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Wes's Burb build/update/maintance

Wes Harden said:
Didn't realize the trans was different than a normal th400.
Figured the output shaft and tail would be correct for t case, but not a 100% on that.
Noticed the thicker flange.
If I was running 40s this trans could work :haha:
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Wes, the output shaft on that TH475 is the same dimensions as the GM 4x4 version used from ‘80~’84 NP-205’s with a figure eight adapter to case pattern with the “short” 32-spline NP-205 input gear.

The straight cut 1st & 2nd gear planetary gears are a little noisy but doable/livable and were made to minimize thrust forces on the case that regular helical cut gears would cause under extreme loads.

Don’t let it go for a song-n-dance because it’s at the top of the chain as far as factory offerings go.
 
not much time with new acquisition. I did find the date code T1205AWB. Tonawanda plant, 12-05, 1989 truck manual trans, LE8 vin W. quick search says this engine had 8.7-1 compression ratio. Maybe not a stretch to get it to 9
 
Wes Harden said:
not much time with new acquisition. I did find the date code T1205AWB. Tonawanda plant, 12-05, 1989 truck manual trans, LE8 vin W. quick search says this engine had 8.7-1 compression ratio. Maybe not a stretch to get it to 9
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That’s great there’s a little more squeeze in the last of those carb’d motorhome chassis 454’s.
Just a thought on the OEM cast iron intake manifold short comings - they are extremely pathetic and if ya’ notice the carb base mounting point is actually lower then the height portion of the ports.

Weiand ( sp? ) manifolds ( now owned by Holley ) makes a decent intake specifically fort peanut-port big block heads - other manufacturers state they offer for this application but they are actually regular oval-port intake runners.

This manifold is not a high performance piece just more like the way it should have been from the beginning and its intended RPM range starts at idle, just what a good torque motor needs instead of a highly restrictive factory intake.

IMG_7206.png

IMG_7204.png
 
We can get that BBC running sweet for you whatever way forward you decide, lots of options, big blocks rule!

An intake manifold and hydraulic roller cam would be my first recommendation.

Headers are a worthwhile upgrade, but not for everyone.

If budget allows, cylinder heads are a huge upgrade, but also a huge dent in the wallet.
 
tarussell said:
That’s great there’s a little more squeeze in the last of those carb’d motorhome chassis 454’s.
Just a thought on the OEM cast iron intake manifold short comings - they are extremely pathetic and if ya’ notice the carb base mounting point is actually lower then the height portion of the ports.

Weiand ( sp? ) manifolds ( now owned by Holley ) makes a decent intake specifically fort peanut-port big block heads - other manufacturers state they offer for this application but they are actually regular oval-port intake runners.

This manifold is not a high performance piece just more like the way it should have been from the beginning and its intended RPM range starts at idle, just what a good torque motor needs instead of a highly restrictive factory intake.

View attachment 523942

View attachment 523943
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Got a line on a 14096242 intake 1969 vintage
What say ye on these.
Yeah i noticed the intake mounting was a little Pug ish.
Plus the egr is in a sucky spot even if blocked off

nvm I just realized this a SBC intake.
 
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As long as the upper and lower mounts are a matching set they shouldn't be any different between BBC and SBC unless the aftermarket moved the engine from the factory location.
 
popped the intake today this what i found.

20260320_150018.jpg20260320_150108.jpg
It is a mystery to me how this might have happened. The inside of the engine is very clean, but the out looks like 60k miles. For the most part I am not finding witness marks on the bolt heads. The oil was black as can be, no water in oil. Wondering how many bent valves. This is looking like an expensive MAW.
After picking that intake up I am very much leaning in the Aluminum direction lol.

edit EGR port are plugged solid with carbon, and undisturbed, if the intake had been recently removed that carbon would have been scraped off to install new gaskets.
 
I would definitely go with an aluminum intake. The performance upgrade and the weight savings are my thoughts.

I am guessing that you are going to do a thorough inspection, especially after finding that!
:eek:

I like the roller cam in my BB, but I understand that it may be more dollars than some want to spend.
 
