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#727530 - September 04th 2017 11:08 pm Slant 6 rebuild time.  
Joined: Aug 2002
Posts: 12,995
lukester Online content
lukester  Online Content


Joined: Aug 2002
Posts: 12,995
Lake City Florida, United Stat...
Friday on the way to the FVC meeting and van-in. I was 50ish miles into a 90-100 mile trip. I was pulling our 5x8 enclosed club trailer. Something I now regret. Everything seemed to be going fine. I was going up a minor incline when the engine started to lose power. I managed to get to the top of the minor hill. But I could tell something was wrong. I had lost power. My oil pressure would bottom out if I gave it gas. I lay of the gas and it would bounce up & down. As I was looking for some place other then the ditch to pull off the road. When BANG ! then what sound like lose coins being shaken in a metal coffee can. Very, very loud. As I pulled off the road. My temp that was running fine shot to the top and I over heated. Smoke pouring out from under the hood. Water every where. After 230k miles I think she is dead Many vanners want me to swap to a 318. I can get a free 1980 318 that was running when pulled but needs a total rebuild. The 318 was matched to a A904 trans. How ever. I really think I want to keep my 225 but have it rebuilt a little more then stock. I do not want to do any thing that requires a different transmission. I had this one ( A904) rebuilt at the beginning of this year.

So I have done hours of searching and still have questions of how I should have the 225 rebuilt.I have already done the HEI ignition swap years ago. No lean burn.

RV cam?
Headers ?
Bigger exhaust?
Higher compression?

Need some advice from Reed or any other slant six experts. I won't know until later this week or next what has happened. I had it towed to the shop Friday afternoon and he was closed today for the holiday.

Any advice would be greatly appreciated.


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Arianrhod:2003 Chevy Astro
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Serenity:1985 Chevy G-20
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Freedom:1990 Ford E-150
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#727531 - September 04th 2017 11:28 pm Re: Slant 6 rebuild time. [Re: lukester]  
Joined: Jun 2010
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frscke1 Offline
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Joined: Jun 2010
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Van Diego California
Sry to hear that Luke ....


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#727537 - September 05th 2017 9:31 am Re: Slant 6 rebuild time. [Re: lukester]  
Joined: Mar 2016
Posts: 197
Hasan Ben Sobar Offline
member
Hasan Ben Sobar  Offline
member

Joined: Mar 2016
Posts: 197
Tucson,Az.
What is your budget?


Tucson-it's a dry heat...like an oven
#727538 - September 05th 2017 10:47 am Re: Slant 6 rebuild time. [Re: Hasan Ben Sobar]  
Joined: Aug 2002
Posts: 12,995
lukester Online content
lukester  Online Content


Joined: Aug 2002
Posts: 12,995
Lake City Florida, United Stat...
Really wanting to keep it under $3500. Parts and labor.


[Linked Image]

Arianrhod:2003 Chevy Astro
Black Magic: 1985 Dodge B-250
Serenity:1985 Chevy G-20
The Outcast:1983 Ford club wagon
Freedom:1990 Ford E-150
Outcast Vanners van club
member of the Florida Van Council
Support your local 2%
#727539 - September 05th 2017 10:48 am Re: Slant 6 rebuild time. [Re: lukester]  
Joined: Aug 2001
Posts: 11,278
Reed Offline
Maniac
Reed  Offline
Maniac

Joined: Aug 2001
Posts: 11,278
Fircrest, WA
Before you make any rash and expensive decisions, wait and hear what the mechanic tells you broke. It definitely sounds like an overheating situation. It might be something as simple as a blown head gasket, leaky radiator, or blown radiator hose or thermostat housing gasket. The oil pressure is concerning, but it is odd that it it varied with the throttle. The "coins rattling in a coffee can" noise might have been pinging from preignition due to overheating.

If the motor was still running, then you had compression in at least some of the cylinders. The short block might actually be OK.

Due to its smaller displacement, a slant six should be built to match its intended use. If your goal is to use it in a van that will pull a trailer, you need to make sure you build it to maximize horspower and torque in the 2000-2800 RPM range. You also need to have the right gears in the back. If you are going to pull a loaded 5x8 trailer then I recommend 3.55 rear axle gear at the highest, and 3.7s or 3.9s would be better. Remember, Dodge put the slant in six-ton dump trucks back in the 60s, they just didn't go very fast. The slant six can do the job if the gearing is right.

My recommendation is to wait and hear what the mechanic finds. If it is something simple like a blown head gasket or a tooth jumped on the timing chain, just fix that and keep on trucking.

However, if you do have to rebuild the motor, I recommend the following:

(1) upgrade to a two barrel carb. The factory two barrel carb package (the "Super Six") used a Carter BBD or a Holley 2280. This is a great upgrade and will improve power and often economy. However, parts are getting harder to find and more expensive. The intake manifold is the same for all cars, trucks, and vans, but vans had special van-only air cleaners and kickdown linkages. The doghouse required a special offset air cleaner and a different kickdown linkage to clear the van trans shift linkage. You can use your stock one-barrel air cleaner and weld in a section from a 318 air cleaner to get the right size hole for the neck of the carb. You can also run a cable style kickdown linkage that can be found on eBay for cheap. I recommend keeping the stock closed element air cleaner but using a factory style cold air intake. Another option would be to get an Offenhauser four barrel intake manifold and run either an adapter plate to use a two barrel carb on it or run a small four barrel carb with the secondaries locked out. You don't want to put too much carb on the motor. Other people have had good success adapting a Motorcraft/Autolite 2100 carb.

