WTF? Bro, this test is so inconsistant it isn't even funny. You could cause someone to ruin a head with your silly experiment trying to lap valves because they're showing the same results as you are - which are flawed. You need to have springs and keepers and have valve set up like it would be if it were operational before you test it. Testing a valve without a spring an 25mmHg doesnt do anything except show people that you're a n00b. Or at least you play one on YouTube.
OK... firstly, I never claimed to be an 'expert' and this was NEVER intended to be a "how to" so please don't use this as one. This video was created for a select few people to show a forum the idea I had for bench testing what I found to be a poorly seating valve. After hand lapping the valve, it was evident that it was not making full contact around the valve seat. To prove it to the shop, I took this video. I did the SAME TEST with the springs INSTALLED with the same exact results.
static check prove leakage...hand lap valves for seal...When engine run...valve rotate..loose valve guides cause leakage...hand lap before every event for best results. Combustion chamber leak-down test should prove no more the 2%
He mentions a "crack", hmm, if the seat has a crack that requires machining. You are right a tighter seal would be achieved with the spring, retainer etc, (it's not the full component of the valve train at rest being tested for leaks). I assume this "crack" he refers to is the difference in angle cuts of the valve crown to the valve seat resulting in a "gap".
Pretty much. Time for a head rebuild. Or, on the cheap, grind away all of the carbon you can and lap the valves. Check head surface for flatness (resurface if needed) and pop them back on. You should notice the difference!
Um, depends on your level of skill whith your hands, just dont use a power tool on the valve stem to spin the valve with grinding paste. Make fire indian style with the suction cup valve lapping tool (very cheap)
WTF? Bro, this test is so inconsistant it isn't even funny. You could cause someone to ruin a head with your silly experiment trying to lap valves because they're showing the same results as you are - which are flawed. You need to have springs and keepers and have valve set up like it would be if it were operational before you test it. Testing a valve without a spring an 25mmHg doesnt do anything except show people that you're a n00b. Or at least you play one on YouTube.
ItsDamianLOL 1 year ago
Where I can find purchase vacuum tester ??
Please help me guys !
MisterAtallah 1 year ago
@MisterAtallah try Harbor Freight.
ItsDamianLOL 1 year ago
Where's the valve spring?
TeacherPHD 1 year ago
@TeacherPHD
top of the head dipshit
sk8er51472 1 year ago
You did not mention if the valve and seat were stellite or stellite faced versions.
What should vacuum be?
The guage only goes to 30 in. hg.
Normal is supposed to be 22 in. at idle in park.
But decelleration will give about 25 in. hg.
Why the higher reading, if the valve is leaky?
seapeddler 1 year ago
OK... firstly, I never claimed to be an 'expert' and this was NEVER intended to be a "how to" so please don't use this as one. This video was created for a select few people to show a forum the idea I had for bench testing what I found to be a poorly seating valve. After hand lapping the valve, it was evident that it was not making full contact around the valve seat. To prove it to the shop, I took this video. I did the SAME TEST with the springs INSTALLED with the same exact results.
4strokeonly 2 years ago
ANOTHER IDIOT 'EXPERT'
JOJOBANANAZ1 2 years ago
static check prove leakage...hand lap valves for seal...When engine run...valve rotate..loose valve guides cause leakage...hand lap before every event for best results. Combustion chamber leak-down test should prove no more the 2%
TeacherPHD 2 years ago 2
You guys have no idea how much more valves play in to the system of seating. this guy sucks!!!
BOSS5652 2 years ago
This comment has received too many negative votes show
your mom has nice valleys
jayguy173 2 years ago
Hey this guy didnt have that valve under valve-spring pressure!!!
i reckon he would have had far less leaking if that valve was seated under spring pressure.
marek0086 2 years ago
He mentions a "crack", hmm, if the seat has a crack that requires machining. You are right a tighter seal would be achieved with the spring, retainer etc, (it's not the full component of the valve train at rest being tested for leaks). I assume this "crack" he refers to is the difference in angle cuts of the valve crown to the valve seat resulting in a "gap".
BigBullBully 2 years ago
he really shouldnt be using the term "crack". What he means is GAP.....as in....a VALLEY.
marek0086 2 years ago 5
+ 1
beabertbiker 2 years ago
Agree, it need the valve spring
adrianalanis20000 2 years ago
Vortec heads are damn good.
Hmmm, I shoulda checked the valves on my 113 heads before I put the heads on my motor.
Timothayyy 3 years ago
so how do u fix the leak?
marek0086 3 years ago
Regrind the valve and remachine the valve seat.
smithraymond 3 years ago
i just pulled the head off my 250 straight 6......and the intake ports are black!
Does this mean that my intake valves were leaking?......combustion pressure pushing exhaust-gas back through the intake valves??
marek0086 3 years ago
Pretty much. Time for a head rebuild. Or, on the cheap, grind away all of the carbon you can and lap the valves. Check head surface for flatness (resurface if needed) and pop them back on. You should notice the difference!
smithraymond 3 years ago
Head rebuild??.......its just the valve and valve seat that need to be fixed up.
Are u saying i should buy NEW valves??
Cant i just re-surface the valve-face and valve-seat??
Is 'lapping' the valves/seats a piece of cake to do??
marek0086 3 years ago
Um, depends on your level of skill whith your hands, just dont use a power tool on the valve stem to spin the valve with grinding paste. Make fire indian style with the suction cup valve lapping tool (very cheap)
BigBullBully 2 years ago
Comment removed
marek0086 2 years ago