Low compression in #4 after rebuild

[V12StealthHunter]

Hello everyone. I recently completed a basic top to bottom rebuild of my 1.6L engine. Rebuild was initiated due to having no oil pressure and oil leaks from every damn seal on the engine. Honed the cylinders, polished the crank, new bearings, rings, valve stem seals, oil pump, water pump etc.. and had the machinist clean up the heads and do a basic valve job as well. Not my first rebuild but no pro either. Certainly my first rebuild with problems

Cranked it a few times to get oil pressure, but got nothing. Did some searching online and tried a trick I found on the forums where someone removed the oil filter. I removed the oil filter, cranked it a few times, and got oil out the filter housing. Put the filter back on and voila, I had oil pressure!

Tried to start it but got nothing. Even checked TDC with a dial gauge again and all the timing marks lined up perfectly. Kept turning the distributor until I could start it easily. According to my timing light, its 50deg BTDC. I've double and tripled checked the timing, and it is nowhere near the 5deg BTDC as required by the manual. The strobe light shows the mark on the crankshaft pulley at the 12 o'clock position when #4 fires. So nowhere near the 3 timing marks on the timing belt cover.

The engine will start and idle without the choke. Decent oil pressure. About 60 when cold and settles at around 40psi at operating temp. No leaks either. But it was rough so I kept pulling HT leads until I found that pulling #4 did nothing. I went out to pepboys and rented a compression tester kit. These auto parts store testers are notoriously inaccurate (I've seen up to 50% off) as people abuse them but this is what I got, 100, 110, 120, 35. Given that the rings have probably not seated yet, I was not expecting very high compression but clearly something is wrong with #4.

Waited for the engine to cool down and double checked all the head bolts were at 61lbs. Everything looked OK.

I will be getting hold of a leak down tester tool tomorrow. Hopefully I should be able to isolate where the leak is from.

Clearly the Italian car Gods are unhappy with me. Any ideas what could have happened?

I will be tearing the top end down with a vengeance this weekend.

[baltobernie]

A real head-scratcher, for sure. The fact that your marks are way off leads me to think that maybe this and #4 are related.

Any chance that you may have incorrectly swapped intake and exhaust cam wheels upon re-installation? Are the camshaft timing marks correctly aligned with TDC?

ps Always fill the new oil filter with oil prior to installation. These suckers hold almost a quart (unlike modern cars) so it takes a long time to get oil to the bearings starting with an empty can.

[V12StealthHunter]

When #1 is at TDC, the timing marks on the cam gears (the little holes) line up perfectly with the notches on the cam boxes. Would this still be possible if the camshafts were swapped?

I actually always prime the oil filter prior to first start. I also use redline assembly lube on all the bearings and a light coating of engine oil in the bores.

[RRoller123]

Yes it would, the holes are offset different from the alignment pin on each cam, but they can still be set to line up if they are swapped, which would yield incorrect cam timing.

[V12StealthHunter]

I vaguely recall installing new seals into the cam boxes one at a time so not sure how I could have swapped it.

But here are some photos at TDC #1 and cam timing marks aligned. The dirty looking oil is just my purple coloured assembly lube mixed with engine oil. There is no water/emulsification going on there.

You might need to right click on the image and open it again to see it properly.

[131]

What are the valve clearances on #4?

[RoyBatty]

You are saying you are TDC 1 for these images. Yet the cam lobes on #1 are opening the valves.
You are actually more likely TDC #4 for those images. I get the impression you understand the difference between TDC Compression and TDC Exhaust.

I vaguely recall installing new seals into the cam boxes one at a time so not sure how I could have swapped it.

But here are some photos at TDC #1 and cam timing marks aligned. The dirty looking oil is just my purple coloured assembly lube mixed with engine oil. There is no water/emulsification going on there.

You might need to right click on the image and open it again to see it properly.

[V12StealthHunter]

Bad use of terminology. I am TDC Compression on no.4. The cams look right to me (i.e. they don't look swapped).

I'll measure the valve clearance and I'm going to do a leak down test now as well.

[V12StealthHunter]

I just did the leak down test. Cylinders 1,2,3 all hold pressure well. I went up to 60psi and they all hold it no problem. But #4 is leaking through the exhaust valve. It won't hold more than 5psi.

I'll pull the head and take it back to my machinist. If I need to replace valves, are stainless valves worth the extra money?

[So Cal Mark]

yes

[RoyBatty]

Good mekanikin!

[V12StealthHunter]

Maybe a bit of good news. I tried to measure tappet clearance today over no.4 cylinder and the exhaust side is 0. Even the intake side was too tight at 0.012". Must swapped a shim or two. I naively didn't do valve adjustment after the rebuild. Serves me right. Hopefully my compression issue on #4 is just valve clearance. I've ordered the special Fiat tool for the job. I'm too tired to be doing this bush mechanic style.

What I'm still curious about is the 50deg BTDC ignition timing I needed to start the car in this condition. The fuel in the car is very old (> 1 year). But would that need so much advance?

[fiatfactory]

.

[djape1977]

looking at position of cams on the pics, i'd say timing is way off

[V12StealthHunter]

looking at position of cams on the pics, i'd say timing is way off

Care to explain?

The way I see it, it looks right;
#4 is about to start power stroke
#2 is about to start compression stroke
#1 is about to start intake stroke
#3 is about to start exhaust stroke

What are you seeing?