Head Valve size to use on Stroked 360

[dodge truck]

Hello,
I'm starting to build a very mild 408 using the kegger and FI. Should I use 1.90 intake valves or 2.02?
Engine RPM will be idle to 3000 RPM. Thanks

 

[Yeret]

I've wondered about a 408 with the kegger for a while but seems no one's really done one. I imagine that the engine won't have much for horsepower but should have totally awesome low-end torque!

Since you're using the kegger (and presumably factory cam?), I doubt that you'll notice much of a difference between 1.92" and 2.02" intake valves.

And don't forget to get the tuning dialed in when you're done. Since it's a stroker, you'll probably need a wideband and datalog the engine's fuel/air mixture. Send the stuff to a good tuner, such as Flyin' Ryan, and he'll dial everything in for ya. It'll cost a bit but the results will be MUCH better.

 

[dapepper9]

I would retain stock heads if you're using the kegger. No point changing then, intake is going to be your restriction anyways. They use the 1.92/1.60 combo

 

[dodge truck]

Ok thanks, that's what I wanted to know that the 1.92 is a good match for the kegger and maybe the better choice for unshouding the valve compared to a 2.02.

The kegger intake will be extruded honed and stuffed to increase the velocity. I was also going to change the cam for something with more lift.

My plan is to install the AEM wide band and start logging idle and tip in A/F. Have Ryan work off that base map since I'm not straying too far from OEM. Install next size up injectors try and keep things simple.

 

[dapepper9]

Sounds like a pretty good plan that you've thought through.

Just out of curiosity, this sounds like a pretty purposeful build, what are you doing for cam choice?

 

[Okiespaniel]

Ok thanks, that's what I wanted to know that the 1.92 is a good match for the kegger and maybe the better choice for unshouding the valve compared to a 2.02.

The kegger intake will be extruded honed and stuffed to increase the velocity. I was also going to change the cam for something with more lift.

This is the kind of build I'm interested in. An extremely reliable low comp stroker with good low/mid range torque and hp. Good for towing and mild off roading.

I wonder if using a set of 1.7 rockers would yield just enough lift

 

[dapepper9]

Myself, I would go for a new cam over using 1.7 rockers. The 1.7s bump lift on factory cam from .410 to .436 if memory serves me correct but with the stronger signal of the stroker basically making that factory cam seem smaller, I'd want a little more duration. Something like this https://www.summitracing.com/parts/cca-20-744-9/overview/make/dodge is kind of what I'd go with. Lower operating range that the stroker would further shorten but would allow for significantly more airflow than the factory stick. But that's just my opinion

 

[pacofortacos]

As far as I know the later 5.9's had a bigger cam in stock.
My 01 had the same lift as the 5.2 when measured with a dial indicator and lift with 1.7's was in the .460-.470 range as intake and exhaust were slightly different.

 

[dapepper9]

That's against just about every other piece of documentation out there so if you could provide anything to back that up that would be wonderful.

Even if that's the case, cubes eat the duration and extra cubes will do it more so

 

[Yeret]

Myself, I would go for a new cam over using 1.7 rockers. The 1.7s bump lift on factory cam from .410 to .436 if memory serves me correct but with the stronger signal of the stroker basically making that factory cam seem smaller, I'd want a little more duration. Something like this https://www.summitracing.com/parts/cca-20-744-9/overview/make/dodge is kind of what I'd go with. Lower operating range that the stroker would further shorten but would allow for significantly more airflow than the factory stick. But that's just my opinion

Assuming OP uses factory-style pistons, which have a considerable trough, I calculate that cam as still generating over 9.6:1 dynamic compression ratio. A tune to run that setup is going to have to pull a lot of ignition timing and I'm even sure if that's going to be enough.

I've been lead to believe over the years that, with regards to dynamic compression ratio, 8:1 (iron heads) or 8.5:1 (aluminum heads) is the way to go if you don't want to either have a knocker that makes no power or a knocker that blows itself apart the first time you nail the throttle.

Exact numbers seem hard to come by, but I'm thinking our factory cams have large duration but shallow lift, a pretty crappy combination for performance, but excellent for valvetrain longevity, especially considering the large-bore lifters that Mopar engines have traditionally come with. With regards to compression, I've calculated that the factory stick, with the best average numbers that I could find (.050" lift duration, can't find "advertised" duration), generates a perfect 8:1 dynamic compression on a 360 with zero deck and factory-spec head gaskets. Of course, a zero-deck factory block is like a unicorn: you ain't gonna find one.

But, even with sloppy deck clearance, it seems that even the factory bump stick with it's relatively hefty duration isn't going to keep a stroked 360's dynamic compression under the "blow up now" mark. Unless you pull back timing or add a bunch of fuel, one of which is going to suck power and the other of which is going to suck your wallet.

Maybe I'm arm-chairing it too much. I think that the cam Pepper picked out would generate astounding low-end torque in a 408 stroker, but I think that the tuning to dial it in would leave a lot of power on the table even in the range that the cam would want to operate at. Unless you're planning on running racing or AV gas, in which case...that would be interesting, LOL.

 

[dapepper9]

Assuming OP uses factory-style pistons, which have a considerable trough, I calculate that cam as still generating over 9.6:1 dynamic compression ratio. A tune to run that setup is going to have to pull a lot of ignition timing and I'm even sure if that's going to be enough.

