I just freshened up my small block with new rings and bearings. Everything else is the same. It was idleing around 8-900 rpm, now it gets below 1500 and it is like the motor shuts off. Sounds fine and runs smooth then just shuts off. At 32 degrees the motor shuts off and rolls backwards blowing air and fuel out the carb. At 15 degrees the motor stops then surges, stops, surges, etc. What is going on?? I'm guessing I have a bad distributor. What would a motor run like if the mechanical timing was off one tooth on the cam?

could have the distb off one tooth...

honestly guys... there's really no such thing as 1 tooth off...timing is timing, no matter where you put the ditributor, you could twist it until the timing was right (assuming nothing hit the firewall)

not sure where or how your reading 15 degrees or 32 degrees, but it sounds like your timing is not advanced enough.

Normaly I run the motor at 32 degrees advanced. I check it on the dampner on the crankshaft. With the motor shutting down then rolling backwards at 32 degrees it kinda sounded like it was too far advanced so to see what would happen I turned the timing back to 15 degrees. Then it shut off and surged forward several times.

are you totally positive you got the timing gears for the cam on correctly?
Does the motor run ok except for idling?
Do you got a vacaum gauge?
if you do, what's it look like at 2000 rpm, and at the lowest stable idle you can get.

What about valve adjustment? Hydraulic or solid? How did you adjust them? if you gotta couple too tight it would run like you describe.

At 32 degrees the motor shuts off and rolls backwards blowing air and fuel out the carb. At 15 degrees the motor stops then surges, stops, surges, etc
I dont quite understand...32 deg at ildle? greatly over advanced...hard starting?
I assume basically a stock engine?
intial about 4 to 8 deg...about 32 all in 2800 to 3600 rpm...with no vac attached.
U sure u have the right vac advance unit...assuming an early engine this should starting a couple inches above idle vac...just inside on the vac adv unit there are some numbers, the 1st is inches of vac it starts at.
is the centrical mechansuim working ok and smooth, bushes ok? no play in the shaft?
Using a aftermarket chome dizzy tie down? these are notorious for not holding firm.

The only thing stock about the motor is the block. Light weight eagle crank, H beam rods, JE pistons, dart heads. Solid roller cam, lash checked out fine. I check timing around 3000 rmp. There is no vacuum advance on the distrubutor. Motor starts and runs great until 1500 rpm and it just shuts off then rolls backwards. I don't have a vacuum guage.

vacaum leak is my best guess then

I don't have a vacuum guage.
The most simple yet one of the most telling intruments u will ever use.
Consider this ...an engine is no more than an over grown vaccuum pump...anything go wrong or not right...it effects vaccuum.

Pull a valve cover off and check the #1 cyl valves when the crank is at TDC #1 compression stroke. If you installed your cam and crank out of phase it should show.
It sounds like you may have a vacuum leak issue but it could also be timing. The engine wouldn't sound normal above 1500 rpms if the cam gear was installed wrong I wouldn't think, where it would sound OK with a vacuum leak.
How do the plugs look?

Both intake and exhaust valves have lash with #1 at tdc. Plugs looked good. I tired replacing them today to make sure but the local parts store didn't have the correct ones... Will start looking for a vacuum leak..
Thanks for all the advice. It helps and may save money!

i had a problem like that come to me the other day with a customer. come to find out when someone put the carb on, the arm that pushes on the accelerator pump was bent. so when you give it fuel, it was gettin air only and no fuel. it acted that exact way. check it out anyway. if not, i'd do a quick vaccume test and start with the timing from step one. good luck.

sounds like timing... or plug wires out of order...

distributor off a tooth means nothing, unless you can't rotate the distributor becasue something hitting the firewall or a runner...

however, if you leave the wires on cap, and pull the distributor, and then re-stab it off a tooth, with the wires and cap indexing in the same place.. will put you off about 20 degrees LOL...

having the cam/crank off a tooth, can cause all sorts of problems... and depending on how big the cam is, you migth not notice a thing lashing it...

but it won't run for **** depending on exactly how far advanced or retarded it is....

confirm that the ignition is OK (check wiring, plug wires, etc) before pulling the front cover off... if you have your cam card... you migth be able to check the cam position in relation to the crank with the degree wheel, and dial indicator to confirm or rule out the cams position...

if your cam is off 10-15 degrees... god only knows how it would run.and ignition timing would mean absolutly nothign,

make sure you don't have a vaccuum leak anywhere... that could cause problems like you are describing too


good luck