low compression after rebuild

[shawnb]

Hello, I just finished my first rebuild on 1979 A-4. It came out of my Catalina 30. Some background, I bought as project and motor was completely disassembled "basket case" I spent this winter reassembling the A-4. What I have replaced;
Bolt on
Fuel Pump- electric
Alternator
Distributor- electronic
coil
starter
rebuilt water pump
Internal motor work
rings
valve springs
honed walls
lapped valves- reused
reused bearings and pistons as they were within spec.
really really really good cleaning and all new gaskets.
Oh, and rebuilt carburetor.

So I am ready to bench test and expect it to start right up...........No, it turns over and appears to have fuel and fire and at the correct time...
Checked compression 60psi on all four cylinders? Is this why it wont start? I have changed so many things that its a bit difficult to know where to start.

Any thoughts?

Thanks,

Shawn B

[Sony2000]

I would tell myself, she will run and wear in while running.
Some SAE 30 squirted on the rings to help the compression, a cc. of gas in each cylinder and fire her up, then keep her running. Timing is important.

[Mo]

Not uncommon to have low compression numbers with rebuild. Yes, pour some oil in cylinders through plug holes and fire it up and keep her running. She will smoke allot doing this... No high revs, let her run a few hours if you can and let her break in a bit.

Turn off raw water until it starts...once it starts open the thru hull for raw water...Also keep an eye on water and cooling when doing this...it's easy to get fixated on one thing and get nailed by another.

Close eye on oil pressure.

[romantic comedy]

back to the basics:

Fuel? Always can give a squirt of ether to see if it is getting fuel. Are you using fresh gas?

Spark? could you be 180 degrees off? Are the wires in the correct order? Do you have nice fat blue spark?

Agreed that a bit of oil can help to get it started.

[marthur]

Compression requires a good seal between the piston rings and cylinders. Until the rings have seated, you will see lower compression. Don't worry about that until you run it and the rings begin to seat.

Even though your numbers are low, you should get some fire. Check that your timing is not 180 degrees out. Check the mixture and make sure you are using full choke. A squirt of starting fluid might help. It should run!

[Al Schober]

Shawn,
My first ever rebuild, I had no spark - drove me nuts as all the parts checked good. Turns out the coil wire to the distributor was on the wrong side of the insulating washer at the points!
But you say you have spark? I'd be very suspicious of the timing being 180 deg out. Each turn of the crank gives one TDC on piston #1, but the #1 plug is only supposed to fire on every other turn. That would be the TDC after the compression stroke.

[Dave Neptune]

clarify

Shawn spark is at TDC of the compression stroke!! The "other" TDC is the end of the exhaust stroke and the beginning of the intake.

Dave Neptune

[ndutton]

All the guys are cautioning against timing 180° out because we've seen it over and over and from very knowledgeable members and their knowledgeable neighbors. It's an easy thing to check just to make sure. Perhaps you could tell us how you established the distributor/rotor position after the rebuild. That could give us clues.

What the guys are not saying (except for marthur) but I believe they're thinking is 60 psi/cylinder should be enough to get her running.

[wsulli]

I helped a friend with his rebuilt a4 it would not start many tries several days, on day 1 I said maybe its 180 out, checked and rechecked for days. Finally he flipped the distributor 180 and it STARTED.

[Dave Neptune]

Id

When the piston is at the top~~TDC~~the valves will be closed and it is time for the spark.

The dist points wherever it gets installed. If #1 is at TDC of the compression stroke start the wiring on the cap from where the rotor is pointing that is now #1 plug wire~~~etc with the firing order.

Dave Neptune

[shawnb]

Timing is everything

She fired right up after correcting the timing issue......now I have smoked the garage out and wife said enough. Looks like I can finish engine install on Saturday. Thanks everyone!

[ndutton]

Great news Shawn.

Anybody else besides me notice the collective troubleshooting from the membership is getting better and better as time goes on? Based solely on information in the original post, 5 of 10 replies mentioned timing and a few others how to do it. And look how it played out.

Good going guys.

[Al Schober]

Does this mean I get a bonus in my check this week?

[Administrator]

Al:

Having achieved the exalted status of MVP, there is (currently) no higher calling in the Afourian world to which you can aspire, so a promotion is out of the question, but we will consider increasing your year-end bonus (percentage-wise!).

Bill