Budget Build 5.9 for a 71 Scamp

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OK, laundry can wait.

michiganpat said:
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.
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Also note that light-duty B-vans with the V6 ran the 32RH (A998) to the end in 2003. Jeep Wranglers and 2.5 Cherokees ran them 80s to 2003-different bellhousing pattern, but the low-geared internals can be swapped into your older case by any good trans rebuilder.

forphorty said:
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.
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I saw a similar setup on the Power Tour-Magnum swap from a Durango, in a Dart Sport. He relocated the battery to the trunk and mounted the ECM in the old battery location.

ScampNYC said:
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.
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I'd go 999. If you find a V6 B-van (any year, mid-80s to 2003!), grab it. That's a lockup 998 with low first gear. If your slant had an automatic, should be 100% plug and play.

273 said:
A 5.9l with headers and 4bbl basically makes 300 hp, but if you want a mild cam don't let AJ's made up scenarios stop you from doing it, AJ don't get power is generally added throughout the powerband. Here's a 5.9l with headers and 4bbl, stock cam VS a mild roller comp cam shown on the screen as you can the engine gains from 3,000 rpms+ and no signs of any real loss under 3,000 rpm, so if you want a cam go for it will give you gains you will notice no matter your gearing and stall.

View attachment 1716477327


Here's LA low cr 360, with a bunch of mods VS stock 2bbl, headers, mild ported heads, xe250h and xe268h cams 4bbl etc.. Still makes better power everywhere over stock.

View attachment 1716477334
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This. I have what might be the WORST possible case for a big cam-manual transmission and 2.76 gears. It pulls fine from a stop even on a hill. Cam is a Hughes SER1418ALN10-214/218 degrees at .050", .532/.539" lift, 110 lobe separation, 106 degree centerline. Pulls fine from 1200rpm even in 4th gear.

ScampNYC said:
Got the heads off today.

The cross hatch is still visible, and no ridge, so I'm thinking I should be able to reuse the bore and pistons if luck prevails.

The amount of sludge in the lifter valley is a little concerning though.
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That's not unusual. :( This a pickup engine?

Also, does anyone know what that oil cooler is? Is it for the trans? Or the PS system? Or something else?

View attachment 1716477432

View attachment 1716477433

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Power steering cooler. If you do a lot of city use (or if you autocross), it helps. Was this from a 2500 or 3500 series pickup, or a 15-pax van? (Wait, truck accessories, so not a van.)

ScampNYC said:
Sweet. I figured the whole damn way! That's the only way to hot tank it, right?
I'm doing this on a budget, but its important to me to be thorough ... and have nice paint job on the motor. I did a 2k hemi orange paint on a 440 and it was just so damn beautiful. I think this one I'll do in blue.
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Other than a new oil pump and pickup, I would probably not TOUCH the bottom end. The lowest-budget parts are the ones already there! Plastigage the bearings and send it.
 
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ScampNYC said:
might be buying a 904 tonight.
What would be a good convertor to use?
Mild 360, mild cam, my rear gears I'm sure are 2.xx
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Probably stock. If it's good, reusing your slant six converter gives a bit more stall...and it's free.

TT5.9mag said:
I think it’s 70,71 (don’t quote me though) where the 904 got part throttle kickdown. I’d look for a trans that has it already. It’s not a deal breaker because you can add it, but it is another cost.
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He should have it in his old (slant six) trans. If so, easy swap.

ScampNYC said:
Why no hone, bearings, rings? That stuff isn't that expensive...
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Because...it's not needed. Honestly, I would leave it alone...I trust 20-year-old factory parts more than most of the Chinesium.

Also, everyone here probably knows this, but I have not seen it here, so I'm posting it: LA and Magnum 360s are both externally-balanced. But it's a DIFFERENT IMBALANCE FACTOR. Therefore, make sure you have the right converter/flexplate and harmonic balancer. If you buy a converter online, you want a 318 converter for neutral balance.
 
Dyno from my car-stock rebuilt Magnum 360 with headers, cam, and 650 AVS on an air gap intake.

