Budget Build 5.9 for a 71 Scamp

[ScampNYC]

Hey guys, I had another thread called "What to Do with My Scamp" in which I described how I have a slant- six equipped 71 Scamp with oil pressure problems.

At the end of that thread, I decided to pick up a 5.9 Magnum to replace the worn slant six.

In this thread, I want to chronicle my build and ask some questions along the way.

My goals with this build and swap is to do it as cheap as reasonably possible. I also want to have the engine make decent power, but have great street manners. I have done the hot rod thing, I've had a 440 4 speed, multiple cars with lumpy cam and headers, and this time I want to make something that has good torque but is fairly civilize and super reliable.

Actually, what I really want is for this Scamp to be a dependable, comfortable daily driver.

I'd like:
- Around 300 hp
- Air conditioning
- Power steering
- Cast iron manifolds! Yes, that's right.
- Hoping to reuse my rotating assembly (crank, cam, piston, rods, roller lifters)

Right now my spend is:
$375 for the motor.

Tonight I started tearing it apart. It looks a little sludgey in there, more than I was expecting. Hopefully the bores look okay. The motor had 101k miles, according to the junkyard.

As I start pricing out all the needed parts, I am really shocked to find that the motor itself is pretty much going to be the cheapest part of the build! Crazy that an aluminum intake is now $500. Last time I did this, they were $300.

One thing that really has me worried is the accessory drive. This may break the bank!
I'm looking at a complete set up — initially I was hoping to run the factory Magnum serpentine setup but from what I understand, to do that you have to run the Magnum timing cover, which means no mechanical fuel pump. I'd rather not have an electric fuel pump buzzing away. Is it true I can't use the Magnum belt bracketry with the LA timing cover?
Looking at Bouchillon and CVF, I am at about $1000 or $1400 plus tax, respectively, for a complete bracket and pulley set up, including the AC compressor. Any alternative ideas that may get my my goals be cheaper?

 

[remytherat]

Crazy that an aluminum intake is now $500

Ebay chinesium is 130 bucks and works well. That's what I have. It's a copy of the edelbrock airgap.

initially I was hoping to run the factory Magnum serpentine setu

You will have to run the magnum cover and waterpump as well as a good electric fuel pump. If you are interested in the magnum accessories I think it's a worthy sacrifice.

Around 300 hp

You will be close in stock form with a 4bbl intake. If you want to add in a mild cam it'll bump you over 300. Up to you.


Should be pretty straightforward. I did a similar swap not too long ago.

 

[318willrun]

Just 4bbl and headers will give you your 300 hp. Magnums usually have good bores, can see the factory cross hatch usually

 

[340sFastback]

Looking forward to seeing the progress. Awesome some NYC pictures too.

 

[MadScientistMat]

Don't worry about the noise of an electric fuel pump. I'm running an external Walbro 255 lph unit and I can just barely hear it priming at key on. Definitely can't hear it over the Flowmaster when the engine starts. If you want quieter, you can put a pump in the tank pretty easily. There's no need to spend hundreds on a fancy fuel tank; there are a lot of pumps that will fit through your factory sending unit opening.

 

[ScampNYC]

Interesting. Does anyone know if the Magnum bracketery, especially the AC bracket, will work with the Air Gap maniffold?

And as far as the eBay chinesium air gap manifolds, there are many out there. Any of them better than the others? Also, are they all drill for both LA and Magnum heads? Anyone know of one that is only drilled for the Magnum heads? Would like to not have those little plug thingies on the unused bolt holts.

 

[ScampNYC]

... if I can use the magnum serpentine set up with the chinese Air Gap that means I already have all the pulleys, existing ac compressor, harmonic balancer, PS pump... I stand to save a lot of money. All I need is a $60 pump!

 

[michiganpat]

the stock magnum intake has the water inlet offset to the passenger side of the vehicle. most, if not all of the knockoff air gaps have it centered, so you may have to do some bracketry modifications. the edelbrock manifold has it offset to the passenger side of the vehicle like stock, so it might be worth the couple hundred dollar difference to not have to fart around with trying to mod the bracketry. https://www.edelbrock.com/shop/inta...elbrock_series_multi=13007&efm=12766&efn=3654

for a cam, get the stocker reground by bullet cams. Bullet Cams Master List. 20 years ago, I had a mag headed, stock bottom end '85 318 roller cam motor, and I used their HR259/316 lobe for the intake (259adv 208@.050 127@.200 0.316 lobe lift/.505 lift with mag 1.6 rockers) and the HR265/320 on the exhaust (265adv 212@.050 131@.200 0.320 lobe lift/.512 with mag 1.6 rockers), on the original cam's 110 LSA installed at 106, IIRC. used stock rockers, and Hughes #1110 valve springs. with hedman headers, an RPM air gap, and 600CFM edelbrock carb, that engine ran very strong, able to move my 3.55 geared chrysler 5th ave to keep up with a 1st gen LX with a 5.7 hemi. the 300hp crate motors used a stock truck cam, with this cam, I'd wager you'd be something closer to 340-350HP, and I still had 16" of idle vaccuum, pretty tame idle, and great performance from idle-5000+ RPM.