Can hydro-lock bend push rods instead of rods? Otherwise, I would guess broken timing chain. It's hard to miss a shift in an automatic, but I have seen motorhomes fairly submerged. If it ran out of oil, there will be other signs.
 
Wes Harden said:
popped the intake today this what i found.
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Why are we still missing the "dislike" button?

On the bright side - didn't you secretly dream of new heads anyway? I guess you'll have to do a pretty thorough inspection now before proceeding. There may be a reason it was cheap, but you would have caught it for sure when you did compression test.

Sorry, it's bad news for you, but it's good news for us. Usually, we'd have to tell the poor guy how to troubleshoot it....
 
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That sucks it has some issues but keep this in mind going forward - compare all needed machine shop work/costs to things like stroker rotating assembly kits from the aftermarket.
They are very comparable nowadays to what you must pay for proper machine shop costs of bone stock OEM parts.

This is also very true for head work v/s new heads that are absolutely superior to what ya’ got.

Hydraulic roller cam lifters and pushrods are a bite in the backside but are so much worth it !
Just trying to warn ya of the better parts you could end up with v/s the full machine shop treatment costs if needed.

No matter what I’m so glad ya’ got a big block to use because even the gayest peanut-port versions are full of torque and it only gets greater with more useable power as the parts get better !
Ya’ don’t have to use that extra power while driving regular or towing ( if built with superior aftermarket goods ) but it’s nice to have it available if the need arises.
They just can’t help but make torque no matter the combo of parts used and if better parts are selected the power will be on demand too.
 
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Yeah you can darn near buy a crank cheaper than to turn and polish it. Unless its a forged crank, then its definitely worth it.

And heads, by the time you add up new guides, valve job, valves, springs, retainers, chiropractor bill, etc, you could of had aluminum with the right springs in them.

Is it a 4 bolt main block?
 
folkenheath said:
Yeah you can darn near buy a crank cheaper than to turn and polish it. Unless its a forged crank, then its definitely worth it.

And heads, by the time you add up new guides, valve job, valves, springs, retainers, chiropractor bill, etc, you could of had aluminum with the right springs in them.

Is it a 4 bolt main block?
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Not sure yet, i kinda got discouraged after pulling heads.
 
I like the big block Wes. Needs work but in all reality you know would be ina much better place building one vs stuffing a used long block with zero history on it. Even built mild will be a stump puller and won’t break a sweat pulling the burb around. Recoup some funds for the build by selling the TH475.

The fact that the small block in the burb is doing the job right now means you don’t have to be in a huge hurry to build the big block. Spread out the cost over some time and then put it in.
 
folkenheath said:
Yeah you can darn near buy a crank cheaper than to turn and polish it. Unless its a forged crank, then its definitely worth it.

And heads, by the time you add up new guides, valve job, valves, springs, retainers, chiropractor bill, etc, you could of had aluminum with the right springs in them.

Is it a 4 bolt main block?
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So it is a 4 bolt, cast crank.20260322_160015.jpg20260322_160024.jpg
all the rod were stamped for the cylinder, I didn't think GM did that. Possibly a rebuild ? In a class motor home ? Warranty maybe?
wasn't able to turn the the crank using the flex plate by hand. I pulled #5 and #8 they were the rusty ones.
20260322_162603.jpg
rings are gummed up and half way stuck on #5
Skirt is thrust side, hardly any wear. Rod looks straight piston moves and slide on wrist pin easily.

20260322_162839.jpg
only 1 valve relief
20260322_162757.jpg
what could that 10 be ?
20260322_162658.jpg
#5 cyl, no ridge on cylinders.
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This is #8 cylinder, wiped out with blue shop towel. Both compression rings on 8 were stuck all the way around.
20260322_160933.jpg20260322_161541.jpg20260322_161553.jpg20260322_162114.jpg
everything is clean, I don't get how gunky the oil rings are. Every part seem to be genuine GM
20260322_164636.jpg
#5 combustion chamber are these heads prone to cracking ? I could not find a spot on the head gasket that indicate a water leaking into cyl.
20260322_164611.jpg#8 both pictures
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