100% the exact same thing I do. I do a compression test, record 1st and 5th pump when engine is new. I use this is a guide on general health on the engine. When i get a compression test that is off, i will pull my leak down tester to see where i should be looking..... Can i hear the air coming out the exhaust, intake or crank case, and that is all i will use it for. Have seen a lot of people chase there tail because there leak down test wasn't good on a cold alum engine.

I have Holley EFI and a Racepak. I also have a vac guage in the car. Usually you use a 1 bar map sensor to datalog the vacum. My valley tray is tapped for the vacum source . 1/8 pipe thread and i use -4 line for the best leak free connection. You can use pushlok also. I know it is possible to log the vac with an MSD grid , but im sorry i cant tell you how.

Ok cool I will follow the same for the compression test.
thanks to both you,
So I can just Tap 1/8” npt anywhere on valley and convert to a -4 to say a Moroso Analog gauge for now?
What kind of readings should I see during idle, during a run etc. what’s the good and bad spectrum?

Sure you can plumb a gauge in the driver comp with -4 or -3 or pushlok. WHat vac should you see....hard to say, what your looking for is that it doesnt drop severly during a pass. It can be 5-7 at idle and 10-15 during a pass. Or it can be higher or lower, what your really looking for is consistent readings.....when the vacum decreases your losing ring seal or have a leak somewhere else ( valve cover, timing cover pan gasket etc) The reading while making a pass is whats important. Especially for a nitrous engine, its the best indication of how well the rings are sealed up

Lots of good advice here. A vacuum gauge in the car is the best way to monitor and engines health. While its great to note oil pressure as we all know you can loose rod bearings and never see oil pressure waiver . If you start loosing vacuum you have some issues.

Those plugs look like HELL why is the question, I agree start with a compression test and then if you must follow up with a leakdown. FWIW 8% on a cold engine is pretty damn good, but it dont mean a lot without the compression test, especially at 8%. AS bad as those plugs appear(looks like oil but pictures can be deceiving I suppose) I would be digging a bit deeper. If its got valve seal issue and was started up and shut off a few times they could get ugly quick, especially depending on heat range. But oil and nitrous dont play well together so I would definitely want to get handle on it.

Those plugs look like crap, but they're what I'd expect to see from a big inch nitrous motor idling around on really cold plugs w/ a crap vacuum pump. Aerospace Components pumps are the worst on the market.

FWIW...I know a lot of guys that don't use any valve seals on their race engines. I always use at least intake seals.

Thanks, I do hear many opinions on Aerospace, easy enough to get a Moroso and use the just the pump I suppose.
Yeah these are -10 plugs the he used for hits so I'm going to comp test tonight and throw in some -8 and see what we see
I'll share what I find tonight so you all can give some input so I know where to go next depending on this round of test.

I love this site for all the help you all provide and now that I have it back after 17 years
(had to sell it when I got divorced and the guy was good enough to sell it back to me after all these years)
I don't want to hurt anything gotta good combo finally.
Mopar people have always been the best

Certainly lots of race engine without valve seals out there. Not sure I would go that way with a nitrous deal. Oil will promote detonation, never a good thing but worse on the bottle for sure.

As for the vacuum pump I would use something better. Hard to beat a Moroso 3 vane an no regulator IMO for most. Moroso 4 vane is better and Star would be the top if you are looking for maximum vacuum.

Results of compression cold

#1 one bump 100 & 5 bumps 195
#3 one bump 100 & 5 bumps 190
#5 one bump 100 & 5 bumps 190
#7 one bump 100 & 5 bumps 195

#2 one bump 95 & 5 bumps 195
#4 one bump 95 & 5 bumps 190
#6 one bump 95 & 5 bumps 185
#8 one bump 98 & 5 bumps 194

Any thoughts on these readings?
Thanks you

You can leak down the remaining cylinders now, just to record the number for future reference. #^ is a tad lower than the rest but nothing alarming. I woudl be more alarmed by the actual number period more than one cylinder being a bit lower than the others. But not knowing you cam specs or compression who knows. Just seem to be a bit low on pumping overall to me. But again lots of things can make that change.

Put some plugs in it, see if she smokes when you fire it up(valve seals leaking/missing)and then let her rip tater chip.

Yeah do not know the compression
But I attached the Cam specs if you can see it
Also the piston card disregard the hand writing some one was taking a note and used the card..
So your worried on the 190s?

I’ll finish the other cylinder leak downs tonight but I have to ask.
Why some folks say leak don’t tell much ya gotta do compression the another
Says compression won’t tell me much need to do leak down, gets a bit confusing.
Compression health if cylinder/rings I thought
Leak down health of same plus valves, seals, head gasket …?
Just asking so I am crystal and taking things out of context.

I have a set of R5671a-9 and -8s do you think the 8s will be ok to start
I realize the -10s were his nitrous plugs and are to cold.
Thanks again

Al, my current engine will pump 90-95 on the first pump and then 140-145 after 5-6 pumps. The compression is 13.7 but the cam is WAYYY different than the one shown in the post above.
The readings are pretty consistent, i would say the engine is healthy as long as it has some decent pan vac, while making a nitrous pass

Ok thank you,
Can you elaborate on your cam compares to mine

im sorry but im not going to put my cam card on here, no reason to. BUT its nitrous specific and its a lot bigger.

No problem man I wasn't looking for specifics, just wanted to know how to relate to your answer I appreciate it thank you.
I'm not to worried about sharing my stuff just want to ensure I'm getting anything fixed up that I need to is all.
I doubt I run into anything other than a grudge race here and there.
I'll get the pan vac installed to and see what it says and hopefully I can finally get to go play
barring the rest of the leak down, r still seeing oil on the new set of plugs.
Which I'm changing to hotter plugs to do a couple of motor pulls

See if you can see any valve seals by looking through the valve springs with the valves in the close position
If not add them ASAP before you get the motor into detonation due to that much oil in the combustion chambers

Will do Cab, I'll look when I get home this afternoon, thank you.
Here's what I could get done last night on the leak down test, an out of time for the last two...

COMPRESSION TEST
CYLINDER 1 BUMP 5 BUMPS CONDITIONS
1 100 195 cold
3 100 190 cold
5 100 190 cold
7 100 195 cold
2 95 195 cold
4 95 190 cold
6 95 185 cold
8 98 194 cold

LEAK DOWN TEST
INPUT PSI CYLINDER PSI CONDITIONS
1 100 88 cold
3 100 86 cold
5 100 86 cold
7 100 92 cold
2 100 89 cold
4 100 86 cold
6 100 cold still need to test
8 100 cold still need to test

Is that the seal with the little spring tension showing in there?
About as clear as I can get from my phone and a pen spot light on it.