Compression dissapeared

[Scrapson]

We got it idling but it’s still rough. The fuel mixture screw is out 2 turns so it would idle it smells rich but I’ll take it back in a 1/4 turn. I don’t remember what the idle screw is at but I think it’s a turn and a half It sounds like a vacuum leak and I’ve had this problem before I still don’t know what causes it to happen. It has power when I’m driving it and it revvs fine but it take a while to idle down and I think it was the throttle linkage I broke last night.i thought idle on them was 800-850? That’s what it likes the most. 

[datzenmike]

There is no setting for the idle speed OR the mix screws. All are different and adjusted for the engine they are on.

 

To set the idle mixture....

On a warmed engine with timing (12⁰) and valve lash set, reduce the idle speed screw as much as you can so that any improvements in idle mixture adjustments are more noticeable. Engind must be below 900 RPMs or the distributor mechanical advance will mess with your adjustments. Turn the idle mix screw in till the engine stumbles or out, depending on which direction improves the idle quality most. The idle will probably smooth  and increase in speed so turn the idle down and continue to adjust the mix screw in and out searching for the strongest smooth fastest running. Turn in 1/8 increments and allow a few seconds for the engine speed to stabilize. You may notice a 3/4 of a turn between in and out where the idle doesn't change.... just set roughly in the middle. Continue this in and out (may take 7 or 8 adjustments) till you cannot improve the idle quality and the engine is idling at 700-750. The idle mixture only adjusts the idle and off idle up to around 1,100 RPM where the primary circuit begins to tip in and overlap it.

[Scrapson]

It still won’t idle but the timing is adjusted just by hand no timing light to 8-9 degrees because that’s where it liked it  I tried 11 and 12 all it did was backfire and bog at 12 I think I figured out the idle thing though so we’re on the right track I’m going to test it for vacuum leaks through the intake manifold and brake booster. 

[datzenmike]

Backfire through the carb?? That's lean under acceleration. (possibly bad intake leak) Primary jet part blocked. 12 is the recommended setting and it will run at this. Adjusting the timing to fit the conditions is just wrong. Find out why it backfires and fix this. 

[Idaho Hillbilly]

This is a painful thread to read through 

 

1 hour ago, Scrapson said:

It still won’t idle but the timing is adjusted just by hand no timing light to 8-9 degrees because that’s where it liked it  I tried 11 and 12 all it did was backfire and bog at 12 I think I figured out the idle thing though so we’re on the right track I’m going to test it for vacuum leaks through the intake manifold and brake booster. 

 

How do you know it's at 8-9 degrees or that you were at 11-12 if you didn't have a timing light? Judging by the rest of this thread, I'm thinking that you don't have the experience to know those #'s by feel. Get a test light and do the job right. Like Mike just said, don't adjust to the conditions. Set the timing at the recommended spot and then getting it running properly from there.

[Stoffregen Motorsports]

Right. No timing light = no idea of where the timing is set.

 

You can get a cheap timing light for as little as $25. Go buy one and stop guessing.

[datzenmike]

Maybe it was at 16 and is now at 12.

[banzai510(hainz)]

hes looking at the dist marks on the plate I guess.

Cant go by this. You need the light to see it at the crank. Incase the distributor was installed wrong. and since he said he had no light this whole time all the info on "I set it right" is out the door.

2 degs is not going to kill it if the dist was installed correctly. But if a tooth off then yes it will backfire.

 

a key is if the dist is crank all the way to one side is a abvious clue .

 

get a timing light

[Scrapson]

I’m bringing a timing light to school to get some help from a teacher on it since I can skip the first half of the day anyways. It has good power I found the vacuum leak so we’re doing pretty good right now. I was judging the timing off of what it was as before but I don’t think it should’ve changed much since I never pulled the distributor or anything else. Only the cylinder head and manifolds 

Edited February 28, 2020 by Scrapson

[datzenmike]

Removing the distributor does not affect the timing if you unbolt (2 x 10mm) directly from the top of the timing chain cover. The distributor is 'keyed' to only fit in that one position.

