Testing 454 Heads for Leaks with WATER?

[savatreatabvr]

I'm considering buying a set of used heads for my mid '70s 454. On YouTube there are videos on using water to check for leaky valves, they just pour water in the ports and look for leaks. Heads are off the engine of course! But people are saying that even new heads will leak a little, is this true or is the water test fool proof?



THIS IS NOT A 454 HEAD, JUST USING PIC FOR REFERENCE!

[undertaker72]

the best thing to do is have them magnafluxed , it will find the demons , if any

[mrolds88]

I think he's looking at valve condition vs cracks. You can use that test to get a reasonable idea of condition. If they weep a little, you can still lap them when you throw a set of valve seals on before you install.

[manimal]

Gasoline or better yet, rubbing alcohol is better that water. I've been doing that for about 20+ years....works great. Will also find a bent valve.

[savatreatabvr]

Originally Posted by manimal

Gasoline or better yet, rubbing alcohol is better that water. I've been doing that for about 20+ years....works great. Will also find a bent valve.

So even with gas or alcohol valves should not leak a drop, correct?

[Gregski]

like Lance said use gasoline (smaller particles) and you will know right away if there is a leak rather than waiting for hours or over night

I put a large dry clean piece of cardboard on the garage floor then put something under the head when I set it down upside down so it is nice and level yet I can easily see the drip or puddle stains below

then poor gasoline from a 2 gallon red jug canister into a small glass jar (don't use a red party plastic cup cause it will eat right through it) then from the jar carefully into each chamber (oh yeah with the spark plugs screwed in of course) this way you don't make a mess and have false positives cause you missed the chambers and pored the gas all over the head

fill one chamber at a time and look under it for stains, take a pic when you see the stains so you can document which valves leaked

dirty valves with carbon deposits won't sit / seal tight so all you have to do is take a leaky valve out one by one so you know where it goes and wire push it off with a soft wire brush wire wheel then put it back in and re test if it still leaks re lap them with some lapping compound and a rubber hose on the end of a drill

[BigBlocksRule]

Put a few drops of soap in a spray bottle and fill with water. Spray in the chamber, use an air gun to pressurize the port. Watch for bubbles, just like with a tire.
All this shows is how well the valves seat. It won't show cracks in the chamber, etc. - have 'em magged!

[Iwegian]

Originally Posted by Gregski

like Lance said use gasoline (smaller particles) and you will know right away if there is a leak rather than waiting for hours or over night

I put a large dry clean piece of cardboard on the garage floor then put something under the head when I set it down upside down so it is nice and level yet I can easily see the drip or puddle stains below

then poor gasoline from a 2 gallon red jug canister into a small glass jar (don't use a red party plastic cup cause it will eat right through it) then from the jar carefully into each chamber (oh yeah with the spark plugs screwed in of course) this way you don't make a mess and have false positives cause you missed the chambers and pored the gas all over the head

fill one chamber at a time and look under it for stains, take a pic when you see the stains so you can document which valves leaked

dirty valves with carbon deposits won't sit / seal tight so all you have to do is take a leaky valve out one by one so you know where it goes and wire push it off with a soft wire brush wire wheel then put it back in and re test if it still leaks re lap them with some lapping compound and a rubber hose on the end of a drill

I use a turkey baster instead of a glass jar.......easier to control and cut down on spills.

[manimal]

Originally Posted by savatreatabvr

So even with gas or alcohol valves should not leak a drop, correct?

"some" seepage is to be expected on a used head. The valves may be able to be lapped back in, but a GOOD valve job would be better. The reason I say use Gas or rubbing alcohol is it will dissipate and not cause rust.

[savatreatabvr]

Back in 1984 I did a 3 angle valve job on my 1972 Mach 1 351c heads in high school auto mechanics and screwed them up big time! I'd rather do the work myself on my 454 so I'm thinking about buying some stones and trying again or should I stick with a basic 1 angle valve job? I'm assuming the 1 angle valve job is much simpler and the stones are probably cheaper?

[BigBlocksRule]

May be cheaper but it'll cost you a ton of flow as compared to a modern valve job. It's not that expensive to have someone do either a 3-angle with stones or 5-angle with a cutter on a Serdi or similar machine. Particularly for street machines, the valve spends much more time at low lift where flow is more affected by the valve job.