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I noted in the video that he just pulls to 20 and then pops it off. There is a beep you can hear in the background so I don't know if it is checking for leaks with some sort of vacuum differential between the pump and pad.
I built a pad and stuck it on my A/C vacuum manifold, attached to a 3CFM Harbor Freight pump:
If I stick my finger over the hole it will pull 30.
Here's the results I have so far:
The picture below shows a test I did this morning. Both valved have soaked overnight in Chem Dip and have been cleaned with a Scotch Brite pad and a brass brush. Valve seats with just a Scotch Brite pad (green scrubby). The valve on the left HAS been lapped. The one on the right HAS NOT.
Results from the right valve that HAS NOT been lapped (control):
Here is the result from the left valve that HAS been lapped:
So the lapped valve pulls 21inHg of vacuum. The non-lapped valve pulls 15inHg. So I know that I am getting a better seal with the cleaned and lapped valves (which hopefully fixes the leak down test failure), but how much SHOULD I be getting? I can't seem to find an answer anywhere on the internet.
Last edited by Eric Dorenbush; 12-31-2018 at 08:32 AM.
Just got word from a buddy that owns a machine shop that 18-22inHg is about normal, so I'm going to move forward with finishing this passenger side head. If anyone has different information on the vacuum test let me know.
Current plan is to be cautious and minimize potential damage and excess work. So, I'm going to vacuum test the piston to verify ring seal. Then I'll finish the passenger side head and bolt it back to the block. then I'm going to redo the leak down test on the passenger side and compare the results with the failed test from earlier. If it all checks out, then I'll pull the driver's side and repeat the process.
Are you going to do that motor a favor and get a set of headers on there that give it a chance to breathe? Seems like that 4.6 could be so much better if it were allowed to exhale in a decent fashion. At this point I'd also do a new cam and intake manifold. I don't think a loss of torque would be that noticeable versus the power gains you'd experience....especially given that you've all but disassembled the motor now! New chain, tensioners, guides, potential valve job, etc. should have that 4.6 running tip-top for a long time. Especially when you put some good hardware on there. Shoot, why not shoehorn a blower on there for giggles?
Are you going to do that motor a favor and get a set of headers on there that give it a chance to breathe? Seems like that 4.6 could be so much better if it were allowed to exhale in a decent fashion. At this point I'd also do a new cam and intake manifold. I don't think a loss of torque would be that noticeable versus the power gains you'd experience....especially given that you've all but disassembled the motor now! New chain, tensioners, guides, potential valve job, etc. should have that 4.6 running tip-top for a long time. Especially when you put some good hardware on there. Shoot, why not shoehorn a blower on there for giggles?
So I mentioned before that the exhaust manifold is done, I'm not putting that rusted and pitted thing back on the truck. It already has custom made exhaust- Dual in/dual out with an h-pipe and flow masters. I'm currently not yet sure what direction I'm going to go yet. The research I've done indicate that short tube headers are a negligible gain and long tubes require the cats to be push back and the pipes would need to be modified.
Because of that, I've narrowed it down to 2 choices:
1- Replace the old cast iron manifolds with Dorman cast iron manifolds- $198.98
2- Buy a welder and fabricate my own- $?
Both of my vehicles have exhaust pipe sections that need replacing, especially my truck due to the corrosion from getting it in the nasty water in south Texas the other year doing flood rescue work. I'm holding off on deciding until both heads pass the leak down test and I know there won't be any more surprise expenses, since this went from a cheap spark plug sleeve job and intake manifold replacement to a top end rebuild.
After doing research into intake manifolds, I'm going to keep the stock cast aluminum intake manifold. All the aftermarket ones shift the power band higher in the RPMs. Same with the cams. Most of the manifolds are geared towards the 4.6l in the mustangs so that makes sense for that application, not so much - I think- for my heavy towing and lower speed off road use. The plastic Dorman intake manifold is not going to go on my truck.
I am going to port (gasket match) and polish the heads, intake manifold, throttle body and plenum. I'm also doing a rough polish on the outside of the intake manifold and will be paining it with high temp paint- mainly to help keep the dirt accumulation down.
The timing chains, gears, and phasers look to be fine so I will probably leave those. The timing chain guides and tensioners look fine, but I will be replacing those.
There's no potential valve job- the valve job is in progress as you can see from the posts above.
I'm not going to do a blower without rebuilding the block since the pistons and rings are also high mileage. Depending on how the heads work out and what the expenses come to at that point, I will probably move up to a bigger throttle body for a bit quicker response. I've had a K&N 77 series CAI on there for years.
I already have a mild pre-loaded tune in it with my SCT tuner. Depending on how it runs afterwards I may get a custom tune for it to smooth things out a bit. It probably needs it anyways with everything I've already done to it previously (including the re-gear to 4.56 I did) and what I'm planning to do to it.
I'd go with shorty headers at least, if not long tubes. Redoing the exhaust placement is not that big a deal compared to the extensive motor work you're doing. But after all this work, for me personally, it would be a waste to put those gnarly, restrictive log manifolds back on. Even if you were to upgrade intake manifolds, the cam is going to keep the power band mostly where it is now but allow for more air. You could always send the stocker out for extrude honing, and then port match the heads after that.
I'd go with shorty headers at least, if not long tubes. Redoing the exhaust placement is not that big a deal compared to the extensive motor work you're doing. But after all this work, for me personally, it would be a waste to put those gnarly, restrictive log manifolds back on. Even if you were to upgrade intake manifolds, the cam is going to keep the power band mostly where it is now but allow for more air. You could always send the stocker out for extrude honing, and then port match the heads after that.
I don't disagree with you- but it is a matter of cost and prioritizing things. Redoing exhaust placement isn't a big deal but I do need to go get a welding machine for that. My Broco Exothermic torch won't be quite appropriate for it. I'm not sure I'd do shorty's. Too much cost for little to no gain. If I don't do long tubes or custom fab them myself- I'll probably put new stock manifolds on since they are cheap and just use them a s a placeholder for future upgrades.
The cams might fix things- but it isn't as simple as just buying one and putting it in (at least from the research I've done and the advice I've been given). I'd need to do data collection, establish goals for them and probably need to get them custom made. And then there's the tuning that would be mandatory at that point.
I think maybe this summer I'm going to hunt around for a used iron block and set it up in the garage to do a complete rebuild on it from the bottom up, over time. then next year maybe do a complete swap or just keep it on hand in case something goes wrong with the current one.
12-30-2018, 04:29 PM
