Need advice on leakdown and compression results.
I wonder if you cracked a piston. Well pull the head off and start to see what is there. I would also check for a bent valve. You also might have blown the head gasket out with the hydro-lock. Spanks good idea on the LS9 valve covers - interesting the bumps they have in them. You probably need to do a leak down also but you can do it cold just factor that in looks like the guy above was 7% delta (35 vs 28) in a bad situation. Even a 700 hp motor in good form will still have 15 cfm of blow by at WOT.
TECH Fanatic
Joined: Jan 2009
Posts: 1,056
Likes: 470
From: Bostwick, GA.
Yep... Bon Ami in a ketchup squeeze bottle.
Get the engine warmed up, raise the rpm and give it a "snort", watch the engine stumble and blow some crap out the exh.
Recover the rpm, give it another shot, change the oil and filter.
Check for oil consumption during next oil change cycle.
Years ago, on 2 strokes with chrome/Nikasil bores plated bores, we'd simply install the rings dry, with no lube on the rings. It worked. But that's not a V8, so I wouldn't recommend it in this application. Interesting how many different approaches there are to hasten ring seating...
Years ago, on 2 strokes with chrome/Nikasil bores plated bores, we'd simply install the rings dry, with no lube on the rings. It worked. But that's not a V8, so I wouldn't recommend it in this application. Interesting how many different approaches there are to hasten ring seating...
Thread Starter
Launching!
Joined: Apr 2021
Posts: 236
Likes: 95
From: New Athens IL
I pulled the engine from car and have it on the engine stand.
I ordered a new leakdown tester just to rule out a bad gauge since my original is 22 yrs old. Ill update when I have results later this weeks with my findings.
I ordered a new leakdown tester just to rule out a bad gauge since my original is 22 yrs old. Ill update when I have results later this weeks with my findings.
TECH Resident
Joined: Mar 2012
Posts: 858
Likes: 402
From: Texas
We used it on the old slant 6 Chryslers in forklift trucks.
Bon Ami in a ketchup squeeze bottle.
Get the engine warmed up, raise the rpm and give it a "snort", watch the engine stumble and blow some crap out the exh.
Recover the rpm, give it another shot, change the oil and filter.
Check for oil consumption during next oil change cycle.
Bon Ami in a ketchup squeeze bottle.
Get the engine warmed up, raise the rpm and give it a "snort", watch the engine stumble and blow some crap out the exh.
Recover the rpm, give it another shot, change the oil and filter.
Check for oil consumption during next oil change cycle.
What happens to the leftotver particles?
These are my results as a reference point. All leakage was going through my catch can as best I can tell. Higher % and I felt more air coming out. ~60k mile SBE ls7 with lots of track miles. I’m going to just keep flogging it.
Cold Leakdown results1: 18%
6: 22%
4: 19%
2: 9%
8: 8%
3: 23%
5: 18%
7: 12%
Cold Leakdown results1: 18%
6: 22%
4: 19%
2: 9%
8: 8%
3: 23%
5: 18%
7: 12%
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On The Tree
Joined: Sep 2009
Posts: 111
Likes: 57
From: Akron, OH
The baffling is way better than any aftermarket solution. I don't know if I can link it here, but they're available from michigan motorsports for $150 a pair with gaskets and bolts. The baffle design is similar to LS3 valve covers, but the top of the cover is bumped up to accommodate a larger baffle volume without impinging on the rocker arms. The underside clearance is the same to an LS3. Also nice that the coil packs bolt directly onto them without a bracket, so they're a bit cleaner looking.
You can see the oil/vapor needs to travel from one end of the valve cover to the other. The red cap is the factory quick disconnect. There's a company selling press in 10AN fittings. You remove the stock fitting and drill out the hole to 9/16" and press in the 10AN. The factory fitting is for 3/8 lines, but the ID is less than 1/4".
I've had Holley, BTR, modified BTR, and now these. Road racing and autoX is a royal pita for oil control. I'm at the track again this Saturday and really hoping I can get through the day without oil drama lol.
