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Old 12-05-2017, 02:09 PM   #1
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1977 28' Argosy 28
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headers or ceramic coated manifolds?

So I'm leaning towards getting some headers. Doug Thorley headers to be specific. I have the manifolds off currently and today the thought hit me. I'm not really looking for performance(although an increase in low end torque is welcome) or hot rod sound, just to reduce temps under the doghouse. Does anyone think that ceramic coating the manifolds would give me a decent result without spending 700 dollars for headers?
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Old 12-05-2017, 02:51 PM   #2
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MoPar made Hi-Perf cast iron manifolds in the late 1960s for the car engines as part of optional package. Maybe helped up to about 2400-rom.

The normal logs on a big block run out of room at 17-1800/rpm.

Thorley Headers made their reputation decades ago with the Tri-Y design. Improved TQ off idle into the middle rpm range (2500+). The usual Hooker Headers were lighter metal, but featured full-length runners. Large inner diameter. Best for racing. But not for sustained high heat. The shorter-runner Thorleys were optimized for heavy vehicles with adequate gearing (for which your Moho qualifies; its not a 2.73-year Highway Cruiser sedan).

Were yours mine I’d have the Thorleys. A mandrel-bent system past that with (constant inner diameter not press-bent) tubing is the other end of the equation to get the most from them (including a chambered muffler). Press-bent reduces the interior diameter. If it’s from 2-1/2” down to 1-3/4”, then the latter is what the shine “sees”. That’s then the same effective size.

Smooth flowing joins from each bank to a 3” pipe is standard. Muffler can be larger in/out, and maybe 10-15’ back from y-junction I.D. can be reduced to 2.5 where the system reaches past the drive axle. (Otherwise 3.0”). Velocity and heat are directly related. Piping too big loses flow.

I’d run 3” from header collectors thru a Y and back to chambered muffler set back a ways (one can test for proper muffler placement by installing pipe well back with no muffler. Wake up the neighbors by going for a drive and check for the hot Point on the single pipe after getting to muffler shop. That’s where it needs to go. Simulate a highway ramp accel tin).

And have some 1.5” braided copper ground strap to install at both ends of single pipe.

Whether or not to have the headers coated (and by whom) is another question. The standard factory spark plug heat shields need to be installed, and high heat fabric boots to go over the wire ends will be necessary.

Consider building sheet metal shields that extend out a number of inches from the outer valve cover area to control heated air under doghouse. Have them coated also. A carb shield can be bought and also coated.

The F/A ratio and engine initial & mechanical timing will also need to be altered.

A factory dual-snorkel air cleaner where the vacuum motor-operated cold or hot air intakes needs to work. The Headers will need a pair of shields (coated) so the engine can pull preheated air at startup and mix cold/hot to maintain intake temp of about 105F (if you want engine longevity & fuel mileage). There’s at least one Moho around here with improper air intake. Wrongly designed, wrongly sized and without hot air capability.

Pull the intake manifold to clean the exhaust heat crossover. Consider a short four-hole phenolic resin carb spacer (Moroso , IIRC).

Cool fuel and hot intake is the thing.

So long as you have a pusher electric fuel pump at tank and a new mechanical, adequate pressure and volume should prove out with the headers. But insulate all engine fuel lines.

If you want to get fancy, we’d use a Cagle vacuum reference fuel pressure regulator ahead of a standard Holley piece. High vacuum kept flow low, engine demand opened it up. The Holley was set to deliver more than the Cagle could pass; the excess returned to the tank.

I bring all this up as the heat problem with headers is what causes most to get rid of them. Have to do some planning. A bit of fab, and usually some fitting.

The motor will distinctly hang on longer before downshifting. Some tweaks on a TH400 are what we’d do to help that, but y’all have a 475 or something I’m not familiar with possible differences.
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Old 12-05-2017, 04:13 PM   #3
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Originally Posted by Scottorious View Post
So I'm leaning towards getting some headers. Doug Thorley headers to be specific. I have the manifolds off currently and today the thought hit me. I'm not really looking for performance(although an increase in low end torque is welcome) or hot rod sound, just to reduce temps under the doghouse. Does anyone think that ceramic coating the manifolds would give me a decent result without spending 700 dollars for headers?
Here's what the Thorley's look like on my 74 Argosy. They are ceramic coated inside and out.

Engine on the test stand.
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Installed.
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Brad
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Old 12-05-2017, 04:27 PM   #4
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Slowmover, your knowledge is always very appreciated! BUT..dang. It made me rethink even going headers! I didn't realize I would need to do much more than bolt on the dang things. I'm certainly rethinking just throwing the manifolds back on.

Brad, I love how that looks. I do like the idea of opening the doghouse and seeing those beauties under there. Your heads are so shiny also! makes me old dirty engine look shameful.

