GT6 Mk3 only runs well with VERY advanced timing. Any ideas why?

[johny]

oh no reason why it wont start ok but whether it'll run well on standard ignition setting is another matter. Dont rush it though....

[nicrguy1966]

1 hour ago, johny said:

oh no reason why it wont start ok but whether it'll run well on standard ignition setting is another matter. Dont rush it though....

I haven't touched the distributor, so hopefully the ignition timing with regard to TDC shouldn't have changed.

I do need to reset the rockers on values 1 & 2 before attempting to start.

[johny]

ah the dizzy is driven from the camshaft so there will have been a small advance in ignition timing. Also yes tappets must be set to correct clearances....

[nicrguy1966]

Just now, johny said:

ah the dizzy is driven from the camshaft so there will have been a small advance in ignition timing. Also yes tappets must be set to correct clearances....

Bother (I was thinking another word)

[Puglet1]

This thread is better than Peaky Blinders ……. At the end of each chapter you’d be left with a real cliff hanger!

I Can’t wait to find out what happens next !👍

[johny]

Hope its not going to get as violent😱

[nicrguy1966]

It started!

Without a radiator, so I couldn't run it long enough to push the choke in, but nothing I've done has bricked my car!

Very relieved. 

Now I'm going to clean up the cooling connectors that appear to be caked in limescale, refit the radiator and take a trip to Halfords for some anti freeze.

[Pete Lewis]

so you know your CDSE carbs are adjusted by sticking a long allen key down the dashpot tube  there are special silly priced tools to do this

but if you remove the air piston you can use a key down the dashpot tube  the art is a std setting that the small delrin washer on the head of the needle should

be level with the base of the air piston  thats the starting point .    the key turns a fixed threaded ( Nut) and rotation will raise or lower the needle 

if you have temperature compensators ( small plastic covered unit ) on the side this needs to be twiddled remove its cover and turn the small nut to 

close the plunger  SHUT you dont need this emission aggravator  

ie it bleeds air bypassing the throttle so if its open when it should be closed you cannot set the idle mixture ..ever.

just something else to dream about Ha !!

Pete

[Iain T]

42 minutes ago, Pete Lewis said:

  the key turns a fixed threaded ( Nut) and rotation will raise or lower the needle

Pete, to help is there a factory amount of turns from flush for a basic setting? 

My money is on fuel/carbs and not cam timing.....but a useful learning curve! Advancing the ignition and slightly higher tick over has compensated for very weak mixture. Anyone want a 10p bet? 

Iain 

 

[johny]

I believe the sparkplug colour is ok though🤔

[nicrguy1966]

43 minutes ago, johny said:

I believe the sparkplug colour is ok though🤔

Yes, a nice colour on all plugs.

[nicrguy1966]

I went for a drive. To start it was a bit sluggish, but I did a roadside adjustment of the ignition timing (by ear) and it improved.

I was only driving to warm up the engine so I could get the strobe out and set the timing, but while adjusting the distributor, I noticed a drip from one of my hoses, so I had to go back to Halfords for a new jubilee clip. Now I can't do anything until the engine has cooled down again and I fit the new hose clip.

Final checks and adjustments tomorrow. So far the verdict is that it isn't any worse than before, and I might have a little more power in the mid range (2500 to 3500). Also, one of my tappets is making a lot of noise, so another job for the future 

[Iain T]

15 minutes ago, nicrguy1966 said:

Yes, a nice colour on all plugs.

I'm still to be convinced, yes I can be stubborn but in the nicest possible way 😂. Our engines like a bit of black round the plugs and deep tan electrodes. If they look a bit paisty the mixture is too lean. 

I can't wait for the next installment! 

Iain 

Edited October 17, 2023 by Iain T

[johny]

Where is the ignition timing now or didnt you get a chance to check it?

[nicrguy1966]

3 minutes ago, johny said:

Where is the ignition timing now or didnt you get a chance to check it?

Waiting for the engine to cool so I can replace a hose clip, then I'll need another drive to warm the engine up again!

So it's all slipped to tomorrow.

I did hear pinking under acceleration on my drive so I probably need to retard it a little.

[nicrguy1966]

2 hours ago, Pete Lewis said:

so you know your CDSE carbs are adjusted by sticking a long allen key down the dashpot tube  there are special silly priced tools to do this

but if you remove the air piston you can use a key down the dashpot tube  the art is a std setting that the small delrin washer on the head of the needle should

be level with the base of the air piston  thats the starting point .    the key turns a fixed threaded ( Nut) and rotation will raise or lower the needle 

if you have temperature compensators ( small plastic covered unit ) on the side this needs to be twiddled remove its cover and turn the small nut to 

close the plunger  SHUT you dont need this emission aggravator  

ie it bleeds air bypassing the throttle so if its open when it should be closed you cannot set the idle mixture ..ever.

just something else to dream about Ha !!

