Jump to content
MapleNuts

L20b power loss/valve problems?

Recommended Posts

Haven't had a chance to work on it yet due to school and work but i'll definitely post once i'm done. Should go fine after watching your videos hainz, thanks for making those by the way.

Share this post


Link to post

You can check if the valves are leaking by laying the head flat with the valves up. Put the spark plugs in and filling the space around the valves with water and let them sit. If the level drops you got a leak

Share this post


Link to post

Water is too thick, use diesel fuel.

Share this post


Link to post

drop the oil pan if your doing a front cover.

 

all this time you can buy a timming chain wedge. 5-8 $ on amazan but 5 and give them away

 

 

I work on motor 1/2 hour a day all is needed till done

Share this post


Link to post

Alright so i finally finished replacing the head gasket and the valve stem seals.

Seems the car is still getting some oil or gas (seems to have a gas smell but i'm no expert) onto the 4cyl spark plug and a little on 3cyl. I smell the same smell when i open the oil filler cap that is on the spark plug. 

Could it be

1. the fuel pump diaphram is bad, gas mixing with the oil, thinning out the oil and somehow making its way into the cylinders?

2. somehow its not burning up fuel all the way and its just gas on the spark plug, because it is still backfiring like crazy and i'm positive it is trimmed correctly.

and if any of those things were the case why is it really only affecting cyl4?

Share this post


Link to post

Unburnt gas and your backfire are related I would think.  I would start with your plug wires - order correct I'm assuming?  A bad wire could show up intermittently and give you headaches.  missing - and you have unburnt gas in those cylinders.  

Share this post


Link to post

I just ordered spark plug wires, plugs, coil, cap and rotor, and a fuel pump so hopefully that will do something. Order is correct and it's not missing

Share this post


Link to post

If faulty fuel pump the oil level would get higher.

 

Backfire???? out the exhaust or the carb???

Share this post


Link to post

afterfire out the exhaust (everyone wrongly calls it backfire though).

it wouldn't get much higher if it was just a small leak though?

Share this post


Link to post

Out the exhaust is raw fuel and air that was not burned in the cylinder. The simplest cause is an interruption of the spark to a cylinder or several cylinders. Fuel and air is pumped into the exhaust where it explodes. 

 

This can be from bad points. It can also be bad wires, cap or rotor that allows a spark from one cylinder to escape to ground and there is a misfire. 

 

As mentioned a cylinder that does not fire will pump gas into the oil.

 

 

I just ordered spark plug wires, plugs, coil, cap and rotor, and a fuel pump so hopefully that will do something. Order is correct and it's not missing

 

Don't forget the points!

Share this post


Link to post

Put on the new cap, rotor, coil, plugs, plug wires, cleaned and set the points to 0.020. and its still afterfiring. 

Could my distributor be bad? i'm still really only smelling gas on cyl4 plug.

I've messed with the carb mixture screw to see if it was just running to rich but that's not the case.

Could this be a problem with my intake manifold somehow? i've got no damn clue

Share this post


Link to post

Idle mixture screw only adjusts the idle mixture... and it adjusts ALL cylinders.

 

 

Put on the new cap, rotor, coil, plugs, plug wires, cleaned and set the points to 0.020. and its still afterfiring. 

Could my distributor be bad? i'm still really only smelling gas on cyl4 plug.

I've messed with the carb mixture screw to see if it was just running to rich but that's not the case.

Could this be a problem with my intake manifold somehow? i've got no damn clue

 

Take the cap off and watch the points open and close while turning the engine over with the starter. If the points open on all lobes of the distributor cam you must assume that everything is working.

 

If everything should be working maybe it is. This leaves a poor sealing combustion chamber. Do a compression check. Maybe you have a burned exhaust valve.

 

But first did you ever check the valve lash? Specially on number 4???

Share this post


Link to post

Here's a video of the points in slow motion. seems the spark isn't consistent. Does this call for new points, condenser, or distributor?

 

Its pretty much 120 across all cylinders for compression test

 

I'll have to double check the lash but i believe its good

Share this post


Link to post

Pull the coil wire off and hold near ground. All four sparks the same?

 

If not then one of the cam lobes is worn down or perhaps the distributor shaft or bearing is worn. Does the shaft wiggle?

Share this post


Link to post

seems all four sparks are the same off the coil. the shaft doesn't wiggle either

Share this post


Link to post

Then assume the spark isn't the problem. Are the valves set to the right clearance??

Share this post


Link to post

Just did another valve lash, there is less afterfire, but there is still a problematic amount of afterfire. And wouldn't my points sparking inconsistently in the video be an issue too?

Share this post


Link to post

seems all four sparks are the same off the coil. the shaft doesn't wiggle either

 

Though we laid that to rest....

Share this post


Link to post

A compression test might show a low cylinder but not why.. Even better a leak down test which are just two gauges separated by a small orifice. The input gauge valve can be adjusted to 100PSI and on the other side of the restriction the other gauge reads a percentage showing the loss. (because there will always be some leakage) 10% would be very good and also not that likely. 15% to 20% would be average to fair. Above 20% bears looking into. A leak down test puts compressed air into the closed cylinder. A leaking intake will hiss out the carb, leaking exhaust valve out the tail pipe. I'm leaning towards a bad exhaust valve or seat or both. Hissing sound out the valve cover breather can be broken piston and/or rings. Air bubbles in the rad can be a blown head gasket.

Share this post


Link to post

Did u say that u tried adjusting ur carb and no change? When u turn the idle mixtute screw, ur rpm should either go up or down. Did it? Do this while the car is not on. Turn the idle mixture all the way in, cw, but dont force it. Then turn out ccw sttart the car, it should run. Drive around for a bit and check ur spark plugs. It should be tan in color, if its black and sooty then your running rich. Your rpm should be around 800. Btw where are u located

Share this post


Link to post

Haven't tried that method of tuning yet. But i did turn it in untill it started stalling, and then backed it out about a full turn. It still after fired then and it felt like it was running lean. I'll mess around with it a little more and see what i can do.

I'm in washington, king county area

Share this post


Link to post

IM hoping the timming is correct.

a swap in dist that set wrong.

 

 

gas smell in oil can be fuel pump.

 

always ck the spark at output of the coil!!!!!!!!! not the points. Belive it or not you don't want spark at the points if perfect. Spark cause the pitting that why the capicator(condenser)

Share this post


Link to post

After adjusting the carb, what color was your spark plugs?  Also for more specific and detail on how to adjust your 32/36 go search on this forum for weber tuning.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

By using this site, you agree to our Terms of Use.