I’ve carried out a compression test on my R53, it’s low even for a BVH… I did a leak down test and everything seemed very good however I did have to manually crank it to hold pressure, making me think that my timing is off between camshaft and crankshaft. I have Newman PH3/4 cam & BVH. Just not sure how to manually time it, I’ve checked TDC and valves are closed but maybe the valves are closing a little too late so it’s not getting the full 85mm stroke of compression. And ideas of how to time the two up?

Compression figures were 105/105/110/110 which from the tests I’ve done would say Piston Rings, Head Gasket and Valve Heads are all good. I have free’d up the dampeners on the rocker arms as they were solid with no movement.

Mileage just over 60,000miles.

All advice/solutions wanted 🙏 thank you in advance.

 

are you asking how to time the engine? I'm pretty sure bentley and tis have this procedure

 

I’m wondering how I would work out if I’m a couple teeth out on the cam sprocket if valves are closing too late that compression isn’t building up enough. It’s even across cylinders so either timing or rocker arm dampeners are an issue but no clue how to get to the bottom of it.

 

Your compression figures are very low. They should be in the 140-150 range with no more than 10% loss between cylinders on a healthy motor. That definitely indicates ring wear as valve seats shouldn't create that much loss. Your valves will stay open longer due to the very high lift of that PH4 cam. A high flow exhaust and/or ported head would be important to help remove that additional air. Have either?

 

ring wear was my thought until I bought a compressor and did a leak down test which showed less than 5% leak on all cylinders when I manually cranked it to TDC, my thought as to why the compression test results in low figures is because the valves are not closing in time for the compression stroke ei a few teeth off correct timing or the rocker arm dampeners aren’t doing their job which is compressing when valves are supposed to close. I have free’d them up one and it helped the tapping noise a lot but then the noise came back, unfortunately didn’t get compression figures when the noise had gone to check test my theory. Cars 95% put back together so on Monday next week I can finish it off and start it up. Hoping I have ideas n solutions to A) Timing B) bring rocker arm dampeners back to life properly.

Also, I have a 4-2-1 manifold and full miltek high flow exhaust no CAT and a ported and polished BVH.

 

Timing aspect can be tricky to determine if its off. Even after doing a timing job the teeth will not line back up after a single engine revolution. I believe after a certain amount of revolutions they would but i have not found that process.

The only way to accurately time the engine is with the gold links and timing marks on the cam sprocket and crank. As pictured below, best of luck moving ahead.