Bad compression on 454

[amdg]

How bad is it if the compression on a Chevy 454 is no better than 50 to 60 lbs??

[LETMGROW]

Originally Posted by amdg

How bad is it if the compression on a Chevy 454 is no better than 50 to 60 lbs??

Is this on one, two or more cylinders?
Lynn

[Gpsmith620]

I am afraid to tell you , your Motor is toast, you have a major problem either bad valves or piston rings or head gasket . Have been a rep for Cat and Waukesha Engine for 30 years, you will need to pull it and rebuild it !!

[amdg]

Originally Posted by LETMGROW

Is this on one, two or more cylinders?
Lynn

Cylinders #6 & #8 are "missing"; 50 to 60# is the average for all of them.

[amdg]

Originally Posted by Gpsmith620

I am afraid to tell you , your Motor is toast, you have a major problem either bad valves or piston rings or head gasket . Have been a rep for Cat and Waukesha Engine for 30 years, you will need to pull it and rebuild it !!

I was afraid that would be the case...phooey. Now I have to decide if it is worth it.

[Dtwallace]

Time for a create motor, that one has seen it's better days.

Replacing with a create motor is easier and less expensive these days than doing the overhaul yourself.

Two choices', long block, or short block.

Long block as you probably know, comes with heads already refurbished and installed.
Short block means you'll be talking you old heads to the machine shop to have them done.

I'm guessing you already know all this, so I see no need to go into the sources.

Good luck, and happy trails.

DTW

[spyderRV]

Pull the head, not too hard. I had a 1990 454 where the steel head gaskets went bad at 100,000 ish miles, about 15 years. New gaskets and all was good.

[Unplanned]

Confused. Is it a 454 or 8.1?
Pop in a crate motor, otherwise your rig is pretty much worthless.
Good Luck.
Something like this?
https://www.summitracing.com/int/par...et?prefilter=1

[LETMGROW]

How many miles are on this engine? What year is the engine?
Before I jumped to conclusions I would try a different compression tester. I have seen these tools fail before and give low readings.
How does the engine actually run? Does it just skip some or is it really lazy? Are you getting black or blue smoke from the exhaust pipe(s)?
If you pull the oil filler cap with the engine idling do you see or feel excessive pressure or oily spray coming out of the cap opening?
Did the problems start all at once or did they come on gradually?
Having all the cylinders drop compression all at once is unusual. There is a possibility you may have a timing chain which has jumped a few teeth.
Lynn

[AKIQPilot]

Originally Posted by LETMGROW

How many miles are on this engine? What year is the engine?
Before I jumped to conclusions I would try a different compression tester. I have seen these tools fail before and give low readings.
How does the engine actually run? Does it just skip some or is it really lazy? Are you getting black or blue smoke from the exhaust pipe(s)?
If you pull the oil filler cap with the engine idling do you see or feel excessive pressure or oily spray coming out of the cap opening?
Did the problems start all at once or did they come on gradually?
Having all the cylinders drop compression all at once is unusual. There is a possibility you may have a timing chain which has jumped a few teeth.
Lynn

All good questions.