Club Triumph

Hi Guys, I am trying to sort out my timing I am running a fast road cam, and would like some help how many degrees BTDC with the engine running at 850/950 rpm should I be looking for, this is on my MK3 GT6 with a 2.5 lump thanks.

Advance your distributor till revs rise. Retard distributor just to the point where revs drop again. That should be right.                                                                                                                                                                                                                                                                                                                                                                                                         Laurence

Along those lines, I start like that then road test and adjust until I can make the car "pink" then retard a tiny bit.

I did that on a 4 cylinder fast road cam etc, and when the rolloing road chap tried ti improve it, he couldn't.

Of course, all this relies on the distributor having a decent advance curve. It can be worthwhile testing it, a bit crude but read the advance at idle, 1200, 1500 2000 etc up to about 3000 and compare it to the book curve. Or maybe a TR5 curve which may be more appropriate to your engine? Distributor doctor can supply springs to play with to alter that.

Thanks guys,  that's what I've done the distributor has been upgraded o electronic, I have twisted the distributor until the revs rise then start to drop off, then backed it off a tadge, then checked with the strobe and its way off the scale on the bottom pulley, so I think the previous owner must have replaced the pulley, when I road test I still get a pinking noise, the carbs aren't spot on yet as I need to stick a few miles on then it's off to the rolling road, I am trying to get it as close as posilble before then 

Keep retarding the timing until the pinking stops...

Thanks guys, I shall play tomorrow afternoon

George,

If you are new to GT6s, and Triumph 6s in particular, you may not know that the pully doubles as a crank damper, to suppress torsional vibration.    There is a solid hub and an outer ring, joined by a strip of rubber.

If the rubber loses adhesion, then the outer ring will turn on the hub, and the timing marks become nonsense.    I suggest you check where TDC on No.1 is, using a piston stop - lots on ebay for pennies.

These go into the spark plug hole and are longer, so that the piston contacts it before TDC.   Turn the engine by hand until this happens and mark the outer ring at the timing pointer.  Turn the other way and do the same.  True TDC is exactly halfway between those marks.   If the timing marks disagree, then your damper ringhas moved!   You need a new one, or to have the old rebuilt

I'm studying this problem, and if you get another I would be most grateful for the old one, as I need some "known bad" pulleys for testing!

Good luck!

John

You might also want to check the mechanical advance in the distributor is actually working at all?

With the cap off, gently twist the rotor arm in the direction of normal rotation.  You should get approx 10 - 12º movement (if you have a delicate touch you may even be able to feel two stages of spring pressure).  When you release it it should return fully to it's starting position - twist the other way to make sure it's gone all the way back.

If it doesn't behave as described, especially not returning fully, it needs sorting out before going any further.

Nick

PS There are various distributors, Lucas and Delco, which will physically fit, with various different curves.  As your engine is modified, there is no particular reason why any of them should have the right advance curve for it, though some may be close enough.  Any tuner who tell you that vacuum advance doesn't matter and can be disregarded/ disconnected, even on a road car should be avoided.....

Thanks for your input guys, Nick the distributor has been complety overhauled and is now electronic, and yes I can feel the wee springs as i twist it,

John, I have stuck a bit of masking tape on the dizzy side and marked it where Number one lead is, then popped the plugs out again,  Had a look at ebay Found an old plug popped it in the lathe and ten mins later I have a piston stop gauge, I machined a ball end on a long allen bolt popped it in the old plug, wound the engine over and with a DTI on the allen bolt checked the timing marks all okay, I had to rotate the bolt so that the piston would slide it out of the old spark plug body.

tomorrow is a new test it day I shall keep you all informed, thanks again guys

George,

Impressed  y your handiwork, but that's not a piston stop, its a piston indicator.  And suffers from the same problem(or more?) as using a DTI on the piston crown with the head off.   The dwell of the piston at TDC makes judging exactly where it is difficult.  A stop mesures it EXACTLY.

With your skills, you can put a thread insode the plug body, and a length of threaded rod to fit.  The with a lock nut on the rod, you can set the stop where you like - best is just above mid stroke. 

I'd show a picture, if this site wasn't the least user friendly there is.  How do you post Pics???

John

Yes very true, at least I can measure the movement coming up and when the DTI stops mark the pulley, then do the same going down, 

posting photo's I haven't mastered it yet, sometime's copy and paste works this is the initial setting up, the photo's are always there in the preview but when posted they are missing ?

as I was saying where did the photo vanish to, it was in the preview ??????

A swift update, just done a 30 mile run with no pinking, a little bit of pre ignition when I turn the key off, the oil pressure runs at 20/25psi at a constant 2000rpm, and when I turned the engine off the temp gauge went off the clock, if I leave the rad fan on it cools down fine, when driving 60 mph and around 2k rpm the engine temp is just below the "N", I was surprised to see a wispy jet of smoke coming from the oil cap breather hole, I have fitted an oil catch tank, this was dry, The engine has only done about 80 miles since the rebuild, oh well back into the garage, Who was driving the Black GT6 through Four Marks this morning, I was in the Mimosa one, are you local ?

any ideas what has caused this hot spot 

ok photo vanished AGAIN getting **ssed off with not being able to post photos

it's a hot spot right behind the dip stick next to the coil

now copy and paste don't work 

"...tomorrow is a new test it day I shall keep you all informed"

I'd be really interested in the rolling road results when you get them, particularly what was done to get best results.

Will do Don, we might have to wait a bit though,  I am just pulling the cam out I think I must have a blocked oil way for the paint to blister on the engine block, where the first and second cam journals are

I had similar issues - and may still be chasing the best set up... but at present on a TR5 style cam she won't easily idle much below 1100rpm - when she's at 12* BTDC - with maximum advance about 32.

George,

You're not allowed to post pictures unless you're a member.

Petty, I know, bu that's life.

John

Quoted from JohnD-

George,

You're not allowed to post pictures unless you're a member.

Petty, I know, bu that's life.

John

Only club members can upload photos to the site. HOWEVER everybody can included images in their posts by hosting images elsewhere.  If you have mages on SmugMug, Flickr or similar you can post a link to that.  Just paste the link into the box labelled source, that you will see when you click on the picture icon or that appear after clicking on the insert tab.

Quoted from Guppy916-

Will do Don, we might have to wait a bit though,  I am just pulling the cam out I think I must have a blocked oil way for the paint to blister on the engine block, where the first and second cam journals are

If you've really only got 20 - 25 psi pressure at 2000 rpm you might not have any oil getting to the front two cam journals as they are last in line.  Are you getting any oil to the top end?

You should get at least 20 - 25 psi hot idle (800 rpm)

Nick