 

[michiganpat]

also, are you thinking you want it to be a cruiser? something to get out on the freeway with? if so, you might want to consider a 998 trans (beefy 904). some of the nice things with that are the lower power loss compared to a 727, the 2.74/1.54 first/second gear vs. 2.45/1.45, and you can get them with mechanical/hydraulic lockup (M body) or electric/solenoid driven lockup (IIRC, EFI trucks 87-up). lockup gives you the opportunity to use a higher stall/looser converter without any highway slip. pair that with a 2.76 or 2.94, and it'll still be a hoot around town, but not be cranking 3000+ RPM going down the freeway at 75 MPH. in my 5th avenue I mentioned above, I was actually running a 3.55 rear gear with a 42RH (A500, the 4 speed OD version of an A998). but to do one of those in an A body will require serious transmission tunnel and torsion bar crossmember modifications.

if you want to row your own, finding an A833 OD paired with 3.23's or 3.55's would be great, too. gears are 3.09/1.67/1/0.73 my slant duster has the A833OD/3.23's, and it's a pleasure to drive down the freeway, 70MPH is a tick over 2100 RPM. put 7K miles on it this past summer.

 

[HankRearden]

I did this swap in my 70 for pocket change.
The truck power steering pump bracket hits the battery tray. Use a van power steering pump bracket. Intake and car oil pan from Assault racing (China) . No name car oil pick up.
Dorman ac compressor bypass pulley.

Cut the ac bracket to clear the thermostat housing and hose.

 

[340sFastback]

Some of the AC compressors are a tad shorter then others to help clear thermostat housing. Seem threads on here covering that topic.

 

[forphorty]

On an episode of Roadkill Garage, they did a 5.9 swap with the factory acc drive into a Duster and had to move (chop up ? , I can't remember) the battery tray and use a small battery to clear the ps pump.

 

[volaredon]

The crate engines Mopar sold had an LA front (timing cover out) that's exactly how I'm gonna set up my magnum in my truck. V belts not serpentine

 

[michiganpat]

also, I'm not 100% sure factory truck exhaust manifolds will work on an A body without firewall modifications. hopefully someone else knows and will pipe in.

 

[ScampNYC]

On an episode of Roadkill Garage, they did a 5.9 swap with the factory acc drive into a Duster and had to move (chop up ? , I can't remember) the battery tray and use a small battery to clear the ps pump.

Hey, this is awesome. Thanks for mentioning this, I am watching this episode tonight. Should be a lot of great inspiration there. I guess they had the truck PS bracket? Hoping if I find a van bracket I can keep the battery tray intact.

 

[ScampNYC]

the stock magnum intake has the water inlet offset to the passenger side of the vehicle. most, if not all of the knockoff air gaps have it centered, so you may have to do some bracketry modifications. the edelbrock manifold has it offset to the passenger side of the vehicle like stock, so it might be worth the couple hundred dollar difference to not have to fart around with trying to mod the bracketry. https://www.edelbrock.com/shop/inta...elbrock_series_multi=13007&efm=12766&efn=3654

for a cam, get the stocker reground by bullet cams. Bullet Cams Master List. 20 years ago, I had a mag headed, stock bottom end '85 318 roller cam motor, and I used their HR259/316 lobe for the intake (259adv 208@.050 127@.200 0.316 lobe lift/.505 lift with mag 1.6 rockers) and the HR265/320 on the exhaust (265adv 212@.050 131@.200 0.320 lobe lift/.512 with mag 1.6 rockers), on the original cam's 110 LSA installed at 106, IIRC. used stock rockers, and Hughes #1110 valve springs. with hedman headers, an RPM air gap, and 600CFM edelbrock carb, that engine ran very strong, able to move my 3.55 geared chrysler 5th ave to keep up with a 1st gen LX with a 5.7 hemi. the 300hp crate motors used a stock truck cam, with this cam, I'd wager you'd be something closer to 340-350HP, and I still had 16" of idle vaccuum, pretty tame idle, and great performance from idle-5000+ RPM.

This is great info, thanks. If I do a Eddy intake, that's a $350 price difference but still cheaper than sourcing V belt pulleys, balancer and brackets, unless by grace of god I find a used set.

And good call on the cam regrind, someone on my original thread also recommended Oregon Cams. I'll have to do a price comparison. Bullet Cams is on the East so shipping may be better. I plan on keeping track of every dollar for this build!

Seems like valve springs will be a must as well.

