Charper732

First off, leakdown is designed to be tested at 90psi. Not 208. It can be pretty hard to just set the motor at TDC and do a leakdown. What i do, although it involves 2 people is set the cylinder just before TDC and then have the second person slowly apply air pressure. As I hold a LONG breaker bar on the crank bolt and i slowly rotate the engine til i see the least amount of leakdown %

You cannot test 2 cylinders without rotating the engine. Cylinder 4 was on valve overlap. Thats why you had 60% leak.

30% leak is a lot. New is less than 2% good is less than 10%.
Rebuild after 15%

Dwnfrce

To clarify, the 208psi was from the compression test. Leakdown test was done at 15-20 psig.

Two clear problems for me: the motor wasn't warm and I didn't follow the order. I'll reassemble and warm up, then go for the order of 1-3-4-2.

I'll search and find a write-up on the forums versus a general guide.

F1TwoThousand

Leakdown has to be done at 100psi. Or do it at 50psi and multiply the reading by 2 and that will give leakdown %. https://youtu.be/LR-PGUgykxU

If cyl 1 is at top dead center the white timing mark on pulley will lign up with mark

Dwnfrce

The instructions on the tester i've got weren't specific, but when i went above 20psig it pegged the Leakdown gauge past 'set' so I dropped it back to 15-18. I should have checked DIYGuys. I'll watch the video and try it again tomorrow.

Dwnfrce

All right, quick update. The tester is different from what the DIYGuys used, so the procedure is different. The Pittsburgh tester I have has two gauges but the second gauge isn't an identical pressure gauge to the first gauge like the OTC version used in their video. The Pittsburgh second gauge is a lower pressure gauge with a face that shows percentage leakage versus psig. You can Google the image to see what I'm talking about. I also found another video from a guy with a B series motor using the same tester I have, and he performed the procedure in the same manner, per the instructions, so I'm confident enough in the outcome.

I re-ran the test using the correct cylinder order with respect to TDC: Cyl 1-3-4-2. Big difference veruse the wrong order, and no variation despite two cycles of tests Cyliner leakage maxed at 20-22% on Cyl 4, reducing to around 13-15% on Cyl 1. Leakage appears to be coming from the valves, as neither the radiator cap opening nor the dipstick opening were showing any signs of bubbling.

I feel better overall, even though the results aren't ideal. I plan to move forward with the fuel and tune, and then on to the kit assuming all goes well. If I get the same boost bug that's going around, which seems highly contagious, and look to go bigger, I'll circle back around and rebuild the head.

Thanks everyone!