Camshaft recommendations - 4 door Dart

[Frankbassman]

Hello all,

I'm getting ready to build a 5.9 Magnum. Very interested in getting as much compression as possible while running 89 octane for best efficiency but if that is impossible, I will understand and recalculate accordingly.

I know some few have had luck with similar, so seeking advice. Looking for streetability with good power, not afraid of some lope but no top fuel behavior.


Car details as it sits:

'73 Dart 4 door (probably 3400 lbs)

42RH transmission (med stall, about 2100rpm)
Ford 8.8 rear with 3.73 gears (limited slip)
26.5" tires
VERY tired 5.9 magnum out of a '97 Ram.
625cc street demon thermoplastic deal. Works.
True fenderwell cold air intake routing.
Air Conditioning (RV2)

Cooling system is up to snuff.

My top piston choice is H116CP30:
1.66" compression height (stock is 1.612 I believe)

Fel pro head gasket 519SD(0.050" compressed)

If the stock piston depth at TDC is 0.050", the new pistons would put me 0.004" above the deck.

So with gasket, I'd be at 0.046 deck height.

Magnum chamber CC: 62cc

+5cc valve reliefs = 67cc

Compression using 4.030 bore: 10.8:1

I know that is high. I have been reading about the magnum's detonation resistance. How good is it with a good quench (and cam) as above?

Frontrunner cam: comp 20-746-9

https://www.summitracing.com/parts/...l6uHpAcGMNn3KCfHsTlYF5wCrlZYnnauKc_2#overview

2nd place: comp 20-745-9

https://www.summitracing.com/parts/...8-2eB5yUV-cMJiNvfk6HWu5ChJZ1mydRoCemwQAvD_BwE

3rd: Some hughes cam, don't know which

Very open to suggestions from the pros.

I am reading that the intake close point will heavily influence the octane requirents, but don't know enough to make a confident choice.

Has anyone done similar? How did your quest turn out? Highly interested in your input.


Thank you all


-Frank

 

[Garrett Ellison]

@TT5.9mag, what are your thoughts on the 10.8:1 and .046 quench with 89 octane here with the iron magnum heads. Do you think it could be tuned into a happy place or would you also like to see a little more piston dish?

 

[RustyRatRod]

Just don't run a two door cam. It could end up down on power. ;)

 

[TT5.9mag]

@TT5.9mag, what are your thoughts on the 10.8:1 and .046 quench with 89 octane here with the iron magnum heads. Do you think it could be tuned into a happy place or would you also like to see a little more piston dish?

I dont like it and wouldn’t build it if someone asked me too. Especially for a 4 door street cruiser. You will constantly be fighting the tune trying to make it run on garbage gas. Could it be done? Sure. Should it be done? No. Why not just put good gas in it? Or why not just build it at 9.5 comp if you’re stuck on running cheap gas. There is zero reason to push the limit of tunability here and doing it would take the fun out of driving it.

 

[Frankbassman]

Hey guys, thanks for the pointers.

CA has 91 octane gas and I am ok with using that, but was moreso wondering what the limits are to understand them.

I am looking at IMM machine and they offer to open their iron heads to 72 cc.

With 5 cc valve reliefs = 77cc which puts comp at 9.6:1

How is that? And, would 20-746-9 work well? Or are there better ones?

Again, thanks all. This is why I wanted to ask you all.

-Frank

 

[Illahe]

Hello all,

I'm getting ready to build a 5.9 Magnum. Very interested in getting as much compression as possible while running 89 octane for best efficiency but if that is impossible, I will understand and recalculate accordingly.

I know some few have had luck with similar, so seeking advice. Looking for streetability with good power, not afraid of some lope but no top fuel behavior.


Car details as it sits:

'73 Dart 4 door (probably 3400 lbs)

42RH transmission (med stall, about 2100rpm)
Ford 8.8 rear with 3.73 gears (limited slip)
26.5" tires
VERY tired 5.9 magnum out of a '97 Ram.
625cc street demon thermoplastic deal. Works.
True fenderwell cold air intake routing.
Air Conditioning (RV2)

Cooling system is up to snuff.

