351 roller dissy

[albanygt40]

Hey Guys

In the middle of building a 408 stroker and am up to buying a dissy. Can anyone recommend a dissy to suit the 351 style block and what gear to get ? I have retro Hydraulic roller cam installed.

There are so many to choose from. I like the E-Curve dissy but it's only available for the 302.

[boofhead]

I like the MSDs with a 6A ignition box. I would get one with the vacuum advance. For example, the MSD 'Ready-to-run' series MSD-8354 [note: you can get different gears for them). It can run with or without the ignition box though I would throw a MSD 6A into the mix (only if the budget can go that far).

The gear depends on what material the cam is made from. Normally they would be a billet cam but a retro is likely to be cast iron. It is easy to tell by looking between the lobs and seeing the finish. If it is machined at all then is will be a billet - if it is rough cast finish then it is a cast Iron. The gear matches the metal (so Case Iron = Iron gear, Billet (Steel) is Steel gear (or bronze or carbon fibre).


What heads are you running in your 408?

[albanygt40]

Heads- whimped out and got AFR 205's, I wanted 225's but was worried the motor wouldn't make the revs or air speed for them to work properly.

408
Scat 4 inch cast crank
Scat 6.2 rods
Probe forged pistons .060
decked block
line honed crank bearingings
Main stud kit
Head stud kit



Yes I plan to run a 6A........Is there a Dissy like the E-Curve to suit a 351? I like being able to change the advance graph with the turn of a screw driver......

[boofhead]

No the E-Curve is not available for the 351 and not going to be any time soon,

http://www.msdignition.com/forum/showthread.php?t=13100

The distributor I suggested has the ability to change the mechanical advance curve. It is not a switch as it is in the E-Curve though you set it once and never really touch it again (until you swap a cam again) so I am not convinced the convenience is worth much.

The 205s will be fine for the torque monster it is. Sure the 225 would have been better - your moving a hell of a lot of air with that engine. I am sure you will be happy any way.

[albanygt40]

I just read up on the dissy you suggested and have added it to my next Summit order. I will get the 6al and blaster coil with it as well.

I like the way you can change the rev limit and changing the springs for advance changes seems easy. I also like the way they say an ECU can read the output as I plan to change out to a fuel only ECU down the road.

What do you suggest in regards to timing maps? I was thinking of using an all in early timing advance curve or the light silver springs. I was also thinking of setting the all in timing to 33deg and base timing to 8deg.
I think I would need to change the advance bush as it is factory set to 20deg.

[hybrid]

Why fuel only?
You can get really good fuel economy by playing with advance along with your fuel, and it's really not much more work.

[albanygt40]

first reason is that the EFi will be down the track so knowing the Dissy I have now will produce a signal an ECU can read (trigger from) is good.

Second is i have had a few Wolf V4 ecu engines in the past and found that once set I never really played with the ignition after that ,so a good dissy that is set up right means less hassel, no crank sensors, knock sensors, setting up timing graphs and timing configs 36-1 and so on. Noise in the circuits and so on. The best set up i ever had was Wolf 2D with a stand alone dissy. Very simple and reliable.

I am not saying programmable ignition is bad, just want to keep it seperate in my case.

[hybrid]

Fair enough, but you don't need all that stuff for ignition. You really only need 36-1 and cam sensors etc if you want to run COP.

I'm running ignition with just a MSD distributor.. no knock sensors, no crank sensors.
IMO, configuring timing in the ECU is easier than changing springs etc in the dizzy.

[albanygt40]

Each to their own. Alot of the American ECU's are fuel only, the system I am leaning towards is fuel only. Like I said I have had both set ups and prefer them to be seperate or stand alone. I have spent hours changing timing points, trying different maps. So to me changing 2 springs in a dissy is simple and an effective way to go.

What ECU are you running? What MSD dissy are you running? I assume some sort of dual sync set up if you dont have a crank sensor?

[hybrid]

I'm using a Microsquirt (same as Megasquirt but smaller).
Dissy is an MSD for a late model windsor which has fixed pickup.

No need for dual sync. The ECU just fires the MSD 6A/Coil each time it receives a pulse from the dizzy. The dizzy is configured to a known advance (say 10 degrees), which is set in the ECU. The ECU then calculates the advance from there
So the Dizzy looks after delivery to the right cylinder, same as normal.

I don't see how you can get the granularity with mechanical advance, but as you say, "to each, his own".

[albanygt40]

How does the motor run?

[hybrid]

This is the only running video I have... in a pretty poor state of tune.
I won't get the tune too much better until I can get it out on the road.

[albanygt40]

Seems to run ok. Yeah needs a bit of tuning but it's running which is the hard part.

What about some details on how much it cost and where you got it from?

[hybrid]

I did a bit of a writeup here:
http://www.mustangtech.com.au/Content/p ... id=14.html

Mine is the microsquirt ECU, but it's the same code as the MS-II which I listed pricing for. The microsquirt is smaller and has a water proof plug etc, which was originally designed for motorbikes. Not really required for cars.

The full size units are also easier modified if you want to add nitrous control, launch control, idle control, and lots of other fancy stuff that the community has designed.

[gotohellgadafi]

Just a quick tip....make sure you use the rev limiter......somewhere between 6-7grand.
I had mine taken off at one stage, revved the girl to 7grand and POW! off came two of the roller rockers.(AFR 225 heads)
Had to change the studs to allow an extra 200tho for the posi's to hold onto....and put the rev limiter back on