Catcams Jamming In My Head!

[B1ack_Mi16 67]

How on holy earth is this possible?

 

I really have only testfitted the cams before with a couple of the bearing caps on...

 

Well.. however tonights I've fittet valve stem seals to my head, and fitted springs, valves ++

 

Now I fitted the cams, and they just jam in the bearings when tightening the bearingcaps.

I've lubricated it properly, and when trying to rotate the cam-pulley using both my hands, it's almost so much resistance I can't rotate it at all.

 

Have anyone experienced this before? I'm sure I'm using the correct bearing caps so that's not the problem

[Pugnut 9 1 Cars]

I'm sure I'm using the correct bearing caps so that's not the problem

 

so its the same caps from the same head in the same place?

[pug_ham 240 3 Cars]

Kristian,

 

Have you fitted the cam bearing caps the right way round? If even one of them is fitted the wrong way they will nip them cams & prevent it from turning, just like the big-end bearing caps.

 

Saying that though you'd have to be pretty strong imo to be able to turn the cam against the springs by hand.

 

Graham.

[B1ack_Mi16 67]

Kristian,

 

Have you fitted the cam bearing caps the right way round? If even one of them is fitted the wrong way they will nip them cams & prevent it from turning, just like the big-end bearing caps.

 

Saying that though you'd have to be pretty strong imo to be able to turn the cam against the springs by hand.

 

Graham.

 

 

They're all the same way (the caps). And the mech-lifters are still not in place, so the lobes are running free and I think it should turn really easily. Need to check the diameter of the cam bearings when I get home this evening, and take it from there.

[Dom9 2]

You probably won't be able to turn the cam over by hand if the valve springs are in there, as Graham said... If the cam is just running in it's bearing caps with the valve springs and buckets though, that isn't good news!

 

Just grab a set of verniers and check the Catcam and maybe drop the head at your machinist and see if he can check that the bearing caps are in line and not out of round...

[PumaRacing 1]

They're all the same way (the caps). And the mech-lifters are still not in place, so the lobes are running free and I think it should turn really easily. Need to check the diameter of the cam bearings when I get home this evening, and take it from there.

 

Even without the lifters in are you quite sure that the lobes aren't hitting the valve tips on full lift? If they are then 1) that's why you can't turn the cams by hand and 2) you'll end up marking a lobe or bending a valve stem if you keep messing with it. Then there'll be tears. Stop playing with the bloody thing and put it together properly and let us know how it runs. God knows I'm bad enough about finishing jobs by when I've said I will but waiting for some of you lot to actually get an engine together is like waiting for the next ice age to come.

 

Take the cams back out and measure the journals with a micrometer. Or alternatively see if each cam cap fits each journal snugly without binding. If the caps fit then so will the other half of the bores in the head. I think it's vanishingly unlikely there's anything wrong with the cams. I make no bones about my views on the effectiveness of the lobe profiles from some companies, UK ones mainly, but even so I've never come across one with the wrong size bearing journals on it. I think it's much more likely to be you playing silly buggers and inventing ways to find things wrong that actually aren't.

[B1ack_Mi16 67]

Anyway, I've now put in a standard cam, and it rotates freely, even when the bearing caps are torqued down properly. On the catcam I tested yesterday I only torqued the bolts with my fingers!

 

And I already told you the lifters are not in place, so there's nothing the lobes will collide with.

 

 

And I really can't see any reason for me to get the engine togeather. The shell won't be finished in half a year.. or maybe even not then.

 

I've just measured one bearing journal, and the catcam seem to be approx 0.05mm bigger diameter.

[crogthomas 0]

Where did you get the cams from?

Did you get them secondhand? It sounds like you may have got some that have been specially made oversize, most likely to fit a head that has had the cam caps line bored bigger, to correct some damage perhaps?

[maxi 36 1 Cars]

For the larger profile mi16 cams, the Mi16 head casting needs machining for the lobes to clear.... Have you dont this mate?? In other words, if you dont get the die grinder out, the lobes will hit the head and prevent the cam from turning.

