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TSI 275-4 camshaft timing

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75 Tryota Avatar
75 Tryota greg sterling
Hoping someone out there has already done this and can give me some reassurance in my installation. Established TDC using positive stop method and attached degree wheel to crank and pointer to block. Set crankshaft to 6 degrees BTDC. Installed dial gage on #2 lifter with a preload of .100 mm. Rotated camshaft to get to 1.270 mm lift (2.270 on gage with .100 preload). Installed new chain and cam gear taking care to take up slack on tensioner side.
Rotating engine in clockwise direction I repeatedly get 1.270 mm (.050"winking smiley at 6 degrees, which is good.

I would like to have a second way to confirm that things are in correct orientation. Paul Geithner has listed some specs for the cam, but his numbers are indicated by gray color to be unconfirmed.

I come up with :
.39 mm (.015"winking smiley lift at 28 degrees BTDC opening
1.270 mm (.050"winking smiley lift at 6 degrees BTDC
.73 mm (.029"winking smiley lift at 67 degrees ABDC
8.52 mm peak lobe lift at 112 degrees ATDC

These are all reasonably close to Paul's proposed numbers, but none are right on. The 1.270 mm at 6 degrees is spot on for what cam paperwork notes.

Anyone have known good specifications for this cam? A good way to double check? I was thinking peak lobe lift would give a good second reference point, was not sure if that is taken to be the centerline of the peak or when the cam first reaches it's peak value.

Any help would be appreciated!

Thanks

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spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
Greg,
2.270 -.100 is 2.170 not 1.270 Something isn't right.
All the best,
Paul

75 Tryota Avatar
75 Tryota greg sterling
apologies, pre-load is 1.00 mm, not .100

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tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
If this is a "symmetrical" camshaft (both cams the same, both sides the same). Then "Equal Lift on Overlap" will set your can, or let you check it. Save me 'typing' a long explanation on my phone by looking it up! Lots of descriptions online.
John

75 Tryota Avatar
75 Tryota greg sterling
Thanks, John. I located your previous post on ELOO method and I will get another dial indicator and give that a try. Am I correct in assuming that when I am done, in addition to having ELOO at TDC, when I rotate crank clockwise to 6 degrees BTDC I should have the cam makers stated 1.270 lift at that reference point, thus providing a double check?

TheZster Avatar
TheZster Steven Z
SAINT LOUIS, MO, USA   USA
1978 Triumph 1500 "BLK-BRY"
While all my documents are in storage - I recall that the 275-4 is not recommended by Ted to use the ELOO method..... Can't recall the specifics (do a archives search - you'll find the thread) - and have not done the calculations myself. I put the 275-4 in Blk-Bry last summer.... following the directions provided as it appears you did..... However - before I could get everything squared away properly... I had to put the car in storage. Unfortunately, following the directions provided (unless I screwed up somewhere) caused what seem to be timing issues..... At the time I put her in storage - I was still having to set ignition timing way - way advanced (like 20 - 25BTDC) to get her to even think about starting.... I was going to quadruple check my install but relocation project got in the way...…

Z

75 Tryota Avatar
75 Tryota greg sterling
Interesting information, thank you. That is exactly why I was hoping to have another way of confirming correctness of installation other than just the 1.270 mm lift at 6 degrees BTDC. I have emailed Ted to see if he has a secondary way to check.
It concerns me that I am getting peak lobe lift at 112 degrees, not 110 degrees. of course I have no idea whether that is a meaningful difference or not ! Not sure if peak lobe is to be center of peak or when it first reaches peak.
Thanks to all for their help and apologies to all for my ignorance.

tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
In reply to # 1595775 by 75 Tryota Thanks, John. I located your previous post on ELOO method and I will get another dial indicator and give that a try. Am I correct in assuming that when I am done, in addition to having ELOO at TDC, when I rotate crank clockwise to 6 degrees BTDC I should have the cam makers stated 1.270 lift at that reference point, thus providing a double check?

Yes, unless you have a rubber camshaft!

Cam tuners may shft the timing, which will move the peak power band up and down, so I don't know if that is what your grinder intended, but ELOO is the usual, for symmetrical cams. Easy to shift the tune on modern engines with open cam belts, not so with a chain drive.

JOhn

75 Tryota Avatar
75 Tryota greg sterling
I did specify the non-rubber camshaft when I ordered it !

14GPDJENGINEERING Avatar
Silver Spring, MD, USA   USA
In reply to # 1595809 by 75 Tryota Interesting information, thank you. That is exactly why I was hoping to have another way of confirming correctness of installation other than just the 1.270 mm lift at 6 degrees BTDC. I have emailed Ted to see if he has a secondary way to check.
It concerns me that I am getting peak lobe lift at 112 degrees, not 110 degrees. of course I have no idea whether that is a meaningful difference or not ! Not sure if peak lobe is to be center of peak or when it first reaches peak.
Thanks to all for their help and apologies to all for my ignorance.

