Heya, any of u chappies in lancs fancy giving me a lift (nah just u doing it LOL) to do a cam swap once i get my grubby hands on a 75 cam?

obv will pay generouslyish in beer or whatever floats ur boat.

Al

Arseofbox has done the 75 cam swap before. He floats between Lancaster and Manchester. I'd be interested to see how its done too but i have little knowledge to offer in this particlular area.

Well tbh, its not hard to setup, all shim clearances stay the same, but it involves quite some work as the engine needs re-timing up

Could be done in an afternoon. If you want help, LMK nearer the time and I'll see what I can do..

how do youre time it as theres no distributor

scottc1088 said:

how do youre time it as theres no distributor

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He is talking about cam timing.

Changing the cam is very easy as long as you do what you are being told. The Haynes manual is sufficient. But be prepared that you have to wait for your right shims to arrive.

Something you won't find in the Haynes manual is how to run in the cam as they assume that you are not changing cams.

You should run them for the first 20 minutes a least at 2000rpm or faster.

conflicting responses? one says shims same, one says wait for new ones?

does the ecu learn the new timings from running at 2k?

Oldschool said:

He is talking about cam timing.

Changing the cam is very easy as long as you do what you are being told. The Haynes manual is sufficient. But be prepared that you have to wait for your right shims to arrive.

Something you won't find in the Haynes manual is how to run in the cam as they assume that you are not changing cams.

You should run them for the first 20 minutes a least at 2000rpm or faster.

Click to expand...

The cam timing on the FIRE engines does not change. It does not have a cam varietor. The timing can be altered by re-profiling. The ECU doesn't need to learn about it.

The ignition timing set set in the ECU and allows for variations within the map and the learning capability. It is much more complex than it sounds.

The shimming is always neede when changing cam, re-profiling cam or cutting the valve seats. If anyone tells you different, run fast. I have done more heads than I wanted to.

The running at 2k is to run the cam in and prevent hot spots. It sounds the wrong way round but it isn't.

Sorry to re-open this thread but I can't find the answer anywhere. As you can see from the pic, I have an old head from an 1108 and a cam from a 75 MPi. How do I set the shim height - where do I measure, what do I measure and how? I have a range of shims from different cars and can probably get whatever I need but I have no idea what I am measuring for. The head is going onto the 1242 orange cinq along with a lightened flywheel and homemade induction kit.

I understand the running in bit Oldschool - now fill in the missing bit for me!!

Muchos gracias amigos.

'cnqsnmns

Get some feeler gauges and measure the clearance between the camshaft base circle (not the pointy end ) and the follower. Shims sit in the tops of the follower caps..

Cheers Tom,

Now pretend that I am five years old and you are explaining it to me. I took it all apart, I reckon I know what everything does and how it goes back together but this clearance thing has me stumped.

Do I:-

1. Fit all the cam followers but not the shims and measure down, adding shims to give clearance to what?
2. Fit the followers one at a time and measure with the shim in place, adding or removing height to give a certain clearance?
3. Bring it all to an engineering workshop in a box and pay them money (very last option)

Naturally I am not five, but my Haynes manual died when it was left in the boot of a car with no windows and is now a soggy mess. HHHHEEEELLLLPPPP!!!

And yes, that is a Dremel and the left hand exhaust port has been ground out. I will get 100bhp out of this car if it kills me (which is also a likely outcome)

David.

arseofbox said:

Get some feeler gauges and measure the clearance between the camshaft base circle (not the pointy end ) and the follower. Shims sit in the tops of the follower caps..

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Tom you are a typical engineer. Make it a bit easier.

The pointy bits are called the lobes.

You have to have the buckets in position as they were before you dismantled the head. The shims (which are on top of the buckets and slightly recessed are just like coins with different thicknesses) sit between the cam and the buckets.

