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Tofuball's '94 XFi; It's all about city MPG
Topic Started: Mar 12 2011, 08:59 AM (39,415 Views)
Tofuball
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Strange Mechanic

I believe so.
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Tofuball
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By the way, the hydro lifters on the old XFi engine were frozen solid.
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starscream5000
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Got 70 MPG?

Tofuball
Mar 21 2012, 10:03 AM
I believe so.
That would make sense seeing as you were using a crank gear with the triggers on it for your megasquirt.

You probably ended up with a cam gear from 1994-1995 by accident.
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Coche Blanco
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Tofuball
Mar 21 2012, 10:06 AM
By the way, the hydro lifters on the old XFi engine were frozen solid.
I have yet to figure out what is right. Solid or squishy.
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bogs
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Duct tape heals all wounds

Glad to hear your feeling better :thumb
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starscream5000
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Got 70 MPG?

Coche Blanco
Mar 21 2012, 10:19 AM
Tofuball
Mar 21 2012, 10:06 AM
By the way, the hydro lifters on the old XFi engine were frozen solid.
I have yet to figure out what is right. Solid or squishy.
Solid would be right, but not 100% solid with no play because you wouldn't have any compression. They need to start out empty so that when the motor is first turned over, it will start up. Then the oil will start filling up in the lifters and they will pump up to the designed parameters where the valves will not be held open, but the lifters will be mostly solid.

How much oil does it take for that to happen? Hell if I know....
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Coche Blanco
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But how do they compensate for different cams? I am confuzzled.
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starscream5000
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Got 70 MPG?

Me too :hmm
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Tofuball
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starscream5000
Mar 21 2012, 10:15 AM
Tofuball
Mar 21 2012, 10:03 AM
I believe so.
That would make sense seeing as you were using a crank gear with the triggers on it for your megasquirt.

You probably ended up with a cam gear from 1994-1995 by accident.
I bought one that said it was newer earlier, so I thought I was set.

It was not, it was the old style.
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Tofuball
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bogs
Mar 21 2012, 10:49 AM
Glad to hear your feeling better :thumb
Thanks :D
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Tofuball
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Coche Blanco
Mar 21 2012, 12:45 PM
But how do they compensate for different cams? I am confuzzled.
Usually a setup like this has a shim on top of the lifters that you switch out as the parts wear. My Suzuki GS850 had shims. Many Toyotas do, for example. Some SOHC Volvos have screw adjustments.

I think our cars just eat the difference.
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clarkdw


When they use shims it is without hydraulics. The shims just take up the distance between the cam and the valve till it is a specified distance.

The Metro hydraulic lifters start out soft then as oil is pumped into them they fill the gap between the cam lobe and the valve till there is no gap at all and the lifter is then theoretically solid. When you regrind a cam or wear occurs the lifter simply extends further and keeps continuous contact. That is the beauty of hyd lifters. No adjustment is required as wear occurs. It takes care of it.

When you first start up the engine after cleaning the lifters it takes some time for them to fill completely and eliminate the gap TAKA TAKA TAKA for a little while till the lifter fills up and the gap disappears.
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Coche Blanco
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clarkdw
Mar 22 2012, 12:16 AM
When you first start up the engine after cleaning the lifters it takes some time for them to fill completely and eliminate the gap TAKA TAKA TAKA for a little while till the lifter fills up and the gap disappears.
How does this work if you never clean/open them? Say I put in brand new lifters with brand new oil. run it for 500 miles. Then, swap in a sick nasty cam that needs different length lifters.
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clarkdw


If the cam has been reground to the sick nasty spec it is most likely a smaller base dia than the original so lifter will pump up to the new required height. If it is a new larger base circle cam then you will have some problems with the valve being held open by a lifter that is too tall till it bleeds out the check valve and collapses down to the new required height. Best to release the little check valve in the lifter to collapse it when you first install them and let them find the correct height.
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Coche Blanco
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Makes sense, not sure why i didn't figure that out myself... thanks!
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