beatervette

Do you have correct timing pointer installed on timing chain cover?

jim lockwood

I don't think this is a likely scenario.

If the plug wires are in the right sequence but the wrong direction, the engine won't run. It will fire once per distributor revolution and that's all it will do.

stratplus

Originally Posted by havasumark View Post

OK, So here is the current state of my motor
1. Crank gear dot is at 12 O'clock
2. Cam Gear dot is at 12 O'clock
3. #1 piston is on the compression stroke @ TDC (timing mark on balancer is on zero mark on chain cover)
4. Dist. rotor tap is pointing to #1 cyl.

Just so I understand, and I clearly do not understand.

Shouldn't the alignment be like the diagram in Mikes #49 post, and the dist pointing to #1, and the timing mark on the pointer. Instead of both dots being at 12 o'clock?

Mike Geary

No because with the gears dot-to-dot, #1 is TDC on the EXHAUST stroke and #6 is firing.

So why do they tell you to install the gears dot-to-dot? Easier to verify proper valve (not ignition) timing than eyeballing 12-to-12.

I don't know about later editions, but the early books on building a SBC did not adequately highlight to need to rotate the engine for installing the distributor in the #1 firing position....

MikeM

Look closely and tell me again what you see.

Randy G.

With the wires in the opposite direction #1 and #6 would still be in the right spot on the distributor so at least two would fire correctly for each distributor revolution. 2 and 3 would be coming off TDC and still fire, but very retarded. 5 and 8 would be very advanced and try to backfire the engine. 4 and 7 would be dead holes.

jim lockwood

Randy, I hear what you are saying. And while it makes sense, it doesn't match up with my 1st hand experience.

Friend trailered his GS with a freshly built, but non running engine for me to trouble shoot. The symptom was that it was firing once per revolution (distributor revolution? engine revolution? too long ago and I just don't remember).

My "ah ha" moment was the instant I noticed his plug wires were in the right sequence but wrong rotation. Switched everything and the engine roared to life, as it should have.

Anyway, point being that the engine made no other effort to fire. It didn't almost run. It flat would not run. It didn't even backfire or kick back.

Jim

DSR

Are you trying to start the motor with the initial timing set at zero? Try 8 to 12 degrees BEFORE TOP DEAD CENTER

65tripleblack

Mark,

The above quoted post must put to rest all doubts related to your engine's cam vs distributor synchronization.

Lets move on.

Please post a picture of your distributor and indicate, if you can, the wire positions in the distributor towers using 1 8 4 3 6 5 7 2 going clockwise. If all wires trace to the proper plug positions, your timing marks are pointing (near) zero, both valves in #1 are closed, and the rotor is pointing to #1 position then all is well. I say (near) zero because if it's within 10 15 degrees either way the engine will fire and run. Those finer points can be worked out later and I only say that in case of an unlikely spun balancer (damper) ring or unlikely SNAFU (FOOBAR) timing tab. In order to isolate either of those possibilities you will need a bronze piston stop.

Please see this thread as reference:

https://www.corvetteforum.com/forums...-cylinder.html

Move on

Check fuel pressure at carb inlet. It should be no more than 7 psig.

Next

Swap carburetor for known good one.

Randy G.

I certainly wouldn't run out to the garage and start swapping wires to see for myself! I'll take your word for it.

Sometimes I wish people having problems like this lived closer so I could go play with their stuff and try to fix it. Love the challenge and detective work it takes to figure it out. For me I like to confirm TDC on everything I build, now matter how shiny the timing pointer is that came out of the box. After that it's a no brainer.

DSR

try this. Set the pointer on your harmonic balancer to 10 degrees BTDC. Turn your distributor until the rotor points directly at number one terminal on your distributor cap. Then try and start it.

havasumark

Update!!

I had to step away from the car for a bit. Part do to very high frustration levels LoL!! and part do me traveling.
I have narrowed it down to carb issues, which I believe I have corrected. The one thing I was sure was ok and never checked, was fuel pump pressure. Today I disconnected my fuel line to the carb and stuck a pressure gauge on it. Disconnected the coil and cranked the motor. Pressure was 8.5 or so. I believe that is way to high. should be around 5. My question, Is it proper to check it this was with the gauge just deadheaded in the line while cranking the motor. Would that give me a false high reading..

Thanks,
Mark

Pilot Dan

Based on your test, I would venture to guess you have some hi performance mis matched fuel pump in there, or else your pump has an internal flaw. The WCFB wants 5 or 5.1/2 lbs of fuel pressure. 8.5 is way too high and you are overwhelming the needles and seats on the floats. You can run down to your local FLAPS and get a generic basic pump and once you clean up the plugs, if your carb really is OK, I think it may just do the trick. Pilot Dan

havasumark

Thanks,,

Just wanted to check.. I'm figuring that it's been a big part of the issues I've been having.. That's what I get for not checking it in the first place..

Another lesson learned..

Thanks again,
Mark

Frankie the Fink

8.5 lbs is not good for these old carbs. 5 to 5-1/2 is about right and they'll actually run with 4 lbs or even a little less pressure. The spring and diaphragm in the pump is usually the culprit.

It may not be all of your problem but it certainly isn't helping...

havasumark

Thanks Frankie,

Yes I've had many issues with this startup.. But I believe I've fixed them all.. Can't tell you how many times people have asked me about fuel pump pressure. I was sure it was fine as I was sure it was the same pump I had on it 13 years ago last time I had it running. Finally I did check it and was way high. Somehow I put a different pump on. Shame on me for not checking it at the beginning of my issues..

Mark

Fivepointfive

Line the dots up--12 on the crank, 6 on the cam. Install timing chain.
Turn #1 to TDC. Motor would be on #1 or #6 at this point--both pistons at TDC.
If distributor rotor is pointing to the number 1 sparkplug wire, both the intake and exhaust valves should be closed. (this is the top of the compression stroke and just prior to the power stroke. At this point, one of the valves on #6 will be open--just check the pushrods) Think in these terms: Gas mixture in #1 cylinder is fully compressed with both valves closed. Spark ignites. piston goes down with full power (no place else for exploded gas to go as both valves are closed). Piston heads up and pushes exploded gas out the open exhaust valve., and the beat goes on! Timing and valve lash come next.