Rv 440 + 6-71 ?!?

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Stelldo

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Anyone done this or know anyone? I am talking cheap build. New rings bearings etc... Use stock rotating assembly. Install 906 heads and a blower cam. I have a 6-71 and manifold and the supporting parts. I think with limited rpm and a good tune it could live for a little while right? Flame away!!!:D
 
might work but if its from an RV it won't directly bolt in, the motor mounts, oil pan and pickup are different as well as the oil dipstick tube and manifolds

pretty much just the engine with no accesories will fit
 
It'll work! The weak link will be cast pistons. And adding a second crank key is highly recommended.
 
I would love to have the money to build a good shortblock, but at the moment that is not possible. As long as I can get away with a hone, re-ring and bearings this could be a cheap build.
 
I am thinking you would want lower compression forged pistons and to replace the crank with a forged one also.

I don't think the RV motors were built with performance in mind.
 
I like your idea if the intent is to build a fun cruiser with a blower sticking through the hood, but if you intend to race it please warn us before you pull the pin on that grenade!
:)
 
lrazor said:
I like your idea if the intent is to build a fun cruiser with a blower sticking through the hood, but if you intend to race it please warn us before you pull the pin on that grenade!
:)
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Dang, dont you go pulling any punches now...... haaaaa:D
 
How much boost will you be running?

5psi will be a good starting point. The cast pistons will live. Back the timing off a couple of degrees.
 
Sounds like fun.Just make sure you do your homework on carbs/ignition before.Gives you a little more leeway,safetywise.
 
Stelldo said:
I was thinking 5-8psi tops.
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You are good to go!

What camshaft are you planning to run?
Stock cams work real well with boost as they have a wide LSA(112 to 114)

How many crank driven accessories are you planning on running?
If you arent going with too many acc or engine RPMs than run the stock single crank keyway.

If you plan on running Pow Steering, water pump, and mech fan, with excessive RPMs than you will want to have another keyway cut into your crank.

And always use a harmonic balancer, dont use a crank hub.
 
Alt. and water pump should be the only accessory. I am going to run electric fans. I haven't thought to much on the cam yet.
 
My .02: I had zero room for a fan between the fan and radiator. Pusher fan up front. Mech water pump is fine since it will run off the same belt as the alt. I see no point in running an electric pump. I also dropped the PS to pick up some clearance between the blower drive and radiator. Space is at a premium with a BB Blown a-body. Trust me.

The advice on cams above is standard however BDS blowers recommends a cam with 110* LSA for street use. That's what I had on hand and that's what I used. You'd be fine with that unless you were racing and wanted every last ounce of power. Engine will run cooler too.

You're gambling with a single crank key but may be fine. The blower companies all recommend a double key. I have a hub instead of a harmonic balancer. The belt absorbs harmonics. Either approach is valid (assuming the engine is internally balanced). If you go the balancer route, an SFI rated unit is recommended (not a stock one).

5-7 psi will make plenty of power on the street. But do the research and know what your static compression is before choosing a pulley combo. No point in genading the thing the first time around the block. You will have to overdrive a 6-71 to make boost on a 440. Around 7% will put you in your target boost range.

Opinions will vary. As in everything, it's your choice to follow advice or not - what's important is that you make informed decisions. Also, even with a budget build in mind, be prepared to spend more than you thought.
 
Thank you for all the insight. I appreciate all the comments. I will definately go with the double keyed crank. I have a hub as well. I was going to use that as long as I could get the rotating assmebly balanced internally. If it has a cast crank (late 70s) that may be a problem getting it balanced. The more I think the more I want to spend. At least new pistons on the mind...
 
If everything checks out ok when I tear it down I will more than likely use the stock stuff.
 
try ebay for some cheap forged pistons.. On the chart you see that at 8-1 compression and 8 psi is a final compression ratio of 12.4-1 kinda high for cast pistons.. not sure what the stock comp ratio is of your 440 but Id try to find out..
 
I am wondering how you know they are cast pistons?? The 413 that my Pops has in his Duster is from a Motorhome and it has forged dish pistons AND a forged crank! IIRC the comp ratio is like 7.8:1. The pistons have a large hole with a nipple in the center. First time I seen pistons like them. The pistons are .090 down the hole too!

Also wondering if the 6-71 is big enough. My buddy has a 440 with a 8-71, its a monster!

Just askn'!!
 
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