Two degrees can make a difference. I suggest aiming for 108 to 110 degrees -- center of peak lift. You can do with only one dial indicator.

By rearranging the equation :

Inlet centerline = (inlet duration/2) - inlet open

to; inlet open = (duration/2) - inlet centerline

measure the duration at 0.050 lobe lift

also see this thread ---- https://www.triumphexp.com/forum/spitfire-and-gt6-forum.8/dial-indicator.925936.926182/#msg-926182



Dennis smiling smiley



Edited 2 time(s). Last edit at 2019-02-11 01:40 PM by 14GPDJENGINEERING.

75 Tryota Avatar
75 Tryota greg sterling
I will try to get back on the motor tomorrow and re-check everything. Can't try ELOO until I get another TDI. Will noodle around with some of the information you have all been kind enough to provide.

Just for fun, consider this logic and let me know if am I way off base for even thinking of it. I have already established TDC on crankshaft using positive stop method, which most agree provides the most accurate result. With timing chain off, if I attached a degree wheel to the camshaft, then created a positive stop for the inlet lifter, I could then determine "top dead center" for the camshaft, which should be the lobe peak, in a similar fashion to what was done with crankshaft. Once the camshaft is at lobe peak, I would then rotate the crank to 110 ATDC and install timing chain without moving the camshaft from it's lobe peak location or crankshaft from 110 ATDC.

Any reason this shouldn't work? Since measuring with TDI's can be a bit tricky and costs a few bucks if you don't have any, this might cost less and provide better results. Of course that all depends on whether I can use lobe peak at 110 ATDC as a setting point.

I would just really like to have a second reference point to prove that my camshaft location based on 1.270 mm (.05"winking smiley at 6 degrees BTDC is correct before slapping it all back together.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1596020 by 75 Tryota I will try to get back on the motor tomorrow and re-check everything. Can't try ELOO until I get another TDI. Will noodle around with some of the information you have all been kind enough to provide.

Just for fun, consider this logic and let me know if am I way off base for even thinking of it. I have already established TDC on crankshaft using positive stop method, which most agree provides the most accurate result. With timing chain off, if I attached a degree wheel to the camshaft, then created a positive stop for the inlet lifter, I could then determine "top dead center" for the camshaft, which should be the lobe peak, in a similar fashion to what was done with crankshaft. Once the camshaft is at lobe peak, I would then rotate the crank to 110 ATDC and install timing chain without moving the camshaft from it's lobe peak location or crankshaft from 110 ATDC.

Any reason this shouldn't work? Since measuring with TDI's can be a bit tricky and costs a few bucks if you don't have any, this might cost less and provide better results. Of course that all depends on whether I can use lobe peak at 110 ATDC as a setting point.

I would just really like to have a second reference point to prove that my camshaft location based on 1.270 mm (.05"winking smiley at 6 degrees BTDC is correct before slapping it all back together.

If the head and valvegear is on the motor, you don't need DI to perform ELOO, just a set of feeler gages, and a degree wheel.
(The factory markings only work with the original parts from that individual motor).

I just got a new MSC catalog in the mail, on p. 41 I see a DI for $11.99, measures to 0.001", which is all you need.
If you want to play baseball, you need a bat, ball, and gloves.
If you want to work on cars, you need tools.

BUT, as previously mentioned, the TSI cam is not symmetrical and so cannot be timed using ELOO.

Accurately finding max lift on a cam lobe without an instrument is very, very hard to do, tougher than finding crankshaft TDC.
And since the TSI cam lobe profile is not symmetrical, you cannot use a stop to find it either.


Attachments:
Triumph ELOO cam timing.pdf    63.1 KB

75 Tryota Avatar
75 Tryota greg sterling
Already purchased second TDI. Is it a known fact that TSI cam is not symmetrical? There seemed to be some question regarding that point.
Just trying to come up with a good method of confirming that what I have measured as 1.270 mm (.050) at 6 degrees BTDC is indeed that.

Thanks!

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1596084 by 75 Tryota Already purchased second TDI. Is it a known fact that TSI cam is not symmetrical? There seemed to be some question regarding that point.
Just trying to come up with a good method of confirming that what I have measured as 1.270 mm (.050) at 6 degrees BTDC is indeed that.

Thanks!

If it was symmetrical, Ted (who has been working on Triumphs even longer than I have) would not have told you that ELOO will not work, and to use a different method.
But why not just ask him?

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