The Stovebolt Site Forums The Shop Area Engine Shop Need help getting 283 back to life!

I'm a rookie at engine rebuilding and need help getting her going again - all suggestions appreciated, here's status:

1) Quadruple-checked TDC - by compression gauge, by observing valves (intake closing approaching, exhaust opening after)

2) Rotor points to #1, actually seems just past (about 5.30 when looking from front, not 5.00)

3) Points adjusted so just opening, vacuum pointed about 1/2 way between #4 and #6

4) Plug wires - #1 wire on cap immediately to the left of the door on distributor - 7 o'clockish

5) Spark confirmed, spark wire order triple-checked

6) Gas to rochester 2G carb...if anything, maybe too much gas - seems like inside carb is may be too damp - possible flooding? I had to loosen repo gas cap as pressure really builds up - read on the web that I need to cut spring in half to have pressure relieve easier.

7) Good compression - tested #1 at +/- 100 psi

8) Double-checked valve adjustment - checked out at 1/2 turn tighter than 0 lash

When I try starting, it tries to fire and I get "pfft, pfft, pfft, pop" - kind of hear compression. This is with just a squirt or two of gas or starter fluid and no choke or just a little choke, foot off accelerator. If I'm more generous with the accelerator - 1/3 or 1/2 down, or if I pump several times I get an exhaust backfire, which sounds like a rifle shot.

So, any suggestions? Do I just play with the distributor, trying a little more or less advance? Is it a carb issue? Is it possibly an air leak in the exhaust (I don't like how the y-pipe joins with the pipe to the muffler pipe - it may gap)?

I have concerns about continuing to try to turn over without success (although oil pressure appears good while cranking)...

Be sure you're using the right cylinder for checking TDC. When the #6 cylinder is at the split overlap position, #1 is on compression, ready to fire. The front cylinder on the driver's side is #1- - - -#6 is the third cylinder back on the passenger's side. Get #6 "rocking"- - -intake opening and exhaust closing, then time the distributor to fire #1. Companion cylinders that come to the top at the same time:

1 8 4 3
6 5 7 2

When #1 is on compression, #6 is on overlap. Ditto for 8 & 5, 4 & 7, and 3 & 2.

It sounds like you've done everything right except you've got the engine timed to fire at the top of the exhaust stroke- - - -not good!
Jerry

http://www.selectric.org/06main/283firing.jpg

4 degrees before TDC, 6 degrees before TDC, or TDC according to my MOTORS manual.

So is the rotor pointed at the #1 plug wire when the points open and TDC mark on damper is lined up with the 0 on timing mark increments scale?

Joe

Joe - rotor is pointing just past #1 cylinder (about 5.30 when looking from fan; 5.00 would be right at #1 cylinder) when timing marks are at TDC. Points are just opening. #1 plug wire is still about 1 1/2 plug wires away on the distributor, at about 7.00.

Jerry - Thanks for the reply. I'll check again but I'm 99.99% sure I am on compression stroke, per compression gauge and valve observation.

If you're actually on the compression stroke, then you have a point gap and/or timing issue. The points should have approximately a .020" gap with the rubbing block on the highest point of the cam, and the points should be just barely open as the spark fires. Once the points are set, align the timing marks somewhere in the 0-10 degree range with the distributor rotor pointed toward the #1 plug wire, and turn the distributor housing clockwise until the points close. Then turn it CCW until they just barely open. I use an ice pick type test light with the pigtail lead grounded and the ignition switch on. Touch the probe to the coil tower that connects to the distributor. With the points closed, the light will not burn. Turn the distributor housing CCW until the light comes on, and lock the adjustment down. You will be within 2-3 degrees of the correct timing.
Jerry

OK - is my problem that I'm pointing rotor at #1 CYLINDER (5.30 on the clock dial) at TDC instead of pointing rotor at #1 WIRE location (about 7.00 o'clock) on the distributor cap at TDC?

Line the rotor up with one of the cap terminals- - - -it doesn't matter which one, and use that as #1. Follow around clockwise with the rest of the firing order- - -8-4-3-6-5-7-2. I taught my students the "girlfriend" method of remembering Chevy firing order:

18- - - -too young
72- - - -too old
43-65, just right!

Jerry

OK - will try - looks like later chevy distributors had #1 at 5 o'clock vs. old ones at 7 o'clock...maybe that's why engine assembly manual directed aiming rotor at cylinder #1...

The distributor doesn't care which wire begins the firing order sequence. It fires one spark plug every 45 degrees no matter what. Way back in the early days of the 265 V8 the distributor housing had to be clocked a specific way because a flat spot in the housing had to line up with an oil passage to supply oil to the passenger's side valve lifters. That got changed about 1958 or so when they put a full-circle groove in the housing to route the oil to the lifter gallery.
Jerry

Thanks for all the help, Jerry and Joe! I simply advanced the wires at TDC one terminal counterclockwise so #1 wire lines up with rotor at tdc.

I don't have it started yet but very very close - it fires around the horn but won't keep going when I let off the starter...also backfires out of the carb occasionally. Too advanced or too retarded maybe?

Recheck your firing order- - - -it's very easy to get 5 and 7 reversed. They're side by side on the driver's side of the engine, and on the distributor cap.
Jerry

Can you get a helper to slightly rotate the distributor one way or the other while you are trying to start the engine?
Joe

OK guys - still struggling and proceeding cautiously as I am concerned about many unsuccessful starting attempts. I've now confused myself on the distributor so:

- when I align the rotor with the #1 wire at TDC, the rubbing block is on the flat part of the distributor cam, and rotor is dead center on #1 wire.

- when I rotate the distributor housing CCW to the point that points JUST open, this is obviously at the end of the flat part of the distributor cam...but, necessarily, this means the #1 wire tower is now CCW of the rotor, therefore behind it as it moves clockwise, therefore not making contact to send spark?

Am I over-thinking this?

As long as the cap is indexed properly on the notch in the housing, the rotor/cap relationship is designed to work. Yes, you're over-thinking it. You're not another engineer are you? We've got a bunch of them on the site that are so anal-retentive I'm sure they must own stock in Ex-Lax!

You could back up the distributor one notch on the gear so the spark has to jump forward a little at idle, but I don't think that's a good idea.
Jerry

Jerry - started up and ran like a champ! Thanks again - if you I'd like a quick video to join the celebration pm me your cell number or email address.

Thanks, but my computer has a problem with video for some reason- - - -says I need a new Flash Player download, but the download never finishes! Gremlins!
Jerry