Bad lifter?

[phantom]

Hello.

So my 440 was completely rebuilt by a shop two years ago, New pistons, cam, hydraulic lifters, heads, intake ++. Got the car registered about a year ago, so havent driven the car much after rebuild. But last summer the car started misfiring, although rearly at first, but got worse before i put it in storage last fall. Got the same problem now after driving it for a few weeks after picking it up again from storage. Changed the oil after pick up, 20W-50 Dynocat.

When i run down the highway, no problems. Over 1800rpm the car runs on all cylinders. But if i come to an intersection, and rpm goes lower than 1500-1800rpm, it only runs on 7 cylinders. But as soon as i bring it up to 1800-1900rpm for maybe 2-3 seconds steady, you can hear and feel the 8th cylinder also coming to life. If i floor it when i am over 1800rpm, it takes off, not missing a beat, but when i try from start, it just bogs on 7 until i hit ca 2000-2200rpm before it fires on all 8. I suspect it runs on 7 at idle also when its hot. From Cold start all cylinders fire because all of the header pipes get hot simultaneously.

Had my engine Builder come by and try to adjust the rockers, but it didnt help. But he said one of the hydraulic lifters were very soft compared to all of the others. He could lift the rocker almost 1/4". Could this be the reason for the misfiring?

[DownZero]

Curious is to why such a heavy weight oil on a recent rebuild?

[BLK 68 R/T]

Hello.

So my 440 was completely rebuilt by a shop two years ago, New pistons, cam, hydraulic lifters, heads, intake ++. Got the car registered about a year ago, so havent driven the car much after rebuild. But last summer the car started misfiring, although rearly at first, but got worse before i put it in storage last fall. Got the same problem now after driving it for a few weeks after picking it up again from storage. Changed the oil after pick up, 20W-50 Dynocat.

When i run down the highway, no problems. Over 1800rpm the car runs on all cylinders. But if i come to an intersection, and rpm goes lower than 1500-1800rpm, it only runs on 7 cylinders. But as soon as i bring it up to 1800-1900rpm for maybe 2-3 seconds steady, you can hear and feel the 8th cylinder also coming to life. If i floor it when i am over 1800rpm, it takes off, not missing a beat, but when i try from start, it just bogs on 7 until i hit ca 2000-2200rpm before it fires on all 8. I suspect it runs on 7 at idle also when its hot. From Cold start all cylinders fire because all of the header pipes get hot simultaneously.

Had my engine Builder come by and try to adjust the rockers, but it didnt help. But he said one of the hydraulic lifters were very soft compared to all of the others. He could lift the rocker almost 1/4". Could this be the reason for the misfiring?

I would say so...1/4" is a lot.

[c00nhunterjoe]

the loose rockers requires further inspection before running anymore. Based on the dynocat, i assume you are in europe? I dont think dynocat has zddp in it.

[phantom]

Hey guys and thanks for all the replies
The car had sat for three days when we checked the rockers, all were hard except the one.

Yes i am in Norway, and Oils With zink is hard to come by here, although it says the Dynocat 20W-50 Supreme Classic GT has some zink additives in it, i was recommended this oil. But, the last oil that was in the car was Driven HP-1 15W-50, but this oil is hard to come by here. Bought that oil from my engine Builder, as he orders by boat from the US, but he was empty now.
But after further Research, i found a vendor that imports the HR-1 to Norway actually. Think the 15W-50 would be better?

What do you think about the misfiring? The loose rocker is on the exhaust valve on cylinder 4.

[BLK 68 R/T]

Is the valve to tight in the guide? That could be the source of a 1/4" of play as well.

[INTMD8]

Can you shine a flashlight down to see if the lifter cup is stuck?

[phantom]

Well, i found the reason for the misfire 
One of the plug boots had a hole in it, probably burned through from the header, and arced over. Changed it, and no misfire. Runs Perfect! Now i have to find some heat Shield covers for the boots, any suggestions?

[jlatessa]

We use the woven fabric ones available at all the hi-po stores.

Try to maximize your clearance by fiddling with the plug wire routing ,
then slip the covers over the terminal boot.

Good luck.

PS you may have to order some wires with different boot angles for troublesome plugs.

Joe

[c00nhunterjoe]

im still wondering about the rocker with 1/4" of movement.

[phantom]

Yeah.
He went and did an adjustment on that rocker, he adjusted it further two turns down compared to the other ones, play almost gone. We fired it up and there is a small ticking sound, he thinks i have a small exhaust leak, says failed lifters are more of a tapping sound? I have taken the headers off a couple of times, may not be sealing completely any more, he wants me to get new gaskets before we do anything more.

[justcruisin]

Have your headers coated, presuming they aren't, it will save your plug wires and make a big difference to under hood temps.

[c00nhunterjoe]

Yeah.
He went and did an adjustment on that rocker, he adjusted it further two turns down compared to the other ones, play almost gone. We fired it up and there is a small ticking sound, he thinks i have a small exhaust leak, says failed lifters are more of a tapping sound? I have taken the headers off a couple of times, may not be sealing completely any more, he wants me to get new gaskets before we do anything more.

There are so many red flags here.

[BLK 68 R/T]

  something else going on.