Help starting my new rebuilt engine

[DirtDonk]

Sure you can..and my touch is not that delicate.

True enough! But that lack of delicacy(?) is made up for by experience.
At least weeks worth of it! (since we don't discuss relative ages in family oriented threads) ;D

Paul

 

[Ourobos]

What???? No...that is NOT how it works. The lobe lift is the lobe lift..period. The only difference in the entire adjustable valve train that would be affected by a .1" difference in pushrod lengths is the mean angle of the rockers. The valve lift is not affected.

That is why, when building a custom engine with aftermarket valve train components, you use an adjustable pushrod length-checker to find the best pushrod length that properly centers the rockers.

And what of duration buddy? Do you realize that with a .100" too long of a pushrod, when that lifter pushes that pushrod to that extra .100" of travel during the max lift of the camshaft, that the duration of the camshaft, AKA with width of the lobe or the AMOUNT OF TIME the valve stays open increase.. Thus the valve is OPEN LONGER.. Simple physics, speed = distance / time.. The speed of the valve opening and closing is SLOWER.. You will also bust lifters and break rocker studs if too extreme.

 

[bmc69]

And what of duration buddy? Do you realize that with a .100" too long of a pushrod, when that lifter pushes that pushrod to that extra .100" of travel during the max lift of the camshaft, that the duration of the camshaft, AKA with width of the lobe or the AMOUNT OF TIME the valve stays open increase.. Thus the valve is OPEN LONGER.. Simple physics, speed = distance / time.. The speed of the valve opening and closing is SLOWER.. You will also bust lifters and break rocker studs if too extreme.

Sigh. A slightly longer or shorter pushrod does not change the range of motion..the lift..the duration..nothing. It changes slightly the baseline angle of the rocker.

We can go in to the "physics" if you want too...I dimly recall that being part of the curriculum in Mechanical Engineering. It was a long time ago...;D

 

[Ourobos]

Well Mr. Mechanical Engineer, that was my field of study at the University years ago too.. So go ahead.

 

[Viperwolf1]

And what of duration buddy? Do you realize that with a .100" too long of a pushrod, when that lifter pushes that pushrod to that extra .100" of travel during the max lift of the camshaft, that the duration of the camshaft, AKA with width of the lobe or the AMOUNT OF TIME the valve stays open increase.. Thus the valve is OPEN LONGER.. Simple physics, speed = distance / time.. The speed of the valve opening and closing is SLOWER.. You will also bust lifters and break rocker studs if too extreme.

So, overhead cams with no pushrods must not work at all? Pushrod length doesn't affect lift or duration, only rocker arm geometry.

 

[bmc69]

Well Mr. Mechanical Engineer, that was my field of study at the University years ago too.. So go ahead.

Show me where pushrod length enters in to any of these calculation examples for valve lift.

I'll wait.

https://www.google.com/#q=valve+lift+rocker+ratio+calculator

 

[bmc69]

Back on the topic...can't wait to hear what effect another round of adjustment has on this problem at hand.

 

[bmc69]

So, overhead cams with no pushrods must not work at all? Pushrod length doesn't affect lift or duration, only rocker arm geometry.

He's talking about dynamically-compensated pushrods. The kind that increase in length as they are being used to actuate a valve opening.

High tech stuff, Viper...

 

[Viperwolf1]

He's talking about dynamically-compensated pushrods. The kind that increase in length as they are being used to actuate a valve opening.

High tech stuff, Viper...

I've seen some dynamic ones but they usually decrease in length and only do it one time.

 

[bmc69]

I've seen some dynamic ones but they usually decrease in length and only do it one time.

Well...there are those too......%)

 

[Ourobos]

Wow.. two morons.

 

[bmc69]

Wow.. two morons.

There are lots more of us. Fortunately for the OP.

 

[ugly74]

Wow.. two morons.

Lets create a different scenario with similar dynamics.

If you have a system with a belt drive, all else being the same (ie, 1" drive sheave, and a 1.6" driven sheave) does the length of the belt in any way effect the speed of the driven pulley?
Nope! Whether they be 6" apart, or 6 feet apart, the final drive ratio remains identical.

Can I be in the moron club, too?

 

[Ourobos]

Apparently you are, apparently you are.. I'm just waiting for the OP to check pushrod length, realize they are too long (possibly a decked block, thinner head gasket etc.), then listen to the brilliant theories as to why the valves were hanging open.

 

[bmc69]

Can I be in the moron club, too?

Yr in! ;D

 

[Viperwolf1]

Wow.. two morons.

I'm not going to resort to name calling but I have to say you are wrong here. Perhaps this discussion on pushrod length needs it's own thread so as not to distract from the OP's problem resolution.

 

[bmc69]

Apparently you are, apparently you are.. I'm just waiting for the OP to check pushrod length, realize they are too long (possibly a decked block, thinner head gasket etc.), then listen to the brilliant theories as to why the valves were hanging open.

And meanwhile, we await your mathematical proof of how varying that pushrod length changes the lift of a valve when the previously long held theory adopted by all engine designers and builders over the last 60 or so years was that the cam lobe geometry defined the cam lift and the rocker ratio then amplified that lift, in a nearly linear relationship to obtain to the valve lift.

You may proceed.

 

[ugly74]

Apparently you are, apparently you are.. .

Yr in! ;D

Woohoo! Nominated and seconded! Ill be struttin all day;D

 

[Ourobos]

Nah I'm good, no need to educate anyone.. Carry on. Waiting for OP to determine why that long pushrod held the valves open magically. As if a pushrod isn't part of the valve lift equation.

 

[bmc69]

As if a pushrod isn't part of the valve lift equation.

Show us. How. Please.