Timing marks

[Tonyloz]

Hi

Ive just fitted a narrow belt system and have now found i havnt got any timing marks

TDC not a problem but has anyone worked out where to mark the pulley for the strobe to set the ignition timing?

Thanks

Tony

[Fireman049]

Hi Tony ~

 

I did the same on my 3A. I've only got the TDC mark but when you use a tuneable strobe light then you reposition the timing mark

with the distributor to the TDC setting when you've dialled up the new timing setting.

 

Hope this helps ~

 

Tom.

Edited March 11, 2018 by Fireman049

[Lebro]

I carefully stamped some marks at 5,10,15,20,25,&30° BTDC, & 5, &10° ATDC before fitting my narrow belt pulley

 

Bob.

[peejay4A]

No need if you have a timing light that allows you to dial in advance. Just set your desired advanced and turn the distributor to bring the timing mark to TDC under the strobe.

[Don H.]

^ This.

[Ian Vincent]

+1 for Bob's solution.

 

Rgds Ian

[Z320]

I own a tuneable strobe light, but made marks on tin belt pulley anyway:

this is very usefull to see the ignition point fast running back and forth by pushing the carbs

with the strobe light on 0°

photo deleted because of limited data base at the forum

A notch is 5°, a bore is 10°

 

edit:

I found the original 0° bore on the Pulley NOT at 0° on my TR4A - but on 1°,

that's why the first notch for 5° seems to be a little bit to close to the original 0° bore.

Edited May 30, 2020 by Z320

[Tonyloz]

So what setting are most people using?

[Ian Vincent]

I have mine set at 11 deg BTDC when idling at 850 rpm.

 

Rgds Ian

 

PS I set it originally by advancing the ignition till it pinked when pulling uphill in top and then backing it of a bit.

[John McCormack]

Very few sidescreen TRs are still stock standard or the same; rebuilt engines with different pistons, extractors, compression changes, cylinder head upgrades, cams, carbies, electronic ignition and modern fuels all affect the optimal timing for each car. None are the same.

 

I set the timing at about 10 deg advance at 800rpm idle. I then advance it bit by bit on the road until it just pings under load. Back it off a degree or two at a time until it doesn't ping. I expect you will get much more power and a smoother idle.

[peejay4A]

Seems a bit far advanced. Iirc the books says 4 degrees BTDC for a 4 cylinder engine but I guess if it will take more advance without pinking then fine, as long as maximum advance doesn’t go too high.

[Tonyloz]

Its a 2.2 with hs6 carbs and a tubular manifold

Standard head and cam at the moment

The rest is tr3a

So will that be different?

[Drewmotty]

Hi Tony

My 3a has HS6 carbs with SM needles, mildly reworked head, 4a inlet, std cam and tubular exhaust so is very similar to yours.

You will need a 10 degree cam in the distributor with final advance set to 32 degrees giving 12 degrees at idle.

Blanking the vacuum advance may give slightly better response at the expense of a couple of mpg on long runs.

You shouldn't experience any pinking with premium price point fuels.

You can ignore the manual as those settings were for old school fuel in a standard engine.

Andrew

[Tonyloz]

Andrew

I dont suppose i could ask you to measure the length of your SM needles?

Just the length protruding out of the bottom of the piston

Thanks

Tony

[Lebro]

44mm from step to tip, parallel part is 11mm so total length = 55mm.

 

Bob.

[Tonyloz]

Thanks for all the info guys

I can now set about getting it to run correctly!

[Drewmotty]

Ill take a look later today.

[Drewmotty]

Here's mine Tony.

[Tonyloz]

Many thanks Andrew...really appreciate you taking the time to do this for me

I now know I've got the correct set up

Tony