Sorry, I need some engine 101 education. What exactly does single overhead cam mean? What is it and what differentiates it from an overhead valve? What does it mean when you see a car say it has 24 or 32 valves?

 

24 or 32 is the number of valves in the engine
say its a V8 and says 32 valve, it means there is 4 valves per cylinder, 2 for exhaust 2 for intake, 24 means there are 3 per cylinder i forgot which side generally has 2 and which has one but for example there will be 2 exhaust valves per cylinder and 1 intake valve.


single overhead cam means the cam is on top of the head if its a single then one cam controls the intake and exhaust valves for each bank i believe. if its a dual over head cam then one cam controls intake and one controls exhaust on each side.

a pushrod engine has the cam in the middle and has rods that go through the heads to control the valves


someone is bound to correct me but thats what i've got for you right now

 

Single-Over-Head-Cam means that there is one camshaft on-top of every head and the lobes push the rocker arms directly (which opens the valves). OHV is the camshaft in the top of the block (driven by the timing chain) that lobes the lifters and pushrods that move the rocker arms that open the valves (one cam in the block). And DOHC (someone correct me if I'm wrong) have two cams per head (one for intake valves and one for exhaust valves).


Ah, I was typing too slow. I got beat.

 

Overhead cam motors are also referred as "Modular Motors"

 

A SOHC engine has a single camshaft above each bank (this means 2 cams on a V engine, 1 on an inline) that in turn actuates the valves for each cylinder. A four-stroke motor cylinder has to have at least 1 intake valve for air a fuel to enter the cylinder, and 1 exhaust valve, to emit the fumes created by combustion. Some engines have 3 or 4 valves for intake and exhaust, but this requires more camshafts to turn more valves, hence double overhead cam, same idea, more cams. Camshafts are driven via a timing belt or chain from the crank shaft.

An overhead valve engine has the valves at the top of the combustion chamber, same as the OHC, however, the valves are actuated via pushrods that link directly to the crankshaft.

A V6, with DOHC will have 24 valves (4 valves per cylinder X 6 cylinders) where as a V8 with 4 valves per cylinder will have 32 valves.

Hope I could be of some help, If you'd like to do some research, the easiest way I have found, is just search wikipedia.org, it will have just about anything you are looking for, and generally with decent pics.

 

i'll sum it up...

OHV = pushrod off the cam actuates the valves. 1 cam in block.
SOHC = cams actuated by their own camshaft. 1 cam per head.

 

Only ford v8 and v10 OHC engines are called mod motors..only because from the 4.6 2v up to the 6.8 v10 3v they all share the same basic design. Hence a MODULAR build and construction assy.

 

^^ valves ....but we knew what ya meant