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Kingcab

L20b 86mm pistons

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And all plugs and wires are new dizzy should be instal properly it's pretty straight forward to do but I will take it off and chek it all

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I've checked just about all the basics. I've been trying everything I can for like 3 weeks now. That's why I'm asking for help I'm totally lost on why it would run like this

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Probably the carb. Sediment stirred up removing or mounting it.

 

Firing order is 1342.

 

Set timing to 12 degrees BTDC

 

Check valve lash just in case.

 

Set engine to TDC turning the crank up to the zero timing mark in a clockwise direction only. If you over shoot back well up and re-do as  many times as necessary. Must be clockwise and stop to remove all traces of chain slack and get a good reading. Now take the valve cover off and look through the top hole in the cam sprocket. You should see the V notch in the back of the sprocket just below and slightly to the left of the small horizontal line etched into the cam thrust plate above it. Like this...

 

otMggUE.jpg

 

If you have this..... the cam is properly timed

 

1/ Are you sure you have exactly TDC as described????? Has to have timing mark set to zero on the pulley notch. Cars with big overlap cams have terribly low intake vacuum so this would suggest your cam is off.

 

2/ Make sure secondary is fully closed at idle.

 

3/ Check carb gasket and/or adapter are not leaking or cracked from over tightening.

 

4/ make sure intake gasket is sealing or manifold properly tightened.

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I really appreciate the help I habe gotten from all of You!

 

I'm still having the same issue though I was wondering if not having an external resister would cause This? As my coil pack does not have a built in one..

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Coil pack?

 

Not just a Coil?

The resister is usually with points and a certain ohm coil....

Do you have a points (single/dual) dizzy or a electric?

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And all plugs and wires are new dizzy should be instal properly it's pretty straight forward to do but I will take it off and chek it all

 

Has it always had a problem?

Did this problem start about the same time the new stuff was put in?

You'd better post a picture of what you are using.

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So I have a 79 l20b I just got done installing 86mm pistons in it and I replaced all the crank bearings as well. Everything other than the pistons bearings and rings carb headers and dissy are stock (engine wise) I can get it started just fine I can get it to idle also, but it has a slight stumble wile idling and it stumbles pretty bad in lower rpms. Can anyone help me figure out why it's stumbling and won't run smooth...

 

 

Yes I got the cylenders bored out 1mm oversize original bore is 85mm and I bored to 86mm and got 86mm pistons. I have timed it a few difrent times advancing the time and reatarting the time, both the timing chain and dizzy. I have adjusted the carb more than several times. And all aftermarket parts I have installed myself. It all ran good before the bore and piston installation.

 

 

I have the it all timed to TDC looks just like the pic. Firing order is also correct. And it's a weber carb freshly cleaned out. No vacume leeks that I could find. And it's idling slightly below 1 rpm. Going to chek valv lashing

What is proper valve lash?

 

 

Compression test #1 cylender 150 #2 #3 #4 all 180 I'm gunna go ahead and take the head off and see what's going on.

 

Other than the low cylinder nothing here explains the problem. If it starts and idles then it must be very close to set up right. So this leaves the carb. If you can't lower the idle below 1,000? then something is wrong here

 

2/ Make sure secondary is fully closed at idle.

 

Have you looked down the secondary and checked it's closed???

Is the throttle cable too tight?

 

 

Go through this link and follow directions. It will give you steps to set your carb up properly. May even point to a problem..... http://www.carburetion.com/Weber/adjust.htm

 

Go through this link and follow the trouble shooting tips.You say fast idle and poor low speed running when warm???. http://www.webercarbsdirect.com/v/vspfiles/images/Weber%20Trouble%20Shooting%20Guide.pdf

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It idle at about 700 rpm but it has a slight studder in the idle and if I give it gas it rumbles and acts like ignition timing is off set( witch I've used timing light 12° is set). And if i floor it from idle it hesates. And the carb has been fully tuned I've been to the link suggested. I've tries 2 difrent carbs even cleaned both inside and out.

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Find a garage and close the door at night. Must be dark and let your eyes get used to it. Fire it up and look under the hood while giving it quick revs. Look for blue sparks jumping from coil tower to the coil negative terminal. Look at all the wires and the distributor cap for blue flashes.

 

Look down the carb and pump the throttle. You should see a strong squirt of fuel from the accelerator pump. Is there???

 

What do the plugs look like? NGK? BPR6ES-11?????????

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Not sure what the plugs exactly just the chek autozone ones. I will habe to chek for the arking spark that sounds like it could totally be the problem I'll keep you updated when I try This!( the dizzy is a hs hit4 non points, coil is stock. Didn't specify earlier)

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Pull them and have a look at them. They may be fouled.

 

Black dry sooty is over rich

Black oily is oily

White or very light color is lean

Light brown or tan is just right

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Every thing that has been menchennd has been checked multiple times and still has the same problem.

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Pull them and have a look at them. They may be fouled.

 

Black dry sooty is over rich

Black oily is oily

White or very light color is lean

Light brown or tan is just right

 

What about the plugs? If the carb was swapped for another and still the same, we can (for now) eliminate the carb as the cause. Spark plugs are where the tire meets the pavement. You can't see them working. Do you have an old set you could clean and install?

 

Do you have the old cap and rotor and wires? Sure would be handy to swap them on and see it this fixes anything.

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I have used my new cap rotor plugs and wires and I have also swapped out plugs and wires and cap with ones I had laying around.

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Well maybe a bad valve then. Possibly that low cylinder?

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Okay guys I got a new head gasket and finely got it all back together started right up the studder in the idle has stoped it sounds really smooth now. But tomorrow I'm going to retune the carb and hopefully get the hesitation,while full throtle to stop. Any pointers would be greatly appreciated!

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Also there is a slight tapping it sounds like it's coming from the back of the head I'm going to double chek valve lash once again and see if it fixes it

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I'll be honest I'm surprised the head gasket was your issue... not saying it wasn't because the new one clearly fixed something..... and ya these heads are a little ticky, i think that's the nature of flat tappet cams....

 

I have a question for you.... what head gasket did you use the first time and the second time?

I ask because the ones that you can get from the parts store are for the l16,l18 and l20b and only up to a 85mm bore....

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Not sure on the brand at the moment but I just used a stock one and put it together the first time after the build and didn't realize my head was worped so re surfaced the head then reused that head gasket and the issue with the idle started. So then I got the same head gasket bran new and put it on and now it doesn't habe the idle problem anymore.

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