Ultimately I'm hoping to just have as reliable of a motorhome as possible without rebuilding the thing with all brand new parts and tech. I thought maybe headers would be a helpful addition to keep the engine area cooler. I might be totally wrong in that thought. If so, I might consider shifting those funds to a fancy self learning EFI and improve reliability and drive ability with that.
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Old 12-05-2017, 04:42 PM   #5
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Slowmover, your knowledge is always very appreciated! BUT..dang. It made me rethink even going headers! I didn't realize I would need to do much more than bolt on the dang things. I'm certainly rethinking just throwing the manifolds back on.
Personally I have zero desire to use the cast iron manifolds. They are huge heat sinks, cause the exhaust pipe to be really close to the starter and don't allow for the lower end torque that is so nice to have on a motorhome.

Quote:
Brad, I love how that looks. I do like the idea of opening the doghouse and seeing those beauties under there. Your heads are so shiny also! makes me old dirty engine look shameful.
I don't expect the clean look to last past a few thousand miles or so

Quote:
Ultimately I'm hoping to just have as reliable of a motorhome as possible without rebuilding the thing with all brand new parts and tech. I thought maybe headers would be a helpful addition to keep the engine area cooler. I might be totally wrong in that thought. If so, I might consider shifting those funds to a fancy self learning EFI and improve reliability and drive ability with that.
I believe the headers do help keep the cockpit cooler because they don't retain the heat, especially with good flowing headers like the Thorley's.

I went TBI but not the fancy type. I went with all GM parts and the install wasn't all that difficult.

Personally I don't think you can go wrong with headers.
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Old 12-05-2017, 05:14 PM   #6
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I think factory TBI is probably a better option than the self learning kits. The self learning kits just looked super simple to install. I haven't looked into what it would take for a factory TBI conversion but maybe I should.
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Old 12-05-2017, 05:24 PM   #7
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I think factory TBI is probably a better option than the self learning kits. The self learning kits just looked super simple to install. I haven't looked into what it would take for a factory TBI conversion but maybe I should.
I just went through the complete process of installing a factory version. Probably the only real custom fabrication was the adapter to bolt the throttle body onto the Edelbrock intake manifold. The same adapter would have been needed for the stock quadrajet intake as well so I didn't feel to bad about that

One of the reasons I wanted to go with the GM TBI was because I wanted to use a 4L80e transmission so it seemed like a no brainer to go GM TBI.

The only real issue was the programming and I got connected with someone that has a sideline business tweaking the TBI code to suit my application. So far the process has gone really well.

WayneG also installed a GM TBI although he went with Affordable Fuel Injection (I think!) who supplied a turnkey installation although he does have a few stories to tell about that path

I opted to buy all the parts myself and then hire the programmer (aka tuner).

Between Wayne and myself we can probably answer any questions you might have on the subject.

Brad
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Old 12-05-2017, 06:09 PM   #8
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So much good info. I think you might be leading me into a direction I hadn't thought. I had considered getting a gear vendors unit but they are so dang expensive. I won't currently have a 4L80E so do you suppose the engine can be made to run without that until I get the courage to tackle that job. I just checked out the affordable fuel injection site and their price isn't too bad at around 1000 dollars for the entire kit. Did you save considerably by buying the parts yourself? I'm not an expert so buying a complete kit might be worth the money to me.
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Old 12-05-2017, 06:31 PM   #9
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If your main concern is heat, wrap them.
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Old 12-05-2017, 07:36 PM   #10
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I just read Wayne's entire thread on the his AFI EFI. Before reading it I thought it seemed like a good buy, at the end of the thread I am skeptical about buying a kit from them.
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Old 12-06-2017, 07:11 AM   #11
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I just read Wayne's entire thread on the his AFI EFI. Before reading it I thought it seemed like a good buy, at the end of the thread I am skeptical about buying a kit from them.
As I was making my decision to go with the GM TBI I seriously considered AFI. I actually talked to them a couple of times and was just about ready to pull the trigger when I started reading the GearHead EFI forum suggested by Keyair. There were a lot of negative comments on that site about AFI. Enough that had me rethinking things. Then I was contacted by one of the "tuners" that frequents the site and after much discussion I opted to do as he suggested which was to buy all the parts myself and have him do the tuning. I think in my particular situation it turned out to be a good decision and I'm happy with the results.

All told I would have to say it was around $2k to do a complete conversion the way I wanted it to be done. I could have gone cheaper in some areas but since I'm basically doing a totally new everything on this Argosy I figured I just splurge a little

If you were to ask me if I would go the same route if I had to do it over the answer is yes, I would

It was actually a fun project and I learned a lot in the process. I really like the fact that it can sit for months, but yet when I hook a battery to it and turn the key it fires right up.

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Old 12-06-2017, 11:49 AM   #12
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To be specific about “the heat problem” it exists with either choice. 454s had a really bad rep for exhaust manifold leaks cracking. Had to replace one twice on my Dads Suburban (RING brand).

The headers WILL allow for easier breathing. That’s getting rid of heat, so to speak.

All things I mentioned pretty well apply no matter which choice is made. They all should be done.

The headers take more care in isolating other components from them. I always bought and custom-fitted spark plug wires. That’s where things usually go wrong first. $300 into best wires, looms, fasteners, tools, cap/rotor, etc isn’t unusual. Hard to go wrong with MSD for any or all; and pre-made.

