Kurt in NJ
Well-known member
I have used regular "shop air"--160 lbs or so
8BA compression issues
- Thread starter mrlaser
- Start date
mrlaser
Senior Member
The leak down test resulted in leakage through the carburetor. I removed the intake manifold and the passenger side head. I checked TDC on number 1 and confirmed that with the piston at it's peak elevation on a dial indicator. The bump on the crankshaft pulley was aligned with the pointer. The valve lash was actually excessive being .018 at the narrowest. I have removed#2 intake and exhaust valve and guide. They were easily extracted. Unusually, both guides had the "o" ring installed. It makes me wonder whether the correct, later springs were used? The valve and the seats looked good. Any thoughts or suggestions?
cadillac512
Well-known member
If it were me at this point I would place #1 piston at TDC and slowly rotate the crank pulley 2"-3" left and right watching the valves on that cyl. If they don't move,rotate the crank a full turn and check again. (at this point #1 is on the overlap stroke and turning the crank slightly one direction opens one valve and slightly the other direction opens the other one). As the piston passes over TDC one valve will close while the other opens. If this occurs right at TDC or VERY close, the cam timing is correct and the problem lies elsewhere. If it's very far off, you'll have to pull the front cover to correct the cam timing by lining up the gears correctly.
There have been cases where gears were incorrectly marked....
Terry
There have been cases where gears were incorrectly marked....
Terry
mrlaser
Senior Member
Terry,
I did as you suggested and confirmed that the valves began to open when the engine pulley was moved 2-3" to the right and left of the bump on the crankshaft pulley. Number one exhaust when the engine was rotated clockwise and number 1 intake when rotated counterclockwise. So, I am assuming that the cam timing is correct. Would using the earlier style valve springs contribute to a loss of compression? In the Ford manual the later springs have 7-10 pounds more closing force than those used on the non rotating valves.
I did as you suggested and confirmed that the valves began to open when the engine pulley was moved 2-3" to the right and left of the bump on the crankshaft pulley. Number one exhaust when the engine was rotated clockwise and number 1 intake when rotated counterclockwise. So, I am assuming that the cam timing is correct. Would using the earlier style valve springs contribute to a loss of compression? In the Ford manual the later springs have 7-10 pounds more closing force than those used on the non rotating valves.
40cpe
Well-known member
the rotating valves used a keeper that required shorter springs than the non-rotating valve. A pre-EAB engine would use the longer spring with a non- rotator keeper.
cadillac512
Well-known member
It sounds like the next step since valve timing appears to be correct. The springs really shouldn't be the cause of your poor compression testing results. Any spring capable of closing the valve should allow an accurate compression test at cranking speeds if the valves are sealing well and they have lash.
Terry
cadillac512
Well-known member
The problem with that is the engine won't start yet due to the extremely low compression issue. Hasn't ever been run since the years-ago rebuild. I do believe he's on the right track and following a logical troubleshooting sequence. It's just being obstinate like these things do...to test us!
Terry
big job
Well-known member
Valve lapping is a good sign. However these days no one laps valves anymore a shame.
Heres how we do it; with out valve keepers we stick a shop vac onto a intake port and
the shop vac will snap the valve out of your hand, same with the exhaust then a little PB
blaster on said valve if it doesn't get dry or visual bubbles thats good. Should have said
drop all valves in and do one at a time using the shop vac. Due to I hate mate and the written BS. remove cam gear and rotate by hand to feel the heal of the cam, I learned
that in school my buddy totally blind 'those days there were no brail books. Blind people have superior feel and hearing. Teacher would scratch his head cause this kid would grind valve stems with in a tenth: You will be good with .010 intake and .014 exhaust.
