No suction on intake stroke

I just received an old chrysler 250 flathead 6. When turning it over, there is no suction through the intake manifold. The Valves are new and seated well. I was wondering if the timing chain/gear was installed 180 degrees off, if this could cause the problem? I think that on the power stroke it is blowing air through the intake/carb. There is never any suction at the intake side, but there is suction through the exhaust manifold; this is what leads me to believe that the cam is not synched to the crank properly. Do you believe this is a timing gear issue? Any help would be appreciated. Thanks

 

It sounds like timing, you may be 180 out.

 

Yep or you got a crack somewhere

 

ummm, how do you install a camshaft 180 deg out?

 

Does it have compression?

 

Squirt some oil in the clyinder through the spark plug holes.

 

Could the engine be rotated in the wrong direction ie. marine engine? Would that even matter?

 

Agreed...this would be a good place to start. Check the compression.

 

This sounds likely to me. Or he is just turning it the wrong way.

 

There should never be suction from the exhaust. Could be cam timing.

 

This can be done if you dont align the timing marks on the gears.Duhhhh

 

I would go with make sure you are turning the crank the right direction, clockwise, that is if you aren't using the starter. If you are turning it on the starter and have no intake suction you do have a bigger issue, quite likrly cam related I had a similar issue with a 230 gear on a 235 cam. Gear is the same and presses on to the 235 cam but timing marks are positioned differently.

 

How about valves stuck open?

Had that happen with my old JD tractor when I ran avgas for a while. All the lead clogged up the valve guides and the valves stuck open.

D'Oh! Just read the part where you said the valves were new. How much was disassembled when the valves were done? Was the cam removed?

 

The cam cannot be 180 out if the timing marks were aligned either together or 180. If the cam is out of time then it must be 90, 45, 20 whatever degrees out but not 180 that is only needed for distributor placement. (Refering to a SB V-8)

 

If the valves are stuck open you won't get suction on the exhaust side as discribed.

 

the cam turns 180 degrees for every 360 degrees of crank rotation - can't be 180 out.

 

Your theory doesn't work.

If the cam is 180 out the cam be opening the wrong valve on the wrong stroke.

Intake =intake valve open piston going down.
Compression both closed piston going up
power = both closed piston going down
Exhaust= exhaust open piston going up.

That isn't counting any overlap just the theory of what is happening in the engine.

Turn the cam 180 out and you have the intake open when the piston is going up and the exhaust open when the piston is going down. In theory that changes the engine so that the intake works as the exhaust and the exhaust works as the intake.

InlineNmine are you turning it over by hand or with the starter? turning it over by hand may not turn the engine fast enough to be able to notice any air going into the intake.

 

As far as how someone could get a cam 180 out it isn't that hard when they have been working on one design of engines most of the time and run into one one that has the timing marks in different spots. and then throw in some models of Ford sixes for good measure to really mess with their minds.

 

If the cam is 180 out turn the engine one more turn.

 

Shouldn't the valves be banging the tops of the pistons with the cam out of time that badly???

 

That would be difficult in a flathead motor

 

some of you guys are getting ahead of yourselves. The cam can be 180° out, given that the cam rotates a full 360° (leave the relationship of the crankshaft out of this), as does anything that's round that you turn from start back to the starting point again. If you turn the camshaft halfway around, that makes it 180° "out" of phase. Everything that is round and rotates can be 180° out. Makes no difference how many times the camshaft turns for each rotation of the crank, the cam itself can simply be installed improperly (at its ½ rotation point).

 

can't happen on a flat head...the valves aren't over the pistons.

 

An automotive cam installed 180
degrees out of synch....or you've
got a reverse-ground cam intended
for a reverse-rotation marine
application that's installed right
on the marks.

 

Time for a new ole lady!

 

The old 180 out story again!!?
Guys...Put the cam in time with the crankshaft mark up, and the cam mark down. Right? Okay, now turn the crank one full turn. Omigosh! The cam mark is now straight up, or 180 degrees out! What to do, what to do??? Tear it off and turn the cam a half turn?
Don't be silly. Finish putting it together and fire it up.

 

The cam can be out of time but not 180 out. Worth checking anyway.

 

The motor is an industrial engine out of a forklift. It's a 236 block with a 250 crank in it. I am not sure if the cam was ever changed when the new crank was installed. I am turning the motor over with the starter motor. I believe the compression will check out fine, as it had good cross hatching, little cylinder wear, and new rings. The problem is as mr48chevy called it, my intake has now become an exhaust, and my exhaust has become my intake. I believe i need to tear into the timing cover and change the crank to cam relationship. Mart3406 do you know if the industrial engine applications are reverse-rotation? If so, can the automotive cam be used in these industrial applications? my motor is turning clockwise when using the starter, as is the rotor. thank you for the help so far.

 

Well a forklift drivetrain is backwards as in going forward is away from the radiator.
There's quite a few engines out there with the intake bolted to the exhaust flanges. So it's possible

 

-----------
All the Chrysler industrial engines
I've ever seen were standard
rotation, but with Chrysler, anything
is possible. If some, even small
manufacturer needed a an engine
that spun in the opposite direction
for some type of machine or
equipment they were building and
selling, I'm sure that Chrysler would
facilitate their needs and supply
such an engine. They could do it
quite easily too, simply by
substituting the standard industrial
cam with one of their 'off-the-shelf '
reverse rotation marine versions. By
the way, the Chrysler industrial were
built in the same plant as the marine
engines and marketed by the same
in-house sales group - ie - "Chrysler
Marine and Industrial Division"
If by chance your engine has been
fitted with a marine cam ground for
reverse engine rotation - either
intentionally when new or possibly
accidentally when it was rebuilt and
had the crank swapped before you
got it, you should be be able to simply
swap the cam for a conventional
automotive one. Check the distributor
and/or the distributor drive gear..
Either the distributor and/or the
drive gear might (or might not)
also need to swapped for a standard
automotive type as well.