330 desoto cam problem?

Long story short... bought a "good low mileage motor, just needs rings". Ended up needing everything...

Anyway, it included the "original" cam. Cam looked good, so I sent it to isky to get reground. After assembling the motor, I can't get it to start. It spits fuel back up out of the carb. It did start one time, but idled very rough and died when I tried adding fuel.

Everything is new on the motor, new carb, new dizzy, new valves, great compression in all cylinders, timing is right etc.

I was doing some reading in the Tex Smith hemi book and it says that low deck and high deck cams interchange, but the lifter bore angles are all wrong.

Could I have gotten a short deck cam? Would it act this way?

Thanks
Mike

 

It could be a cam timing issue, or the wrong cam. You will have to pull the cam out to verify what it is...or isn't.

Who did the assembly work? Was the cam properly degreed? What chain set was used? Do you have adjustable rockers or adjustable pushrods?

Inquiring minds need to know in order to be of much help...

.

 

Was it a long or short snout cam?

 

Thanks for the reply.
I did the assembly work with a gearhead neighbor looking over my shoulder.

We didn't formally degree the cam, but set the dots on the gears with the cam at 6 o'clock and 12:00 on the crank. I used the small block timing set from HH along with new lifters and adj pushrods.

I've done a compression check on all of the cylinders after setting the pushrods and it is holding pressure when it should. I was concerned that the valves were being held open and not building compression.

Are there markings on the cam that would identify it either way? I'll pull it back down to check if so.

 

short snout cam

 

The low decks had long snout, so your good there, unless someone moded a long snout to take a modern timing chain!

 

ok, I thought that I had read that all of the desotos had short snouts after '55. This is an S23 desoto (1956).

 

That's what I was saying, if it's a short snout cam you're good to go, unless it was actually a long snout modified to take a modern timing chain. Never had to deal with one of those so I don't know what a moded one would look like. If you're sure it was the original cam that was in the engine you should be good in that dept.

 

Did the timing set you used have a crank gear with three keyways?

 

Sounds to me like you may have some plug wires crossed.

 

There was only one keyway on both gears. I lined up the 2 dots on the gears, but the keyways did NOT line up. Since this is a SB mopar timing set, maybe that is wrong. Should the keyways have gotten lined up instead of the dots?

Plugs wires have been checked a hundred times, made that mistake in the past.

 

How many keyways on the crank gear?

 

I only remember seeing 1 keyway on the crank, but I just talked to Eric at HH for some gaskets and he said that there should be 3 keyways on the crank.

Guess I'll pull it apart and check. I assume that I want it on the center keyway?
Hope that's what it is.
I'll report back, thanks for everyones input.

 

Spits fuel out of the carb, well its one of two things one of those is that you have a reverse flow cam shaft, try taking the carb off and squirting fuel in the exhaust ports.

OK that was just mean but I just couldn't resist.

What it sounds to me like is that you have a timing problem first thing I would do it check the that the plugs leads are on correctly. Make sure that you know what direction the distributer rotates in when you are putting the plug wires on, very common mistake.

Next check your initial timing, simple check is to roll the engine over and when the intake valve just closes it is ready to fire, that should get you near enough to TDC that you can finish it out with the timing marks. Now two common mistakes using this method, one is that the engine is not rotated in the correct direction the other is that the mechanic mistakes the exhaust valve for the intake valve.

If thse two check out it is time to double check your valve timing, you will need to pull your timing cover and make sure that the timing gears ar lined up properly at the very least and a degree wheel is your next option to get it right on the nats ass.

Good luck, I know that you will get it sorted out.

 

What was the cranking compression?

I had similar troubles trying to fire a 392.
I had the distributor off a tooth or two.

If its backfiring thru the carb, its sparking when the intake valve is open.
If its pressurized the intake from the piston coming up with the intake open, then it should be pulling vacuum on the exhaust. That's a whole "nut her" issue.

 

Thanks porknbeaner, i needed a laugh.

I'm getting about 150psi compression on all cylinders when rotating through a couple of cycles.

I watched the piston come up to TDC (through the spark plug hole), which then matched where the rotor should be pointing. Also made sure that it was actually on the compression stroke and not 180 out.

Just to check.... dizzy spins clockwise, 18436572 firing order, From front to rear Left bank: 1-3-5-7; Right bank: 2-4-6-8. Crank spins clockwise when looking from the front of the motor.

I'm really going back to the basics I guess.

thanks for everyones help.

 

Just for chits'n'giggles the simple stuff always gets past me.

 

not the best picture, but you get the idea. Each keyway has a corresponding timing mark. When the timing marks are lined up correctly, the lower gear keyway in use should be to the right of center. .3/4" or so. If you look closely, you will see the gear keyway to the right of the timing mark. (Ignore the damper keyway.)

 

Thanks, I'll check it out.

Wouldn't be the first time that I missed something like that.

 

Several years ago I bought a double roller for a 341. It had 3 keyways and 3 markers on the sprocket. A circle, box, and triangle. It never did work no matter how it was lined up. Could never figure it out, but got to thinking that it might have been for a big block Mopar. I took it to Autozone and compared it to a stock 318 timing set and the marks didn't line up. Go figure. Bill

 

Are you sure the timeing mark has'nt slipped

 

Just a thought. Are you using the stock damper? I'm not, and I had to put a new timing mark on the damper because it was way off. Bill

 

I'm using the stock dampner and I put new timing tape on to match the notch on the dampner for TDC. Will confirm tomorrow when it gets pulled back down.

Can't wait to get this car going....

 

If you turn it to TDC exhaust with the valve cover off the intake and exhaust valve should be open the same amount if a single pattern cam.

 

Well, problem solved... I had mistakenly installed the cam advanced with the timing gear. I never noticed the other keyway.

Also, the dizzy cap that I though was good had tracking marks inside where it was cross firing to every cylinder. In other words, every plug was firing at every 90degrees of crankshaft revolution. I never would have found this if I hadn't spun the engine by hand and watched the timing light on when it fired. Sure enough, plug 1 fired every 90 degrees. Can't build up much voltage that way.

Now it's running good. Thanks for everyone's help in a big way.

Mike

 

On my 330 motor I used a 3 key timing set from Hot Heads. It is a later style mopar kit. I set up dot to dot. Ran lousy, NO torque on take off. Would actually die. I fought with it for a while, then pulled the timing cover to check the setup. Was indeed, dot to dot. Hot heads asked if I had degreed in the cam. No. He said I must do this. I had to do a major offset of the cam to get the degreeing correct. Its no fun to fix, but I would expect that this is your fix. Billk