My top piston choice is H116CP30:
1.66" compression height (stock is 1.612 I believe)

Fel pro head gasket 519SD(0.050" compressed)

If the stock piston depth at TDC is 0.050", the new pistons would put me 0.004" above the deck.

So with gasket, I'd be at 0.046 deck height.

Magnum chamber CC: 62cc

+5cc valve reliefs = 67cc

Compression using 4.030 bore: 10.8:1

I know that is high. I have been reading about the magnum's detonation resistance. How good is it with a good quench (and cam) as above?

Frontrunner cam: comp 20-746-9

COMP Cams 20-746-9 COMP Cams Xtreme Energy Camshafts | Summit Racing

2nd place: comp 20-745-9

COMP Cams 20-745-9 COMP Cams Xtreme Energy Camshafts | Summit Racing

3rd: Some hughes cam, don't know which

Very open to suggestions from the pros.

I am reading that the intake close point will heavily influence the octane requirents, but don't know enough to make a confident choice.

Has anyone done similar? How did your quest turn out? Highly interested in your input.


Thank you all


-Frank

Have you called Ken @Oregon Cams? He is really good with a hydraulic roller re-grind if you have you oem cam.

Gears are fine, but your torque converter is going to come into the camshaft choice.

 

[TT5.9mag]

Hey guys, thanks for the pointers.

CA has 91 octane gas and I am ok with using that, but was moreso wondering what the limits are to understand them.

I am looking at IMM machine and they offer to open their iron heads to 72 cc.

With 5 cc valve reliefs = 77cc which puts comp at 9.6:1

How is that? And, would 20-746-9 work well? Or are there better ones?

Again, thanks all. This is why I wanted to ask you all.

-Frank

How good of a tuner are you? Can you put a curve in a distributor and get the timing where it needs to be at all rpm points? If so you’ll be ok at 9.6 on 89 octane. But start tuning it on 91 and conservative timing and work backwards. I like the 216/224 cam choice for 9.6 but not for the 10.8. Working with Brian at IMM is a great choice. He is excellent.

 

[Frankbassman]

Have not yet talked to Ken at Oregon, maybe I should call him once I have the engine torn down and see the condition of the cam journals.

TTI5.9, I can and am willing to tune.

My dist is out of a van, I swapped in stiff springs and mapped out the advance/rpm, I have that info somewhere...
Has a very short curve. (12 crank degrees)
I think my advance starts at about 1600 rpm and maxes around 2800 currently.

My current timing is 20 idle, 32 total, with vacuum advance bringing in 22 degrees. I can shorten that if need be, change springs, etc... not an issue for me.

FYI, my background is aircooled Volkswagen engines, compression is very touchy on those due to cooling characteristics. Still, my current VW engine is at almost 9.0:1 and cruises all day at 220 degree oil temps at 75 mph in a bug. 180 around town.

I attribute that to the 0.040 deck height and cam choice. Hence why I want to keep this engine tight.

I will contact oregon about cam, and IMM about the heads and keep that 20-746-9 cam in mind.

IMM's heads will be ready for whatever cam I realistically use.


-Frank

 

[TT5.9mag]

Have not yet talked to Ken at Oregon, maybe I should call him once I have the engine torn down and see the condition of the cam journals.

TTI5.9, I can and am willing to tune.

My dist is out of a van, I swapped in stiff springs and mapped out the advance/rpm, I have that info somewhere...
Has a very short curve. (12 crank degrees)
I think my advance starts at about 1600 rpm and maxes around 2800 currently.

My current timing is 20 idle, 32 total, with vacuum advance bringing in 22 degrees. I can shorten that if need be, change springs, etc... not an issue for me.

FYI, my background is aircooled Volkswagen engines, compression is very touchy on those due to cooling characteristics. Still, my current VW engine is at almost 9.0:1 and cruises all day at 220 degree oil temps at 75 mph in a bug. 180 around town.

