Low compression on all cylinders after rebuild

About 3 months ago my head gasket gave way because the coolant passage on the gasket cracked and started leaking so I had the head resurfaced and I took apart the head and cleaned it. I put everything back together the way it was before except the adjustable cam gear wasn't the same because I didn't take note of which angle it was set at before I removed it. So I start the car for the first time last night and it started, then stalled after about 5 seconds running poorly towards the end. After that I couldn't get it to start. I checked for spark and fuel and both were present despite one of the fuel injector o rings leaking pressure. So I do a compression test and I get 55,-,51,41. I couldn't get to cylinder #2 because I lost the adapter for the spark plug hole after stripping the threads to one of the other spark plug holes, great ending to a day. So I really don't want to pull it all apart again but seeing it's probably either bad piston rings or something else I don't really know what else can be done. I haven't done a compression test on it before because I only bought the car a couple months prior. It ran totally fine otherwise. Took longer than originally anticipated because this was all new to me and did some other supporting mods while it was apart. The car is a B230f+t swapped 242.

Has this been chronicled on Reddit or is that another head job?

If you're getting consistently low numbers I'd verify test equipment (and setup/useage) before condemning anything. Cranking 7 times at WOT?

No I this is my first post about it. I just used the only compression tool I had so possibly incorrect readings. No I didn't know that WOT would effect the results so I might give it another go tomorrow and crank for longer. I just stopped cranking when I saw the psi wouldn't go any higher. But I thought the low compression would just be the reason for no start at all.

Sounds like you probably don't have access to a leakdown tester...

Is the gauge and adapter sealing well? Shrader valve installed? Plenty of easy mistakes to make that really send you in the wrong direction.
If the readings are accurate first thing ide look at is cam timing, slap that gear at 0 and make sure you're not off a tooth.

I just used one that looked like this: https://www.harborfreight.com/compression-test-kit-8-pc-62638.html?utm_source=google&utm_medium=cpc&utm_campaign=12144811130&campaignid=12144811130&utm_content=117789279278&adsetid=117789279278&product=62638&store=&gclid=CjwKCAjwoMSWBhAdEiwAVJ2ndllYfp9pTnl8EkDTWGCsnqWTagzJYzK5zynsSngbQ6Ob5UMeV2Jj8hoCaZkQAvD_BwE

I'm not 100% sure if I'm getting a proper seal but I looked at the pressure gauge on the tool and the reading was very slowly dropping, I'm not sure if I was actually seeing it or just imagining it.

Are you doing this solo?

Find (or make) and friend to help, one cranks with the throttle down while the other insures no leaks are present.

Double check timing too before your too deep into worrying about the bottom end

Alright for sure. I'll go buy a leak down tester tomorrow anyway. Probably a good tool to have.

As far as I know a leakdown tester needs shop air, no need to buy one unless you have verified cam timing.

I'd go over the cam timing again but this time really make sure that #1 is at TDC by not looking at the crank pully but by actually verify though the sparkplug hole how high up the piston really is. Reason: harmonic balancer crank pulleys are known to let go of the vulcanised rubber inside it. If that has happened the relationship between the actual crank position and the TDC mark on the crank pulley will be lost. In which case you will never be able to time it all up correctly even if you use the TDC mark

stev said:

So I start the car for the first time last night and it started, then stalled after about 5 seconds running poorly towards the end. After that I couldn't get it to start. ... So I do a compression test and I get 55,-,51,41.

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Sounds like the timing belt skipped a bunch of teeth during the brief run. Maybe the tensioner jammed and didn't take up the slack, or wasn't tightened down enough. I'd re-check the cam/crank alignment. You can use a straw or chopstick through the #1 spark plug hole to find TDC and compare it to the crank pulley 0deg mark.

Edit: as a quick check, here's a picture of the cam lobe at TDC #1. The flat of the lobe is about parallel to the ground. [I know this isn't very accurate, but ~50psi compression is off by a lot.]

What cam is in this? Sounds a little to me like cam timing was off on reassembly and you smacked a bunch of valves and that's all she wrote.

I have no idea, there weren?t any markings on the cam when I took it out and the previous owner just said it?s a IPD cam, not sure if it?s a turbo one or not.

Well, thank you guys for the reply?s. I went to take a look at the valves through the spark plug holes and found a little present. I must of left a paper towel in one of the intake pipes and started it. Explains why it died so soon after starting. https://imgur.com/a/tBMoe0V

That's certainly not what I guessed. Since you found 1 paper towel, and compression is low across the board, there were probably towels in all the intake pipes. Fortunately, I don't think the paper towels would cause any lasting damage.

I'd take the intake manifold off and fish out whatever towels remain. Disconnect the coil and injectors, remove the plugs, and crank it over to blow out whatever bits got into the cyls. Re-run your compression test here and hopefully all cyls will be back to normal.

At least paper burns. Hopefully it didn't bend a valve

stev said:

I must of left a paper towel in one of the intake pipes and started it.

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Those pesky towels!
2 stories about towels/plugs..
Story 1: Friend rebuilt 600cc 4-cyl motorcycle engine, left towels in the intake ports, bent a few intake valves.

Story 2: My dad builds and ships a lot of race engines. Owner forgot to remove a plug when installing the oil feed from the external tank. Smoked the motor, but it did do ~20min of racing on assembly lube and what little oil may have seeped past the plug... and that's pretty impressive! Owner was not happy, and blamed the shop. Fun times!

what part of so-cal you in stev?

If your close to me, I wouldn't mind giving you a hand. I live in Esco.

I'm out in Orange. The car is doing fine now. Did a compression test: 128,121,125,119. Borderline fine but I haven't torn into the bottom end of the motor to help fix the compression. And I never lapped the valves because they passed the "water leak down test" when i had the head out.

My shop is on Batavia. If you ever want to meet up I?m usually there a couple times a week.