 

Maxi

[B1ack_Mi16 67]

For the larger profile mi16 cams, the Mi16 head casting needs machining for the lobes to clear.... Have you dont this mate?? In other words, if you dont get the die grinder out, the lobes will hit the head and prevent the cam from turning.

 

Maxi

 

Yes, the casting have been machined (look closely on pic on page 1), and cams are completely new and did not order any special bearing journal diametres.

[DrSeuss 0]

you could use plastigauge to see the clearance differences if you had any.

[PumaRacing 1]

I've just measured one bearing journal, and the catcam seem to be approx 0.05mm bigger diameter.

 

On each cam the front two bearings should be 21.95mm and the back three 19.95mm. That's 2 thou clearance on the 22mm and 20mm bores in the head. If the journals on your cams are actually the nominal size of the bores then indeed you have a problem but maybe the std cams you measured were a bit worn. What are the actual sizes you've just measured on these new cams?

[bobs205 0]

I no this might sound silly but have you got the cam's in the right way i.e the cam belt spocket notct/cam key to the cam belt end

Edited January 18, 2006 by bobs205

[B1ack_Mi16 67]

On each cam the front two bearings should be 21.95mm and the back three 19.95mm. That's 2 thou clearance on the 22mm and 20mm bores in the head. If the journals on your cams are actually the nominal size of the bores then indeed you have a problem but maybe the std cams you measured were a bit worn. What are the actual sizes you've just measured on these new cams?

 

The cam's have the same measurements as you mention here...

I've found out that bearing-cap 1 and 3 actually is fine, but the 3 others will jam.

I'm gently attacing the bearing faces in the head with sandpaper wet-sanding with oil, know it's a bit dodgy, but now I really don't care..

[M3Evo 0]

Oh my GOD! You're going to all the effort of rebuilding an engine and then buggering up the head like that?!

 

There's no way in the world you'll get the journals round!

 

Sorry if that's a bit harsh, but it just seems a shame that's all.

 

T'other thing is that they'll never be cylindrical either, they'll be kinda.....wobbly shaped!

Edited January 18, 2006 by M3Evo

[PumaRacing 1]

The cam's have the same measurements as you mention here...

I've found out that bearing-cap 1 and 3 actually is fine, but the 3 others will jam.

I'm gently attacing the bearing faces in the head with sandpaper wet-sanding with oil, know it's a bit dodgy, but now I really don't care..

 

Absolutely don't do that!! It isn't the problem. There may be small burrs at the split lines where the caps meet the head. This is common on all line bored split units such as main bearing bores, big end bores etc. These burrs can nip a journal if tolerances are close. Feel for the burrs with your fingernail. One or two light strokes with a small oilstone held at about 45 degrees to the split line will remove them. If you have no oilstone then wrap some fine wet and dry paper (240 grit) round a bit of metal like an old valve stem. Then try the cams again.

 

Also check for any other burrs, dings and general unwanted damage on either the bores in the head and caps or on the journals themselves.

[B1ack_Mi16 67]

Oh my GOD! You're going to all the effort of rebuilding an engine and then buggering up the head like that?!

 

There's no way in the world you'll get the journals round!

 

Sorry if that's a bit harsh, but it just seems a shame that's all.

 

T'other thing is that they'll never be cylindrical either, they'll be kinda.....wobbly shaped!

 

At least the head isn't good at all anyway, when it comes to the valve-seats, valves and port shape, so this can't be too bad making it a little worse

 

I'm not doing any sanding in the bearing-caps, and ain't it these that'll take most of the loadings anyway, as the cam's are pushed upwards when pushing on the lifter..

 

There's no burrs ++ in the bearing journals btw.. and the cam's actually seem to rotate in the 3 other heads I've got.. so things must be done to this one to make'em fit. Strangely...

[PumaRacing 1]

How do you know it's the head half of the bearings that need work anyway? You could be sanding material out of those without improving anything and effectively making things worse. It's more likely to be the caps being just a fraction out of alignment than any size error. You'll be getting emery grit everywhere if you aren't careful and then it'll have to come apart again for cleaning. This sort of thing should have been checked before the valves were fitted. There are rarely any shortcuts to doing a job right.

