Mopar Muscle Association UK

Morning all...
Been a bit of a delay; not had a chance to sort the vacuum out yet but will update when I do.
This mornings fun was 'compression check' - basically following some long and VERY useful conversations over 'what else to do while engine is out for rear seal' (you know who you are; thankyou ! ) it was suggested a compression check would be a good place to start.
After all, engine has had 'a life' and had a lot of 'sniff' so a compression check would give me an idea if rings were hanging in there...

Interesting results actually - learned quite a lot this morning.

1) Learned that there are loads of variables for converting compression ration to PSI readings - so really its a 'ballpark thing'. Obvs the higher the compression ratio the higher the PSI. Its more about an even spread.
2) My observations suggest that as I worked through my readings fell by about 20psi - I have concluded that as the smell of fuel increased (and the rings got wet) the pressure dropped slightly. In fact I retested the first one at the end and the drop was just that - 20psi between reading #1 and #2.
I remember from my rotary days, once you flood a rotary engine you just cant get it to start - they have no compression if 'wet'. Assume this is the same phenomenon.

So - results dont look too bad. Its all squashing. (Although not 'within 10%' - but there is fudge-factor ambiguity here. Will run control tomorrow.)

Conclusions -
- All cylinders hold pressure.
- Highest was 175psi (195 dry)
- Lowest was 155psi

Compression ratio ~10.5ish:1

Oh, and one for you plug doctors.

500miles ish. 350 motorway, 100 tooling about, 50 being nailed

Look a little dark to me; rich. #8 and #6 a little cruddy.

EDIT - Well tested #7 and 5 again after 8hrs rest. (dryish). 185 and 175 respectively. (up 30/15psi respectively). I think the conclusion is that first tested gets the best reading. The lowest last time matched the highest this time. So it seems that 'dry' they will all do 175/185. I am happy.

Interesting thread Morgan re upgrades....looking forward to seeing this motor go down the strip now you've got a proper engine in her !!!

Rich. Have you been talking to Pete ? His mission in life is to disrupt my cruising with this drag racing business...


Yeah, its in and sorted now.
Few funnies - rear seal had gone/shrunk so big oil leak made a mess - sorted now. Still fiddling as I had a problem with dizzy (turned out to be rotor or cap or both). It goes like the clappers now - BUT (and hands up if you saw this coming) only when nailing her. And wow does it rev. Down low cruising she is pretty rough - its got quite a cam/compression in it. For my usage it could probably use calming down a bit cam wise but thats not a job for me... this year is for fettling and having fun - or rather it should have been had it not been for lockdown !

Why put a "Drag race" motor in a "Cruiser" then??



Only kidding!!!

All the best!

(See you at the track....)

morgan wrote: Wed Apr 29, 20 12:20 pm Rich. Have you been talking to Pete ? His mission in life is to disrupt my cruising with this drag racing business...


Yeah, its in and sorted now.
Few funnies - rear seal had gone/shrunk so big oil leak made a mess - sorted now. Still fiddling as I had a problem with dizzy (turned out to be rotor or cap or both). It goes like the clappers now - BUT (and hands up if you saw this coming) only when nailing her. And wow does it rev. Down low cruising she is pretty rough - its got quite a cam/compression in it. For my usage it could probably use calming down a bit cam wise but that's not a job for me... this year is for fettling and having fun - or rather it should have been had it not been for lockdown !

Hi Morgan good to catch up, yes these upgrades will always test your patience ..and wallet !!.Been there done that when I put the new stroker engine in my Charger it also had a big lumpy cam in it...bloody thing hated tick over and low speeds in fact I Think it ruined a great cruzing motor but that was my fault got carried away.....like you do...
Look forward to seeing you maybe later in the year when all this virus crap is out of the way....who knows I might even bring my Chevy to MOPAR meet !!
Be safe..Rich.

Pete wrote: Wed Apr 29, 20 12:46 pm Why put a "Drag race" motor in a "Cruiser" then??

Because i am 12 and cant help myself...

morgan wrote: Wed Apr 29, 20 1:08 pm

Pete wrote: Wed Apr 29, 20 12:46 pm Why put a "Drag race" motor in a "Cruiser" then??

Because i am 12 and cant help myself...

Good answer Morgan - I suspect that applies to a lot of us.

morgan wrote: Wed Apr 29, 20 1:08 pm

Pete wrote: Wed Apr 29, 20 12:46 pm Why put a "Drag race" motor in a "Cruiser" then??

Because i am 12 and cant help myself...

I am 14!!

Unfortunately, I also have the body (and sadly the face) of a 60 year old!!!

does he know!!!?

dave