Best is you take a piece of paper and make 8 columns and number them from 1 - 8. Then write the letter combination I - E -I - E - E -I - E - I (one letter per column) in the columns. I is for inlet and E for exhaust. Before you fit the 75 cam extract the shims and read the value on the back of the shim. Write it down from valve 1 - 8. Valve one is always timing belt end. Turn the cam in the torqued down stage (20Nm on the cam bearing bolts and make sure that the pointed bit of the lobe to be measured is exactly in the 12h00 position. Write the gap in the column under the relevant valve number.
The valve clearances should be for the inlet 0.4mm +- 0.05mm and for the exhaust 0.45mm +- 0.05mm.

Work out to which thickness you have to change and record it. It might be that some of the shims remain in the same position, which means you were lucky. Otherwise some might go in other spaces and if you are unlucky all of them have to be changed.
Insert the fealer gauges to determine the width of the gap. If you haven't any gap, you need a thinner shim. Write the gap down

What did you do to the exhaust port and why?

Oldschool said:

What did you do to the exhaust port and why?

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I am smoothing it out in the name of tidiness of course... I was in the process of learning how to gas flow a head in a kitchen with a dremel - isn't it obvious? With the same clarity as your shim reply (thank you) please explain what I should and shouldn't do to the intake and exhaust posts with my Dremel. I so owe you a pint....

D.

You should be trying to open up the ports a bit on the inlet side, I presume you're not going to get a spare head and cut it in half, so go carefully, you don't want to compromise a water way or similar.

Use the manifold gasket as a pattern for how large to go, then do the same with the inlet manifold.

Exhausts are a bit more complicated as too big can ruin the scavenge effect.

Cheers

D

rallycinq said:

I presume you're not going to get a spare head and cut it in half

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Not unless I really bork up this one...

(I had four spare heads at last count - my wife is packing my bags as we speak)

So take a bit out of the inlets, take the high spots off the exhaust and don't mess about too much is the idea? How about surface finish on the inlets? Mirror/smooth/slightly roughened/very rough?

cinqsandminis said:

So take a bit out of the inlets, take the high spots off the exhaust and don't mess about too much is the idea? How about surface finish on the inlets? Mirror/smooth/slightly roughened/very rough?

Click to expand...

Basically remove flow restrictions...

Surface finish...well too far to one extreme and flow will go poor. Aim to leave it about the same as the roughness of it as it is cast. This helps mix the air and fuel together better and also give swirl...which is good!

As for the tools to use, you'll want a deep reach (flexible coupling) attachment or whatever theyre called to reach into the ports, if youre gonna go deep into it.

IIRC, David Vizard has written some very good stuff on P+P techniques - ast least an article that he wrote in PPC Magazine a few months back looked brilliant...

You need to have a step up between the exhaust port and the manifold. In the exhaust port you widen the ports, but as said in the previous post, don't overdo it. Also you try, where possible to smooth the corners to improve the flow. You cand grind the valve stem guides back.

On the inlet you don't want to have a step at all, but you shouldn't polish the ports unless you have a direct injection, which you haven't anyway. Again you don't want to take too much material away. You will get frightened when you see a cut up head. I have some hanging around here and can tell you it looks deceiving until you cut one up.

The inlet manifold should have a slight taper and it is important when you extract that sort of power per liter that it is bench flowed.

cinqsandminis said:

I am smoothing it out in the name of tidiness of course... I was in the process of learning how to gas flow a head in a kitchen with a dremel - isn't it obvious? With the same clarity as your shim reply (thank you) please explain what I should and shouldn't do to the intake and exhaust posts with my Dremel. I so owe you a pint....

D.

Click to expand...

I will come over to get it.

Oldschool said:

I will come over to get it.

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Its poured and waiting - how about a ClubCento run to Ireland? We have four speed cameras and they aren't switched on most of the time - cheap ferry crossings, nice scenery and some of the twistiest roads in Western Europe.

I measured everything and apart from two 4.22mm shims and a 4.30mm I'm ready to go. As with most things, once its explained its hardly brain surgery.

Thanks for all the replies - will update on progress when the head is bolted on.