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dadstoy · 10-25-2019, 10:42 PM

Quote:

Originally Posted by ROBERTSUNRUS

Hi, and you most likely have a Turbo 475 transmission.

Yup, a 475. I misspoke there! Thanks Bob. I hadn't even finished my bottle of wine before I wrote that...but it was a real shitty day and my mind is spent! Ha Ha

martin300662 · 10-26-2019, 02:17 AM

Quote:

Originally Posted by dadstoy

Yup, a 475. I misspoke there! Thanks Bob. I hadn't even finished my bottle of wine before I wrote that...but it was a real shitty day and my mind is spent! Ha Ha

I guess most of us knew exactly what you meant Dean, considering the TH475 is just a TH400 with straight cut gears.

For me the ideal setup would be simple....454HO Chevrolet performance crate engine Connect & Cruise package with the 4L85E. Yes it is 500lb/ft@3500rpm, but more importantly over 400lb/ft@1750rpm, all usable power without swapping to fuel injection. Guaranteed to work out of the box.

gaiaenviro · 03-18-2020, 11:26 AM

OK, so I am now in the position of need for engine rebuild/replacement after the air cleaner nut got sucked in to the engine at 70 mph. From what I have gleaned from this thread, it seems that boring the block .030/060 over, roller cam/lifters/rockers, high flow oil pump, oil coolers, new radiator (specific to mine), MSD ignition, and new heads is the way to go. Am I missing anything? Thanks!

Keyair · 03-18-2020, 11:10 PM

That sucks(no pun intended!).
I would not go 60 over unless you have no choice. Some MkIV blocks can be bored up to 100 thou over with careful measurement, but they don’t last long I’ve heard.
My understanding, and in some way experience is that the bigger the overbore goes, the thinner the walls get. This leads to flexibility in the bore which reduces ring seal, and therefore blow by. I’m sure it also makes the block weaker and therefore more flexible.
I’ve also heard that under big loads this compromises the headgasket sealing too.
You want the maximum “Mass” in the block for thermal stability.
If I was going to rebuild a 454 for Motorhome use, I think I’d got with a minimal overbore and maybe a 1/4” stroker crank kit. At about $1200/1500 for the complete kit, with new crank, rods, pistons and bearings. They are as cheap as replacing/rebuilding the stock parts. Also, they are new parts and have not been through heat cycles, and then weakened further by grinding undersize. They are also made of better materials, and better quality machining.
Just my 2c.
You just hand the parts to the machine shop and tell them to bore to match.
All in all, unless you are a wacko, like me, buying a crate GM 502 might make sense.

choctawmel · 03-19-2020, 09:15 AM

Quote:

Originally Posted by gaiaenviro

OK, so I am now in the position of need for engine rebuild/replacement after the air cleaner nut got sucked in to the engine at 70 mph. From what I have gleaned from this thread, it seems that boring the block .030/060 over, roller cam/lifters/rockers, high flow oil pump, oil coolers, new radiator (specific to mine), MSD ignition, and new heads is the way to go. Am I missing anything? Thanks!

That's want I did.
Make sure to use a heavy duty valve spring locks. I didn't and paid the price.
Dropped a valve outside Los Cruces. NM. Shop there rebuilt it and it run like crap all the way home. Died soon after and I replaced it with a 12 valve cummins diesel which I'm still tinkering with. But then it's my hobby.

Paul J Mauro · 03-20-2020, 06:19 AM

well it looks like we will have lots of time to work on our toys this summer. wife just informed me colorado said -stay away visitors - I guess we dont go in april ,this will be the year I put a new engine trans in our 345 before we end up doing it on the side of the road

ROBERT CROSS · 03-20-2020, 06:44 AM

Just an Idea...🤔
"Connect & Cruise crate powertrain systems
Our engineers did all the hard work, designing and calibrating carefully matched Connect & Cruise powertrain systems for
optimal compatibility and performance, while also identifying the complementing engine and transmission controllers, torque converters and supporting installation kits."

"With 84 Connect & Cruise combinations, Chevrolet Performance provides the ultimate powertrain solution without the need for third-party tuning, sourcing parts you need (with a 24-month/50,000-mile or E-ROD 36 Month/50,000 Miles Connect & Cruise limited warranty included) to help protect your ride. The calibrated controllers are designed for retrofit installations in older vehicles, for easier and quicker installation. The result is a premium package that offers the dependability of Connect & Cruise and the confidence of Chevrolet Performance."

