If it's never seen leaded gas (new machine work
on the seats) you can end up with valve recession
really quickly if the seats burn.
Your knocking could easily be the valve not closing completely.
See if when turning the engine by hand, what kind of clearance
you have under the rocker arm on that cylinders valves.
Another option, if loud knocking.... is poor machining tolerances
and/or bad installation procedures having led to a broken
piston ring.
Paul Tegler
ptegler@cablespeed.com
www.teglerizer.com
----- Original Message -----
From: "Mike Welch" <mikew@turbopower.com>
To: <Spitfires@autox.team.net>
Sent: Wednesday, November 27, 2002 3:03 PM
Subject: of all the luck...
> Everyone on this list should have a good Thanksgiving, because all the
> bad luck seems to be with me. My '69 Spit ran great for about 1k miles,
> then developed a very loud knocking sound and complete lack of power.
> Fortunately, I had a '74 engine lying around, so I put that in. Lo and
> behold, after about 1k miles, it started having the same problem. With
> the first engine, I didn't open the engine up to find out what was wrong
> (I was saving that pleasure for the winter), but I've done a little
> investigation on the '74 engine. It idles fine, but when it gets up to
> about 1500 rpm it starts knocking, very loud knocking. There is visible
> smoke coming out of the push-rod journals for 1 cylinder (#4) when it is
> knocking.
> Here's the real question. I rebuilt the '74 engine myself, but had
> the head worked on by a local machine shop. They were supposed to
> convert it to a no-lead-head so I've been using unleaded gas. Looking
> at my bills from them, they didn't charge me for the conversion (no new
> valves/seats), just the machine work, so I'm not too confident that I
> was using the right gas. What are the symptoms of using unleaded in a
> leaded engine?
>
> Mike Welch
> God Bless America
> -------
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