[Scrapson]

Okay so what affects the distributor timing I pulled up to work 2 days in a row oil leak and all it’s been pretty good I get a few that’s a cool pickup I’ve missed those comments. 

[datzenmike]

The adjustment on the distributor for setting the timing. It's on the side... 8mm? bolt you loosen and the distributor can be twisted clockwise to advance and counter clockwise to retard. Use a timing light that flashes when the #1 plug fires. This lights up the mark on the crankshaft pulley as it passes the timing scale behind it. Turn distributor to get 12⁰ and tighten the bolt to hold the setting. 

[banzai510(hainz)]

scapson

you said vaccum leaks before. what were they?/Where at?  I rarely have this proplem

[Scrapson]

The vacuum leaks were from the EGR plate to the manifold from my carb over hanging just a hair to touch it so I filed down the EGR plate. It idles now but it still got a slight vacuum leak I gotta find and I think it’s from the broken stud that tightens the bottom of the EGR the threads got pulled out from over torquing is my guess. I haven’t tried timing with a light before and done it successfully but I’ll figure out from my teacher hopefully today. I found the oil leak it’s from the oil pan gasket so yay me for having to replace that probably this weekend. 

[banzai510(hainz)]

on (cast)aluminum parts you don't have to over tighten stuff!!!!!!!!!!

[Scrapson]

I know that from my thermostat debacle. Anyways it is sucking just barely enough air where it idles with the choke on so I’m onto the right track with the EGR thing besides that it’s got no threads. It is leaking oil like a siv when I turn it off and it’s extremely slow while running though. 

[Scrapson]

It runs and drives minty has power it idles it does the right boom thingy I mean she’s perfect no leak today so either the leak fixed itself or I just didn’t see it. It has oil. Remember kids always check the sprockets for proper amounts of torque if it is not spinning the cam when you tighten it down it’s not tight enough keep going when it moves the cam it’s tight. Check the hole in the sprocket to see if the dowel is in. Compression since then is unknown but is high enough for it to run. 

[Scrapson]

Update, It makes a knock knock noise and I said who’s there it said shiny oil soup. All that matters is that I won the race against a hardbody Nissan it felt so good to win a race. Remember to replace rod bearings if your doing a head gasket. 

[wayno]

The head gasket and rod bearings have nothing to do with each other.

I have changed lots of head gaskets and the engines ran great afterwards.

 

[Scrapson]

I dunno what happened I was just like why not what’s the worst that could happen.the worst happended I blew up about 3 miles down the road and got flat towed down some sketchy back roads to my friends house who I had just raced. I still won though so... anyways it’s time for more power and an extra gear. 

[wayno]

[datzenmike]

So, let me get this straight. You went through pages of building and fixing and learning, all this, to abuse and blow up your engine? Then say "I don't know what happened" But that's ok because you won a race???

 

 

Indeed wayno.

 

 

 

 

 

 

 

 

[Scrapson]

Yeah pretty much I love my L20B but like I don’t wanna spend the amount that they want on a rebuild kit at some point if I don’t end up selling it I’ll rebuild it and then go kart it with the 4 speed. Yeah I know wtf why, well I didn’t think it was as much as it was but like when that perfect launch happened it was over I stayed in it. fastest 0-60 on flat ground though so that was cool I guess. I keep getting told to just shove a KA in it or sell the pickup neither are good options. 

[datzenmike]

7 minutes ago, Scrapson said:

Yeah pretty much I love my L20B 

 

 

Uhhhh.... no you don't. And you won't love a KA either.

[Idaho Hillbilly]

If I were you, I'd just stop now while you're already behind. Buy a bus pass and just stay out of the engine bay. Maybe...(and I'm hesitant to even recommend this) save enough money to let someone who actually knows what their doing work on your truck and then you can just drive it.

I'm normally all in favor of people learning but you seem to have zero F*$!s to give about doing it right, so.....