RE: Valve Spring inserts

["Stegmann, Steve" <Steve.Stegmann@domain.elided>]

Eldon,

Since you're trying to educate us. Consider this.

Last year I checked the compression on my 345.  I took all the plugs out but
didn't have a warm engine, wasn't runnable at that time.  I got readings
from 150 to 172 psig. 

I passed these reading by Super Scout and he didn't seem surprised, but he
did say it sounded like an engine fresh from an overhaul.  I had originally
thought my Scout had 150,000 miles but he thought it was probably 50,000 if
the engine hadn't been overhauled.  I never had thought the engine had been
out, but who knows?

When I consider the compression ratio it seems that I should get 14.7psia x
8.5 =124.9psia (or 110.2psig).  I usually pump each cylinder till it won't
climb anymore.   At the end of each stroke the exhaust valve opens and we
suck in a new charge. So it's not like we're "pumping up" the cylinder.
We're just pumping the gauge till the pressure in the gauge is equal to the
maximum pressure in the cylinder after the end of the compression stroke, no
way can it get above that. This just compensates for the additional volume
inside the gauge.

So what have I missed.  Is the actual compression ratio   around 12:1 and
something like the "effective" compression ratio the 8.5:1 that is
advertised.  Do you know what the volume in the cylinder head is?

I'm lost.

STeve

> -----Original Message-----
> From:	Tom Harais [SMTP:tjhemh@domain.elided]
> Sent:	Friday, April 16, 1999 2:47 PM
> To:	EldonMcf@domain.elided; Stegmann, Steve; n9ads@domain.elided
> Cc:	ihc@domain.elided; rscow@domain.elided
> Subject:	Re: Valve Spring inserts
> 
> Eldon:
> 
> Your belief in differnces between "regular" and "A" engines makes sense.
> I've often heard that the "A"s dropped the stellite valve seat inserts
> (sometimes it's said, only on the intakes and not the "hotter" exhaust
> valve seats). But, this seemed contradictory for two reasons. Everyone
> else
> was going to hardened valve seats at the time the "A"s came out, due to
> reductions, and eventual elimination of, lead in gasoline. And two, I have
> never heard that IH engines after a certain year weren't long lived. I've
> heard of '76s with 300,000 miles and the heads had never been off the
> block. My thought was if the valves were sealing that well for that long,
> they used damn good valves and had hardened seats or  inserts.
> 
> One of these days I'll pull the original heads of my '76 with 304A and see
> what's what.
> 
> Tom H.