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Old 09-21-2012, 12:15 PM
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please help me diagnostic this problem

yes Ford engine...

Inline six 300 CID

I installed this engine in a Granada, I already have several threads speaking of this swap, I love the way it came out, but the point here is this:

The engine runs great but when I let off the gas and the engine slows down to idle, it starts shaking and missing badly, if I don't give it a little gas it will stumble and die.

While it's aproaching idle I can hear the exhaust poping, (it only has a glasspack and the pipe is 2" first half and 2-1/2" the other half)

It behaves exactly like when you do a valve train adjustment on a SBC while running, once you tigthen the nut past zero lash and the engine starts shaking.

It makes me believe that the lifters are like "pumping up" while it runs at speed and they remain stretched when the engine slows down.

After something like 40 seconds of shaking, the popping noise goes away and the engine starts idling smoothly.

I'm pretty sure the valves are being kept slightly open while running, this is why it won't idle, but when the lifters bleed down the valves seat and seal and the engine idles smooth.

What do you guys think? am I correct?

could it be that maybe somebody shaved the head and the pushrods are now too long and the lifters are having trouble with this? or maybe the lifters are worn or stuck? (the engine sat in a corner for like 10 years)

I was thinking that shimming the rockers up a bit may fix this problem? I started a thread asking if this valvetrain could be converted to adjustable but didn't get much help there.

It has a brand new carburator ignition and distribuitor, so no tuning problem.

Please help me with this problem.

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