 

[ScampNYC]

I did this swap in my 70 for pocket change.
The truck power steering pump bracket hits the battery tray. Use a van power steering pump bracket. Intake and car oil pan from Assault racing (China) . No name car oil pick up.
Dorman ac compressor bypass pulley.

Cut the ac bracket to clear the thermostat housing and hose.

Seems like you have some experience here, nice! If I cut the AC bracket, you think I can still mount the AC compressor?

 

[HankRearden]

Seems like you have some experience here, nice! If I cut the AC bracket, you think I can still mount the AC compressor?

It won't fit as designed. My plan is to figure our a bit of a work around. I think I can build a mount to offset the ram compressor. And it will just sit a little higher off the bracket but it hasn't been a priority

 

[ScampNYC]

also, are you thinking you want it to be a cruiser? something to get out on the freeway with?

To be honest... not much! This car will mostly be used to bomb around the outer boroughs of NYC. It is a whole 'nother world here. Probably won't see much high-speed use! Or at least, not built with that intention. I do like the 904 recommendation. I also found a 727 lockup trans near me, supposedly NOS from mopar for $850, comes with whole "retrofit kit" including brand new driveshaft, linkage in a box, inspection cover, all brand new from the 80's. But having a lockup trans scares me, I don't know if that a mistake for some reason.

I also happen to have a 46rh laying in my garage. It's a spare for my 92 Ram Van. Would be cool to use it, but the amount of chopping and fabbing it would take goes against the carefree spirit of this build.

 

[ScampNYC]

It won't fit as designed. My plan is to figure our a bit of a work around. I think I can build a mount to offset the ram compressor. And it will just sit a little higher off the bracket but it hasn't been a priority

Hmm. Yeah makes sense. Maybe if I use the Eddy intake with the offset thermostat hole the AC would fit just fine.... hard to say unless someone else has done it.
I wonder if I could buy it, test fit it, then return it if it doesnt work out...

 

[HankRearden]

Hmm. Yeah makes sense. Maybe if I use the Eddy intake with the offset thermostat hole the AC would fit just fine.... hard to say unless someone else has done it.
I wonder if I could buy it, test fit it, then return it if it doesnt work out...

Concensus is it fits fine with eddy intake. But I'm a cheap ***

 

[Bobzilla]

The Edelbrock 7577 is made specifically to fit the Magnum heads. It has the correct bypass hose location and angle to match the Magnum water pump bypass connection. It has the correct offset thermostat housing location to clear the Magnum air conditioning bracket. If I recall correctly, the one weird thing was the holes for the heater core hose connection is smaller than it should be and needs to be enlarged. I have to double check that though, as I am going from memory.

The van power steering bracket previously mentioned does lower the pump for added clearance at the battery tray. There is also a Jeep Grand Cherokee bracket and power steering pump setup that has even more clearance, but those are less common in junk yards.

If you choose to outfit your engine with v belts and run a mechanical fuel pump, the brackets should all fit the Magnum block and heads. Some holes are in the same locations, but Magnums added some locations that the LA stuff does not need.

 

[Bobzilla]

Here is the layout differences between the accessory mounting holes of Magnum heads and LA heads. I was going to redo this so the upper Magnum holes are on there but I have been busy. Top is front of the right bank cylinder head and bottom is front of the left bank cylinder head.

 

[AJ/FormS]

I'd like:
- Around 300 hp

What's magic about 300 @ say 5200rpm?
How often are you going there?
What gears are in your Scamp?
My guess is 2.73s. If that's true, yur looking at 5000= 57mph in First; and 96mph in Second. never mind 140 in Direct.
In First gear, there is little to no wind resistance, so all that power more or less goes to tirespin.
You said;

I want to make something that has good torque but is fairly civilize and super reliable.

Then leave the engine alone.

For low-speed/ low rpm performance, just install a 2800 convertor, a Sure-Grip, some SlapperBars, maybe some sportier gears, and call it done.

 

[ScampNYC]

@Bobzilla – thanks so much for the great info. It is SO helpful. I love this forum!

Ok so right now, what I'm thinking is I will get the Edelbrock 7577, a van or Jeep PS bracket, an electric fuel pump and keep all my Magnum accessories.

I have found a van PS bracket, but interested in the Jeep bracket. Is this what I would need? link
And then a pump and pulley, which I suppose is differnt from a van/truck pump and pulley? That would add cost.

@AJ/FormS – Good points. I think I will pretty much leave the motor alone. I will consider a cam regrind, perhaps.


A few random questions:
- What is the consensus on reusing head bolts?
- What is the difference between Schumacher conversion mounts and Trans Dapt mounts? The Trans dapt ones are about $85 cheaper.
- Any input on the best set up for cast iron manifolds? I will not be getting the high-dollar super rare 340 ones, thank you very much. But other than those, which offer the best performance?