I attribute that to the 0.040 deck height and cam choice. Hence why I want to keep this engine tight.

I will contact oregon about cam, and IMM about the heads and keep that 20-746-9 cam in mind.

IMM's heads will be ready for whatever cam I realistically use.


-Frank

Excellent, sounds like you get it. I’ll tell you this though, if you stab that distributor in a 9.6:1 magnum and try running it on 89 with that short and quick of a curve it’ll do two things really well, loose power and rattle. You’ll need to slow the curve down a bit through peak torque, and put the timing back in it up at peak power.

 

[RustyRatRod]

I dont like it and wouldn’t build it if someone asked me too. Especially for a 4 door street cruiser. You will constantly be fighting the tune trying to make it run on garbage gas. Could it be done? Sure. Should it be done? No. Why not just put good gas in it? Or why not just build it at 9.5 comp if you’re stuck on running cheap gas. There is zero reason to push the limit of tunability here and doing it would take the fun out of driving it.

I totally agree with this, lock, stock and barrel, 100%.

You say you can tune. Great! There are however, things you cannot tune for. Here's one example.

Getting stuck in a traffic jam on a 90 plus degree day. The car in front of you will be fartin its hot exhaust right into your grille, further exasperating the issue. There's this thing called heat soak, maybe you've heard of it.

That's when engines get saturated with so much ambient and operational heat, their effect on the coolant and cooling system becomes exponentially higher than normal. They are now "super heated" if you will.

This is the point when engine temperatures keep rising, despite the cooling system's ability to keep the engine under 190 degrees on any given "normal" day.

Do you know what all of "that" does for detonation? It's a recipe for disaster, plain and simple. You get hot spots that form in the chambers, on the pistons, just anywhere they can lookin to cause trouble and now, since all of this additional heat is in another inviting element...high compression, well...there you go.

Lastly, consider this. The change from one point of compression to the next higher, say from 8:1 to 9:1 only results in about a 3% net gain in power. You wanna risk all that for 3%.

Not me, brother.

 

[TT5.9mag]

I totally agree with this, lock, stock and barrel, 100%.

You say you can tune. Great! There are however, things you cannot tune for. Here's one example.

Getting stuck in a traffic jam on a 90 plus degree day. The car in front of you will be fartin its hot exhaust right into your grille, further exasperating the issue. There's this thing called heat soak, maybe you've heard of it.

That's when engines get saturated with so much ambient and operational heat, their effect on the coolant and cooling system becomes exponentially higher than normal. They are now "super heated" if you will.

This is the point when engine temperatures keep rising, despite the cooling system's ability to keep the engine under 190 degrees on any given "normal" day.

Do you know what all of "that" does for detonation? It's a recipe for disaster, plain and simple. You get hot spots that form in the chambers, on the pistons, just anywhere they can lookin to cause trouble and now, since all of this additional heat is in another inviting element...high compression, well...there you go.

Lastly, consider this. The change from one point of compression to the next higher, say from 8:1 to 9:1 only results in about a 3% net gain in power. You wanna risk all that for 3%.

Not me, brother.

Not to mention the biggest problem. To get it to run on 87 or 89 without rattling you gotta pull a boat load of timing out of it which kills all the power. For most people it’s better to build lower compression street stuff if you’re going to limit yourself to street fuel. If you want to push it to the edge, narrow the tuning window WAY down, and find the limit you have to be willing to blow stuff up and start over. Most guys aren’t. And to that end, most guys are happy with 400-450 hp and 91 octane, that’s easy to do and a simple recipe.

 

[RustyRatRod]

Not to mention the biggest problem. To get it to run on 87 or 89 without rattling you gotta pull a boat load of timing out of it which kills all the power. For most people it’s better to build lower compression street stuff if you’re going to limit yourself to street fuel. If you want to push it to the edge, narrow the tuning window WAY down, and find the limit you have to be willing to blow stuff up and start over. Most guys aren’t. And to that end, most guys are happy with 400-450 hp and 91 octane, that’s easy to do and a simple recipe.