1717614393912_John_Ferguson06012024_@_1740422_b_.jpg
 
not sure, would a drivers side F/M/J manifold fit an A? I ran cheap hedman headers on my 5th avenue and never had an issue with sealing or with mashing the tubes that went under the steering linkage
 
Jarlaxle said:
Other than a new oil pump and pickup, I would probably not TOUCH the bottom end. The lowest-budget parts are the ones already there! Plastigage the bearings and send it.
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Hey thanks for all your info man. Question on this. I want to tear the whole motor down so I can bring it in to get hot tanked. The amount of sludge I saw makes me really want to do this, also I want to get a good coat of paint on her too. So, your logic about the bearings makes sense, but I am wondering if I can tear it down, inspect the bearings, and if they look good, reuse the bearings? And so the same with the rings. It would save me probably $200 give or take, and every penny counts on this build. But not sure if its worth it..

Also, reusing the convertor from slant 6 is a cool idea I had not thought of. I didn't even know that was possible. I think I'll do this, especially if I may be upgrading down the line with a different rear end, and changing the converter to match. Question, if I am rebuilding the 904 I found, is it a bad idea to use the old, used convertor with the rebuild trans?
 
ScampNYC said:
Hey thanks for all your info man. Question on this. I want to tear the whole motor down so I can bring it in to get hot tanked. The amount of sludge I saw makes me really want to do this, also I want to get a good coat of paint on her too. So, your logic about the bearings makes sense, but I am wondering if I can tear it down, inspect the bearings, and if they look good, reuse the bearings? And so the same with the rings. It would save me probably $200 give or take, and every penny counts on this build. But not sure if its worth it..
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Why are you so adamant about hot tanking it? If it's in good shape, why?

Also, reusing the convertor from slant 6 is a cool idea I had not thought of. I didn't even know that was possible. I think I'll do this, especially if I may be upgrading down the line with a different rear end, and changing the converter to match. Question, if I am rebuilding the 904 I found, is it a bad idea to use the old, used convertor with the rebuild trans?
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As long as the old trans and converter are in good shape, I'd do it.
 
ScampNYC said:
Hey thanks for all your info man. Question on this. I want to tear the whole motor down so I can bring it in to get hot tanked. The amount of sludge I saw makes me really want to do this, also I want to get a good coat of paint on her too. So, your logic about the bearings makes sense, but I am wondering if I can tear it down, inspect the bearings, and if they look good, reuse the bearings? And so the same with the rings. It would save me probably $200 give or take, and every penny counts on this build. But not sure if its worth it..

Also, reusing the convertor from slant 6 is a cool idea I had not thought of. I didn't even know that was possible. I think I'll do this, especially if I may be upgrading down the line with a different rear end, and changing the converter to match. Question, if I am rebuilding the 904 I found, is it a bad idea to use the old, used convertor with the rebuild trans?
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i think if you're in that far, it's in for a penny, in for a pound. i understand a shoe-string budget but personally, i think that's kind of false economy on the bearings and rings once you're that deep.

that being said, if everything looks minty and the clearances are acceptable? *shrugs* sure why not. just make sure everything is labeled precisely.

the problem with running an old converter in a freshly built trans is that you're gonna cycle whatever old junk is in there right on thru your new hotness. at the very least find a way to flush it if you can. or most of it.
 
junkyardhero said:
i think if you're in that far, it's in for a penny, in for a pound. i understand a shoe-string budget but personally, i think that's kind of false economy on the bearings and rings once you're that deep.

that being said, if everything looks minty and the clearances are acceptable? *shrugs* sure why not. just make sure everything is labeled precisely.

the problem with running an old converter in a freshly built trans is that you're gonna cycle whatever old junk is in there right on thru your new hotness. at the very least find a way to flush it if you can. or most of it.
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Ok, I'll continue the teardown and see what I find, then go from there.