 

Lay each cam in the head without caps fitted, press down by hand and see if they turn ok. If so it isn't the lower half of the bearings that are the problem. Fit one cap at a time and see what happens. Try tapping the cap with a soft hammer or a bit of wood before tightening the bolts before assuming the clearance is tight. It might just be alignment. In fact what I think might be happening is this.

 

When you fit the cams in the normal way with valves, springs and lifters in place the cam is held up out of the head until each cap pulls it down. This also means that the cam itself helps aligns each cap as you tighten the bolts. Without lifters in place the cams just sit flush in the head. The caps are relying on the dowels to align them and you only need a thou of movement relative to each dowel to take up the small running clearance that is meant to be there. I suspect if you fitted everything normally with the lifters in place this 'problem' will disappear. You might try it before doing any more sanding.

 

You do have every dowel still in place I presume. And presumably there's no chance the caps got mixed up with those from another head at some time?

 

Another thing to check is just fit all the caps without the cams there and make sure you can't feel any misalignment at each split line with a fingernail.

[sorrentoaddict 1]

I can just add here that sometimes, if the camshaft bearing caps have been (in a previous life/owners) improperly torqued up, or improperly dismantled (as there is a special dismantling-unbolting-order sequence advised by PSA), it might have happened that one or two of the caps are somewhat distorted, and it might be also a reason for failing to align perfectly this time.

 

just make sure follow the other advices given already here, and go step by step,

maybe there is nothing really wrong ?

 

 

cheers

 

 

alex

Edited January 19, 2006 by sorrentoaddict

[M3Evo 0]

For some reason or other, I seem to recall that they're all numbered, but not sequentially (if that makes sense) Like cap '1' is at one end of the head with cap '3' beside it.

 

That might well be (and probably is) completely wrong though!

[PumaRacing 1]

For some reason or other, I seem to recall that they're all numbered, but not sequentially (if that makes sense) Like cap '1' is at one end of the head with cap '3' beside it.

 

That might well be (and probably is) completely wrong though!

 

It is. Anyway it's basically impossible to get them in the wrong place. The end two are unique and number 3 clearly goes in the middle. The two intermediate ones have different sized journals so one of them wouldn't even clamp down if you tried to fit it in the wrong place. The same applies to the 8v engine which has different sized journals on every one of the five bearings. Admittedly not that that stops people breaking the caps on the 8v by fitting them back to front or in the wrong order. As the old saying goes, however hard you try to make something foolproof there's nothing quite so capable of cocking things up as a really determined fool.

 

The best way to deal with both these heads is get the end two and the centre cap tightened down first because these are relatively hard to get on the wrong way round. Then make sure the other two tap down solidly against the head face before tightening them. The numbering on the 8v is admittedly confusing because unlike most engines the gearbox end of the engine is called number 1 so it's not hard to mistake where the 2 and 4 should go but if you check each cap against its journal on the cam first the difference in bearing sizes is immediately apparent.

 

Anyway this is becoming a very long and time consuming thread for something I don't actually think is a problem in the first place. I've seen plenty of cams a bit tight in the head to start with but they sort themselves out fine after running for five minutes.

[M3Evo 0]

what the hell am I thinking of then!?

[mfield 20]

Firing order of a mk1 audi coupe

[B1ack_Mi16 67]

Have handed the head over to my enginebuilder now.. He was gonna look at it, and said he might go over it with some rotating sandpaper thingy on the drill So that seem almost as dodgy as my own sanding yesterday..

 

gonna be a pretty dodgy 2.3 engine this one.

[taylorspug 7]

Have handed the head over to my enginebuilder now.. He was gonna look at it, and said he might go over it with some rotating sandpaper thingy on the drill So that seem almost as dodgy as my own sanding yesterday..

 

gonna be a pretty dodgy 2.3 engine this one.