He could knock off one whole point and still get into trouble on 89.

I'll also add this about 89, though it's unrelated to "performance".

89 octane is the biggest ripoff in the history of mankind. Only TWO points higher than 87. The difference between the two is 100% unnoticeable. No way, no how will you ever feel the difference and it won't amount to a hill of beans in the difference at "warding off" detonation. That's just laughable. Now, switch over to 90 non ethanol of it's in your area and you might have a chance.

Before you say I don't know what I'm talking about, I have a slant 6 with a measured 10.6:1 and although I CAN run it on 87 with no spark knock (that I can hear) I run it on 90 non ethanol. When I first got it running, it was a challenge to tune out detonation, but I did it with the help of some good members here.

And no, I didn't build it with that much compression on purpose. It was an accident when the head slipped off the broach at the machine shop. I had to take it to another to get it straightened out and by the time all was said and done, it had around .180" knocked off. Chambers went from 58cc (stock) to 34cc. So I know a little about tuning.

Oh and lastly and I'll shut up, you're using hypereutectic pistons I see. That's a huge LOL right there.

 

[Garrett Ellison]

If you put a piston with a decent dish in it with that quench and build it at 9.2:1 or so, you'll be be a lot happier with the drivability while being able optimize the tune for performance. The street and cruising manners will make up for the little bit of power you might (I say might because it could very well be less once the timing curve is adjusted to cope with the extra compression) sacrifice by dropping compression.

 

[volaredon]

Hey guys, thanks for the pointers.

CA has 91 octane gas and I am ok with using that, but was moreso wondering what the limits are to understand them.

at a buck to a buck-ten PER GALLON more, Im not....

 

[Illahe]

He could knock off one whole point and still get into trouble on 89.

I'll also add this about 89, though it's unrelated to "performance".

89 octane is the biggest ripoff in the history of mankind. Only TWO points higher than 87. The difference between the two is 100% unnoticeable. No way, no how will you ever feel the difference and it won't amount to a hill of beans in the difference at "warding off" detonation. That's just laughable. Now, switch over to 90 non ethanol of it's in your area and you might have a chance.

Before you say I don't know what I'm talking about, I have a slant 6 with a measured 10.6:1 and although I CAN run it on 87 with no spark knock (that I can hear) I run it on 90 non ethanol. When I first got it running, it was a challenge to tune out detonation, but I did it with the help of some good members here.

And no, I didn't build it with that much compression on purpose. It was an accident when the head slipped off the broach at the machine shop. I had to take it to another to get it straightened out and by the time all was said and done, it had around .180" knocked off. Chambers went from 58cc (stock) to 34cc. So I know a little about tuning.

Oh and lastly and I'll shut up, you're using hypereutectic pistons I see. That's a huge LOL right there.

This^^^^ Just say NO to hyperutectic!

 

[TT5.9mag]

If you put a piston with a decent dish in it with that quench and build it at 9.2:1 or so, you'll be be a lot happier with the drivability while being able optimize the tune for performance. The street and cruising manners will make up for the little bit of power you might (I say might because it could very well be less once the timing curve is adjusted to cope with the extra compression) sacrifice by dropping compression.

At that compression I’m not even putting a piston in it. The stock magnum 5.9 is 9.2:1 and they make great power.

 

[TT5.9mag]

Oh and lastly and I'll shut up, you're using hypereutectic pistons I see. That's a huge LOL right there.

This^^^^ Just say NO to hyperutectic!

Wait, what? I’ve made serious power on hypereutectic pistons. My turbocharged 8.1 vortec makes stupid power with em and has a BUNCH of miles. If you can keep it out of detonation they work just fine.

 

[RustyRatRod]

Wait, what? I’ve made serious power on hypereutectic pistons. My turbocharged 8.1 vortec makes stupid power with em and has a BUNCH of miles. If you can keep it out of detonation they work just fine.

That's gonna be a big if with this build.

 

[Frankbassman]

Thanks again for the replies all, I am taking it all in. Today I started undoing things on the car to yank the engine.