And I'll do a little research on finding a way to flush the convertor... good call
 
remytherat said:
Disregard that guy. He's obsessed with some **** he had twenty years ago. Every thread always gets side tracked to needing 200psi compression and 4.11s.
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It's unbelievable. The sad part is how many people on here get suckered into believing his crap. Then when you start to question him, he cries about being attacked and questions your Christianity. lol
 
nckennyb said:
I have a 360 magnum in a 1974 Duster. I used a 318 manifold on the driver's side and the manifold from a 1999 Dodge pickup in the passenger side. I hogged out the 318 manifold to match the ports and made the outlet as big as possible without weakening it too much. I did have to grind the head a little bit in the area near the rear head bolt for clearance with the 318 manifold. I have the Eddy Air Gap which works fine with the accessory drive from the 1999 truck. Mine is a factory air car so I'm using the A/C compressor and all from the truck. I didn't research enough prior to and used the truck PS bracket so I had to move my battery to the other side of the car like a Ford. I has plenty of power through those exhaust manifolds. Exhaust pipe is a pain in the tail with that tight turn on the driver's side though coming off the 318 manifold. I cut a bunch of slices of a 2 1/4" pipe and welded them together to make a tight elbow instead of making an elbow that's half crushed to death using a pipe bender.
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This ^^^^^ is the kinda thing you need to listen to. You can tell when someone has actually DONE it VS someone who hasn't done anything in 20 plus years. Ole Kenny there has probably modded more stuff in his lifetime that we'd all like to hear about. I'll also add this. I BELIEVE the Magnum truck manifolds with the 2 1/8" openings will fit the 67 and up A bodies. I'm unsure if they fit with power steering, but I know I've seen some guys here do it. You might look into that as well.
 

ScampNYC said:
Hey thanks for all your info man. Question on this. I want to tear the whole motor down so I can bring it in to get hot tanked. The amount of sludge I saw makes me really want to do this, also I want to get a good coat of paint on her too. So, your logic about the bearings makes sense, but I am wondering if I can tear it down, inspect the bearings, and if they look good, reuse the bearings? And so the same with the rings. It would save me probably $200 give or take, and every penny counts on this build. But not sure if its worth it..

Also, reusing the convertor from slant 6 is a cool idea I had not thought of. I didn't even know that was possible. I think I'll do this, especially if I may be upgrading down the line with a different rear end, and changing the converter to match. Question, if I am rebuilding the 904 I found, is it a bad idea to use the old, used convertor with the rebuild trans?
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Every single internal part of an engine has a tolerance, a measurement, or a specification, that can be measured and compared to the service manual. Any parts that measure within a specific range can be reused. Any parts measured outside of that range need to be replaced. It’s that simple. Rings, bearings, pistons, lifters, camshaft, they all fall in to this category. I’ve torn down a bunch of magnums, rings are almost always ok, bottom end bearings are almost always ok, (unless the plenum gasket was bad and the engine was eating oil, then the rod bearings are trashed). The cam bearings are 50/50, usually that’s what determines my level of “rebuild”. If you do replace Rod/main and cam bearings you need to get out your measuring tools and set all the clearances. If you reuse them, you know it ran before so you at least know it had clearance and oil pressure.
 
On my magnum the rings and main bearings were in great shape. Rod bearings were a little worn, likely from the classic plenum issue causing detonation. Cam bearings had the consistency donut icing. Completely disintegrated when I ran my finger across them.

Pretty common situation on these. Good luck.
 
Don't know if its been mentioned but pay attention to head gasket thickness. Some are .054 inch, others are .039, and some thinner ones too.
 
340sFastback said:
Don't know if its been mentioned but pay attention to head gasket thickness. Some are .054 inch, others are .039, and some thinner ones too.
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Oh yeah, good note.

So I measured my piston to deck clearance, using a dial gauge. Not sure if you are supposed to measure from the dished portion of the piston, or the higher, flat area of the piston, so i did both.

My measurements were:
  • .0435 to flat area
  • .0565 to dished area
On MagnumSwap.com, they recommend using .028 thick gaskets, saying "Fortunately, there’s an easy solution for getting some of that compression back — opt for a skinnier-than-stock head gasket. We used Mr Gasket .028 thick gaskets on our shop car, and we’ve never had a failure or a leak. They’re about half the thickness of a stock gasket."

