Engine Woes

[Alfretta]

Hi Guys,

Recently my 1.8L alfetta sedan has been starting with blue smoke out the back (yeah, I know that's par for an alfa ... but not mine!), so I decided to check the compression:

Spec: 9.5:1

Mine:
#1 Dry 7.5 Wet 9.0
#2 Dry 7.5 Wet 9.0
#3 Dry 10.3 Wet 12.0
#4 Dry 3.0 Wet 3.0

I last checked the compression about a year ago, and happily got 9.5:1 on all cylinders .... so I almost when bug-eyed when I saw the #4 reading!!!

Dismayed, I took the cam cover off to check the valve clearances to see if there was something obvious ... and guess what, there was!

Inlet spec: 0.016-0.018 "

#1 0.012
#2 0.013
#3 0.009
#4 <0.002 (i.e. no clearance)

Exhaust spec: 0.018-0.020"

#1 0.020
#2 0.019
#3 0.021
#4 0.021

So it seems as though the lack of clearance on the #4 inlet valve is responsible for the poor compression on #4 cylinder.

Can anyone tell me (guess) what I can expect to find under the cam follower of #4 inlet valve when I take it off this weekend???

Also, any ideas on how #3 could achieve such a high compression??? If it gets any higher then I might start filling up with diesel!

Cheers.

[lunchcutter]

I don't think you should expect any damage on the follower it just means the valve wont have been shutting completely hence your low compression. The only thing I can think of for that really high compression is massive carbon deposits on the top of your piston and/or the combustion chamber in general but I didn't think they could make that much difference? It could indicate overfueling of that cylinder, but you'd expect number 4 to also be overfueled if you're running a dual carb setup. Maybe compare the condition of the spark plugs in all 4 cyclinders to see if you can learn anything more about fuel to air ratios in each cylinder.

[Alfretta]

Hey Lunchcutter (lol!),

Thanks for your input ... interesting idea for the high compression in #3 ... it's a dual carb setup, and the plugs look more lean if anything ...

Anyway, I'm currently rebuilding a 2L to swap into the alfetta ... I'll probably post some pics when I get around to taking the 1.8L apart.

[Q.V.]

Probably it's "oil compression" due to much oil in the compression ring zone. Worn or slipped intake valve seal may be the cause