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09-29-2017, 09:56 AM | #1 |
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Location: western Mass
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exhaust crossover and pressure testing
hey guys, I pulled the 8ba down in my roadster this spring to freshen a few things up... basically all it seems to need is a new gasket set and some paint if the pressure test turns up ok. I found 30" of weld in the pan rails, but it was rebuilt and running for 25 years like this. i have smelled a little coolant in the exhaust so I'm concerned about whether it's the head gaskets or exhaust ports cracked.
when the motor was put together it had the old school copper penny tapped into the exhaust crossover holes trick done to it. well on tear down one was missing and the other looked to be pretty close to falling out as well. This car is only run during warm weather so I don't want heat in my manifold. I don't want problems with boiling the gas on this thing with ethanol.... on a side note... I'm in western mass (springfield/six flags area) can anyone recommend a shop near me that I can bring a complete motor minus heads/intake/water pumps and have them pressure test it?? tried scrounging up a set of testing plates from a retired engine builder I know but every call I get I'm getting pushed out further. |
09-29-2017, 10:25 AM | #2 |
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Location: North Pole, Alaska
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Re: exhaust crossover and pressure testing
You can pressure test it yourself. I made a gasket for head(didn't have a spare head gasket laying around) then put a plumbing plug, the type you tighten, inside the head outlet. Plug the temp sensor holes. Install a good water pump and gasket, and use the same type plug with a small hole for air chuck. attach a gauge and add air.
You can see if it loses pressure, but I like to fill it with water. That way if it leaks, you will see it. You can also spray it with soapy water(with just air). Of course, you have to test each side separately.If you want to get fancy, put some dye in it. Typical flathead pressure is about four pounds, I put approx 25-30 in. Not scientific, but it works and it's low cost and you can do it at home. |
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09-29-2017, 11:11 AM | #3 |
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Re: exhaust crossover and pressure testing
You could consider doing a magnaflux on the deck surfaces.
This will be a preliminary to the pressure test, and cheaper. Look at the area around the valve seats and cylinder edge. With a test plate you can see this combustion area. I would use a test plate, with air pressure- spray water with a bit of soap in it. Look everywhere, but check pan rails, behind the valve springs, exterior. Contact me if you wish. Karl |
09-29-2017, 11:29 AM | #4 | |
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Re: exhaust crossover and pressure testing
Quote:
Don't know if they can provide what service you require but you can give them a call. http://eastwoodsautomachine.com/contactus.html
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09-29-2017, 12:53 PM | #5 |
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Re: exhaust crossover and pressure testing
The test kits run around $250 but when you think about how long it would take to fabricate that stuff the price looks better & better.
One that has had cracks repaired in the past already shows the vulnerability. It must have frozen up somewhere back in its life for sure. The pan rails are the first thing that cracks but who knows where else it might. |
09-29-2017, 01:11 PM | #6 | |
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Re: exhaust crossover and pressure testing
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Quote:
as for the pan rails that is the obvious worry. when the rails crack the possibility of the exhaust ports being damaged is very real. The motor is pretty much a stocker with aluminum heads and dual 97's... no real pushing it hard. if it's leak free it's going back in. |
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09-29-2017, 01:37 PM | #7 |
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Re: exhaust crossover and pressure testing
I'm sure the caps are likely water jet cut pieces of just flat plate with neoprene gasket. If the deck plate part is fabricated thick enough, it could be used as honing plate less the seal.
I've seen a few that had coolant come out the exhaust port as soon it was poured in there. The siamese ones like to crack more than the end ones but who knows? |
09-29-2017, 07:19 PM | #8 |
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Re: exhaust crossover and pressure testing
We made ours, but then again we have a 50ton iron worker and punched all the holes. Used a old headgasket to lay it out. Got the neoprene from a local industrial rubber supply. $20 and some time and used what plate that was in the shop.
Same goes for the plates on the water pumps. Used a gasket to lay it out. |
10-02-2017, 01:40 PM | #9 | |
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Re: exhaust crossover and pressure testing
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10-02-2017, 02:21 PM | #10 |
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Location: Minnesota, Florida Keys
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Re: exhaust crossover and pressure testing
I made something to do preliminary testing. It was a plate the bolted onto the thermostat housing with a tee screwed into it that had a schraeder valve on one leg and a pressure gauge on the other. I made plates for the water pump openings out of 1/4" aluminum, but found no matter what I used for a gasket, they would leak on the one edge. I believe they would have to be 1/2" aluminum or 1/4" steel to hold. Anyway, I ended up using some vinyl caps I got from Amazon to cap the lower water outlets. Unless your water pumps are in excellent shape, you will get leakage around the shafts. I was able to test for leaks however, because I made fittings out of old spark plugs that I put in the plug holes and put a kid's balloon on each one. Believe me, if you put 5 lbs of air pressure on this setup and you have ANY leakage in a cylinder, the balloons will detect it. One of my water pumps would hold pressure and one would slowly leak down, but this was enough for me to determine that there were no water leaks in the block.
