Everyone has asked and i will ask again. Did you bleed the lifters before installing them? If not, that caused the valve to hit the piston on the first head.And it may have bent valves on this head too. With the backfire through the intake, either valves are bent or they just arent closed...

What turbo are you replacing the t25 with?

The amount of material removed all depends on how much pressure is put on the head while on the sander. It's basically a table belt and the head is held in place by hand. The true sign of the belt sander is the sanding scratches seen in the pic, end to end of the head. The cross marks are done...

It was belt sanded the the cross hatch was put on it by wrapping sandpaper around a file and sanding cross then flipping it 90* and doing the same. I've worked in several machine shops and seen it hundreds of times. The radius you see if from the original milling of the head. They were feeding...

Set the maft as tho you have 450cc injectors. Aux 0, base 2. Do you have it set for the correct size gm maf that you have?

He said he used royalpurple asse mbly lube.

He is talking about the plugs driven into the crank where the oil cross holes were drilled. Not like a small where it's just drilled from main to rod journals. The dsm has intersecting oil holes.

Center Diff Spider Gear KIT – Jacks Transmissions LLC

I'm not going to argue with you. But before you start saying someone is wrong, you should do some research on why some gauges are liquid filled in the first place. That being said, dry gaugesare more prone to fluctuations due to teptemperature than liquid filled gauges. And most of the time, the...

80 grit works fine

Sand it down to bare metal when you attach it. And I would try a tapped bolt hole instead. Self tapping screws are too likely to come loose.

Also, check the fuel vent/vapor lines and make sure it isn't blocked. If so, you could be pulling a vacuum on the tank which could cause fluctuations.

Next time you see the pressure dropping, go back there and see it the wires are hot. If so, try changing the ground location.

The autometer liquid filled gauge I used had a vented case and I never had any variations from hot or cold. Regardless though, he said his fuel trims started increasing which prompted him to look at the gauge. That to me would say it isn't a gauge issue.

What do you have for fuel pump wiring? Good ground? Rewired?Also, is the fuel tank vapor line still functional or do you have it blocked off?