As already said some re pop timing gears are not stamped correctly so watch that. Now
if satisfied put back together get the battery open throttle turn engine over'starter' put
your hand over carb. you now should feel vacuum, or try 12vt battery no vacuum and
no vacuum on your hand means no no way it will start ! (piston goes down it sucks fuel)
Hopes this helps. sam
Heres how we do it; with out valve keepers we stick a shop vac onto a intake port and
the shop vac will snap the valve out of your hand, same with the exhaust then a little PB
blaster on said valve if it doesn't get dry or visual bubbles thats good. Should have said
drop all valves in and do one at a time using the shop vac. Due to I hate mate and the written BS. remove cam gear and rotate by hand to feel the heal of the cam, I learned
that in school my buddy totally blind 'those days there were no brail books. Blind people have superior feel and hearing. Teacher would scratch his head cause this kid would grind valve stems with in a tenth: You will be good with .010 intake and .014 exhaust.
As already said some re pop timing gears are not stamped correctly so watch that. Now
if satisfied put back together get the battery open throttle turn engine over'starter' put
your hand over carb. you now should feel vacuum, or try 12vt battery no vacuum and
no vacuum on your hand means no no way it will start ! (piston goes down it sucks fuel)
Hopes this helps. sam
Tinker
Well-known member
The problem with that is the engine won't start yet due to the extremely low compression issue. Hasn't ever been run since the years-ago rebuild. I do believe he's on the right track and following a logical troubleshooting sequence. It's just being obstinate like these things do...to test us!
Terry a flathead will start with 30lbs compression. It'll run bad with no power, but if you have some vacuum and if you have a decent ignition/spark and fuel, it'll fire. It's not a diesel engine.
https://www.youtube.com/watch?v=kkHZyjiT_wk
But who knows on this one...
Last edited:
mrlaser
Senior Member
I have seen that video before. It only increases my frustration that even after a complete rebuild , it won't even try to start 
.
I am nearly finished with the valve lapping. Does anyone have an alternative way of replacing the valve spring keepers since I assume that few people have the tool pictured in the green Ford manual?
.I am nearly finished with the valve lapping. Does anyone have an alternative way of replacing the valve spring keepers since I assume that few people have the tool pictured in the green Ford manual?
mrlaser
Senior Member
While waiting for suggestions, I came up with this solution. I found a washer with an inside diameter which matched the diameter of the valve sleeve. I epoxied the washer to the valve spring compressor to ensure stability. This enables the valve spring to be compressed and the keepers to be put in place. The unit was placed in a vice to allow both hands to be used. It worked perfectly. I'm sure there are other ways to safely install the keepers but this worked for me.
Attachments
Frank Miller
Well-known member
I did mine in a drill press.
Bored&Stroked
Well-known member
Since you have the heads off - oil the bores a bit while you're at it (I use my hand to manually rub in some engine oil or assembly lube). Also, use some decent assembly lube on the valve stems (where they're in the guide) and might as well put some 'break in' lube on the bottoms of the lifters. This engine has sat awhile, so getting her "greased up" is never a bad thing.
On cam timing - I think your check is good, but just to further elaborate. If you have #1 cylinder on TDC (compression stroke), then both valves should be closed. As you rotate the crank clockwise, you should see the exhaust valve just start to open right before BDC and as you continue around the exhaust should fully open on the way back up (exhaust cycle) - and when you're back to TDC, the intake should have just started to open and the exhaust is just about closed. (This is the beginning of the intake cycle).
My bet is that the valves were not seating - due to however they did their work and the need (in this case) to lap them a bit. The valve you showed was probably an exhaust valve - given the big/wide seat on it.
Keep us posted - nice work on your end!
On cam timing - I think your check is good, but just to further elaborate. If you have #1 cylinder on TDC (compression stroke), then both valves should be closed. As you rotate the crank clockwise, you should see the exhaust valve just start to open right before BDC and as you continue around the exhaust should fully open on the way back up (exhaust cycle) - and when you're back to TDC, the intake should have just started to open and the exhaust is just about closed. (This is the beginning of the intake cycle).
My bet is that the valves were not seating - due to however they did their work and the need (in this case) to lap them a bit. The valve you showed was probably an exhaust valve - given the big/wide seat on it.
Keep us posted - nice work on your end!