Someday, I am going to finish these by making better block off plates, but I haven't gotten around to it yet. I believe that, even with only the vinyl caps, this setup has the advantage of be able to be used in the field, The plate with the gauge, the vinyl cap, and 4 kid's balloons and a portable air supply will allow you to separate the "wheat from the chaff" just about anywhere. |
10-02-2017, 04:47 PM | #11 |
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Re: exhaust crossover and pressure testing
Tubman,I like that. Simple tool to do a complex job.
John |
10-02-2017, 06:25 PM | #12 | |
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Join Date: Dec 2013
Location: Minnesota, Florida Keys
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Re: exhaust crossover and pressure testing
Quote:
If you want to make your own, I had 10 of the thermostat housing plates made "on the come". The other components are pretty cheap if you get them from Amazon. Say the word and I'll send you a plate and a vinyl cap (I had to buy them 10 at a time, as well). Old spark plugs and balloons are available locally. Tubman |
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10-09-2017, 12:20 PM | #13 |
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Location: western Mass
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Re: exhaust crossover and pressure testing
Ok guys.. decided to attempt this myself. My brother had some foam rubber sheets so I made a gasket to use with my heads and stock waterpumps. I will put a air chuck regulated in the head.
What psi should I shoot for and does anyone have a recommendation for a solution to spray in the ports to foam up that won't rust up the motor? |
10-09-2017, 01:15 PM | #14 |
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Location: North Pole, Alaska
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Re: exhaust crossover and pressure testing
Use dawn soap and water, you can blow it out with air after you check for leaks.
Spray it in. If it leaks you will see the bubbles. I have found tiny leaks on truck brake systems this way, even ones you cannot hear. |
10-09-2017, 01:44 PM | #15 |
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Re: exhaust crossover and pressure testing
Tubman, your a putzer, welcome to the few of us who love to putz with Flatheads.
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10-09-2017, 02:34 PM | #16 |
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Join Date: Nov 2012
Location: western Mass
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Re: exhaust crossover and pressure testing
Well.. dawn worked well... no worries about getting anything rusty... this thing is junk. number 1 exhaust cracked and leaking at 10psi. Center exhaust on driver side is the same.. time for a new motor... not a happy hot fodder right now.
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10-09-2017, 03:29 PM | #17 |
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Location: western Mass
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Re: exhaust crossover and pressure testing
Tried posting pictures.. but they are too big.. oh well maybe tomorrow. Really too bad. Motor runs great and was rebuilt 25 years ago with probably 15k on it in the roadster... easy miles and it shows inside. Except for the cracks!
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10-09-2017, 03:58 PM | #18 |
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Re: exhaust crossover and pressure testing
Pins pins and more pins...and then a sleeve or 2...welcome to the wonderful world of flathead overhauling...
If it is a good running engine pinning a couple of cracks is perhaps an option...it takes time so will cost a few bucks though. |
10-10-2017, 09:05 AM | #19 |
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Re: exhaust crossover and pressure testing
Waterglass it and drive on.
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10-10-2017, 02:08 PM | #20 |
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Location: western Mass
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Re: exhaust crossover and pressure testing
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10-10-2017, 02:32 PM | #21 |
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Location: western Mass
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Re: exhaust crossover and pressure testing
here's the pics from my afternoon yesterday. spent 2 months asking around for the "proper tool" or a recommendation for a shop when I should have done this from the beginning. took me a couple hours to make it up and test both sides.
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10-10-2017, 02:45 PM | #22 |
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Location: San Antonio, Texas
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Re: exhaust crossover and pressure testing
The only problem with using the heads for pressure testing is that you can't tell where the cracks are as well as you can with plates if properly made. If a person doesn't want to pin the leaky cracks then it won't matter much. Some cracks are in places that can't be pinned anyway like the ones down inside the center exhaust port area. If it's in the valve pocket and doesn't go too far down into the bowl, it can be pinned. Most exhaust valve seat area cracks can be seen with the naked eye so that's the first place I check.
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10-10-2017, 02:50 PM | #23 | |
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Re: exhaust crossover and pressure testing
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10-10-2017, 07:09 PM | #24 |
Senior Member
Join Date: Nov 2012
Location: western Mass
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Re: exhaust crossover and pressure testing
Ok.. just picked up a stock rebuilt 8ba never fired! Got a good deal. Swap out my stuff and go!
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10-11-2017, 12:30 AM | #25 |
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Location: North Pole, Alaska
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Re: exhaust crossover and pressure testing
Sorry about the test results, but sounds like you have another Candidate ready to go. There are plenty of flatheads still out there.
I was going to put a 40 motor in my 35, but procrastination led to a low mileage 59AB that fell in my lap! |
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