Pete

I have one of those expensive tools somewhere, but I have no idea where. My garage is like an Aladdin's cave of treasure.

[daverclasper]

1 hour ago, nicrguy1966 said:

Also, one of my tappets is making a lot of noise, so another job for the future 

I don't know how flat your rocker pads are, the valve tips can wear an indent and setting with feelers leaves too large a gap. there are ways around this

To identify a noisy rocker, then when idling, push a thinner gauge old feeler in the gap and the rogue one should quieten down

[Pete Lewis]

3 hours ago, Iain T said:

is there a factory amount of turns from flush for a basic setting? 

no not as far as i know the top adjust with its small washer set flush is the base setting and ive always found that works 

on bottom adjusters its around 3 turns down from flush but peoples idea of flush and 3 what !!!   can be varied 

pete

 

[nicrguy1966]

13 hours ago, daverclasper said:

I don't know how flat your rocker pads are, the valve tips can wear an indent and setting with feelers leaves too large a gap. there are ways around this

To identify a noisy rocker, then when idling, push a thinner gauge old feeler in the gap and the rogue one should quieten down

So far nothing has been badly warn on the engine. I had a reconditioned engine fitted about 15 years ago and do fairly low mileage (3-4k per year).

[Josef]

I’ve just had to completely strip my Herald’s engine (complications with custom thrust washers…), which best guess is 20-30k miles post previous rebuild, most stuff is turning out to be pretty unworn thankfully, but my rockers and rocker shaft are all pretty knackered. So worth a check even if you think wear is unlikely.

[Pete Lewis]

1 hour ago, nicrguy1966 said:

push a thinner gauge old feeler in the gap and the rogue one

Think Dave picked this up when i did Twiddle days at club HQ 

good fun but cant do it now  cant hold spanners zimmer frame and iron lung and ball cock  all at the same time  Ha !

maybe we organise one for the spring 

Pete

[nicrguy1966]

6 minutes ago, Pete Lewis said:

Think Dave picked this up when i did Twiddle days at club HQ 

good fun but cant do it now  cant hold spanners zimmer frame and iron lung and ball cock  all at the same time  Ha !

maybe we organise one for the spring 

Pete

Holding a feeler gauge, screwdriver and 1/2 ring spanner all at the same time is enough of a challenge for me!

[Pete Lewis]

no  poke the test feeler in while its running   if it goes quiet  then adjust down a bit more  , one job at a time not all 3    

its possible to reface the rockers with a grinder (not tried a file  )  they are hardened pads .

f you ever find some wire feelers they dont bridge the wear pad  but they are rarely available

things like ClickAdjust solve this but they are not that easy as they make out , as you have to determine how many clicks you need ....  manic 

Pete

[JohnD]

Your pic from above, niceguy, and it shows the distributor rotated clockwise from the normal position, which is with No.1 lead at 'six o'clock'.    This I presume is the "Very advanced  timing" that you have found necessary.      But why, everyone cries!

The legbone's connected to the ... kneebone, or in this case the dizzie drive shaft is connected to the distributor drive gear and thereby to the cam shaft, and to the oil pump.   The pump has a 'dog' on the end of its shaft that connects to the drive gear.    But when assembling these parts, the pump must go in long before the others.    Then when inserting  the drive gear, the pump shaft must be rotated so that the dogs match, AND the gear must be inserted several degrees away from this orientation, as the hypoid cogs  between camshaft and drive gear rotate the gear as it descends into place.    The objective of this fiddly manoeuvre is to orientate the drive slot in the face of the gear to match the peg in the end of the Dizzie drive shaft, so that the dizzie is then in the correct orientation, with 1 at six o'clock.

Phew!  A picture is worth a thousand words, but I can't find a  diagram of all three (Pump, drive gear, dizzie) as they are always in different sections of the parts catalogue!

What I'm saying is that it is possible to assemble these parts in as many positions as there are cogs on the drive gear!   That's 16, I think, so the possible error is in multiples of 20 degrees.

I suggest that is your problem, nice guy!   Your cam mistiming is trivial, carb tuning likewise, neither could account for the advance you need to use.     It's the Distributor!   Take it out, look at the slot in the face of the drive gear.   It should be in a "five past seven" position , but note, the slot is slightly offset, which should be to the left, thusly:

Alternatively, just move all your ignition plug leads one place counter-clockwise!  Then re-time!

Simples!

John

Edited October 18, 2023 by JohnD

[johny]

But surely John if the strobe shows the spark coming at 13* BTDC then everything has got to be ok with the dizzy, at least at idle anyway? Or are we missing something....