408 Stroker build who's keen to watch this one :)

[Bruceynz]

Stock 5.9L Cam Specs



Intake duration 249
Exhaust duration 269

Intake lift .410"
Exhaust duration .417"

Centerline 109
Install centerline 117

my current cam

Basic RPM Range: 1000 to 5200
Valve Lift Intake: .496
Valve Lift Exhaust: .496
Duration Intake: 262
Duration Exhaust: 270
Duration at 050 Intake: 209
Duration at 050 Exhaust: 217
Lobe Separation: 110

 

[Oldiron440]

In my opinion that would be a better choice and the direction I would go. I thought there was a way to use more than .525 lift with magnum heads.

 

[Bruceynz]

use MP springs which I have in my indy x heads

The Forgotten Valve Spring | Mopar Magazine

 

[Bruceynz]

I just want the car to pull hard off the line, I am not after a 12.8 second drag car. This was the reason for the smaller cam and the valve spring limitations, 20/20 I prob should of just used better springs and the 1200 - 5700 cam.

 

[Oldiron440]

I haven't figured out why when it comes to cams OEM engine sizes are used and not displacements. Over the years I've had many conversations with Comp and Lunati cams on displacement vs. duration and it's only been the last few years that they even note strokers in there catalogs.

 

[Bruceynz]

Do you guys think there is any advantage of bolting on my 770 street avenger? means on the primaries its running the engine on 385cfm which doesn't sound to big and then just play with springs in vac secondaries?

My 600 seems to work ok, just need to put smaller jets in and get the mixtures right under load, I am not biased to the 770 of anything would like to run with the 600!

 

[Oldiron440]

I've read several times that the Holley 770 is a 750 cfm carb, I no idea why they call it a 770.
The thing about vacuum secondary carbs is they are very forgiving as to witch size you have. I'm sure either size will just fine.

 

[4speedjim]

I wouldn't change carbs, get the 600 dialed in first. Your not looking to float valves. X heads can handle a .650 max lift cam, La-X or Ma-X with the #3806 valve seal. Stock Magnums are .525-.530 safe max. Suppose you could pour money over the stock Magnum heads and get more lift, but I don't know if that's the best way to empty your wallet.

 

[Bruceynz]

Ok - The 408 build has come to a holt for now! My good friend in NZ has convinced me to get the 360 dialed in correctly before I go rushing a head on build another motor! I am kind of 60% there already lol lol

So far this is where things are at:

- 600 Holley should be big enough to feed my 360 to 5500rpm
- My mixture is rich under hard acceleration (AFR 10.6)
- My cam (209/217 @50)I have is a bit on the small side and I could get away with the next cam up I have 221/225 @ 50
- My ignition timing is at 34 degrees, this article here 5.9L Magnum Engine - Make Mine A 5.9 with EQ heads suggests they will go best at 38 degrees (that may depend on cam and DCR) any advice?
- Do I need a better distributor, my current one is a proform cheapy setup.
- My converter stalls at approx 2200rpm

So I guess first I need to get carb sorted, then get ignition timing dialed in to 38 and see if it pings!

 

[Bruceynz]

This is my idle from my howards 209/217 cam
The buzzing sound is the Holley electric fuel pump, so noisy!

This is a photo of the tach - looks about 700rpm

and this is what the carb tuner wrote for jet sizes on carb

this would suggest its got stock jets and PV

 

[jasperjacko]

Oh man! get an in tank pump! lol

 

[Bruceynz]

so with the standard setup in my carb (I thought he had changed jets but looks like he hasn't) been a long time since it was done, but I do remember him saying he noted on carb how it was setup. Would you expect a stock setup carb to run 10.6 afr, if not a suspect my AFR gauge is not reading correctly

 

[Oldiron440]

How long does it read that, is it for a short blip or is it over a several hundred rpm spread? The reason I ask is that the power valve opening will cause an over rich moment.

 

[Opticon77]

Electric fuel pump to carb? Check the fuel pressure at the regulator as well. With carbs only needing something like 7psi max I imagine it would be easy to overdo it.

 

[Oldiron440]

I've been looking around a bit and the 408 builds I've seen are good for 480 - 500 hp not even trying hard.
I think it would be real hard leveing power on the table, I mean the reason you build a stroker in the first place is more power.

 

[Bruceynz]

I dunno where I wrote it now but what I have is indy x heads, stock size valves, stock heads, setup for .600" lift with MP springs and retainers, air gap and 770 street avenger, I have a 2200 stall in there at the moment behind the 360 so that may jump up a little with 408 so all that is left is the cam choice, my trans is a built 904 and rear end is 3.23 open but do have a LSD unit to go in. Mag block is only good for 500hp??? my trans is built to 450hp and a 8.25" with LSD only good for about 450hp

BTW - our fuel is rubbish here, its about as good as your 87 in the USA, we can get 98RON but RON is crap rating compared to MON. SCR is only good for about 9.3:1 but I do know talking with AJ Forms that choosing the right cam can bleed DCR down to work.

My setup will be SCR 9.8:1

I don't have 2.02 valves, I don't have alloy eddy heads, I have iron heads that are a bit better than stock.

I am going to build the 408!! just slowed down a bit at the moment.

 

[Oldiron440]

RACE GAS | Racing Fuel Concentrate

 

[Bruceynz]

Found this, I have these heads, but what's got me intrigued is the small cam, link at bottom of page.

408

360

INDY CYLINDER

 

[Oldiron440]

Indys website doesn't make any sense, 80hp between the two motors and the only difference is the carburetor?

 

[Bruceynz]

one is a 360 the other a 408, same cam, different carb, but that cam spec is what I have in my current 360 209/217 @ 50 with EQ heads and I tell you they are pretty much the same head! I am lost, my car is not a 380HP monster lol lol