Bob
🇺🇸

gaiaenviro · 03-26-2020, 12:18 PM

Quote:

Originally Posted by gaiaenviro

OK, so I am now in the position of need for engine rebuild/replacement after the air cleaner nut got sucked in to the engine at 70 mph. From what I have gleaned from this thread, it seems that boring the block .030/060 over, roller cam/lifters/rockers, high flow oil pump, oil coolers, new radiator (specific to mine), MSD ignition, and new heads is the way to go. Am I missing anything? Thanks!

New wrinkle, what are your thoughts on say an ATK 8.1 Long Block from Jegs rather than the rebuild? I drove a 1-ton for years with that engine and an allison transmission so am familiar with the setup. Ultimately I'll be going back in with an 8.1, but do I rebuild the original or buy a rebuilt Vortec 8.1? Any advantages to either one, besides ease of effort? Thanks!

ROBERT CROSS · 03-26-2020, 03:06 PM

FWIW....59+years ago when I was a young apprentice, my German mentor came to my rescue on a Volvo 164 that I had dropped a washer down the FI intake.
To my horror he calmly started the engine opened the throttle and held it so until the noise stopped as it exited the engine. He just shrugged his shoulders and said 'been there, done that'.

Now, to the point.
I would go with a FI BB to take advantage of the more up to date improvements. Plus all the reputable builders will offer a warrantee. A big plus to consider.

Bob
🇺🇸

jeffmc306 · 03-26-2020, 03:25 PM

Quote:

Originally Posted by gaiaenviro

OK, so I am now in the position of need for engine rebuild/replacement after the air cleaner nut got sucked in to the engine at 70 mph. From what I have gleaned from this thread, it seems that boring the block .030/060 over, roller cam/lifters/rockers, high flow oil pump, oil coolers, new radiator (specific to mine), MSD ignition, and new heads is the way to go. Am I missing anything? Thanks!

I stumbled across an article on Hot Rod about a motor home big block rebuild and it's pretty straight-forward. If anything, worth a read:
https://www.hotrod.com/articles/bolt...ome-big-block/

dadstoy · 09-23-2021, 01:31 AM

Here is a nice article on vacuum advance and ignition timing. Who knew it can help keep your engine running cool?

https://www.motortrend.com/how-to/16...gnition-timing

Saint007 · 03-23-2022, 12:06 PM

Thanks for all that info , Im newbie just got my first 1986 Airstream 345 it has about 110,000 miles on 454 is running rough I need to a tune up or some one recommended replacing the original carburetor for a new Eldebrock 650 he sad he's getting better performance , what do you think is a good advise ?

Waipio Rim · 03-23-2022, 05:20 PM

Lots of possible reasons for rough running. I would start with a compression test to confirm that the engine is ok internally. If it is and the plugs, plug wires, and distributor look old they can all be replaced for less than the price of a carburetor, giving you a new ignition system. The quadrajet on our 1990 345 was old and leaky, it was always flooding the engine. I got an exact replacement rebuilt unit from Summit, it works fine.

Gregsch · 03-25-2022, 05:55 PM

I bought a rebuild kit from Carb Junkies, watched a few videos on you tube and rebuilt my quadrajet a few years ago. Truth be told I probably had more than $400 worth of my time involved in the process but, the thing runs , starts and idles great. The new TBI conversions are clearly the best option but, if you are on a budget the quadrajet is a viable option.

udidwht · 02-26-2023, 01:30 AM

One can get a condenser/oil cooler combination set up for some of the 'P series' coaches...http://acmeairparts.com/home.html

I did this job on my 1994 Fleetwood Southwind Storm back in August 2022. I replaced the condenser/oil cooler combo and while I had it out clean out the radiator fins which were very dirty (impossible to do from the front side). Then replaced the AC drier, O-rings and pulled vacuum. Then re-filled the AC system.

System held 30in of vac for nearly 22 hours. Readjusted the air gap on the compressor to within spec. It was at .09 (spec is .04-.08). Blows nice and cold.

I documented the repair here:
https://www.gmt400.com/threads/conde...-cooler.59140/