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2.5l timing weirdness

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SpitnSawdust Avatar
SpitnSawdust Richard Simpson
Lewes, east sussex, UK   GBR
1969 Triumph Spitfire MkIII "Little Blue"
So i rebuilt the engine and checked the cam timing and the front pully tdc about 4 times.
Yet when i come to set up the ignition timing it wont start or idle smoothly until i give it about 20 degrees plus advance! Spent hours dicking about with a 123 unit trying to get it to run right with the "proper" timing numbers. Just plonked the old dizzy back and twisted it till it worked and the vacuum gauge settled at 20ish but the timing light shows it really advanced.
Would a non standard cam affect the timing that much or can the pully damper twist as a result of torquing up the pully bolt?

Cheers
Rich

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clshore Carter Shore
Beverly Hills, FL, USA   USA
The 6 cylinder front pulleys are not solid, they are dampers that employ a 2 piece construction, bonded together with a layer of rubber between.
With age, the rubber deteriorates, and the outer rim (having the timing marks) 'slides' out of position with respect to the inner hub.

The purpose is to damp torsional vibration and flexure of the crankshaft, preventing breakage.

Not sure about current availability, but they are rebuildable by specialists.

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Lizzard d id
san jose, CA, USA   USA
In reply to # 1601999 by SpitnSawdust So i rebuilt the engine and checked the cam timing and the front pully tdc about 4 times.
Did you use a piston stop method to find / set tdc ?

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TriumphFan Avatar
TriumphFan Silver Member Jim S
Cumming, GA, USA   USA
1967 Triumph GT6 MkI "Cantankerous"
In reply to # 1602002 by clshore The 6 cylinder front pulleys are not solid, they are dampers that employ a 2 piece construction, bonded together with a layer of rubber between.
With age, the rubber deteriorates, and the outer rim (having the timing marks) 'slides' out of position with respect to the inner hub.

The purpose is to damp torsional vibration and flexure of the crankshaft, preventing breakage.

Not sure about current availability, but they are rebuildable by specialists.

I would not reuse a 40 yr. old damper. I had mine rebuilt by DamperDudes for a little over $100. They don't have any in stock so you'll have to send them yours. Turnaround is fast.



"If you didn't build it, it's not really yours"

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SpitnSawdust Avatar
SpitnSawdust Richard Simpson
Lewes, east sussex, UK   GBR
1969 Triumph Spitfire MkIII "Little Blue"
Yep. Made one from a plug and used a degree wheel.

In reply to # 1602019 by Lizzard
In reply to # 1601999 by SpitnSawdust So i rebuilt the engine and checked the cam timing and the front pully tdc about 4 times.
Did you use a piston stop method to find / set tdc ?

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SpitnSawdust Avatar
SpitnSawdust Richard Simpson
Lewes, east sussex, UK   GBR
1969 Triumph Spitfire MkIII "Little Blue"
And i took a photo the last time to remind myself i had defo checked it...

In reply to # 1602019 by Lizzard
In reply to # 1601999 by SpitnSawdust So i rebuilt the engine and checked the cam timing and the front pully tdc about 4 times.
Did you use a piston stop method to find / set tdc ?


Attachments:
IMG_20190308_154912.jpg    41.3 KB
IMG_20190308_154912.jpg

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TheZster Avatar
TheZster Steven Z
SAINT LOUIS, MO, USA   USA
1978 Triumph 1500 "BLK-BRY"
Same quandary here.... I installed my new cam- checked it 3 ways to Sunday - over and over... used the piston stop - calipers - etc..... Yet still have an issue with my timing.... (way, way to advanced)…. Now I'm down to deciding if I interpreted .05 lift @ 4 BTDC properly..... I've checked my cam timing 5 times (.05@ 4 btdc) - yet something - "something" is off..... My TSI cam recommends not using the ELOO method.... so I followed their directions to the letter....

Good luck - and hopefully someone will shed light on your issue - and I will be watching closely...

Z

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SpitnSawdust Avatar
SpitnSawdust Richard Simpson
Lewes, east sussex, UK   GBR
1969 Triumph Spitfire MkIII "Little Blue"
Phew... Not just me then.
I also used ELOO on the cam.
And the picture shows the pully mark is bang on with the piston stop tdc on the degree wheel(the middle green marking).
And yet it wont run right until i advance it off the scale!
Im resigned to tuning it by "feel" in conjuction with the vacuum gauge.
Anyone want a timing light?

I suppose the damper could be moving off piste when the engine is running but if it was that knackered id expect to be able to wobble it around. And i cant imagine it moving back when the engine stops.

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TheZster Avatar
TheZster Steven Z
SAINT LOUIS, MO, USA   USA
1978 Triumph 1500 "BLK-BRY"
In reply to # 1602078 by SpitnSawdust Phew... Not just me then.
I also used ELOO on the cam.
And the picture shows the pully mark is bang on with the piston stop tdc on the degree wheel(the middle green marking).
And yet it wont run right until i advance it off the scale!
Im resigned to tuning it by "feel" in conjuction with the vacuum gauge.
Anyone want a timing light?

I suppose the damper could be moving off piste when the engine is running but if it was that knackered id expect to be able to wobble it around. And i cant imagine it moving back when the engine stops.

