Cam bearing journals

[Tonka777]

Long story short, had a sudden coolant drain, used a block tester to diagnose a combustion gas leak into the coolant. Took the head off (AMK) found it was cracked. Bought a bare head from ebay, had it skimmed, started the rebuild, swapping cams etc from my old head then read in the Bentley manual that the cam bearing caps are machined to the head.

New head didn't come with bearing caps, waiting to hear back from the seller to see if they have them still.

If I can't get the original caps for the new head, am I left with a scrap head?

Is there any way I can measure clearances etc IF I were to use the caps from my old cracked head? They'd be matched to the cams from the same head, if that makes any difference?

See loads of bare heads on ebay that don't have caps, so I'd guess that a few people have used different cam bearing caps on replacement heads.

Thanks

 

[<tuffty/>]

Caps are line bored on the head... no guaranty that caps off another head will align... could end up with them being too tight and bind or too loose and lose a bit of oil pressure or flap about enough to cause excessive wear or stress on the cam..

I would personally not buy a head without its caps or with caps from another head...

You could measure the journal bores once assembled to check and make a call on the results...

The following has a little info regarding radial tolerance and run-out
http://workshop-manuals.com/audi/a3...ylinder_head_valve_gear/servicing_valve_gear/

It plausible you could mix and match caps from different sources and then maybe get a machine shop to line bore the tighter ones but would imagine that to be a more expensive route than sourcing a complete head...

<tuffty/>

 

[Tonka777]

Your thoughts align with mine Tuffty.

Foolishly didn't check for caps when I picked it up, not a mistake I'll make again!

Thanks for the link

 

[AGB-S3]

Ebay is a tricky place for sellers these days , you might get a refund, if you take the stance, with ebay , the item is not usable , due to missing parts , as the sale was invalid.

The item was not as described .. ie, as the caps are inseparable from the head .. what was offered was just a block of alloy , as it cannot be used as a head

G.

 

[Tonka777]

The seller is a member here, and has been very helpful, and most amicable with everything, including issuing a refund.

Wish I'd seen the classified ad here instead of going via ebay, could have ensured the caps weren't lost then too!

 

[AGB-S3]

Good out come then, I brought a 5 cyl audi 80cd back in the 80's and the engine was worn out, the main agents had fitted new valve seals and sold the car on , 500 miles later , blue smoke and a set to with the garage , but as the bores and guides where , well past there limits, the argument was simply it was not as advertised .. a re con engine ensued .. good outcome , car ran for years ..

 

[Tonka777]

Semi good outcome. I'd paid out for it to be pressure tested and Skimmed, and had just finished fitting new stem seals when I realised my mistake.

Would have been considerably more costly had I fitted the caps from my old head without doing some research though.

Now looking for another head, so pm me if anyone has one!

Bet you wish you still had the 80!

 

[AGB-S3]

Bet you wish you still had the 80! ,

nice car to drive , bit heavy on front tires p600 back then , other than that it used no spares , other than a front off side stub axle, that fell off [ sheered due to a crack] during , changing the front disk's .. eventually the shell welded ribs rusted , to the extent , the jack pushed the floor up .. game over

 

[Tonka777]

Sad times!

 

[AGB-S3]

only problem it would never stop, non vented disk's, stop once , then drive on the gear box .. > stress corrosion I think, I had a suspension kit on the car, some what stiffer than normal , which would of loaded the shell more than expected , the rally ones where continuously welded ... I came across one of a similar age , not a mark on it , that one had a 5 speed close ratio box , mine was 4 + over drive , went faster in 4 than 5

oh and clutch cables every 18 months /2 years , due to the addition of a jockey wheel ... local agent used just swop them .. bit of sod to fit , would feel a twang , then you had 3 go's of clutch .. once drove it back from warrington , liverpool and the tunnel with no clutch , started it in first ..