Magnum Build Advice Needed

[MiradaCMX80]

Well....I have my little 318 running good, and have been driving the car a lot. Meanwhile, one of my friends is spending my money quickly. I have two 360 Magnum truck engines coming to me for dirt cheap. One is a 96, the other a 2001. I also have a new in box set of Hooker headers that fit my car, again, dirt cheap. We have decided to go ahead and build one nice 360 Mag out of the 2 and put it in the car whenever it's done. I'll keep the 318 in storage, complete.

I've already decided on a 3.55 sure grip rear end over the winter time. I'll keep driving the 318 on that until the Magnum is built. Now I'm thinking about what to do for the Mag. The heads will be the first thing checked to see if they're any good. If they're not, I have been looking at the EQ Magnum heads. Then the short block. As I understand it, a stock Magnum short block is 9:1 compression, and is more than capable of doing what I want it to do.

My questions have to do with roller cam selection, and intake/carburetor. Would the stock FI cam be ok for carb use? Some folks are telling me to tighten the lobe separation up a little to run better with a carb. I really don't understand how that works. Others said "It's fine, slap a carb on it and go." A smooth idle or a slight bit of chop, doesnt matter to me. A good matched combo does. It'd be nice to reuse the Magnum valvetrain without any fancy pushrods or rockers, but I'm open to suggestions. The intake doesn't seem to hard to figure out...EQ heads can be had with an LA pattern to expand the selection, but I'd like to hear what you guys like to use. Carb selection too...CFM, Holley, Demon, or Edelbrock.

I'm looking for a step above stock, I suppose. A nice street combo. 4 barrel Magnum 360 with headers, dual exhaust, A998 worked over a bit, lock up retained if feasible and a matched TC. 3.55 axle with my 27 inch Radial T/A's. Don't need to turn 8000 RPM...5000-6000 would be fine. It appears that even a stock cam Magnum can hit 300hp easy (The old MP Magnum 300 crate engine comes to mind.)

I also plan to dress the engine as an LA with the LA valve covers, timing cover, water pump and V-belt drive. I want to make people think when I open the hood

Looking forward to your advice, lots of knowledgeable people here.

 

[brotherGood]

Im pretty much lining up to do the exact same driveline combo (360/998/3.55s)

Im going to but better springs and retainers in so I can run more cam using factory heads. I have an M1 currently, but I hear the Crosswind (or whatever they're now called) have really stepped up their quality. I'd love to use anything from Fitech to even the Holley EFI, but that'll come down to budget.

Im hoping to replicate the 380 hp crate personally, but I'll be watching this.

 

[Duke5A]

I don't think EQ heads are even made anymore and if they are they're no longer Australian. Just inspect the two sets you have first. A better flowing head over stock isn't going to net you anything since your power goals are not really that high. Factory Magnum heads will support 400 horses.

Honestly, tear it apart for inspection and it all checks out reuse the factory long block - even the cam. Spend the money on an Edelbrock RPM Air-Gap intake, MSD billet distributor and an oil pan.

You can chase a factory looking motor if you want, but why? You would be giving up some of the advantages of the Magnum motor. Keep the serpentine belt setup and 10 bolt valve covers.

An intake, carb and headers will put you right at 300 horse power using the factory cam.

Biggest pain in the ass is the torque converter balance. B&M stopped making weighted flex plates for the 5.9L Mag/904 combo a long time ago. You'll need to have the proper weight welded to the torque converter...and speaking of converters, leave that stock too. The cam in that motor starts developing torque very early and will suit the factory converter well.

You'll also need to plumb in an electric fuel pump if keeping the serpentine belt setup. Almost forgot that. Don't worry, the low PSI units are dirt cheap.

Finish it off with 2.25" dual exhaust.

 

[MiradaCMX80]

I don't think EQ heads are even made anymore and if they are they're no longer Australian. Just inspect the two sets you have first. A better flowing head over stock isn't going to net you anything since your power goals are not really that high. Factory Magnum heads will support 400 horses.

Honestly, tear it apart for inspection and it all checks out reuse the factory long block - even the cam. Spend the money on an Edelbrock RPM Air-Gap intake, MSD billet distributor and an oil pan.

You can chase a factory looking motor if you want, but why? You would be giving up some of the advantages of the Magnum motor. Keep the serpentine belt setup and 10 bolt valve covers.

An intake, carb and headers will put you right at 300 horse power using the factory cam.

