351 roller dissy

[hybrid]

7 grand shouldn't hurt your engine like that.. it obviously wasn't right from the start.

[albanygt40]

AFR 225's what motor you running?

I have settled for 205's but can still change to 225's.........

[hybrid]

I'm running Dart Pro1 195s in my 347.

[boofhead]

I would go for the 225s on the 408. It really is a big motor. They will also provide more room if you want to get extra out of her - use the Cam to suite your needs.

My 306 build I have 170 Twisted wedges so comparing to my 347

347/306 = 1.13

My 347 build I have 195 Canfields. So lets see -

195/170 = 1.14

So I am keeping up as engine size is increasing the intake port size is staying around the same flow potential. So lets look at the 408..

408/347 = 1.18 where this then is the target e.g., flow vs size ratios
205/195 = 1.05 choice one is going to restrict the flow
225/195 = 1.15 this gets the go as it is close.

Close and preferred is the 225s for your performance 408. The 205 would be great on a hot 347.

As far as advance goes on a performance - I tend to like lots of static advance. Not a great deal of mechanical advance that is all in by 2500 - 3000 RPM. This all depends on the CAM and profile of the engine so you need to play around a little. Any way, lets say total advance needs to be 36 deg - I would make sure it is all in by 3000 RPM (or a little less), with a static advance of 12 deg that make it 24 deg mechanical advance.

Get the right springs (maybe weights) to make sure its a maximum 24 deg and is all in by 3000 you should be sweet. It is where I would start.

If you want the rev limited then the 6AL includes the limiter circuit.

BTW: You can have the MegaSquirt run fuel only if you wish. Infact, roghtly speaking MS 1 was only fuel, then MS2 added ignition and MS3 adds sequential and Coil on Plug features. I do agree keeping it simple is not a bad idea - my friends system I set up it uses the standard distributor TFI though the MS controls the Ignition and Fuel. It is a flexible system.