IMHO my comments for what they are worth.......
Harlan Jillson wrote:
>
> Hi All,
> I just got a 18GF engine/transmission (O/D) out of a '68 B parts car
> to go into one of my cars. First on the agenda was to do some basic
> check out and see how much work needed to be done before installation,
> so I figured I'd check oil pressure and compression for starters.
> The info. I have from Haynes and Bentlys lists compression ratios of
> 130 PSI for the LC 8:1 engines and 160 PSI for the HC 8.8:1. Here are
> the readings I got, plugs removed turning over with the starter motor.
> #1 198 PSI
> #2 200 PSI
> #3 198 PSI
> #4 185 PSI
> Any comments?
My '52 YB on a 7.2 compression ratio gives out 120psi, with its soft
camshaft overlap. These readings appear fantastic. The head that should
be fitted is a 12H1326 casting number, the combustion chamber capacity
should be 43cc, the inlet valve should be 1.625" dia, the exhaust 1.345.
According to Lindsay Porters book the readings for a 8.8 compression
should be 160psi.
The MARINA 18V engines readings are 190psi, see below for the reason....
As and added attraction/distraction, I was under the
> impression that the 18GF was a ECC engine, and as such would have
> an air injector head.
The head...as above, 18GF was a USA spec engine, October 1967 to October
1969. In Porters book, the only difference from the 18G to 18GC is the
inlet valve is bigger, ( was 1.565"). October 1969 brought the 18GH
Federalised engine with exhaust emmision control.
This one doesn't, so did the non-ECC heads have
> smaller combustion chambers, thereby giving me a higher compression
> ratio accounting for the above numbers. Any guess as to what the CR
> would have to be to generate the above. ( I guess another possibilty
> would be cam timing from a hotter cam contributing to the CR.)
A hot-cam with a large overlap actually reduces the low rpm readings,
hence the single-carb Marina with its cooking camshaft giving
190psi....perhaps you have a saloon car camshaft?? 18V Marina has 8.8
compression.
>
> Another good sign I think, this engine generates 55 Lbs of oil pressure
> (cold) cranking it over with the starter motor only ( aka not running). The
> oil is standard 20/50 castorol.
Agsin, excellent.
>
> I'm thinking of cleaning up this thing, replaceing all the exterior hoses
> and gaskets, the front and rear seals and running it as is for a while. Any
> comments from the learned?
>
> Harlan.
Neil.
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