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Old 15-05-2015, 07:50 PM   #3
iain ambrose
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Join Date: Jul 2005
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With the last engine i'm ashamed to say that I simply fitted the camshaft without checking it properly.
It's certain to say that a camshaft should not have flat lobes after 30k especially as i'm a bit OCD with servicing.
This time I plan to check and confirm all the parts used and also blue print where possible to hopefully produce a quality engine build.
I started with the camshaft and bearings.

First thing to check is the cam thrust bearing.

Looking at the manual it states up to 6 thou gap is acceptable but I want to be looking at around 1 thou.
Straight away we have a issue
I looks like the bearing splays when fitted into the case as it runs nicely on it's own in the camshaft.
A quick flat sand on the thrust side should help.

Nope, it's gone from no clearance straight to 6 thou
Looking at the thrust surface it's uneven where I have sanded so it's in the bin.
These are mahle units so not impressed.
T25 engines run a single thrust stock but i've decided to order a set of double thrust and see how they fit.

Next, check the cam lift:

The two exhausts come in at 267 and 269. (1 % variance).
The two inlets are both 283.
One inlet has a slight +- 1 thou variance on the lobe bottom, the others all look fine.
The potential issue with having an uneven lobe bottom is that it affects the hydro lifter as it maintains a zero gap.
As the valve returns to the closed position any variance in the cam lobe bottom will result in unwanted lift.
I believe this is one of the issues with my current cam as a rolling road test indicated a valve not fully seating.

I'll be checking that lobe again.
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Last edited by iain ambrose; 17-10-2017 at 10:05 PM..
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