HMMMM , with all this talk about Au$$ie heads and higher Octane , I think I'll just stick with the 8.33 (at 30 over) pistons and use the $$$ saved from the heads to get a new bump stick and intake. Wonder if roller rockers & lifter valley baffle would help out???
78 F 100 Ranger XLT 400 2WD Long bed







I know a little bit about a few things , and nothing about a lot of things.

 

You can back off on the timing to get these engines to run 10:1 with pump gas but they don't run very efficient that way and power output is way down. It is better to design for the gas you can get so you get full HP and torque out of them.

 

The answer to my woes and the solution I am trying is at the thread titled "Aussie heads and flats again"...User Danlee was very helpful to me, and I am going with Aussies and slightly dished pistons with Edelbrock cam, intake, carb, timing set, etc. Check that thread for my final build setup. When it is done I'll post pictures and how it works.

DiMora

 

i done just what your looking into.i love this combo.
i used a je pistons(a 15cc dish).but the cheaper route would be to have 351c pistons bushed to fit your rod.it will give you alot of differant options.the main thing to look at when your starting to look into doing this is the comp.height of the piston.that is were the top of the piston is to the top of the deck.
i think that is a very improtant issue with this motor.
its been 2 years since i built this motor or even talked about.so i`m a little rusty,just like my old truck.i`m thinking the dyno numbers were something like 470hp 490ftlbs.not bad for a smog motor.now the cam was doesn`t come in till 2200rpm.but it is for my toy and it`s not a big factor for me.
if you want some part numbers give me a few days and i can find them.
i do run premium fuel.but my gtp has to run on it too.and when i really want some power i go to the local paint store and make my own fuel additive,the same thing that the oil companys use for octane.for $25 you can make 50gals. of 104 octane fuel.no cool smell like turbo blue but about $3 a gal cheaper you got to give up something.

 

The pistons weren't too bad...$85.00 for the set of 8. The ones I went with are made for a 400M, so deck height shouldn't be a problem...if it is, my builder has a full machine shop, so he can fix them for me if need be. I am glad you like your setup; I think I will like mine as well.

I am interested in learning about your homeade octane booster...what exactly do you get from the paint shop?

 

I have changed my mind so I am going to let you know what I did.
I check my deck height and it had been milled before to 10.245 so I had to order different pistons than I had thought. The final CH that I use is 1.655 with a 13CC for CP of 9.20 with .010 deck.

This was just the combo that I had to use. Custom pistons are expensive. I think to have them pin fit and rings was a little over $800.00

 

To answer this. You need to know your actual compression ratio(time ABDC when the intake and exhaust are shut) if your cam has the intake open the whole way up well u aren't compressing anything. Static CR is determined just by how much the cylinder can compress. The stock 400m ran like **** due to poor cam timing. So they could run on low octanes. You just need to look at your cam card and determine how far the piston moves up the cylinder according to the card(in degrees of crank rotation) before both valves close. Then take your CR measurements and make a decision. My 302 has 9:75:1 and runs good on pump 93. Mid grade makes it pop and knock tho. Hope I could help

 

Raised from the dead! Your absolutely right Dalton, but 14yrs ago it wasn't as much common knowledge, as it is today. We do need an up to date thread on the subject of dcr tho. Something with details like deck height, and squish. Dcrs used with what head and maybe what being used for timing. A what combos works thread etc.