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How would you build a 73’ Motorhome 400/727 drivetrain? #3097375
11/26/22 07:54 PM
11/26/22 07:54 PM
Joined: Jan 2003
Posts: 20,865
San Jose,CA
migsBIG Offline OP
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While waiting for another car project to drop into my lap, one of my pals told me they scraped at the tow yard a low mileage 73 motorhome with a good running 400 engine and 727 with e-brake/drum tail shaft. I have a couple mothballed project I could just swap off the truck specific parts and drop them in and be good. But I’m kinda lazy. Dropping an engine in and pulling it out to build later is a waste of time in my eyes. So depending on the set up, it could be a fun street, twice a year strip motor. I could put an early forge crank in it, but not sure what to do with the rest of it. Pump gas and budget ideas would be best if someone has a suggestion. I do believe in aluminum heads and the stocker stuff would go on swap meet spot.

Last edited by migsBIG; 11/26/22 10:21 PM.
Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: migsBIG] #3097419
11/26/22 10:46 PM
11/26/22 10:46 PM
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Bend,OR USA
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Cab_Burge Offline
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Sounds like a perfect candidate for belt driven super charger, change the cam go have fun with it. Thick piston tops, low compression H.D. design pistons and valves that are made for abuse at WOT for long times pulling grades work
I would try and get it running and then do a warm compression and leak down test on it and go from there, if it tests good go have some fun devil up If not fix it first and then go have fun with it, I would shoot for under 8.0 lbs. boost on pump fuel with no inter cooler scope

Last edited by Cab_Burge; 11/26/22 10:46 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: Cab_Burge] #3097529
11/27/22 12:08 PM
11/27/22 12:08 PM
Joined: Jan 2003
Posts: 20,865
San Jose,CA
migsBIG Offline OP
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$6k blower on a $600 engine? that sounds interesting, but I see that making more problems than I could take on. Appreciate the info though. up

I would like to upgrade to a Torque Storm blower one day, but I have nothing needing that at the moment.

Last edited by migsBIG; 11/27/22 12:10 PM.
Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: migsBIG] #3097571
11/27/22 02:26 PM
11/27/22 02:26 PM
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So Near, Yet So Far
topside Offline
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So Near, Yet So Far
Cheap turbo setup ?
Probably a wash at best vs higher-CR pistons.
Packaging vs rebuild, choose the effort you prefer ?

Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: topside] #3097587
11/27/22 03:48 PM
11/27/22 03:48 PM
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EchoSixMike Offline
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Turbo and E85. S/F....Ken M

Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: EchoSixMike] #3097908
11/28/22 06:56 PM
11/28/22 06:56 PM
Joined: Jan 2003
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San Jose,CA
migsBIG Offline OP
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Originally Posted by EchoSixMike
Turbo and E85. S/F....Ken M


I had a friend who did that with a small block and a big cam on a 80k mile engine. When I seen him a year later and asked how hi build went, re reached into his pocket and pulled out his keychain. On a small ring was a chunk of metal. Apparently when he was test launching, the motor let go, blew a hole on the side of the block and proceeded to oil down everything under his car. He said‘I will never put turbo on a $40 engine ever again’. He complained he could still smell burning oil for months even after power washing the car twice. 😂😂

I’m thinking this motor will come apart, might have to see how the bottom-end is. Might have to save some money up to build it so it survives for awhile. Might have to upgrade to a forged crank at least.

I do appreciate the ideas everyone and thank you for posting those here. 👍🏼

Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: migsBIG] #3097912
11/28/22 07:05 PM
11/28/22 07:05 PM
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Cab_Burge Offline
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All of the stick shift 400 motors came with steel cranks and special different looking crank balancer, I may still have one of cranks and balancer from a 1976 3/4 ton stick shift pickup motor that I used the block for stroker motor shruggy
If you're interested in those parts, I'll go through that stack of parts to make sure I still have them luck shruggy

Last edited by Cab_Burge; 12/03/22 08:38 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: migsBIG] #3097914
11/28/22 07:07 PM
11/28/22 07:07 PM
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Central NC
gch Offline
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Aluminum heads,properly sized cam of your choice,rpm intake and some headers with a 750 carb of your choice and you have a strong running dependable motor so long as the bottom end checks out.No need for a forged crank unless you want to for whatever reason.

Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: gch] #3099235
12/03/22 02:23 PM
12/03/22 02:23 PM
Joined: Jan 2003
Posts: 20,865
San Jose,CA
migsBIG Offline OP
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Cool I'll get specs on stuff and get back on here. wonder what a good intake will be for it.

Re: How would you build a 73’ Motorhome 400/727 drivetrain? [Re: migsBIG] #3099306
12/03/22 06:44 PM
12/03/22 06:44 PM
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Md.
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carnut68 Offline
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I'd throw a Purple shaft 509 in with an SD intake and 3800 convertor. boogie Just messin with ya.







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