Timing mystery - absolutely doing my head in - please help

[Icsunonove]

Right I've timed up loads of engines before (including my 4AGZE a few times) and always found it an easy job that takes only a few minutes...

Not this time...

Garrick's new gold trackcar (Mk1a) had a dodgy distributor so we changed it for the one from Betty (also a Mk1a). Now unfortunately the part number has been rubbed off this distributor but it was fitted to a 1a engine.

On trying to time it up I got it one tooth too advanced and couldn't get it in range. On moving it on one tooth it was too retarded.

I've now gone to extreme lengths to try and find out what is wrong and I have.

Here's the adjustment available:



Now this was measured quickly with a ruler and I estimated that the angular adjustment available was 20 degrees, which would mean an equivalent of 40 degrees crank angle.

Last night I accurately measured the advance range with it a tooth too advanced. I found that the range was 65 degrees BTDC to 28 degrees BTDC. That's a difference of 38 degrees (which is roughly what I was expecting)

Now there are 13 teeth on the distributor drive gear which means 28 degrees between teeth (equivalent to 56 degrees crank angle).

So if you retard it one tooth you would get: 9 degrees BTDC to 28 ATDC, in other words you can't get it in range



Has anyone else had this problem? I am completely at a loss to understand how this can be.

The only solution I can think off is to remove the knock pin from the pinion, move it round half a tooth and weld it back in place!

Anyone got any advice?

[cartledge_uk]

Thats bizare,

Have you checked all the basics first? Leads on the right holes, cam belt on correct, all cylinders firing. Etc. our golf never ran right and the garage put the leads on wrong over 10 years ago and everything was adjusted to compensate and it was running like that for 8 years untill I noticed it


Which dizzy cap do you have? can you slot the hole and rotate the dizzy cap a few degrees to bring into range?

[PW@Woodsport]

not meaning to be an absolute dunce here but you are shorting the diagnostic pins out when trying to time it up arent you? sorry if thats blantantly obvious tom.

Also are you 100% sure the cam timing is correct? ive seen loads of exhaust cams out one tooth (this throws the timing all to hell)

just a few ideas mate

[firstmk1]

Also are you 100% sure the cam timing is correct? ive seen loads of exhaust cams out one tooth (this throws the timing all to hell)

What symptoms would this give?

[Sports Toyota Breakers]

Absolutely F-all power low down.

Jon @ STB

[anthonyg]

Also are you 100% sure the cam timing is correct? ive seen loads of exhaust cams out one tooth (this throws the timing all to hell)

What symptoms would this give?

When i fitted my gze engine it took me ages to figure out why it was slow and wouldn't rev past 5k then upon inspection found the exhaust cam to be a tooth out............

[greglebon]

Tom..

I did PM this, but it seemed reluctant to leave my outbox..!

Looking at the Dizzy I have here, and bearing in mind the drive has 13 teeth, If you remove the roll pin and rotate the drive cog 180 degrees, the adjustment range will be altered, bringing the angle you need into range?

Is it defo on the right way?

If you look at the roll-pin hole from one side, it is in line with a tooth: from the other side it is inline with the gap between teeth........

If its right, then when the dimple in the drive cog (to the right of the roll-pin) is lined up with the mark on the dizzy housing, then the marked tooth on the top sensor wheel (G) should be pointing almost 12 o clock.
The "flat" for the rotor will be at 3 o clock.

Now there is a possibility I may have assembled MINE wrongly, but I did it by the book.......

[PW@Woodsport]

surely unless someone has had the dizzy apart theres no need to do this?

it should be within range from the word go....

[flippin'eck]

Might not be thinking straight here but is there a vacuum advance thingy & could that account for the 'extra' degrees needed?

[edit] scrub that, went and had a look at my spare dizzy in the garage, they don't have a vacuum advance do they

The connector has 3 terminals.., couldn't be that the ecu actually controls the advance by a few 'extra' degrees somehow, like the old vacuum systems? could it?

From reading around it seems it does, but how.. if it's electromechanical (some sort of actuator in the dizzy ) maybe that could account for it?

Just ideas, I'm probably massively wide of the mark

[Icsunonove]

Thanks for replies.

It's still not fixed and even with a different dizzy it is only just possible to get it in range (so there's something wrong somewhere). And as Paul says you can't mix dizzys and engine types (as I have found out personally it won't run properly).

The static cam timing is apparently correct. The marks on the crank pulley are correct. The exhaust cam does not appear to be a tooth out. The inlet cam is not a tooth out.

The timing is being set up with E and T1 bridged. I have a persistent code 11 fault.

Please could anyone who has had a code 11 fault and fixed it please enlighten me.

I think for piece of mind the cam covers should be removed and the cam timing checked. What angles should the cams open and close?

Thanks in advance for any replies.

[OlberJ]

Silly question time no.2

Are the exhuast and inlet cams in the right place?

[PW@Woodsport]

ah i think ive got it.... code 11 is TPS idle switch fault.... from memory this has an adverse effect on the ignition timing,the two go hand in hand,so if the TPS isnt set up correctly or faulty you cant set the ignition timing properly..... i think its that.

[LimeyMk1]

Agree with Paul, we had exactly the same problem with Richard (RedMk1)'s car when we put another engine in. I couldn't get it timed properly and it was the TPS that was faulty.

I've still got a pile of TPS', one of which Paul sent me, so if you need one let me know.

[PW@Woodsport]

be aware a late and early TPS are different....and they wont interchange unless you swap the whole throttle body or just the butterfly spindle.... the TPS drives are at 90* to each other,so a late spec wont bolt to an early.... who knows that may even be your problem!

Has the TPS wiring been cut and a different shaped plug been added?

god i know some useless crap...

[Tony jinxy froude]

Yep ive had the same thing, get the TPS sorted first & the timing will fall into place, the TPS will defo have an adverse affect on timing & will always be at least 10 - 12 degrees out all the time , hope you get sorted tom... by the way, the TPS can be a right royal pain in the ar$e to set up , Jinxy

[Icsunonove]

Really appreciate the replies, thanks all

This is all (possibly) making sense now.....

[IanClements]

Had the same problem for the last couple of years, need to have the dizzy round to full advanced to get normal timing. Will defo check the TPS next week so thanks from me as well!

[System-G]

I didn't realise there were two threads running on this topic. I posted about the TPS findings in the other thread not realising they had been posted here

[greglebon]

surely unless someone has had the dizzy apart theres no need to do this?

it should be within range from the word go....

Sure.....but if its had replacement oil seals, etc..?

Just a thought, thats all.....!

[mr2mk1chick]

Interesting, and nightmare-ish

I hope we can find time to do all this

It kind-of explains why we knicknamed 'Bolly' as 'Bolly-backfire' after a trackday
as it must have been way advanced to make up for a dodgy TPS