E361T Progress - 671 to 671T

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Re: E361T Progress - 671 to 671T

Postby oldspwr » Thu Jun 02, 2016 6:57 am

Last but not least was installation of the Isspro pyrometer. I had remembered the dual chrome ones on Steve S’s 359 and they were located in the package tray right below the headliner. So I decided to mount ours in the same place. I started with an Isspro R602-10...

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Since they don’t make ones this size with chrome bezels anymore, I wound up buying a stainless washer from McMaster and turning it in the lathe to fit over the gauge...

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And then I drilled the mounting holes...

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Then I removed the header panel I made, drilled the 2 3/4" mounting hole and polished the bezel and the button head screws...

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And here is the finished product...

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More to follow...
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Re: E361T Progress - 671 to 671T

Postby oldspwr » Thu Jun 02, 2016 7:18 am

The next day we took the truck for a test ride and everything worked well. The noise in the cab was greatly reduced at cruising speeds and we were building between 12 and 13 psi of boost total. The following day we had our ATCA club meeting and we decided to take the truck. For our May meeting Dave & Kevin Lewis host a picnic at their shop before the meeting and we had a nice turn out of trucks...

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The next day after our trip to Scranton with the truck I noticed a lot of oil under the truck. At first I thought I was pushing oil out of the air box inspection covers so I would up replacing the gaskets on all 8 of those.

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While I was under the truck I also decided to remove the breather just above the starter. The starter was fairly wet and sure enough oil was leaking from the bottom of the breather. It looks like I damaged the gasket when I inspected it last summer...

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So made a new gasket for the breather and reinstalled it. I wound up dropping the starter to make life easier but quickly remembered how heavy it was!!!

Now that things were wrapped up with the turbo I decided to replace the injectors. I had a rebuilt set of N70’s to replace the N65’s. One of the things I needed to confirm was what height to set the injectors at, either 1.460” or 1.484”. The Detroit book says 1.460" for N70's Turbo with standard timing and 1.484" for N70's Non-turbo with advanced timing. I decided to set them at 1.460” and the following weekend we swapped the injectors and re-ran the rack...

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More to follow...
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Re: E361T Progress - 671 to 671T

Postby oldspwr » Tue Jun 21, 2016 11:38 am

Well I might as well share the good with the bad...

About a week after we installed the new injectors I decided to take my son to his Karate class with the truck. It’s only about 20 miles and about halfway into our trip the turbo failed. I heard a ‘thud’, then noticed the boost pressure was 0 and started pouring smoke out of the exhaust. I had to get the truck towed home, no fun...

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After disassembling the turbo I discovered the shaft was bent and the bearing was wiped out. My best guess is that the nut on the intake side was not torqued correctly because I could spin it off with my fingers. But that’s just a guess, it could have come loose during the abrupt ‘stop’. While waiting for the roll back, I also noticed a ton of oil dripping under the truck. It turns out I was pushing oil right through the breather on the side of the block. After some further discussion I decided to plug that breather since I had the one on the governor housing and the large breather on the valve cover. Keep in mind the original valve cover did not have a breather...

So after changing the oil and installing another turbo, I went for another short ride up towards my Brothers house. This time I pushed over 2 gallons of oil out of the tube on the governor housing. My thoughts were at that time was that the oil was not returning to oil pan, and after looking through the Detroit manual one of the causes could be excessive crankcase pressure. The manual lists several causes, including exhaust back pressure, a bad blower gasket, bad blower seals or worn/tired rings.

I figured it couldn’t be exhaust back pressure since I had 5” from front to back, I was pretty certain the blower gasket was ok, it couldn’t be the blower since we had it rebuilt with high pressure seals, so I must be the rings??? So I decided to check the crankcase pressure. This is measured in “inches of water column” so with a piece of plywood, 10’ of 1/4" clear tubing and half a yard stick, I made my own manometer.

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I also installed a pressure gauge on the rear air box drain T fitting so I could understand what the total air box pressure was (turbo plus blower.) After running a quick test, I wound up with the following numbers...

