Installing Cam Chain and Timing Engine - Alternative Method

[ukkid35]

I really hate the WSM method for installing the cam chain and timing the engine:

Set the crank midway between Even/Odd TDC

Install both cams at valve overlap

Reverse crank past Even TDC then turn clockwise to Even TDC

Set Even Cam at 1.5mm advance (or not as case may be)

Turn crank clockwise to Odd TDC

Set Odd Cam at 1.5mm advance (or not)

The problem is that nothing turns easily, the cams stick, the tensioner struggles in reverse, the chain jumps teeth

Everything is working against this happening easily, and my blood runs cold every time



This time I have chosen to time the engine differently:

Fit the timing cover, with the cam chain and sprockets in place, but the cams not installed

Fit the Sprocket Retainer on the Odd bank

Set the crank just before Even TDC (by 3 or 4 degrees)

Fit the Even cam as per WSM (either with lifters 1.5mm diff, or even depending on preference)

Turn crank 360 and recheck lifters (it will now be one of the other cylinders where the lifters are rocking)

Adjust as required, repeat until correct

Now do the same for the Odd bank

Set crank just before Odd TDC, making sure that this is immediately after Even TDC with cylinder 8 lifters rocking

Install Odd cam as per WSM

Adjust as required

If at any stage during the adjustment of either side you need to turn the crank anticlockwise, make absolutely sure the tensioner bolt is fitted and adjusted correctly

The Sprocket Retainer will need to be pretty robust if you need to turn the crank anticlockwise during Even cam timing

Typically the Sprocket Retainer is merely static and has no dynamic forces acting on it when checking valve clearance, this is different

This was so much easier than the WSM method that I have used several times, and much quicker as well

Edited by ukkid35 on Thursday 22 November 20:54

[ukkid35]

Out of my 4600 posts on PH, this is probably the only one that has real value to an AJP8 owner

Sadly it has had no traction at all

Oh well

[spitfire4v8]

I've always thought an old worn out cam with all the remaining lobes ground off would make a good tool for setting the cams up. Ie you use one good cam that you're going to be using in one side of the engine, use the smoothed cam in the other side, set the good cam up, then remove the smoothed cam, replace with a good cam,and set it up.
Allows you to turn the engine over with correct chain alingment and no risk of chain/sprocket coming apart.


As an aside, I had an AJP on the dyno a few weeks ago where the cams were timed in incorrectly, that engine gained 105bhp at 4000rpm (with a bit of induction length changing too).

[phazed]

ukkid35 said:

Out of my 4600 posts on PH, this is probably the only one that has real value to an AJP8 owner

Sadly it has had no traction at all

Oh well

I think this just shows that very few people will attempt this and is probably over most peoples heads.

Timing an RV8 is fiddly enough.

Great work though.

[tofts]

Is there a reason no one chooses to use a dial gauge and degree wheel? This would surely be a more absolute method!

[spitfire4v8]

Yes i do (sometimes, I have other methods too .. degree wheel in the engine bay is awkward if all you want is to get a cam timed in at straight up timing) .. but this method described by ukkid is to get the cams somewhere near to begin with before the refining of the timing. TVR give you no marks so you're a bit on your own in that respect other than the WSM for getting the cams in there in the first place.

[ukkid35]

spitfire4v8 said:

As an aside, I had an AJP on the dyno a few weeks ago where the cams were timed in incorrectly, that engine gained 105bhp at 4000rpm (with a bit of induction length changing too).

Spectacular!

I guess with the timing that far out there was a significant chance of piston valve contact

[spitfire4v8]

Yes .. in fact when turning the engine anti clockwise by hand it locked up so it was very close.

[TwinKam]

spitfire4v8 said:

Yes .. in fact when turning the engine anti clockwise by hand it locked up so it was very close.

What do you reckon the margin for error is, in tooth terms? (...let's just say in correct rotation, to eliminate chain slack issue).

[natben]

I am afraid cam timing is way beyond my mechanical ability, still enjoy reading about it and trying to understand it though.

[Jhonno]

I ended up doing something similar with mine, the WSM wasn't working for me.

[ukkid35]

Some photos of the 'pretty robust' sprocket retainer that my dad made for me me (which gives me confidence when turning the crank anticlockwise)

Edited by ukkid35 on Sunday 1st March 19:11

[pmessling]

Must get round to making one. Thanks for the images Paul.

[Bogsye]

Followed this on my rebuild, and it certainly was much easier than the factory instructions. From the previous messing around on my 12k service, I managed to get each bank timed correctly first shot.

Thanks Paul, for taking the time to write this up.

Brian

[M3cerbera]

Maybe if you ever do it again a video would make it a very interesting viewing

[Jhonno]

What is the dia of the bar?

[ukkid35]

Jhonno said:

What is the dia of the bar?

I think it's the same as the journals, about 1"

I'll check later

[Jhonno]

ukkid35 said:

Jhonno said:

What is the dia of the bar?

I think it's the same as the journals, about 1"

I'll check later

I don't know what they are either..

[NuddyRap]

I'd happily give it a go myself were it not for my recent expensive rebuild, so I appreciate your guide even though for a while it won't be something I'll use.

I suspect it is perhaps increasingly beyond the skill or interest of many owners on here, but invaluable.

[ukkid35]

Jhonno said:

What is the dia of the bar?

Here's the design that I sent to my dad, along with the tool that I'd been borrowing from a generous PHer