Biggest pain in the ass is the torque converter balance. B&M stopped making weighted flex plates for the 5.9L Mag/904 combo a long time ago. You'll need to have the proper weight welded to the torque converter...and speaking of converters, leave that stock too. The cam in that motor starts developing torque very early and will suit the factory converter well.

You'll also need to plumb in an electric fuel pump if keeping the serpentine belt setup. Almost forgot that. Don't worry, the low PSI units are dirt cheap.

Finish it off with 2.25" dual exhaust.

I called Hughes Engines yesterday and they said I was right on the money with a stock shortblock. They advised to check the actual CR though, as they can be as low as 8.2:1 even though they're rated at 9:1. He gave me part numbers for pistons and their smallest torque cam which is basically a stride above stock as far as power levels.

He did mention the Iron Ram heads are no more, but the current EQ heads are still a little better than stock IF the factory heads are cracked/unrepairable. We will see.

The stock converter is 1500 stall if I'm lucky....that will still be ok with my engine goal and a 3.21 to 3.55 axle? How do I know how much weight needs to be added, and where? Would my trans guy know that?

Why dress it stock? Simply because I want to. I want it to look original under the hood. Not interested in serp belt setup, but I understand it's advantages. When I lift the hood after a surprisingly good run, I want people to THINK for once. "Wow, just a 318?" But I won't tell them what it really is I'm a butthead like that.

Thanks for the advice/tips! Glad to see my goal is obtainable with ease.

 

[BudW]

I can understand wanting to make it appear to be a "smogger 318" - for I tend to want the same thing. I'm trying to shoehorn in a big block and my ultimate goal is to make it look like a normal stock 318 (yes, I will need a bit more smoke and mirrors than you - but I do think it is doable, but it might require a second or third glance, though).

One suggestion to pass on and a thought:
The suggestion is when you get ready to remove the power plant, and sense headers are in the mix, I suggest dropping the engine/transmission down with K-frame and suspension down as an assembly (or in this case, picking up the front end of car up and away from K-frame/engine/transmission.
It is a royal pain to get headers onto our cars without a ton of butter and a big swear(ing) knife to spread the butter around, when doing it the conventional way. So if you do it the normal way, keep kids (or grand parents) out of hearing range.
If you install the headers onto engine and raise the engine/K-frame up from bottom, it goes in pretty sweet and maybe even less overall effort.

The last idea is any consideration to using the factory beer-keg intake with factory computer to run the fuel injection? Not saying it will look 100% stock but it will use parts that is easy to locate and might end up lighter on your pocket book than buying a carb (or FI setup) for it. Just something to think about.
BudW

 

[MiradaCMX80]

I can understand wanting to make it appear to be a "smogger 318" - for I tend to want the same thing. I'm trying to shoehorn in a big block and my ultimate goal is to make it look like a normal stock 318 (yes, I will need a bit more smoke and mirrors than you - but I do think it is doable, but it might require a second or third glance, though).

One suggestion to pass on and a thought:
The suggestion is when you get ready to remove the power plant, and sense headers are in the mix, I suggest dropping the engine/transmission down with K-frame and suspension down as an assembly (or in this case, picking up the front end of car up and away from K-frame/engine/transmission.
It is a royal pain to get headers onto our cars without a ton of butter and a big swear(ing) knife to spread the butter around, when doing it the conventional way. So if you do it the normal way, keep kids (or grand parents) out of hearing range.
If you install the headers onto engine and raise the engine/K-frame up from bottom, it goes in pretty sweet and maybe even less overall effort.

The last idea is any consideration to using the factory beer-keg intake with factory computer to run the fuel injection? Not saying it will look 100% stock but it will use parts that is easy to locate and might end up lighter on your pocket book than buying a carb (or FI setup) for it. Just something to think about.
BudW

Bud, I love your sense of humor. "Big swear(ing) knife to spread the butter around."

The suggestion is a good one...I was thinking about replacing the giant rubber donuts on the K-frame to body mounting areas anyway. My buddy has some million foot tall jack stands we can put the car on that would make this an easy(ish) job. Heavy on the Ish.

I thought about stock FI, but the Magnum speed density has it's limitations. If I'm reading right, the SS/T truck engine was 250hp in 1998 (I remember because my Dad owned one.) Just bolting a 4 barrel and a dual plane with an orange ignition gets you right at about 300. I'd be leary about an electric fuel pump without first upgrading the electrical system a bit. If I did FI at all, my initial thought was a Sniper or Terminator style 4 barrel EFI that looks like a carb. That's just not a pond I want to wade in right now. I won't toss the idea out though....it'd be a great plan in the future.

