack of oil with adequate ZDDP level or excessive spring rate or both. Often it's confused with the shine put there buy simple rubbing. Use a micrometer and measure.

 

That synchronous carb is consistent with it being a 38/38

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Maybe the cam thrust plate is missing? Otherwise it looks centered on the lobes ok.

 

Sprocket looks worn, never seen one that bad.

 

Cam lobe wear, if any, is lack of oil with adequate ZDDP level or excessive spring rate or both. Often it's confused with the shine put there buy simple rubbing. Use a micrometer and measure.

 

That synchronous carb is consistent with it being a 38/38

 

They had the sprocket in a solution and it looks tarnished a little, but here’s some better pics

 

 

TVJFgAM.jpg

K0vRZBS.jpg

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That won't hurt it but if really dirty it will have to sit a long time. Borrow a power washer or go to car wash with such. Then gloves, large container and hot soapy water with dish soap and bristly scrub brush. Finish with spray carb cleaner, let dry.

 

That carb could do with a going over.

 

There's not much you can preset. Most things are adjusted when running.

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That won't hurt it but if really dirty it will have to sit a long time. Borrow a power washer or go to car wash with such. Then gloves, large container and hot soapy water with dish soap and bristly scrub brush. Finish with spray carb cleaner, let dry.

 

That carb could do with a going over.

 

There's not much you can preset. Most things are adjusted when running.

http://www.redlineweber.com/html/Tech/38_dgas_tunning.htm

 

 

Would this be good enough?

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My last post here about this.

 

Well it does not knock/ping anymore with the ignition timing at 2 degrees before TDC, I suppose if I bought premium gas I could adjust the timing differently, but I burn regular so 2 degrees it is.

It also appears that I am getting way better gas mileage, with the truck empty/no trailer I have got 23mpg before, but as a work truck I don't really do all that good, well 5 gallons just got me farther than I can ever recall the last couple days, I am barely using the pedal, it's different, but I don't believe I have any more power, I just use less pedal for the same power.

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The trouble with removal of the EGR manifols and putting a block off plate on is the loss of the PCV valve. I think that's the top hole that is open. Clean the other two out and fill with JB weld and tap the top hole so the PCV valve screws in. Get rid of those two studs

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The trouble with removal of the EGR manifols and putting a block off plate on is the loss of the PCV valve. I think that's the top hole that is open. Clean the other two out and fill with JB weld and tap the top hole so the PCV valve screws in. Get rid of those two studs

Calling weld shop for a plate tomorrow and I was gonna get a bung welded on.

 

 

Multiple threads I’ve read about this and each had you mentioning the PCV, seems important lol.

 

Is it absolutely neccesary for it to get recycled into the manifold or can I put a breather valve on the hose?

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The PCV is a good thing, before the PCV the insides of blocks looked awful, there were build ups of moisture/dirt/oil/crap so thick it was terrible to even deal with.

Also engines that made the 100,000 mile mark without rebuilding were few and far between, after the PCV they go 300,000 all the time.

Your oil makes it longer also, 3000 miles is easy now, 3000 miles back then before the PCV valve was pushing it.

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