7A cams in 3B head - no compression

[Peter Orban]

Hi Ben,

I am not familiar with that engine, so this question might not be relevant.
Are you sure that the sprockets are installed in the right direction?
On a Golf engine (RV) the sprocket can be installed both ways onto the camshaft, and there are timing markings on both sides. Took me two days to find it, and there was good compression as well.

Good luck, Peter
Date: Mon, 31 Jan 2011 10:39:07 -0500
From: "Ben Swann" <benswann at verizon.net>
Subject: 7A cams in 3B head - no compression
To: <200q20v at audifans.com>,    <quattro at audifans.com>
Cc: 'Ben Swann' <benswann at verizon.net>, s-car-list at audifans.com
Message-ID: <8C39459C9E1249FCB0868828A3D29114 at swansong>
Content-Type: text/plain;    charset="iso-8859-1"

I have virtually no compression on 3B engine that just had the cylinder head redone by
machine shop.  

The head was just rebuilt - valves ground/lapped and new seals.  Using AEB lifters -
supposedly lighter.  Valve springs are stock.

At suggestion of others, I installed a set of 7A cams in my 3B engine.  

I'm fairly confident the cams are installed correctly - 3 sets of eyes on the install
and alignment per Bentley - relative cam orientation did not change when swapped from 7A
head to the 3B head - chain and cams swapped over as a unit. 

Engine at TDC when head pulled and while head re-installed.  Chain sprockets align so
the ---O-O--  are bisected by the valve gasket surface.  Having done this job before
many times, I'm fairly certain this is correct and corresponds with the manual.

However when the engine was cranked to pump up the lifters, it turned over as if there
were no plugs installed - no compression.  I verified that there is virtually no
compression - perhaps 5-10 PSI.

Is it possible that the 7A cams are keeping the valves open even though they are
installed correctly?

Just seeing if perhaps the 7A cams may not be a suitable choice for the 3B, or if there
is some detail that needs to be changed to use them.

Somewhere I recall seeing that the 7A exhaust cam is what should be used, and the intake
may be too much duration.  Anyone know?  BTDT?

Ben


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