Timing Problems

fiveacres · Postby **fiveacres** » 26 Feb 2014 10:47

Hi folks. Looking for some advice re timing on 1980 2.0l motor.
At present when the camshaft is aligned with its timing marks the crankshaft is showing 4 degrees before TDC. I had assumed that when camshaft was at its mark the crankshaft should be at zero.
I believe that an aftermarket performance camshaft was fitted before I bought the car. Would this be a normal setting for a higher lift cam or should I adjust crankshaft to zero.
Any help would be appreciated.

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1980 Persion Aqua Convertible

Workshop Help · Postby **Workshop Help** » 26 Feb 2014 16:55

Once apon a time, in a land far away, I used to campaign across the fruited plains in a 1967 Mercury Comet. It's Ford 200 cubic inch 6 cylinder engine had a case of the wandering timing mark. One day it might read 10 degrees BTDC, the next week it would read 2 degrees ATDC. After some research, it came to pass the rubber portion of the pulley or harmonic balancer had loosened allowing the outer pulley section to move around.

I am starting to suspect our TR7's may have a similar condition. Examining a spare front pulley, there is a rubber insert between the inner section and the outer section. If any deterioration occurs allowing the outer pulley section to move, the timing mark will wander just like the old Ford timing mark would do. If one is unaware of this phenomena, resetting back to the mark will be futile and your idle could increase by some 300-400 RPM.

This is something we need to be aware of and keep an eye peeled for any timing mark variations from the last time the engine ignition timing was set.

Mildred Hargis

Beans · Postby **Beans** » 26 Feb 2014 17:19

They don't "wander" that much, they will fall apart before that.
But it might well bet that your crank pulley is from another car/engine (Dolly 1850 or Sprint).
These have different positioned timing marks, as they use a different timing scale.

<center>

1976 TR7 FHC (needs some TLC ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng
[url="http://www.tr7beans.blogspot.com/"]My full Blog[/url]</center>

Workshop Help · Postby **Workshop Help** » 26 Feb 2014 18:31

While I wouldn't put it past the Speke factory parts boys to do that, this pulley has been on the car since new.

I am also wondering if the springs inside the distributor may be hanging up or the ignition plate is either sticking or sliding in there.

Oh, well, it always something to play around with in these cars.

Mildred Hargis

john 215 · Postby **john 215** » 26 Feb 2014 19:26

Hi,

Retarded cam timing will give better high rev power, but at a guess this was timed up incorrectly when that cam was installed.

The other thing I have come across, not on ' our ' engines I have to say, is if the crank pulley has been loose a at some point then it can wittle away the pulley against the wooruf key on the crank.

Cheers John

LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty Now with an overdrive conversion

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6, BUILT NOT BROUGHT !!!!

jeffremj · Postby **jeffremj** » 26 Feb 2014 21:24

There are a few ways timing drift can happen:

1) chain stretch
2) head skim

Unfortunately, they would give you ATDC rather than the BTDC you have. You can check for stretch if you can lift the chain off the sprocket (vertically) as seen in your picture.

Perhaps the head gasket is an overly thick one - this would move the timing like yours.

I guess it maybe possible that the straight chain guide is not fitted correctly?

The only way to cure your problem, if all else is OK, is to use a vernier cam sprocket.

Beans · Postby **Beans** » 28 Feb 2014 21:02

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by john 215

... The other thing I have come across, is if the crank pulley has been loose a at some point <hr height="1" noshade id="quote"></blockquote id="quote">

Also happens on these engines, when you get an incorrect bolt [B)]

1976 TR7 FHC (needs some TLC ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng
[url="http://www.tr7beans.blogspot.com/"]My full Blog[/url]</center>

dursleyman · Postby **dursleyman** » 01 Mar 2014 09:34

It would be worth checking if the TDC marks are correct and easy to do using a dial gauge in the plug hole. That would confirm the crank timing marks so you have a known starting point.
A lot of performance cams do not use the standard marks and need to be set up to give max lift at a given point, for example 106 degrees after TDC. You have to do that with a dial gauge and you also need to know what the cam maker specified.

Russ

1980 TR7 Sprint DHC
Dursley
UK

http://tr7russ.blogspot.co.uk/

Workshop Help · Postby **Workshop Help** » 01 Mar 2014 11:36

Okay, good people, this is starting to sound like the inspiration for an article to determine true top dead center with it's effect
on the timing marks. Looks like we're going to need to buy a top dead center indicator tool.

Mildred Hargis

Ianc · Postby **Ianc** » 06 May 2014 16:42

Although new to the forum, I am in the process of rebuilding my tr7s engine, and appear to have the same problem, as fiveacres. Please let me know if you have identified the problem. I am considering red rolling the camshaft sprocket to re align the timing marks.

HDRider · Postby **HDRider** » 06 May 2014 22:06

It could also be that the chain is off one tooth. Judging by the photo the timing is off by 8 degrees by the way.

Edward Hamer
Petaluma CA

nick · Postby **nick** » 06 May 2014 22:50

I'm not following any of this. Here are the three things that need to line up. The timing mark on the cam with the mark on the bearing cap. The O degree indicator with the mark on the pulley. The distributor rotor with the rear bolt on the intake manifold. Once those three line up the cam/sprocket and dizy are in the correct position. I don't see where a modified cam makes any difference.

[img][IMG]http://i615.photobucket.com/albums/tt234/nickmi/TR7%201975/Yellow.jpg[/img]
nick
'79 TR7 DHC
'76 TR7 FHC

Stag76 · Postby **Stag76** » 07 May 2014 03:51

<blockquote id="quote">quote:<hr height="1" noshade id="quote">I don't see where a modified cam makes any difference<hr height="1" noshade id="quote"></blockquote id="quote">
It doesn't, unless it's a new cam with the timing mark in a different position (unlikely).

To check TDC, you can make a tool from an old spark plug by grinding off the electrode and forcing or welding a piece of pipe or rod into the bottom of the plug (must be a tight fit if not welded). Insert it into NO.1 Plug Hole, then turn the engine (slowly, by hand) until it stops when the piston touches the tool. Mark the position of the flywheel, and the tooth that lines up with it, then turn the engine the other way until it stops again. Mark the position of the previously marked tooth again, and TDC is when the marked tooth is halfway between these marks. Turn the engine clockwise until the new TDC lines up, then check it against the quadrant on the timing cover. You may have to experiment with the length of the tool you make. If it's too long, the marks will be too far apart to judge properly.

You can also use a dial gauge inserted through the plug hole, but this is awkward.

TR7 Convertible
Sprint Motor
MegaSquirt EFI

Ianc · Postby **Ianc** » 07 May 2014 04:40

With the cam sprocket lined up with the mark on the bearing cap, the timing mark on the crankshaft pulley points to 4 degrees before TDC when the timing chain is fitted. There is no adjustment because the timing chain is taut between the cam and crankshaft sprocket. It appears to me that either head gasket is extra thick, cam has a different timing mark on the shaft or something else that I haven't thought of yet.

jeffremj · Postby **jeffremj** » 07 May 2014 06:12

<blockquote id="quote">quote:<hr height="1" noshade id="quote">There is no adjustment because the timing chain is taut between the cam and crankshaft sprocket.<hr height="1" noshade id="quote"></blockquote id="quote">Have you removed the timing cover to check to see if 148115 is fitted correctly? It could be pushing into the chain and changing the length of chain between sprockets:

Finally, someone may have slotted the timing marker so that it can be misaligned:

Anonymous

Timing Problems

Timing Problems

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