1200 rpm 2.25" of water 6 psi air box pressure (No value in manual)

1500 rpm 3.25" of water 10 psi air box pressure (Manual calls for .7")

1800 rpm 4.75" of water 12 psi air box pressure (Manual calls for 1.3")

2000 rpm 7.50" of water 15 psi air box pressure (Manual calls for 1.8")

2100 rpm 8.25" of water 16 psi air box pressure (Manual calls for 2.0")

More than likely my turbo pressure is getting past the oil rings and creating the pressure in my crankcase. So much that it is preventing the oil from draining back down into the pan.

As a last ditch effort, I removed a 3/4" npt plug in the air inlet and installed a nipple with a 1” hose to try to reduce the overall boost of the turbo. But we still had 8 psi of boost vs. 13 psi so that didn’t work...

With less than a week and a half left before the show in Macungie, we made an executive decision to remove the turbo and put things back the way they were. This was fairly straight forward, all I had to do was adapt the factory 4” exhaust to the new 5” resonator. I also installed a bung in the factory 4” piece so that I could reconnect the pyrometer. 2 nights later we had it running and decided to re-run the crankcase pressure test...

1200 rpm 0" of water 3 psi air box pressure

1500 rpm 0" of water 4 psi air box pressure

1800 rpm 0.50" of water 5 psi air box pressure

2000 rpm 0.625" of water 5 psi air box pressure

2100 rpm 1.50" of water 5 psi air box pressure

So these numbers are closer to the factory specs so at least we can get through the summer with it. Keep in mind that the crankcase pressure went back to normal after the turbo was removed so it ruled out being an issue with the blower, or defective air compressor, etc.

Right now our intention is to inframe the motor this fall after show season is over. Maybe I should retitle this post to “671 to 671T to 671”?????

More importantly, we were able to take the truck to Macungie!!!

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And this is what truck shows are all about... Visiting with everybody!!!

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Re: E361T Progress - 671 to 671T

Postby STRETCH » Tue Jun 21, 2016 12:57 pm

Tom,
Sorry to hear of your misfortune after all the work and effort put forth.

Never fun to come home via the hook..... :( :(

Bright side...lots of documentation on what you did, and what you tested.
We can't thank you enough for sharing the info!

Hope to see you folks soon!

What is the status on the other engine project??

Stretch 8)
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Re: E361T Progress - 671 to 671T

Postby STRETCH » Wed Jul 06, 2016 6:58 am

Tom,

Probably by now some one may have told you to check the pistons.

I just happened to be talking to a couple of veteran "old school" detroit guys here at our shop.

They know i have a couple of 671"s and bust on me regular about my progress (we won't go there..) any way I asked about your change over to turbo. They both said that the turbocharged 671 had a different crown on the piston, thus changing the compression ratio.
Don't have anything in print...but it may be something to look into.

Hope to see you folks soon!

Stretch 8)
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Re: E361T Progress - 671 to 671T

Postby oldspwr » Wed Jul 06, 2016 10:01 am

Hi Stretch...

You're correct, the pistons are different. The non turbo piston give a compression ration of 18.7:1 and turbo pistons are 17.0:1. I talked to handful of guys that put turbo on natural motors without issues, especially since they were hobby trucks and not worked everyday.

I am pretty certain my rings are tired and letting the pressure in the air box go into the crankcase. We are going to do something this fall, either an in frame of the original motor with the correct turbo parts or rebuild another blow. I would like to find an aftercooled silver series block to rebuild.

Without the turbo and just the resonator, the truck is crazy loud :)

As for the 155W project, stay tuned for an update!

Tom
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Re: E361T Progress - 671 to 671T

Postby Mike Pacitto » Thu Jul 07, 2016 7:17 am

Yes, but its is a great crazy loud. I think that the 6-71 is the best sounding engine ever made.
Mike Pacitto
Chelmsford, Mass.
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Re: E361T Progress - 671 to 671T

Postby Huskiedrive2 » Fri Jul 08, 2016 10:09 pm

Don't forget your little 6V-53 Mike. They have a cool sound all their own and red line is 2800!!!
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Re: E361T Progress - 671 to 671T

Postby oldspwr » Fri May 17, 2019 3:56 pm

Remember when I upgraded the 671N to a 671T and then back to a 671N? Well now it’s time to go from a 671N to a 671TAB. Almost 3 years later...

