On a 4 cylinder petrol engine if the camshaft is timed up 180 degrees out,will it run?

Answer 1

Sure it will,,,absolutely.

On Camshaft Timing there is no "180 out" relatively to TDC. upon installation.

*Install Cam 180* Out---"Cam is Upside Down"
*Rotate crank 360* aka 1 full turn

Then where is Cam?
1/2 turn from it was---now Right side Up

*Install Cam "correctly"
*Rotate Crank 360*,,1 full turn
NOW where is cam?

Exactly,,It's 180* Out,,,Upside down again.

4stroke engines spend HALF the run-time lives with their canshaft "180* Out"

...............................................................
If TDC is considered to be 0*
Then STRICTLY regarding Cam Timing>>>>

You can Install>
*ANY Cam
*In Any Engine
*With Any number of Cylinders
*Cam indexed to ANY Cylinder
*At 0*
* Or at 180*

Example:
A V-8"s #5 Cyl at TDC with Cam 180* Out
A Straight 4 Cyl at BOTTOM dead center with Cam 270* Out
Any Engine with Cam timed "By the Book"....

That's ALL Same Thing


The Exceptions are Examples of engines wich are "Compensated for Cam Drive Deflection"

1960's era 427 SOHC is a common example.
The cams were Timed "Off Center" to compensate for Chain deflection due to centrifugal force working against extremely long drive chains.

............................................
IGNITION TIMING,,,is an entirely other matter.

But,,Camshafts??
They are NATURALLY 180* Out for half their entire lives.

Answer 2

Interesting question. The camshaft runs at half the speed of the crank. For each cylinder firing stroke the piston goes through four movements.....

Cam in correct position...
induction: Exhaust valve closed, inlet open
compression: both closed
power: both closed
exhaust: exhaust open, inlet closed.

I think if you shift this 180 degrees there won't be a problem with piston and valve collision - at the top of each stroke both valves will be closed; but the engine wont run because the spark will be timed for the top of the exhaust stroke - BUT....

Some older motorcycles used to have a "spare spark" ignition system. That is, there was a spark at the top of every up stroke, compression and exhaust - it was easier to make the ignition that way. So, if the ignition is of the spare spark type then the engine should run (or I've got it completely wrong - always possible).

Answer 3

You would run the risk of bending some valves when the pistons hit them. Look at the operation of any 4-cycle engine on the net. Imagine if the valves were open when the piston tries to go to top dead center. OUCH! You'll have created a disaster!

Answer 4

Yes it will, have done it, it will run rough, no power etc.to confirm you will find the exhaust valve on 1st cylinder will have just closed as the engine is turned to top dead centre and the rotor arm (if you have one) is pointing to the lead to the spark plug for 1st cylinder. It should be the inlet valve that has just closed.

Answer 5

Maybe but doubtful. All the timing will be the opposite of what it should be. Exhaust valves will be opening when they should be closed and same for the intake valves. If it does manage to run it will not run very well. I suspect major backfiring if you can manage to get it running.

Answer 6

before you try to start it, price up a full set of valves, and fitting, that's what it'll cost to fix, if you dont do the pistons in along with the valves. could be all sorts of different tho, if it's single or twin cam.

Answer 7

no thats the opposite, it has to go in a certian direction. moving it that far back would probably jam it on the second or third piston

Answer 8

no defiantly not, the timing only has to be a few degrees out and it wont run

Answer 9

YES BUT IT WILL RUN POORLY YOU COULD REVERSES THE FIRING ORDER IF YOU THINK THAT IS THE PROBLEM JUST TO VERIFY YOUR SUSPENSION

Answer 10

no not unless u use fairyfuel