And yes, we welded an exhaust extractor into the exhaust pulling on the top of the catch can. MightyMouse sells a remote exit that replaces the air filter with a 10AN cap. I had the can overfill a couple times with the exhaust extractor and all I had was some oil residue on my rear bumper instead of half a quart of oil inside my engine bay lol. Honestly got very lucky that nothing hit the headers and decided to flare up. MightyMouse recommends relocating the breather behind the car or into the airbox for road racing and I see why.
Sorry for the derail, this hits close to home lol. I feel your pain OP.
You can see the oil/vapor needs to travel from one end of the valve cover to the other. The red cap is the factory quick disconnect. There's a company selling press in 10AN fittings. You remove the stock fitting and drill out the hole to 9/16" and press in the 10AN. The factory fitting is for 3/8 lines, but the ID is less than 1/4".
I've had Holley, BTR, modified BTR, and now these. Road racing and autoX is a royal pita for oil control. I'm at the track again this Saturday and really hoping I can get through the day without oil drama lol.
And yes, we welded an exhaust extractor into the exhaust pulling on the top of the catch can. MightyMouse sells a remote exit that replaces the air filter with a 10AN cap. I had the can overfill a couple times with the exhaust extractor and all I had was some oil residue on my rear bumper instead of half a quart of oil inside my engine bay lol. Honestly got very lucky that nothing hit the headers and decided to flare up. MightyMouse recommends relocating the breather behind the car or into the airbox for road racing and I see why.
Sorry for the derail, this hits close to home lol. I feel your pain OP.
If you follow the -10 hose it goes from the can under the headlight area back to the pass side head.
Spanks on my BBC I had a very similar reading on the cold leak down - I ranged from 8%-18% at the end of the day the engine needed to be bored .010 fortunately Diamond makes any size piston I want (4.510 bore).
Thread Starter
Launching!
Joined: Apr 2021
Posts: 236
Likes: 95
From: New Athens IL
I have another leak down tester on its way just to rule out a bad gauge. Will know more in a few days
Thread Starter
Launching!
Joined: Apr 2021
Posts: 236
Likes: 95
From: New Athens IL
New gauge & new results
#1. 10%
#2. 11%
#3. 13%
#4. 14%
#5. 14%
#6. 14%
#7. 14%
#8. 16%
Im sure with a warm engine these numbers as is could get into the single digits. Plus im starting to think my ring gas was wider. For some reason I thought it was .022 & .026. Can't find the build sheet, but im as 2nd guessing myself that it is wider. Think im going to tear it down rehone and re-ring.
#1. 10%
#2. 11%
#3. 13%
#4. 14%
#5. 14%
#6. 14%
#7. 14%
#8. 16%
Im sure with a warm engine these numbers as is could get into the single digits. Plus im starting to think my ring gas was wider. For some reason I thought it was .022 & .026. Can't find the build sheet, but im as 2nd guessing myself that it is wider. Think im going to tear it down rehone and re-ring.
Thread Starter
Launching!
Joined: Apr 2021
Posts: 236
Likes: 95
From: New Athens IL
Thread Starter
Launching!
Joined: Apr 2021
Posts: 236
Likes: 95
From: New Athens IL
I could do that. In my mind im thinking it wouldn't matter nearly as much as all the power comes from the squeeze at TDC. I very well could be thinking wrong.
It will continue to blow out it goes down the hole. The test at BDC will also tell you if your cylinders are out of round and the piston rock has gotten to you. Say you are 16% at TDC and say 30% at the bottom you know you got an issue. Just another reason to take it apart.
Thread Starter
Launching!
Joined: Apr 2021
Posts: 236
Likes: 95
From: New Athens IL
It will continue to blow out it goes down the hole. The test at BDC will also tell you if your cylinders are out of round and the piston rock has gotten to you. Say you are 16% at TDC and say 30% at the bottom you know you got an issue. Just another reason to take it apart.
