Low compression numbers?

[majicwrench]

The actual compression pressure has many variables other than just compression ration. Wild cams result in low cranking compression readings. Heck, the state of your battery and starter will affect the compression pressure. You cannot predict cranking compression pressure just by the compression ratio. But at any rate, it should be way more than 80-lbs.

[RRoller123]

Acording to this source, the 1592cc has a 9.8/1 CR. But this being the internet, it could always be wrong, and I wouldn't be the least surprised:

http://www.esportscarparts.com/Fiat/SpiderHistory.htm

I agree regarding the multiple real world variables, (temp being the most obvious) but taking the CR X atmospheric pressure (IG Law) gives a pretty good starting point for an estimate of what one might expect.

[vandor]

Acording to this source, the 1592cc has a 9.8/1 CR. But this being the internet, it could always be wrong, and I wouldn't be the least surprised:

Seems like they forgot to quote the US-model CR for the earlier cars. Starting with the 1756 they quote the US figures too.

[RRoller123]

@Vandor: Well that makes sense, I seem to remember reading somewhere that the European models were made with higher CRs than the US models. Due to emmissions requirements?

[tinman760]

It's been hard to do anything, due to crazy schedule of work, rain, and Holidays. Seems like there have been many variables involved with the low comp. I did some checking with the carb., and the secondarys are frozen shut, so I have not been getting much throttle opening. Maybe 1/3 of the primary, w/no secondary. I plan to fix that with a 32/36 Empi, that I purchased the other day, from AA. Then I will be able to do a proper check. When time allows, I'll check the timing marks, and install another timing belt. I have no idea how old the other is, and it seems like cheap insurance.

[124JOE]

i would start with a can of PB parts blaster and get that linkage moving
then get it running and loosen the mixture screw
about two turns out then down till it stumbles but never go tight with it
then go back where it was.
after its running a bit better clean its out side with carb cleaner with the car off ofcorce

i also want that 32/36 or a great carb for it as well

[RRoller123]

For those of you who are engineers out there, and I suspect there are a lot since we tend to be insufferable tinkerers, here is a pretty decent paper on prediction of gas/compression pressures in spark ignited engines. It comes from some folks at MIT, the only connection to which I have is having snuck onto their summer softball team by posing as an MIT undergrad (I went to BU just across the river) in 1977. They were smart SOBs, but terrible at athletics. <{:^)

http://www.hcs.harvard.edu/~jus/0303/kuo.pdf

[124JOE]

and is your battery fully charged?

[vandor]

@Vandor: Well that makes sense, I seem to remember reading somewhere that the European models were made with higher CRs than the US models. Due to emmissions requirements?

Yes, lower CR lowers the NOx emissions.