Even dressing the Mag as an LA is sort of just a thought. I WANT to do it, but my ideas change quickly the more I read. Today I saw some Edelbrock finned valve covers for Magnum that I've never seen before....they're very attractive and I just might go that route. For simplicity and more of a stock look, I plan on reusing my existing V-belt drive/LA timing cover regardless. The Magnums coming to me are without their serp drives.

 

[brotherGood]

As far as dressing it stock..I would strongly recommend either using the magnum valve covers, or (if it lines up) drilling the extra 5 holes in the LA covers. The 10 bolt covers seal much better

 

[MiradaCMX80]

As far as dressing it stock..I would strongly recommend either using the magnum valve covers, or (if it lines up) drilling the extra 5 holes in the LA covers. The 10 bolt covers seal much better

We will see. The more I see those Edelbrock covers, the more I like them

Anyone have any videos of their mild Magnum swaps? Would love to see some running and doing their thing.

 

[Remow2112]

This is the cheapest way to deal with the 5.9 to 904 flex plate dilemma.

I would recommend the 96 and up weighted flexplate which will work with any neutral balance converter. I got one from a salvage yard for $35. elongated the 1 hole with a rattail file and used a converter with no weights.


There is an option to get the factory cam reground for more torque but you will have to dig that up been too many years and I don't recall who does it.

My brother and I both ran a crosswinds intake and they work fine. Casting is not as nice as the Edelbrock Air gap but I am not sure they even make the Crosswind anymore.

Keep the serpentine belt setup but spend the $1k and get a Holley Sniper. Been really impressed with mine and the ease of setup. Worth every penny.

Stock heads should be fine because you really seem to be building for torque so high flow at RPM is not what you need. Hughes is correct that you really want is a hot RV cam. Burn the tires up all day but pretty much out of go by 5500 rpm.


Sounds like a fun build!

Dan...

I called Hughes Engines yesterday and they said I was right on the money with a stock shortblock. They advised to check the actual CR though, as they can be as low as 8.2:1 even though they're rated at 9:1. He gave me part numbers for pistons and their smallest torque cam which is basically a stride above stock as far as power levels.

He did mention the Iron Ram heads are no more, but the current EQ heads are still a little better than stock IF the factory heads are cracked/unrepairable. We will see.

The stock converter is 1500 stall if I'm lucky....that will still be ok with my engine goal and a 3.21 to 3.55 axle? How do I know how much weight needs to be added, and where? Would my trans guy know that?

Why dress it stock? Simply because I want to. I want it to look original under the hood. Not interested in serp belt setup, but I understand it's advantages. When I lift the hood after a surprisingly good run, I want people to THINK for once. "Wow, just a 318?" But I won't tell them what it really is I'm a butthead like that.

Thanks for the advice/tips! Glad to see my goal is obtainable with ease.

 

[80mirada]

the crosswind is still available, they are on ebay

 

[MiradaCMX80]

This is the cheapest way to deal with the 5.9 to 904 flex plate dilemma.

I would recommend the 96 and up weighted flexplate which will work with any neutral balance converter. I got one from a salvage yard for $35. elongated the 1 hole with a rattail file and used a converter with no weights.


There is an option to get the factory cam reground for more torque but you will have to dig that up been too many years and I don't recall who does it.

My brother and I both ran a crosswinds intake and they work fine. Casting is not as nice as the Edelbrock Air gap but I am not sure they even make the Crosswind anymore.

Keep the serpentine belt setup but spend the $1k and get a Holley Sniper. Been really impressed with mine and the ease of setup. Worth every penny.

Stock heads should be fine because you really seem to be building for torque so high flow at RPM is not what you need. Hughes is correct that you really want is a hot RV cam. Burn the tires up all day but pretty much out of go by 5500 rpm.


Sounds like a fun build!

Dan...

Yup, you're correct.....torque car, all done by 5000-5500. Not sure I'll embarrass the current OEM's but at least I can give them a run for their $$ and make them wonder "What the heck is a Mirada??" 1996 and newer weighted flexplate...check. I'll see if either of the engines comes with....one IS a 1996, the other a 2001. The best parts from both will build my engine, and I'll resell the rest for more parts money

Serp belt drive....ugh. I feel the OEM serp is ugly, especially when you get the Dorman A/C compressor delete bracket. But, as I mentioned above, my ideas on how to dress it change daily. I need to build the thing first LOL! Sniper style EFI is definitely on the table, but probably not right away.