I've been lead to believe over the years that, with regards to dynamic compression ratio, 8:1 (iron heads) or 8.5:1 (aluminum heads) is the way to go if you don't want to either have a knocker that makes no power or a knocker that blows itself apart the first time you nail the throttle.

Exact numbers seem hard to come by, but I'm thinking our factory cams have large duration but shallow lift, a pretty crappy combination for performance, but excellent for valvetrain longevity, especially considering the large-bore lifters that Mopar engines have traditionally come with. With regards to compression, I've calculated that the factory stick, with the best average numbers that I could find (.050" lift duration, can't find "advertised" duration), generates a perfect 8:1 dynamic compression on a 360 with zero deck and factory-spec head gaskets. Of course, a zero-deck factory block is like a unicorn: you ain't gonna find one.

But, even with sloppy deck clearance, it seems that even the factory bump stick with it's relatively hefty duration isn't going to keep a stroked 360's dynamic compression under the "blow up now" mark. Unless you pull back timing or add a bunch of fuel, one of which is going to suck power and the other of which is going to suck your wallet.

Maybe I'm arm-chairing it too much. I think that the cam Pepper picked out would generate astounding low-end torque in a 408 stroker, but I think that the tuning to dial it in would leave a lot of power on the table even in the range that the cam would want to operate at. Unless you're planning on running racing or AV gas, in which case...that would be interesting, LOL.

The cam i linked; assuming 9.0:1 static comp to match factory advertised; effective dynamic compression is 7.64:1 using comp's cam card intake valve closing point of 57* ABDC @0.06" tappet lift and the fairly standard 0.030 overbore.

This would be a relatively easy to tune in camshaft for most tuners.

 

[Yeret]

Well, looking back at my previous post, I will say that I screwed up the numbers because I punched 58 rather than 64 into the combustion chamber cc part. D'oh! Seems my memory fixated on my Firebird's 305 for some reason.

9:1 static sure sounds about right for the factory engine, although that assumes a massive cylinder quench, something like .080" (assuming .040" head gasket + .040" piston-to-deck clearance). Pretty yucky, really, but totally would not surprise me if the factory clearance was that fat.

Zero-decking the block should push the static into the mid 9's and throwing in a 4" stroker crank looks to push static compression into the high 10's.

Hypothetical numbers are just that, though. It's gonna really boil down to what OP is going to do with regards to machining the block, if anything. Machine shop-work isn't exactly case-of-beer prices these days, LOL.

 

[dapepper9]

Well, looking back at my previous post, I will say that I screwed up the numbers because I punched 58 rather than 64 into the combustion chamber cc part. D'oh! Seems my memory fixated on my Firebird's 305 for some reason.

9:1 static sure sounds about right for the factory engine, although that assumes a massive cylinder quench, something like .080" (assuming .040" head gasket + .040" piston-to-deck clearance). Pretty yucky, really, but totally would not surprise me if the factory clearance was that fat.

Zero-decking the block should push the static into the mid 9's and throwing in a 4" stroker crank looks to push static compression into the high 10's.

Hypothetical numbers are just that, though. It's gonna really boil down to what OP is going to do with regards to machining the block, if anything. Machine shop-work isn't exactly case-of-beer prices these days, LOL.

You can do all of that and still get 9:1. Stroker kits for these engines have some larger dish options available. Compare that to the engine im dropping off at the machine shop in June, hardly anything available for stock stroke and im looking at 10.2:1 static and about 8.3 dynamic lol

 

[Yeret]

Yeah, right, almost...okay, completely forgot about swapping to dished pistons, LOL. I was just assuming he was using factory-style pistons, but then again, I don't even think you can get those with a reduced compression height for a stroker.

 

[pacofortacos]

Factory 5.9 pistons are dished - just more dish sizes available on stroker kits.

0.080" quench on a stock 5.9 is probably one of the tighter ones Lol
The pistons sit down in the bore a decent amount and even then the dish shape isn't ideal to the combustion chamber shape for a good quench.

At least on the 2001 and 2002 5.9's I had apart that is how they were from the factory.

 

[dapepper9]

Yeah the block im sending was 0.051 in the hole with a 0.045 gasket. Factory dish is only like 12cc or something like that

 

[dragracefan]

Since you're probably gonna need new heads anyway, Just get the EQ monster magnums with the 1.970 Intake 1.630 exhaust. Also give Lunati cams tech dept. a call getting the best cam for your truck, they will ask you numerous questions about your truck and what you want to do.

 

[dodge truck]

Ok so I am up to the camshaft.
So what cam do you suggest using EQ heads 1.92/1.63 valves. stuffed Kegger and short headers. I want to keep the 1996 PCM, no tune. Just looking for increased engine displacement.

Is there a off-shelf camshaft or do I need custom grind?

Thanks in advance.

 

[jo3gee]

I use the indy max iron heads with 2.02 valves, but I also have a bored throttle body and a hotter cam. Btw i still use the keg, haven’t replaced it yet. Although, i also have a custom b&g tune because I have 10.5:1 compression.

If you want to keep low end, you are on the right track with the keg and a mild cam. I have used both Crane and Comp in various engines and they have been very helpful determining grinds for specific needs.

 

[dapepper9]

I would talk to a cam grinder for a recommendation. I know what i would use personally but that might not be the best option for you. I know enough of the theory behind cams to be dangerous but they know every detail about them so that's my recommendation