Computer-control fuel and ignition timing take care of the really irritating problems of running a heavier vehicle. Headers and the proper exhaust make it easier to tune. It’s almost always one or two cylinders that have problems with fuel distribution and spark. Have to tune motor to them, not the other six or seven.

Much fun as are drivetrains, steering is the moho weak point. I see Koni FSD shocks are available for the P30 chassis. I’d trash brand new Monroe’s to have those. The suspension and steering (plus brakes) are where to put time and money. IMO, if the motor runs okay, that’s good enough. It won’t get you into or out of trouble. Brakes and steering WILL.

I run big trucks for a living, now. Guess which concerns me more — engine or steering/brakes — with a baffle-less tanker and 47,000-lbs sloshing around in a tank 2/3-full at the legal maximum weight of 80k? It’s the same problem writ larger.

I can’t tell you how often I’ve had to nail the air horns in being passed or in passing a moho as it drifts around or in failing to adequately deal with a crosswind. I will tell you I’m not going to run my truck off of the road to avoid an accident. One does what one can. But it won’t be me rolled over in the ditch.

We can say, oh, that’s a crappy moho driver . . no that’s a crappy suspension & steering not adequately maintained & upgraded. First.

Rebuild the steering column. Not an option. Then the steering the rest of the way.

These things weren’t good when new. Brand new were unacceptable. Needed upgrades. Now rebuild and upgrade.

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Old 12-06-2017, 12:29 PM   #13
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I'm for sure looking at suspension and steering upgrades. Just trying to figure out the path I want to go. I did motor mounts while I had the chance and noticed how squashed the rubber was, after seeing that I looked at all the bushings on the sway bars and they are in terrible shape. I don't know what plays the biggest role in the crappy suspension to know where to start. Once I get it running I do plan on weighing it to get an idea of what the baseline weights are to help distribute weight as evening as possible. If needed, I'll get the springs more in line with the weight of the MOHO in running wet condition. There are obviously a lot of places to upgrade, Just looking for the lowest hanging fruit first and I'll work my way up the tree as time and money allow.

In regards to the fuel injection discussion. I think I'll just get it running and consider it later. I won't be going very far for a while so I don't need altitude compensation for some time. I even walked out to the garage to clean up the old manifolds and slap them back on but one of them will be pretty much incapable of being sealed so it really is header time. I keep thinking something might be easy but then realize it's just not. I didn't really want to wait a month for the headers to be built and delivered but I guess that's just how it goes. Fuel injection could come later, last night I got it in my head that a propane conversion would be wicked cool also. Finding an affordable tank proved to be an issue. After doing a hillbilly propane conversion on my 64 allis chalmers garden tractor, I laugh every spring when it just fires right up. I also kind of though it might be cool to only have 1 fuel requirement instead of gasoline and propane. Sure it won't give me the range but it's possibly more reliable than these aftermarket EFI setups and more friendly to the engine than an out of tune carb. In my hometown the propane always is a bit cheaper than gas which would make the lower efficiency hurt just a bit less. Just more crazy thoughts from someone crazy enough to buy a 40 year old MOHO and try to resurrect it.
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Old 12-06-2017, 01:08 PM   #14
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The problem is propane is twofold: one, it tends to burn so that the cylinders run hot. The heavier the load against the engine, the more so.

Two, worse, it’s energetic gallon equivalent is about two-thirds or so of gasoline (needs research; think that’s diesel), thus price has to be adjusted accordingly. Do it by BTU content per GGE.

It was popular with with country boys had some knowhow. About twenty years ago I hauled home a 1970 Chrysler to use as parts car. Had a propane conversion kit on it from twenty years before. From what I found in the car and via memory it looked like it had been used by a Bell Helicopter tech to make the long daily run in-from the countryside in the middle 1970s. I surmised he bought dirt cheap a great low miles loaded hardtop and proceeded to make it work for him. Start that 375HP TNT V8-440 on gasoline, and once out on the highway cut in the propane. Changeover at the exit to the plant in Arlington. Repeat on the return to the family ranch.

As we had gasoline restrictions some years, he got the most from it by saving the gasoline on board, not so much better fuel mileage. Best of both worlds as it helped clean things up once warmup was complete. Shiny spark plugs. Found a bunch of bolt holes in trunk floor. Don’t know how the hell he vented it. Maybe that “time in country” with MAC-V gave him a taste for such before he returned to The World.

Unless one is in a state like Utah where the propane price was held low, it doesn’t quite pay. Tank weight and low amount of fuel.

Great for a forklift. Or a tractor. If I built a Slant-Six Dodge Dart coupe with a 3+OD trans and lightened for fuel mileage plus some aero work, it’d be worth the trouble but not otherwise. With that motor on propane it’d still be running when the Sun burns out. A car with no electronics. The Rocket Man Special

Home tankage and a scenario like above is where it “works”. But I’d be all in favor of a moho sized frame tank on my Cummins pickup. Extra for the TT, and a kit to extend diesel fuel range. That’s way out in the distance for investigation.

(Yeah, I’ll take another beer, thanks)
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