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Need help. I have been working on a 27 one ton. So far:

Newly rebuilt engine, new cam, new plugs, new vlaves and seats, new valve springs, rebuilt carb. Timing is set with points about to open on number one. Starts but then dies. Choke, starts again and then dies. Press the acclerator when it starts and then it dies. Checked the timing and still right on. Checked the rockers and have them set at 8 and ten. Why is it dying?
Never encountered this one before. Any help would be appreciated.

Could be a fuel supply issue.

That's what I am thinking. I will change out carb today to see if that makes a difference.

That is typical of low or lack of fuel. Tap on the fuel inlet on carburetor with handle of a screwdriver. If the needle is stuck in the closed position it may shake it free. Remove the float bowl with a catch pan underneath. You should get approx. 1/2 cup of gas drain out. If little fuel then check supply to carburetor.

I would, in this situation, with the air cleaner off, have a buddy with a can of starter fluid spray spurts of fluid down the throat of the carb to see if you can keep it running awhile longer...You didn't mention if you had done anything about checking the carb for clogged passage ways...You know...Old gas that had set in there for awhile and turned to gunk/varnish...Check the inside of the float bowl for any residue...for starters...

Chipper is correct also, I've had needles stick before...Once while driving...I had no tools with me, so I picked up a rock off the side of the road and tapped the carb...And off I went...

Runs good on starting fluid for a short and I mean short period of time. Took the carb apart yesterday. checked and cleaned the jet, and the pipe. Set the float at 1/2 inch from the rim. Still the same. Haven't switched out carbs yet.

Did you try disconnecting the fuel line at the carb, then cranking the engine to see how much fuel is coming out...? Should be quite a bit...Have a rubber hose connected to catch the fuel in a glass jar or (gas)can...Or if you have a fuel pressure gauge handy...it should read 3 to 4 lbs....

If the '27 fuel delivery system on the vehicle is the original vacuum canister that draws fuel from the tank, but delivers it to the carburetor via gravity feed, then a pressure gauge is useless. I would be more inclined to disconnect the carburetor fuel feed line and observe if there's fuel flowing from the vacuum pump and if not, then start looking at the vacuum fuel pump. Is the shut off valve at the base of the vacuum tank in the "on" position?

A little more vehicle information is needed. Does this '27 truck have the original style vacuum fuel pump?

Still using the vacumn tank and it has a good flow to the carb. Changed carbs today to no avail. Removed the intake manifold and notice that the intake ports on the head were dripping. Remove the two inserts and they dripped with gas. No this is before I even cranked it and was left over from yesterday. I did get to turn over and catch but only for a short time. When I pressed the accelerator it died. I suspect it is getting too much gas. Checked the spark on all plugs a excellent spark. Truck starts with spark lever about 3/4 up the quadrant and gas level about half way on the quadrant. I think I am getting too much gas and it is choking out.

Here's the proceedure I use to start my '28:

https://vccachat.org/ubbthreads.php/topics/303374/Re:_Cold_Start#Post303374

The carb is set up according to the shop manual.

Cheers, Dean

I use the same procedure to start my 28 and it fires right off. Just tried the 27 one more time. Catches runs a bit and dies. it is either starved for gas or it is choking out. One of the two. Pulled the number 1,2, and 3 plugs...all dry...

If the engine fires and only runs a short time using the carburetor, squirting starting fluid and other situations the exhaust system may be plugged. It can be checked with a vacuum gauge. If the vacuum quickly peaks and then begins to drop as the engine is continued to turn over it suggests restricted exhaust.

Chipper,,hadn't checked that one but will do. Has a complete new exhaust systems with muffler and tailpipe.

I had that problem too! Found it was the coil.
Woodbutcher

After everything I have a theory. I believe that the cam gear is not in sync with the crank gear. The reason I say this...the distributor will not line up right on number one TDC. Just a couple of teeth off. Feedback would be appreciated. Will start the process on Monday to check...

It is a common problem and well known for cam gears and possibly crankshaft gears to be mismarked. The cam gear should be marked on the 15th gear from the keyway. Crank gear on the gap between teeth at the keyway.

If you send me your email in a PM I can email your a page from the Service News and another from the '28 Repair Manual on the subject.

Easy way to check cam to crank timing is to remove rocker cover and bring #1 piston to actual TDC compression and check that the rear valves are changing from exhaust to intake open. If not the cam is out of sequence.
Tony

Chipper...here is my email: skayhebert@aol.com

Check your email to see if I got the address right and you can open the attached files.

Hi Tony,

That is a good suggestion, however if the cam and crank are say one tooth off I don't think you could see it.

My input on the situation is to remove the line from the manifold to the vacuum tank. Block off the line to the manifold. Now see if the engine will start and run. It may take more than one try to burn all the excess fuel. This solution is made on the basis of the valve seat falling out of the vacuum tank top.

If your engine now runs you are good for about 7 or less miles based on the fuel remaining in the vacuum tank.

PS: The only way to correctly check the mating of the crank and cam gear is to remove the crank pulley and the timing cover. Follow the instructions in the repair manual to see if the cam gear is marked wrong.

PPS: It is also suggested that you go to the "School is in Session" for a more detailed discussion on this problem.

The rockers should be "equaly" open / closed at tdc (except on real high performance engines) so if the timing is out 1 tooth the rockers will noticeabley be out of sequence.
Tony

Pulled the crank case cover and worked on the problem. Four hours later here is the summation.

1. The dot (marks) on cam gear and the crank gear don't line up with number one at TDC. Number one is on the down and bottomed out.

2. The marks on the cam gear and the crank gear do line up with the number three piston at TDC.

3. I am thinking I need to pull the cam as it is a new cam to see what I have. Any ideas or suggestions would be greatly appreciated. I have worked on these for over 20 years and never encountered this. I even asked my mechanic neighbor, who has a very successful business, trained by Chevy many years ago and he is stumped. His theory is that it is something mechanical involving the cam.

It runs!!!! had to disregard the punch marks on the cam and crank gears. Brought number one to TDC with both intake and exhaust about 1/16 off of each other. Reset the crank gear by trial and error. Started with spark lever about a half down the quadrant. I would caution anyone rebuilding that if it's a 27 to recheck everything and don't assume something is correct. Thanks to everyone for your input.

Major congrats!! It only takes common sense and persistence to work through the problems on these old Chevys.

Happy motoring!

Dean

One of the hardest things to teach a layman is that you could care less where anything else on the engine is lined up when you mate the "V" and the "dot". Go to the "School is in Session" where I prove this point.