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Leakdown test
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MufflerBearings69
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Joined: 22 Jul 2007
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1968 Ford Galaxy

PostPosted: Mon May 04, 2009 1:54 pm    Post subject: Reply with quote

Hmm I had been so focused on the oil issue I didnt think about fuel. I guess when I put it back together with new plugs I will run it and see what the deal is. If it were oil, my only explanation to that would be intake gasket issue- if it were sucking it in through the PCV through the plenum then they would all have the issue...
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af2
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Location: grassvalley, ca
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1933 Willys Coupe

PostPosted: Mon May 04, 2009 2:45 pm    Post subject: Reply with quote

af2 wrote:
On a leak down you should be listening to: exhaust for leakage, intake for leakage and crank case so you have an idea where to go from there.


Test inclusive:
You have to know where the air is going before comments come.
A 3/8" hose to you're ear tells a lot. % means that the cylinder is leaking. Where? Smile
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squeeezer
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1991 Chevrolet Camaro

PostPosted: Mon May 04, 2009 7:52 pm    Post subject: Reply with quote

did it smoke before the heads were installed????

is this a f.i. motor or carbed?????

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MufflerBearings69
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1968 Ford Galaxy

PostPosted: Mon May 04, 2009 10:00 pm    Post subject: Reply with quote

no it didnt smoke before heads. didnt smoke for the first lil while the heads were on either... One day I noticed it smoking when i left it to warm up...

Still running the electronic fuel injection yep.
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MufflerBearings69
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Joined: 22 Jul 2007
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1968 Ford Galaxy

PostPosted: Tue May 05, 2009 7:26 am    Post subject: Reply with quote

af2 wrote:
af2 wrote:
On a leak down you should be listening to: exhaust for leakage, intake for leakage and crank case so you have an idea where to go from there.


Test inclusive:
You have to know where the air is going before comments come.
A 3/8" hose to you're ear tells a lot. % means that the cylinder is leaking. Where? Smile



Didn't ignore this, just have to get a chance to do it...

So this hose, where would I run it to hear in the crankcase? I can shoot it right down that cylinders intake runner to check there (easy one) but with the valvecovers off...

I could probably slip a smaller ida. piece of vacuum line down the oil drainback hole?
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TSHACK
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PostPosted: Tue May 05, 2009 2:21 pm    Post subject: Reply with quote

Air in the cylinder is the way to go. If you evacuate the crank case I think you could cause gaskets to pull in or draw air from other places than 1 possable problem cylinder . I prefer to do a leak down with the piston at TDC where the cylinder pressure would be the greatest.
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10sec.et
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Location: Houston,Texas
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1969 Oldsmobile Cutlass

PostPosted: Tue May 05, 2009 4:27 pm    Post subject: Reply with quote

TSHACK wrote:
I prefer to do a leak down with the piston at TDC where the cylinder pressure would be the greatest.


....and also the wear on the cylinder wall.

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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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af2
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1933 Willys Coupe

PostPosted: Tue May 05, 2009 4:39 pm    Post subject: Reply with quote

Start from scatch(spelling). Compression test='s.
Good way to find the cylinder/s that are bad.
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MufflerBearings69
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1968 Ford Galaxy

PostPosted: Tue May 05, 2009 8:11 pm    Post subject: Reply with quote

Okie dokie- so reassemble it all, and run a regular compression test?

Sorry if I seem redundant, just wanna make sure I am following...
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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Tue May 05, 2009 8:40 pm    Post subject: Reply with quote

MufflerBearings69 wrote:
so reassemble it all, and run a regular compression test?



just how far did you tear it down ?

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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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MufflerBearings69
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1968 Ford Galaxy

PostPosted: Tue May 05, 2009 10:08 pm    Post subject: Reply with quote

well, rockers were backed off, and had to take the top half of the intake manifold off...

not a ton- just was thinking out loud more than anything Embarassed

finals + car + work = brain starting to boil
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TSHACK
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PostPosted: Wed May 06, 2009 9:21 pm    Post subject: Reply with quote

10sec.et wrote:
TSHACK wrote:
I prefer to do a leak down with the piston at TDC where the cylinder pressure would be the greatest.


....and also the wear on the cylinder wall.


After doing literally several hundred leak down tests on aircraft. It's wild to see the amount of leakage past the rings part way down the cylinder. it better on the way up than the way down. due to where the rings are sitting in there grooves.

MufflerBearings69 wrote:
Okie dokie- so reassemble it all, and run a regular compression test?

Sorry if I seem redundant, just wanna make sure I am following...


In MHO No need to reassemble, yet. run each cylinder back to TDC. hold it there & pressurize the cylinder. then listen. you'll hear any problems.
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af2
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1933 Willys Coupe

PostPosted: Wed May 06, 2009 11:07 pm    Post subject: Reply with quote

TSHACK wrote:
10sec.et wrote:
TSHACK wrote:
I prefer to do a leak down with the piston at TDC where the cylinder pressure would be the greatest.


....and also the wear on the cylinder wall.


After doing literally several hundred leak down tests on aircraft. It's wild to see the amount of leakage past the rings part way down the cylinder. it better on the way up than the way down. due to where the rings are sitting in there grooves.

MufflerBearings69 wrote:
Okie dokie- so reassemble it all, and run a regular compression test?

Sorry if I seem redundant, just wanna make sure I am following...


In MHO No need to reassemble, yet. run each cylinder back to TDC. hold it there & pressurize the cylinder. then listen. you'll hear any problems.
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Terry, Thank you for saying the biggest part of a leak down!!!! "listen"
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MufflerBearings69
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Joined: 22 Jul 2007
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1968 Ford Galaxy

PostPosted: Thu May 07, 2009 1:04 am    Post subject: Reply with quote

Yeah, the part nobody else seems to mention outside of here!!!

"Oh, leakdown was bad? Throw it out" is what people have said to me... the people who trade cars when they look a little worn most likely...

Last final in 7 hours then back to these cars... and learning to hear where the air is going...

All the help is always appreciated whether I remember to mention it or not Very Happy Very Happy Very Happy
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MufflerBearings69
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Joined: 22 Jul 2007
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1968 Ford Galaxy

PostPosted: Thu Jul 30, 2009 11:53 pm    Post subject: Reply with quote

So it has become apparent to me that the damage wasnt from the heads themselves, but to an incident that happened shortly thereafter.

I had the FPR rupture, pouring fuel down the intake. I drove it the last few miles home like this, not knowing exactly what was wrong but limping it along... after this event, the smoking began.

All makes sense to me- what about you guys?

also, the most i hear when trying to pressurize the cyls is in the crankcase... i stuck some hose on the dipstick tube and i hear noise through it- I assume therefore thats where its going. I know for sure its not past the intake valves, as the manifold is taped off to prevent crap falling in, and no tape blown off yet...

I have priced out machine work and parts to build another short block and rotating assembly, and snagged another late model 302 roller shortblock, now to save up the $$$ to make it happen.

As bad as I want to buy a healthy 351w based stroker off a buddy, I cant afford it and the accessories to make it work in there... not til after graduation!

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