I can't use ELOO.... on my cam... but sounds like I did pretty much what you did... and checked it 6 X to date..... Still requires major advance to get her to run.... Something is off.... Just got to figure out what..... Blk-Bry is in storage till second week in May - at which time she goes into a friends racing shop for extensive "figuring out"..... I'll keep you advised.... At the moment - all I can think is "what changed"... that being the cam install (as well as new pistons, new head, new rods, new crank, yadda, yadda)… but none of that should affect timing other than the cam install..... I'm close - just not there quite yet..... I'm at the frustration point of questioning if I can tell 4BTDC from 4 ATDC.... LOL... though I know better.....

Z

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SpitnSawdust Avatar
SpitnSawdust Richard Simpson
Lewes, east sussex, UK   GBR
1969 Triumph Spitfire MkIII "Little Blue"
As far as i can tell the specs on my cam dont match the stanpart stamp it has so i suspect its been reground.
So it could be asymmetrical in which case eloo is out the window.
Unfortunately when i swapped it into the new block i assumed it was stock and didnt bother marking everything up.

I can get it to work and it will shift but i really wanted it all to spec. Maybe i need to embrace the art rather than the science of the crap old car!

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Guppy916 Avatar
Guppy916 George G
Alton, Hampshire, UK   GBR
Hi I think you'd best start from the beginning here's my instructions,


Attachments:
cam timing 1.pdf    257.3 KB

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Lizzard d id
san jose, CA, USA   USA
In reply to # 1602085 by SpitnSawdust As far as i can tell the specs on my cam dont match the stanpart stamp it has so i suspect its been reground.
So it could be asymmetrical in which case eloo is out the window.
So lets look at the cam ?
You have a timing wheel and the rockers are on .

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GT6M Avatar
GT6M Markus Bewley
Scaryport, Cumbria, North West Englandshire, UK   GBR
got t,ask if the frunt pully, and,or timing gears are OE an oft same car.

this meb,e help ye see wot im on aboot.



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Posted December 21, 2017

mebe a wee bit of info eer, IF ye got a mix an match set,!!



theres a variation on duplex timing wheels

The timing marks on all OEM duplex 2.5 saloon enignes an late TR6 are,t same as they use the same camshaft installation figure - i.e. 110 degs - so ye can take a duplex top/bottom sprocket frae a 2.5 saloon and fit to a GT6/Vitesse wid a standard mk1 mk 11 & mk 111 cam as they use 110 degs aswell { asuming you are using a matched top/bot sprocket from the 2.5 + to be 100% sure check the 'mark' on the front plate }

The 150 bhp TR5/TR6 OEM duplex wheel is idential apart frae,t fact that the 35 - 65 cam has an install of 105 degs hence the timing marks are different

so ,potenially if you have a 2.5 saloon bottom wheel and a TR6 top sprocket and align them with the timing marks you could be 10 degs out



caught me oot a lang lang time ago, an took some sussing oot,!!!



Scaryport, Cumbria, Farr Northwest Englandshire, UK

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GT6M Avatar
GT6M Markus Bewley
Scaryport, Cumbria, North West Englandshire, UK   GBR
ohh, easiest way really is the full lift on no 1 inlet valve, direct oft follower.
no when cam starts t,open valves

ie, OE, full lift on cam, 232 or 250 thou,
put crank to where it shoild be in degs BTDC, 110 or early 5/6 105
and fit pulllys

as long as ye got a time in fig,its simples

AND, i tek it ye timed the cam of NO 1 inlet, { 2nd valve } and not NO 1 valve, which would be an exhaust
ye wont be the first or the last t,de this, !!!

f,git all about the lift at 50,or other ways,
full lift direct oft cam is the easiest an t,me accurate way of dooing it

Also, ev ye got the dizzy in the right spot, and or the actuall fire order, 153624
as if its no right, then the arm can be between 2 posts, an actually cross fire between 2 cyls
so check where the dizzy arm is pointing to,
say no 1 cyl on comp stroke, an at say 10 degs ont frunt pully, then rotor should be point,n t, no 1 lead, meb,e a wee bit just in front, but deffo no after it

M



Scaryport, Cumbria, Farr Northwest Englandshire, UK



Edited 2 time(s). Last edit at 2019-03-17 04:20 AM by GT6M.

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SpitnSawdust Avatar
SpitnSawdust Richard Simpson
Lewes, east sussex, UK   GBR
1969 Triumph Spitfire MkIII "Little Blue"
Your right about mix and match. I ignored the marks and did the cam off equal lift on 11/12.

I startex with the dizzy at 7oclock #1 tdc firing....ill go and see where it ended up to get it to run ok.
Pics to follow...
Cheers
Rich

In reply to # 1602557 by GT6M got t,ask if the frunt pully, and,or timing gears are OE an oft same car.

this meb,e help ye see wot im on aboot.



Report post

Posted December 21, 2017

mebe a wee bit of info eer, IF ye got a mix an match set,!!



theres a variation on duplex timing wheels

The timing marks on all OEM duplex 2.5 saloon enignes an late TR6 are,t same as they use the same camshaft installation figure - i.e. 110 degs - so ye can take a duplex top/bottom sprocket frae a 2.5 saloon and fit to a GT6/Vitesse wid a standard mk1 mk 11 & mk 111 cam as they use 110 degs aswell { asuming you are using a matched top/bot sprocket from the 2.5 + to be 100% sure check the 'mark' on the front plate }

The 150 bhp TR5/TR6 OEM duplex wheel is idential apart frae,t fact that the 35 - 65 cam has an install of 105 degs hence the timing marks are different

so ,potenially if you have a 2.5 saloon bottom wheel and a TR6 top sprocket and align them with the timing marks you could be 10 degs out



caught me oot a lang lang time ago, an took some sussing oot,!!!

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