Leak down test

97MarkJA said:
When I started looking for a shop to do my machine work I found that none here have plates for a 4.6/5.4
I called pretty much every machine shop from hudson wi. To fargo nd.
so thats what I got for christmas.. Nice set of torque plates from ccaracing.
I would have thought that with the mod motor platform most shops would have them, I was told for a basic non performance build they dont need them, performance parts are expensive so they rarely if ever see a performance build.
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Did you call bemidji state they are supposed to be one of the few schools that teach performance engine machining.
 
97MarkJA said:
Driller, what made you do the leak down test?
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After installing a new torque converter, I took the car to the track where it seemed down on power from where it had been running. Figuring an ignition issue, I pulled the plugs to inspect and #6 plug looked out of place compared to the others. That lead to a compression test which surprisingly showed low compression on cylinders 6 and 7! The leak down test was then performed to try to determine the cause of low compression.
 
driller said:
After installing a new torque converter, I took the car to the track where it seemed down on power from where it had been running. Figuring an ignition issue, I pulled the plugs to inspect and #6 plug looked out of place compared to the others. That lead to a compression test which surprisingly showed low compression on cylinders 6 and 7! The leak down test was then performed to try to determine the cause of low compression.
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Best of luck with it Driller.
I had a 70 Judge when I was younger, I went from second to third at 6400rpm one day like I had done many times before. Already back into the throttle on the power shift the top bolt in the shifter bracket broke.. she stayed in second but the shifter went to third. Needless to say when I saw 8k on the tach it was too late. Broken rings on two pistons and a busted skirt on a third. Sad day for the Pontiac but I learned a lot with that car.
 
97MarkJA said:
Best of luck with it Driller.
I had a 70 Judge when I was younger, I went from second to third at 6400rpm one day like I had done many times before. Already back into the throttle on the power shift the top bolt in the shifter bracket broke.. she stayed in second but the shifter went to third. Needless to say when I saw 8k on the tach it was too late. Broken rings on two pistons and a busted skirt on a third. Sad day for the Pontiac but I learned a lot with that car.
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Here comes the Judge, Here comes the Judge. LOL Wish you still had that huh?
 
Right on the Mark said:
Here comes the Judge, Here comes the Judge. LOL Wish you still had that huh?
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Yes I do, ram air IV and a 4 speed. A little old lady in Bradenton fl ran a light and hit me square in the door. 76 caddi doing about 45, bent the frame, broke the seat bolts...ugh!
That's when I bought my 65.
 
Right on the Mark said:
Yeah for pass car old granny rebuild not needed but most of time hipo 4.6's are getting supercharged/turbo/nos and 500 hp +. You also have to line hone all the alum blocks on rebuild also. You need all hardware that engine will be put together with too. IE if using ARP head and main studs all machine work must be done with those installed.
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What I was told it is "not a must on Alum. blocks because they move around so much.
Not much to gain by using plates."

We were discussing JA's build.
I don't remember if driller used a teksid block or not.

He builds engines for quick eight, and also for all super classes.
But by no means is he a 4.6 expert, or a ford fan for what its worth.
Because of him I have the "Bite me Chevy boy" ;)
 
ford nut said:
What I was told it is "not a must on Alum. blocks because they move around so much.
Not much to gain by using plates."

We were discussing JA's build.
I don't remember if driller used a teksid block or not.

He builds engines for quick eight, and also for all super classes.
But by no means is he a 4.6 expert, or a ford fan for what its worth.
Because of him I have the "Bite me Chevy boy" ;)
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There is a taper in mains right from Fords machining. In HP use you want this to be to specs as best it can be. All HP alum mods should have line hone. Driller used a Boss block which is cast iron.

FYI The main reason for line hone is when switching to ARP main studs. Line hone HAS to be done 100% when going to studs. And most HP build go to studs.
 
I don't remember the exact specs on drillers build but it was a cast block. I know for what I have in motor parts I could have bought another really nice Mark and I'm sure he's in the same boat. Hopefully its something simple, hoping for the best.
 
driller said:
You got THAT right! :D
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Mod engine parts are like the most expensive parts to build with. But it does work out in the end on high hp engines like 600hp and up. If you where to build a windsor engine you would need after market block 2000 plus. Then you would need aftermarket heads. These are NOT needed with mod engine. You use stock block and heads and make big power FI.
 
driller said:
I presume whatever specifics the pros do, it was done with the build of the short block. They build motors that run much more HP than I'm running.

I will talk to both shops this coming week but the bottom line is the motor will have to come out and be looked at. :(
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Do you have a date for the surgery yet?
 
After more diagnostics and some very limited driving, I revisited the compression test.

Dry test:

Number 6 - 145 psi :rolleyes:
Number 7 - 195 psi :)

Wet test:

Number 6 - 210 psi
Number 7 - 230 psi

I hope that's a good sign.
 
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