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Leak Down Test Results - #8 at 40%

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Old 05-25-2018, 11:35 AM
  #21  
Kingtal0n
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doesn't the fact #8 fogged the WD40, blasted it out of the engine give some clue? If it came AWAY from the valve, then the valve is leaking? So pull the valve out. Swap it with another valve and repeat test? Something like that? Once the valve seals you can test the ring.

You made it sounds like the intake valve is leaking into the intake manifold
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Old 05-25-2018, 11:53 AM
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Originally Posted by Kingtal0n View Post
doesn't the fact #8 fogged the WD40, blasted it out of the engine give some clue? If it came AWAY from the valve, then the valve is leaking? So pull the valve out. Swap it with another valve and repeat test? Something like that? Once the valve seals you can test the ring.

You made it sounds like the intake valve is leaking into the intake manifold
It was so bad that the WD40 that had leaked past the valve was pushed BACK around the intake valve by the compressed air and out of the intake port (I had removed the intake for the test).

Now the heads are fixed and I am performing a final leak-down on the new short block. Rings were leaking for sure with the lack of good oil control. Guides checked out ok.
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Old 05-25-2018, 10:36 PM
  #23  
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Bent valves is a little scary.
I’m not a gambling man so if had any bent valves, I would have replaced them on principle.
Not sure how you can successfully straighten bent valves?
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Old 05-25-2018, 11:16 PM
  #24  
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Hey Ted -
I got your wussy-*** 40% leakdown beat by a longshot... just had a guy drop off a Vette from Mississippi, and I did a leakdown to see if it had other problems than a flattened cam lobe... I just tested one cylinder at 72% leakage, and it's all going by the rings... That makes your little 40% valve leak seem like a performance engine...!

Hey George -
72% leakage past the piston & rings just provides some good crankcase ventilation, right..?

Lars

Last edited by lars; 05-25-2018 at 11:21 PM.
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Old 05-26-2018, 10:21 AM
  #25  
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Originally Posted by lars View Post
Hey Ted -
I got your wussy-*** 40% leakdown beat by a longshot... just had a guy drop off a Vette from Mississippi, and I did a leakdown to see if it had other problems than a flattened cam lobe... I just tested one cylinder at 72% leakage, and it's all going by the rings... That makes your little 40% valve leak seem like a performance engine...!

Hey George -
72% leakage past the piston & rings just provides some good crankcase ventilation, right..?

Lars
And I thought my rings were bad Lars!!!

I installed the heads and performed a leak-down test on the new short block and discovered four (4) chambers with 30-40% leakage out of both the intake and exhaust valves. I talked with the cylinder head builder and he suggests that his attempts to resolve the excess run-out on the valves either didn't work or made matters worse. He returns to the shop early next week and is committed to fabricating a plate to test SBC heads as first order along with working on my heads.

At this time, I am holding on spending more $$$ on these heads. He says he has a nearly complete set of SBC valves to install FREE.

I suspect poor quality valves have been the issue in these heads since day 1. Will see what we find next week.

Gotta pull the heads this weekend and clean out the threads in the short block.

If I pull the trigger on a new set of valves (I & E), are stainless the recommended type for street performance? What brand won't break the bank but give good quality? Manley Street Master Street Flo valves (in sets of 8 of each) appear to be competitively priced at Jeg's and Summit.

Last edited by TedH; 05-26-2018 at 11:15 AM.
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Old 05-26-2018, 10:50 AM
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Originally Posted by TedH View Post
If I pull the trigger on a new set of valves (I & E), are stainless the recommended type for street performance? What brand won't break the bank but give good quality?
Ted -
You can get some very nice valves at fair prices, and actually get a performance increase from the flow. I would buy a set of stainless, necked, tuliped, swirl polished valves, such as ones offered by SI, Manley, or similar - there are several good suppliers for these parts.
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Old 05-26-2018, 11:10 AM
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Originally Posted by ezobens View Post
Bent valves is a little scary.
Iím not a gambling man so if had any bent valves, I would have replaced them on principle.
Not sure how you can successfully straighten bent valves?
Probably burnt not bent. Either way, 5 cents a pound scrap metal. You would NEVER straighten a bent valve unless it was irreplacable low performance collector item type engine. 32 Hupmobile or something.
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Old 05-26-2018, 12:01 PM
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Originally Posted by lars View Post
Ted -
You can get some very nice valves at fair prices, and actually get a performance increase from the flow. I would buy a set of stainless, necked, tuliped, swirl polished valves, such as ones offered by SI, Manley, or similar - there are several good suppliers for these parts.
I am liking the Manley Street Master Street FLO for the potential performance gains. Jeg's has sets of 8 at $88 (on sale).

Once my cylinder head builder weighs in on the specs (ie. if stock specs apply), I may pull trigger Tuesday.
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Old 05-26-2018, 12:03 PM
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Originally Posted by derekderek View Post
Probably burnt not bent. Either way, 5 cents a pound scrap metal. You would NEVER straighten a bent valve unless it was irreplacable low performance collector item type engine. 32 Hupmobile or something.
Builder thought he resolved the run-out but I suspect inferior metal in the valves. Lost faith in the valves in the heads. They came from Indy Cylinder Head in the DART Iron Eagle castings so I thought good quality.
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Old 06-03-2018, 08:38 PM
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Lars.......only you could make a 72% leakage seam like a badge of honor !!!
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Old 06-04-2018, 06:56 PM
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Time for an LS Engine? An aluminum 5.7L electronic fuel infection.. infestation...
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