(2) upgrade compression and the cam. Ideally, you want to shoot for 8:1 or 8.1:1 DYNAMIC compression ratio, NOT stati compression ratio. usually this is achieved by milling the head. But you have to take the time to do all the necessary measurements and calculations first, and you have to pick your cam before you know how much to mill.

Your 85 slant has a hydraulic flat tappet lifter cam. There are some good aftermarket cam profiles that have been researched by slant six enthusiasts and that work well with a hydraulic slant six cam. Read this thread: http://www.slantsix.org/forum/viewtopic.php?t=43301&highlight=cam+low+rpm+torque

I recommend going with one of the Oregon Cam profiles recommended in that thread and having your stock cam reground by Oregon Cam (unless it is damaged beyond reuse).

(3) upgrade exhaust. This is easy- do it. I recommend you upgrade to dual exhaust using a Dutra front manifold and a modified stock rear manifold. Then run 2 inch true dual exhaust or Y the exhaust together after the manifolds into a 2 1/2 inch system before the free flowing muffler and then 2 1/4 after the muffler.

(4) Upgrade the valves and the head. The best bang-for-the-buck in upgrading a slant six is imrpoving flow through the head. Porting, oversize valves, and gasket matching the head and manifolds is a great way to improve power and economy.

(5) Other machining. Obviously you want to balance the rotating assembly, but I also highly recommend taking the time to improve flow in the oiling system. See here: http://www.slantsix.org/forum/viewtopic.php?t=29492&highlight=deburr+oil+passages Since your motor has hydraulic lifters, you really want to have the best possible oil flow through the whole oiling system. On hydraulic lifter slants the lifters are fed oil through the hollow rocker arm push tubes. The oil goes form the crankcase, through the pump, through the block, up to the rocker arms ahft via a hole in the rearmost rocker shaft pedestal, through the rocker arm shaft, through the rocker arms, into the pushrods, then down to the lifter. Don't worry about high volume oil pumps, the stock unit is fine. Try and keep your original oil pump and get it rebuilt- aftermarket pumps are of very questionable quality.

Report back what your mechanic tells you and I can give you my opinion on what should be done.


Windows- they're what make a van worth owning!
#727543 - September 05th 2017 3:44 pm Re: Slant 6 rebuild time. [Re: lukester]  
Joined: Aug 2001
Posts: 11,278
Reed Offline
Maniac
Reed  Offline
Maniac

Joined: Aug 2001
Posts: 11,278
Fircrest, WA
Also, don't forget to check the integrity of the catalytic converter. Those can fail and completely clog the exhaust causing pinging and overheating.


Windows- they're what make a van worth owning!
#727557 - September 05th 2017 10:03 pm Re: Slant 6 rebuild time. [Re: lukester]  
Joined: Aug 2002
Posts: 12,995
lukester Online content
lukester  Online Content


Joined: Aug 2002
Posts: 12,995
Lake City Florida, United Stat...
Update.....
Mechanic believes I threw a rod. No visible damage to the block but the engine is still in the van. He is checking with his supplier for remanufactured engines. Don't know that I want to go that route but it would have a better warranty. I will hopefully know more tomorrow afternoon.


[Linked Image]

Arianrhod:2003 Chevy Astro
Black Magic: 1985 Dodge B-250
Serenity:1985 Chevy G-20
The Outcast:1983 Ford club wagon
Freedom:1990 Ford E-150
Outcast Vanners van club
member of the Florida Van Council
Support your local 2%
#727560 - September 05th 2017 10:31 pm Re: Slant 6 rebuild time. [Re: lukester]  
Joined: Aug 2001
Posts: 11,278
Reed Offline
Maniac
Reed  Offline
Maniac

Joined: Aug 2001
Posts: 11,278
Fircrest, WA
I suppose it is possible. But what caused the loss in oil pressure that led to the rod bearing being starved for oil? Are you sure the mechanic isn't taking the easy way out and opting for the simpler more profitable diagnosis? I just don't trust mechanics these days to do an honest job truly diagnosing older vehicles.

If the engine does get replaced, I highly recommend you keep the carb and distributor on the van now. Be aware that the oil pumps used on reman engines these days are of very poor quality and are known to cause the oil pump gasket to fail leading to massive oil leaks. Also, oil pump drive gears are suspect on reman oil pumps.

In all honesty, it will likelybe more expensive and take longer to get your curent motor rebuilt, but you could control the proces better and get a better end result.


Windows- they're what make a van worth owning!
#727564 - September 06th 2017 8:50 am Re: Slant 6 rebuild time. [Re: lukester]  
Joined: Mar 2016
Posts: 197
Hasan Ben Sobar Offline
member
Hasan Ben Sobar  Offline
member

Joined: Mar 2016
Posts: 197
Tucson,Az.
Up-grade to a 318 or 360. Virtually no hit in MPG's.


Tucson-it's a dry heat...like an oven
#727566 - September 06th 2017 10:08 am Re: Slant 6 rebuild time. [Re: lukester]  
Joined: Aug 2001
Posts: 11,278
Reed Offline
Maniac
Reed  Offline
Maniac

Joined: Aug 2001
Posts: 11,278
Fircrest, WA
Except switching to a V8 will be much more complex and expensive that just rebuilding the six cylinder. Installing a V-8 will require changing many things- transmisison, exhast, radiator, trans cooler lines, possibly wiring, possibly front coil springs, all the engine accessories (pumps and brackets), etc... I have done the swap both ways in Dodge vans- 225 to 360 and 318 to 225.

A custom slant can be built for much less than $3500, especially if he does the installation and removal himself. Switching to a V-8 would amost certainly cost more than $3500 in parts and labor.


Windows- they're what make a van worth owning!
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