I'm from FL, in CA for work, but I drove a bug for 8 years with no AC in FL. I understand heat, heat soak etc. I was running hotter than the bug was.

Humor me. What EXACTLY is a stock magnum 5.9? Correct me where I am wrong. Is it:

9.1:1

Piston to deck: 0.050"
Head gasket compressed thickness: 0.040"
(0.09"deck height total)
Bore: 4.00"
Stroke: 3.58"
Chamber cc: 62 cc
Piston dish cc: 11

Total "chamber" volume: 72cc

Those numbers work out to 9:1 compression.

My question to the class is: if I use fully flat top pistons and have 77 CC's in the head chamber, instead of split between a dish and the head chamber (killing quench), and a TRUE deck height of 0.04", netting 9.6 compression instead of 9.1 for the stock mag, will the 9.6 engine have more, less, or equal knock resistance than the dished piston engine? Isn't the benefit of proper quench the ability to run higher compression while retaining good detonation control, and gaining more efficiency?

I don't understand how a dish in the piston is desireable except from making it "easy" to drop the compression ratio without regard for quench. In the VW world, a big deck height is GUARANTEED detonation machine, and lowering the compression is more desireable using chamber cc enlargement.

Please don't misunderstand me; I am not trying to be argumentative or obnoxious. I am just trying to learn and bounce some ideas with a group who has experience.

Just to be clear, because I see you all are being very clear as well: I struggle with the build it like everyone else approach. If I was ok with that I'd probably be assembling Tesla golf carts. This whole car is an oxymoron: a 4 door has no business with frame connectors, 8.8 rear, 4 wheel disks, reinforced control arms, heavy front sway bar, SS springs, stiff KYB shocks and wider tires, but that's what it has. I bought a 2000 durango with 83k miles and a 5.9 to tool around in, so it is safe to say this Dart will be a toy, but one I will eventually drive cross country.


I'll snap some pics at some point as I go along.

-Frank

 

[RustyRatRod]

With only .004" deck clearance, you WILL need valve reliefs. I believe the stock Magnum compression is around 9.2. Which would be absolutely perfect for what you are wanting to do.

 

[volaredon]

Got a question about true compression on a magnum. Did QC get better with them vs the older engines or something?
I mean it's well known with the older engines that they did not measure up to advertised compression.
My last /6 build came out to only, exactly "advertised" CR., after 0.100" of milling. That one was all actually measured out. And I've read many posts right here on how they were actually in the 7s vs "advertised ". And read many BB and LA posts here that similarly measured out "short" of what was claimed. As built by the factory how accurate was that rated CR on magnum truck engines?

 

[Frankbassman]

Good morning Rusty, 0.040", not 0.004". That would be actually insane. Basically head gasket thickness.

Also yes the h116cp pistons have 5 cc valve reliefs.


Volaredon, curious as well. I am starting to think the mags were better, but not perfect.

-Frank

 

[Garrett Ellison]

A ring of quench on the outer edge of a piston around a dish that is mostly on center of the chamber is acceptable. A dish will not kill quench in that instance. The actual effect of quench is to add “tumble” to the mixture before ignition. The more agitation, the less likely is is to encounter detonation.

 

[TT5.9mag]

Production machining in the late 90s and 2000s was leaps and bounds better than the 60s-70s. The level of acceptable tolerance was much tighter. That being said, magnums aren’t “better” per se but were definitely built to a higher standard because standards and practices naturally got better. They usually measure out pretty close to blueprint spec in my experience.

 

[RustyRatRod]

Good morning Rusty, 0.040", not 0.004". That would be actually insane. Basically head gasket thickness.

Also yes the h116cp pistons have 5 cc valve reliefs.


Volaredon, curious as well. I am starting to think the mags were better, but not perfect.

-Frank

I'm very familiar with those pistons as I've built a couple of engines using them. What's insane about .004" deck clearance? I have a slant 6 on the stand with .007" and a .020" compressed head gasket with a closed chamber head. That's .027" quench distance. Insane? Nah.