How to time your cam in
Turbo Mini Forums

Well today I have spent a few hours in the garage timing my cam in. I thought I'd write a quick guide on how to do it for those of you that are not familiar.

First off I made some supports to hold my engine clear of the bench to allow the crank to turn. I don't have an engine stand and I have not put the engine onto the gearbox yet hence the need to do this. I knocked these up out of a bit of timber I had in the garage.



Sorry for the poor quality, think I have buggered the pictures up when I resized them.

Next job I did was to check the piston to deck height while I had the clock out. This is worth doing to make sure that there is nothing drastically wrong with your build.
Firstly I set the clock up and zeroed it on the block deck surface.



Then I moved it to above the piston raised area, and then turned the crank till TDC was achieved on the clock. I was then able to read off the distance the pistons were down the bore.



As standard, I believe the pistons come to 40thou down the bores. My engine had the top of the block flashed to clean it, the deck height ended up at between 26 and 27.5 thou down the bores. I was happy enough that these were all close enough together.
I also checked the crank endfloat using the clock on the end of the crank nose, and lifting the crank against the thrust washers with a lever in the webs. I got 3 thou which is mid limit.
Next job was to check the cam endfloat. I did this again with the clock by placing it on the end of the cam with the nut tightened, and then lifted the cam carefully with a lever. I got 3 thou endfloat after I adjusted it, which is bottom limit.



After that, I also checked the timing gears for alignment, by setting the clock up on the cam gear tooth edge, and then carefully re-positioning the plunger over the crank gear. I found them to be 30 thou out of line and so I was able to correct them to within 2 thou using selective assembly with shims.



Next up was to fit my timing disc pointer. I made this some years ago by welding a piece of rod to the end of a 5/16 UNF bolt. I then filed a point on the end. The bolt is then screwed into one of the timing gear holes in the block, and a locknut used to secure it at the right length to meet the timing protractor.



I then fitted the timing protractor. I also made this a few years ago, by drilling a 5mm hole in the end of an old crank pulley bolt, and then tapping it M6. This allows the timing protractor to be bolted onto the large bolt. Simple enough but works well, as it allows the disc to easily be adjusted.



The next step is to find TDC using the clock in a similar manner as I did when checking the deck height. This allows you to set the protractor up correctly so as it reads TDC when the engine is at TDC.



Once I had done this, I put the clock in place to measure full cam lift. This allows you to then read off the protractor the point at which full lift occurs, and hence adjust your timing wheels to get full lift where you want it. On the cam I am using full lift was recommended to be at 110 degrees. You will notice I am using a length of stainless rod down into the follwer, usually I would use a pushrod but the ones I had with this engine were fubar'd so I binned them long ago. I have yet to get any more hence had none to use to do this with! If anyones got a set of GOOD pushrods (e.g. no 'pip' on the end due to wear) they want to sell PM me!



There is a little variation to be done on most cams, as most reach full lift and then dwell for a short period, maybe 10 or 15 "crankshaft" degrees. My cam was no exception. Therefore it is needed to take a reading of when the cam first reaches max lift, turning the engine in both directions. For example, if a cam was theoretically supposed to be at max lift at 110 degrees, but had 10 degrees dwell, then you would set it so that it reached max lift at 105 degrees, and stayed there till 115 degrees, hence 110 being the mid point of the full lift period.

I have read a few other methods of timing cams in, but that is the one I use and it seems to have worked fine when I have done it in the past.

Cheers! Tom.

Edited by Tom Fenton on 13th May, 2005.

also tom you could use a peice of wire say to use as a zero indicator by winding this around a bolt and bending this to point to zero.

if you dont want to fab anything.

Tom, if you want to send me the big image files, I could host them for you for better quality... dr.jing<at>gmail.com

**************************************
1967 Cooper 's' Turbo build @ www.drjing.com

I cannot understand how you can masure the piston to deck height with such a device. To measure, you'll have to move it around, which cocks up the accuracy.... Or???...

you'd hope the deck was flat enough to do it that way. Personally id use a depth mic but cant see it being much out with a clock.

Are you rocking the piston when it's at TDC to get the average deck height or just taking the first reading. ?
Pistons rock on the little end which can lead to a false deck height reading and trouble further down the road if not check correctly. And it gets worse the older and more worn the bores get.

Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe.

I did take it a few times to make sure, taking them up to TDC from both directions. Its a freshly bored block and new pistons so should be as good as possible at the moment (I hope)

Sounds OK, I guess. I've never tried it. TBH I guess it's close enough for our crude engines anyway :)

I think its worth metioning that the engine turns clock wise when viewed from the cam pulley end.

Also the cam is timed in with peak lift ATDC (not BTDC like i have been trying to tim mine for the last half hour)


you'd think i'd know this the amount of cams i've timed in.... must be the thinners fumes!

I think it's also worth mentioning, from a very recent post, that those photos would NOT have passed the "V" test

Schrödinger's cat - so which one am I ???

On 24th Nov, 2008 Rod S said:
I think it's also worth mentioning, from a very recent post, that those photos would NOT have passed the "V" test

Yes i moved to the darkside

Instagram @jdm_brett

Yeah. These are infact the most rubbish pictures I've seen in quite some time.

I demand this thread deleted. What's the point of illustrating something so badly that it only creates confusion :)

http://www.youfail.org/

Edited by Vegard on 24th Nov, 2008.

Video that may come in handy!

http://uk.youtube.com/watch?v=la6-EgnCOl4&feature=related

I watched the Bill Sollis building "1380 A-series" DVD yesterday. He explains it well too.... (eventhough he got in trouble with which way the cam should be rotated! LOL)

Dazed and Confused....

point of interest. the kent double row chains can and will stretch quite a bit, as i have found out..

in this case the cam was retarded about 5 degrees, causing all kinds of grief with fuel standoff

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Tom, Been doing a search and reading this guide as I'm going to change the CAM in my engine for an SC specific one. A couple of questions?

- Do you DOT-to-DOT to start with to get things into sync?(I'm thinking of off set keys rather than your setup). Then take the measurements to see how far out you are? (I noticed you didn't have a chain on in the pics but it might just be the pics :) )

- How did you shim the cam for end float? under the triangle plate?

- Was the Dwell figure with the cam?


Thanks for any help.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

yep, dot to dot is the usual way to timing the cam in, a bit crude though, hence the above methos for a 'degree of accuracy'

you should set the cam end float as per haynes (no idea what that is offhand)

most cams come with info re their timing

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Dot to dot is the easy way to start, then you set your protractor to your pointer and TDC, then measure where full lift is. Then you can adjust either with offset keys or vernier setup.

Well timed my new cam in today. I found the attached vid very useful as I finally understood how you take the guess work out of finding the middle of the dwell, for both crank and cam

I got my offset key in the wrong way at first which was good as it confirmed all my timing figures.
The std gear was at 111, the cam wanted 106 and I got 106.5 with the key after first going to 117. so very happy chappy.

I used the TM cam timing disc worked a treat.

http://www.youtube.com/watch?v=la6-EgnCOl4&feature=related

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Thanks again Tom referenced this guide again to time my new cam in three years to the day... Spookey?

Happy chappy again.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Edited by Turbo This.. on 11th Mar, 2013.