408 Magnum New Build, Gutless of idle

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thomasfouraker

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Okay guys here goes......

Just finished putting together what I hoped was going to be a torque monster, between speaking to Hughes, Comp, and a few engine builders this should have been making power off idle.

What I am finding out is I have a truck that seems gutless until about 3000 rpm then it becomes a screamer for sure.

Definitely not what I had intended for my full size Ram that sees a trailer behind it often.

I got my combination off somehow, probably too many chefs in the kitchen during my build:

53x55 FB Throttle Body
Hughes Airgap minor casting cleanup port job
2.02 RT Heads, ported with Hughes 1110 Valve Springs
KB 356 pistons 9.3:1 compression
Eagle I Beam forged rods
Eagle 4" crank forged
Edelbrock headers
Comp Cam 224/230 .536/.544 camshaft 114 LSA installed on a 112 centerline
Factory Stamped Rockers

At this point, what options do I have? Higher Stall, Boost, Cam and Intake Swap?

I have retained the factory multi port injection.

Admittedly I have yet to get it tuned but the truck runs and idles great aside from the off the line lackluster performance.

I plan to get the exhaust done and a Wideband put in within the next two weeks and then schedule a dyno tune to see what's going on.

Thanks!

Thomas
 
I think something is out of time.

But I would not build that engine combo.
Just, IMO...
Stock R/T heads? Some valve seat work and a bowl blending since your lifting the valve as high as you are.
To light on compression
The cam (depending on the rest of the drive train and vehicle weight) is 10* to large, at a min.
The 114 installed and the installed 112 is to wide. It looses cylinder pressure. The 114 should be @ 110 or 108, the installed centerline on a 106/104.
I myself would have moved to a roller rocker.

What is the trucks weight, intended usage, gear ratio & tire size, what trans and stall converter?

If this was for towing....
On the quick, I’d swap out camshafts.
 
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Don’t change the mechanical combination until you get it tuned. It makes a big difference because right now you still have too much factory torque reduction.
 
Running that combo on a factory ECM tune is definitely a recipe for disappointment, and a meltdown if you dont get it correctly tuned
 
I thought there were aftermarket Mopar Performance heads called “RT” that were magnum based of course

don’t fuel injection systems like wider center lines?

the stock stamped rockers will make that cam a little smaller since they are actually 1.46:1 (not 100% number for magnum rockers)
 
I think something is out of time.

But I would not build that engine combo.
Just, IMO...
Stock R/T heads? Some valve seat work and a bowl blending since your lifting the valve as high as you are.
To light on compression
The cam (depending on the rest of the drive train and vehicle weight) is 10* to large, at a min.
The 114 installed and the installed 112 is to wide. It looses cylinder pressure. The 114 should be @ 110 or 108, the installed centerline on a 106/104.
I myself would have moved to a roller rocker.

What is the trucks weight, intended usage, gear ratio & tire size, what trans and stall converter?

If this was for towing....
On the quick, I’d swap out camshafts.

Truck is a 2000 1500 Ram
3:92 gears 33” tires
Factory 2000 rpm stall
Tried roller rockers but the geometry wasn’t favorable so went back to the factory rockers. Roller rockers can be added but I don’t think it’s a make or break right now.
Heads have a bowl blend, short turn work and have been surfaced with a fresh valve job that checked out on vacuum test.
Comp specd the cam entirely based on all the information they gave. Truck, weight, gears, tire size, stall, head flow etc. I questioned the 114 but they said it would allow the computer to function happily.

The best way I can describe it, is it literally feels like a shot of nitrous at 3000 rpm and higher. Below that it feels like I have 10000lbs behind me.

Factory rockers are 1.6
Heads are Mopar performance RT heads
 
Yeah, waaay too much cam for a stock ecm tune... Get it on the dyno and the ecm tuned for your combo, it'll make a biiig difference. And yes, the convertor could use some more stall. Stock convertors are for stock motors. 3.92s with a 33" tire isn't going to be ideal, but is workable. Did you actually degree the cam in, or take the factory at their word?
 
Yeah, waaay too much cam for a stock ecm tune... Get it on the dyno and the ecm tuned for your combo, it'll make a biiig difference. And yes, the convertor could use some more stall. Stock convertors are for stock motors. 3.92s with a 33" tire isn't going to be ideal, but is workable. Did you actually degree the cam in, or take the factory at their word?

It was degreed in. Advancing it 3 degrees only netted about 2.5. Brought it to 111.5. Should have had 4 degrees advance ground into it. I was taking comps advice as gospel.
 
2000 stall with that cam and mombo tires? Never should have bolted things together with that for sure. Should have gotten a converter to go along with that combo. Time to make some calls and get something better matched. 3000-3500 stall ballpark
 
I’d like to say up front I’m so sorry I read right past “computer.” When I said “I think something is out of time” as in timing, be it cam degrees in or distributor off... it seems the computer needs to get done as suggested. But, I’m going to stay tuned to this and learn something. I’m old sckool strong.

I’d go more stall. Yup... just a bit. This was s where in all a custom converter shop. I used to have pro torque around the corner. They were really good to me and happy with what I got. Other places like dynamic or ultimate, etc... should also be considered.
 
I agree with others. With my limited knowledge, that cam is too big for towing. IMO, something 10-15 degrees smaller would be better for towing. Is your converter a lock up? Another factor to consider with your transmission.
 
Get it tuned ASAP and you'll see a huge difference. I would not go through Hughes to get a tune (just my personal experience), but likely go with Flyin' Ryan, Utawesome, or find somebody with HP Tuners/SCT Flash local to you to tune it.
 
Appreciate all the replies and suggestions.

The Torque Converter does lock up. I didn't change anything with the transmission as I expected that the motor would require an overhaul in short order anyways and any necessary changes/upgrades would occur then.

I have a local HP Tuner that can dyno tune it and tell me what all is going on. As soon as I get my exhaust buttoned up and Wideband installed that's the next stop.

Will keep everyone posted. Really don't want to swap components but reckon that may just be what I have to do if the tune don't bring it around.
 
What is your timing set at? (you should be around 34° total). Did you degree the cam?
 
I thought there were aftermarket Mopar Performance heads called “RT” that were magnum based of course

don’t fuel injection systems like wider center lines?

the stock stamped rockers will make that cam a little smaller since they are actually 1.46:1 (not 100% number for magnum rockers)

Yes, you are correct regards those heads
Great heads that make excellent power.
I went mid 11’s with them on a stock stroke 318( magazine enginemasters motor) with a downsized cam, and 10.44 compression at 3400 pounds
 
One of the biggest problems besides the torque converter is the ecm.
Flyin Ryan is the guy to go to.
 
That's not a truck/pulling cam.

Thats a street race cam for a light weight dak.

Imo Your cam should look like a truck cam on paper.. fast rate.. more lift.
@.050 should be near/around 210/218
Lift around .500 112

230's is 6000 rpm
You jumped continents with the @.050
How often will you be there without 4.57-4.88 gears?
So I say the cam isn't ideal for your intended purpose.

Btw I just put 3.92 in mine, perfect. 80 mph at 2350 rpm, better gas, gets put of the hole with very little throttle. The heads are going on next... and I'll probably leave the cam stock and just add the headers.
 
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