After we had all the issues with adding the turbo to the 671 in my Dad’s 361 I decided to remove it and put everything back the way it was. As of right now my best guess is that the rings are just tired and I was pushing boost into the crankcase which was making a mess out of everything. I was also getting a of oil through the slobber tubes (specifically the rear one) and a lot of oil in the exhaust stacks.

On a side note, adding a turbo to a non-turbo 671 seems to be a popular question on FB and half the people say it will work fine (especially for a hobby truck) and other people will tell you it can’t be done. I do know Detroit used different pistons for turbos along with lower compression, etc.

At that time I had discussed with my Dad rebuilding the original engine (in frame) or possibly finding a later block that was aftercooled. I know he liked the idea of keeping a 671 in the truck and to be honest I did too. Of course I could have repowered it with a Cummins, or an 871, etc, but I still liked the idea of a 671. I did a lot of research on these motors and found out that in the mid 80’s they had 320HP truck versions and marine versions went all the way to 485HP (of course with unlimited cooling...)

I had pretty much made my mind up that I wanted to find a mid 80’s 671 that was rated at 320HP, which had a turbo and was aftercooled along with a bypass blower. This would have the TAB designation. T = Turbo, A = Aftercooled and B = Byplass blower. To this made the most sense since I could still use my existing trans, radiator, etc, and just replace the motor.

So I decided to start looking for a decent core to rebuild. After searching online I found a 671 that came out of a fire truck, model 1067-8640. It was located in Camerota’s in Connecticut, but when I called, it turns out they had sent it to auction in Ohio...

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You were able to bid online but it was in a month and a half. So I threw in an opening bid of $200 and waited to for a month and a half. On the day of the auction, it wouldn’t let me bid any higher for some reason and it sold for $250!!! Still thinking I may have some chance of getting this motor, I called the auction house and they gave me the contact info for the scrap yard in Kalamazoo Michigan that bought it. I was able to get in touch with that guy and he wanted $850 for it plus freight. That’s still a decent number for it but I decided against it.

In the meantime I had been talking to the folks at Leid Diesel in Newville, PA, just south of Carlisle. They had the right core in stock and were interested in taking in the original motor as a core as well. So I made the decision to have them build the motor. This was in late December of last year. My plan was to have them build the motor and have it ready to go by the time I was able to bring my Dad’s truck home from the museum.

When I talked to Leid I explained that I wanted to have the motor test run and broken in prior to me getting it. I realize it’s not practical for me to break it in bobtailing with no weight. So at that time I decided to start collecting some parts I needed to complete the motor. The first thing I located was a complete set of Jacobs Engine brakes from a guy in Arkansas that I found on FB. His number was more than fair and I was able to buy (2) masters, (4) slaves, a set of bridges and a set of O ring fuel lines.

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I also located an updated buffer switch in eBay and a complete rebuild kit for a 6V71 (which is the same as the 671)...

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I took everything apart and cleaned it in the parts tank and started laying everything out...

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After everything was cleaned I started reassembling everything...

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And shortly thereafter I wound up with this...

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More to follow...
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Re: E361T Progress - 671 to 671T

Postby oldspwr » Fri May 17, 2019 3:57 pm

The next big step was to find a tall aluminum valve cover. As most of you know these are becoming fairly hard to find and expensive. I called the guy in Lancaster where I bought my original one from and after some searching he called me back and said he couldn’t find one. A week later his son called me and said he had one and a week after that UPS delivered it to my house...

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Ironically this cover came off of the same engine model I wanted my new one based on, 1067-8640...

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My best guess is that this came off of a motor in an International since it was painted red.

More to follow...
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Re: E361T Progress - 671 to 671T

Postby oldspwr » Fri May 17, 2019 3:58 pm

Although it’s a little too long, this spent some time in the parts washer...

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And then came the tedious process of stripping the paint and polishing it. I started with aircraft paint stripper...

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And then sanding with 80 grit, followed by 180, 220, and then 400...

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Finally I used a 6” buffing wheel with some compound. I came out pretty good and it looks a lot better than the picture reflects...

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Well that’s it for now!!!
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Re: E361T Progress - 671 to 671T

Postby Watchmaker » Sun May 19, 2019 6:29 pm

Tom great post as always hope to see it in August!!
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