Anyone have any success with a gasket of that thickness?
Also, anyone know where I can get replacement dowels that go on the block deck? I was going to pull those out to better clean up the deck surface.

The teardown continues. Right now a few of the lifters are stuck in their bores and are soaking in Kroil.
 
i'd advise against the mr. gasket units. known to leak.

felpro sells an 032 or 035 i think? which honestly, will be fine.

make sure you clean the crap out of the lifters. literally and figuratively.
 
Posting this in case it helps anyone in the future.

Last night I got my harmonic balancer off. It was harder than I was expecting. This is the one-piece balancer/pulley used on later Magnum engines. I think there is a more specialized tool out there, but I was able to get it off with a free rental of a 3 jaw puller from Advanced Auto.

First of all, the puller doesn't seem to fit. I tried many different configurations before landing on this kind of odd set up.

I set it up as a 2 jaw puller and used 2 of the longer arms. I was able to wiggle the arms inside the inner holes, where there was just enough meat for the fingers to grab onto. Anyway, hard to describe but here are a couple photos to show how i got it done.

IMG_3742.jpg


IMG_3743.jpg
 
ScampNYC said:
Oh yeah, good note.

So I measured my piston to deck clearance, using a dial gauge. Not sure if you are supposed to measure from the dished portion of the piston, or the higher, flat area of the piston, so i did both.

My measurements were:
  • .0435 to flat area
  • .0565 to dished area
On MagnumSwap.com, they recommend using .028 thick gaskets, saying "Fortunately, there’s an easy solution for getting some of that compression back — opt for a skinnier-than-stock head gasket. We used Mr Gasket .028 thick gaskets on our shop car, and we’ve never had a failure or a leak. They’re about half the thickness of a stock gasket."

Anyone have any success with a gasket of that thickness?
Also, anyone know where I can get replacement dowels that go on the block deck? I was going to pull those out to better clean up the deck surface.

The teardown continues. Right now a few of the lifters are stuck in their bores and are soaking in Kroil.
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distance to the flat area is what you're concerned about. when I built my mag headed 318 years ago I used thin gaskets, I think they were Mopar Performance and .024" thick, but looks like those are NLA. Cometic also has .027" thick ones, too...
 
ScampNYC said:
Oh yeah, good note.

So I measured my piston to deck clearance, using a dial gauge. Not sure if you are supposed to measure from the dished portion of the piston, or the higher, flat area of the piston, so i did both.

My measurements were:
  • .0435 to flat area
  • .0565 to dished area
On MagnumSwap.com, they recommend using .028 thick gaskets, saying "Fortunately, there’s an easy solution for getting some of that compression back — opt for a skinnier-than-stock head gasket. We used Mr Gasket .028 thick gaskets on our shop car, and we’ve never had a failure or a leak. They’re about half the thickness of a stock gasket."

Anyone have any success with a gasket of that thickness?
Also, anyone know where I can get replacement dowels that go on the block deck? I was going to pull those out to better clean up the deck surface.

The teardown continues. Right now a few of the lifters are stuck in their bores and are soaking in Kroil.
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For what you’re doing with the car just get stock gaskets. Forget about deck clearance, or compression ratio, or any other stuff that makes no difference to your goals. Put it together stock and it will meet your target and be dead stone axe reliable.
 
So I finally got all the lifters out.
IMG_3753.jpg


The 8 rearmost lifters were pretty stuck. I soaked them overnight with Kroil, and was able to get them out but rotating them with a 20mm wrench on the flat portion of the lifter while I pushed up from below with a gloved finger!

Funny, the cam has rust one the rearmost 4 lobes. I hope this isn't a problem... I do plan on getting the cam reground, hopefully the regrind takes care of this issue?
IMG_3749.jpg


Other thing I notice was that the cam bearings look pretty bad. I will be replacing these. Any rec's on brand is helpful as always...

IMG_3751.jpg

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