Brand New EVERYTHING - Misfire on 3&4 - HELP

[racer86]

38 minutes ago, '76mintgrün'02 said:

 

I am not sure what you mean by two boosters, but there should be a check valve between the intake runner and the brake booster.

 

I get teased for recommending the Innova 5568 timing light so much, but it is a very useful tool (essential, IMO) and relatively affordable... get it before that changes.  Setting timing based on what it was really isn't very practical.  You've made a lot of changes since then.  The variable light will let you see what the timing curve is throughout the range.  I guess people who don't appreciate variable lights simply have never used one.

 

I don't want to be insulting, but you do have the firing order based on the clockwise rotation of the distributor, right?

 

The black coil needs a ballast resistor inline, as it came from the factory.  The early cars have a ceramic block style, with a coiled resistance wire on the back side and the later cars, with the coil mounted up forward have a resistance wire inside the wiring loom.  If you have a tester, you can see what the resistance is on your coil and add an appropriate resistor to bring that number up to 3 ohms.

 

This stuff really doesn't answer the 1&2 / 3&4 discrepancy, but is important.

 

Did you set your float height for the plastic ones?  I think that is around 35 mm, as opposed to the brass ones that get set around 40 mm.

 

Thanks for all the nice photos.  

 

Tom

 

 

Tom, thanks for your help and I really appreciate going through the basics...it's got to be something simple! 

 

Firing order: Yes, I can confirm clockwise rotation of the rotor arm and leads in the right order based on this. 

 

Timing:  I'll get it on a light when the manifold is back on to check where it's at.  

 

Coil:  The coil comes with a 3 Ohm primary so possible doesn't need a ballast? 

 

Float height:  It's a plastic float I've set to 34mm.  Factory is 35 and, apparently, in racing applications you should run 33mm....I went in the middle as fuel was a concern...but apparently not the issue. 

 

Picture attached of better times....when I could drive it and hadn't spent a fortune making it worse  ha ha ! 

 

 

Edited March 21, 2020 by racer86

['76mintgrün'02]

You are correct.  You do not need the resistor with that coil and your float heights sound right.  It will be interesting to learn what the problem is!   

 

Tom

 

 

[ray_]

Jeez that must have been a hard hit to knock the steering wheel all the way to the passenger side!

 

[kbmb02]

Q: Are the paper gaskets present between the intake manifold and the cylinder head? One ‘combo’ gasket between water divider and #1 cylinder, then individual gaskets at #2, 3 and 4. -KB

[racer86]

5 minutes ago, kbmb02 said:

Q: Are the paper gaskets present between the intake manifold and the cylinder head? One ‘combo’ gasket between water divider and #1 cylinder, then individual gaskets at #2, 3 and 4. -KB

 

Yes, all 4 gaskets are present and new...

[zinz]

I’m with Mike... the header tubes on 3 and 4 indicate little to no heat discoloration. The ceramic on your plugs are very white... indicating a lean/hot condition; but #3 doesn’t look like it’s been firing at all. 
 

Try this. Pull #3 plug from the engine, insert it into its plug wire and hold the electrode against a ground (strut bearing nut is handy).  Have someone crank the engine and check for spark. It should be bright blue/white.

 

You may have a dead plug, or wire. 
 

 

[Hans]

How about using 3 and 4 plug wires on 1 an 2. And then the plugs.

[flagoworld]

The video clearly shows that spraying fluid onto cyls 3 and 4 increase idle... can you try getting closer and spraying less to make sure no vapor is making it into the carb? To me it really seems like a vacuum leak on 3 and 4 based on the vid...

[stone02]

so,

  i think that this is a very simple leak.

when the intake manifold that was removed and

not reused, was put somewhere for later, does

it have three distinct gaskets on number 2,3,4?

if you are not 150% sure that if you were

to take a sharp object to all the surfaces, on the

manifold and then check the cylinder head in the

same fashion, then my $1 bet is that even though

you swear that it looks like all the old gaskets

are gone, one is still there and stacked.

  when the manifold is installed on new gaskets

two are facing out and one is reversed and after

only a few heat cycles, they bond to the surface.

removing them is VERY hard to do. i use a knotted

wire wheel and a custom made scraper to dig off

every gasket, even on the old part. that way next time

i have the parts in hand two gaskets do not end up

stacked and leaking. let us know or post very clear

close-up pictures of all four intake to head mounting

points.

stone

[dlacey]

Wrongly fitted manifold  gasket?? I recall they go on the studs in 4 different orientations but only one is correct...

https://www.realoem.com/bmw/enus/showparts?id=ST13-EUR-07-1973-114-BMW-2002&diagId=11_2395

[Dudeland]

 If you have good spark on  3 and 4, then you need to do a compression test.  I think you popped your head gasket between 3 and 4.  

 

 

 

[flagoworld]

26 minutes ago, Dudeland said:

 If you have good spark on  3 and 4, then you need to do a compression test.  I think you popped your head gasket between 3 and 4.  

 

 

 

 

He did and compression was pretty good between 3 and 4

 

I still think its a vacuum leak on 3 and 4 based on the spray test video.

[Dudeland]

1 hour ago, flagoworld said:

 

He did and compression was pretty good between 3 and 4

 

I still think its a vacuum leak on 3 and 4 based on the spray test video.

Ok sorry.  Seems weird that the plugs aren’t wet.

[racer86]

Hi all,

 

Just to let you know I've not given up on this yet, but also not solved it...for the last 3 weeks the inlet manifold has been at the machine shop....which got locked down due to Covid19.....so who know's when it's coming back!  All on hold, but will report back as soon as I have some progress! 

 

The good new is I now have access to a variable advance timing light...so something else to check when it's running. 

[scatman75]

Get us a closer pic here, i zoomed in and i think i can see a defect on 3 but its hard to say. I know you said they are new gaskets but the latest video is symptomatic of a vacuum leak. The trouble with vacuum leaks is that everything can appear to be fine but a doubled up gasket or a hairline crack will cause issues