.I recently checked compression on a '74 Spitfire that I have begun
>rebuilding. Although it looks fairly goog, I'm not sure what a
>"healthy" 1500cc Spitfire engine should have.
>My results were:
>#1 130
>#2 128
>#3 130
>#4 125
>Does anyone have an opinion on these measurements? Are they close to
>what good compression should be for a 1500cc engine in a 1974 Spitfire?
From my experience, these are *excellent* readings! Only 5 psi
variation and plenty high fot the engine. Looks like you have a nice
"tight" one there.
>Also, I did a tune up on the engine and set the timing to the 2 degrees
>ATDC that my Haynes manual (and the decal under the hood... err, I mean
>bonnet) and the engine doesn't run as well at an idle. The timing was
>previously more like 8 degrees BTDC. Is my timing info wrong?
The manual figures are for emissions performance, not "real"
performance. I typically have run my Spits at ~10 degrees BTDC and they
run/idle well. Look at the numbers for much older Spits and you will
see BTDC timing was the norm.
>When I set the timing to 2 degrees ATDC it was with the vacuum line to
>the distributor disconnected and plugged off. Hopefully I was correct
>in doing so. Any suggestions?
The '74 Spit was fitted with vacuum timing retard, not vacuum
advance. If you set timing with the line disconnected, the timing will
be further retarded when you hook it up. These fourbangers just do not
like to idle smoothly at low RPM with retarded spark! You might get
somewhat better performance if you set timing with vacuum retard line
connected.
That's enough questions for now.
Thanks for any help,
Dave (daveejay@PEAK.ORG)
daveejay@PEAK.ORG
When I grow up I want to be a geek!
|