[updated:LAST EDITED ON 01-Aug-02 AT 11:09 PM (EST)]I have a stock 400 and am wondering if it has 2v or 4v heads, and what do the Aussie heads everybody is talking about have? Plus i wanna get the Aussie Heads, Edelbrock intake and 650 Holley. How does this sound and what would you guys get?

 

>I have a stock 400 and am wondering if it has 2v or 4v
>heads, and what do the Aussie heads everybody is talking
>about have? Plus i wanna get the Aussie Heads, Edelbrock
>intake and 650 Holley. How does this sound and what would
>you guys get?

A stock 400 has 2v heads, and most have a nasty bump in the exhaust ports - meaning that they do not flow quite as well as 351C 2V heads.

Aussie heads have a smaller combustion chamber, which would raise your compression to over 10:1 but due to the quench chamber it SHOULD run OK on high octane pump gas. With a bit of machining and the larger 4V valves, it would REALLY wake up your 400! These heads are available a number of places - notably on Ebay for $250 to $400 in rebuildable condition. You can also buy them rebuilt, with valves, springs, guides, etc, and mildly machined for about $900.

If you would be running it on the street, the setup you describe sounds good. The carb is properly sized. Remember that this motor really shines at low-end torque which is ideal for the street - so build it with that in mind. Be sure to put in a decent cam designed for low-end torque and high compression, and replace the timing gear/chain with a 'straight-up' set. Add headers, dual exhaust, and electronic ignition.

All of these should get you 350 to 400 HP, depending on tuning and the cam. May as well do a complete overhaul while you are at it. All of this will run you perhaps $3000 if you shop carefully and hire it done...

 

[updated:LAST EDITED ON 02-Aug-02 AT 06:07 PM (EST)]there is ONE problem with this - the "quench" effect doesn't work unless the flat part of the top of the piston comes up very close to the head - basically, you need about .040 clearance, which is more or less head gasket thickness. so for it to work, you need close to zero deck clearance. on a 400 with no block deck milling, this means you need a piston with 1.717 compression height.

nobody makes them, as far as i can tell.

regular 351c and 400 pistons are in the 1.65 to 1.67 range, which means that you'd need to mill .047 off to get zero deck - that's MUCH more than normal, and i'm not even sure if the block deck surface is strong (thick) enough to stand that much being cut off. plus, you'd have to cut the intake to match, including slotting the bolt holes. that's a lot of work and expense!

if you just get some pistons for something else and cut them down to the desired compression height and cut some valve reliefs, you'll get like 12.6:1 compression, so that won't work either unless you're going to run race gas. and if you use regular dished pistons, then you loose the flat quench area on the piston top, so you don't get the benefit of the quench heads...

there is a solution - "reverse dome" or "inverted dome" pistons have a dish that is the same shape as the combustion chamber, so you get the quench area but also the lower compression. the trouble is that these are only made in the 351c compression height, so the piston top is still .047 down in the bore. even with the thinnest head gaskets, that's too far down for quench to work.

so what several of us here need is a reverse-dome piston with a compression height that will make quench heads work on a 400. Keith Black makes reverse-dome pistons for the 351c, which they call "D-Cup", plus they make a lot of different "special" pistons for strokers and odd crank/rods combinations and cleveland-headed windsors, so i figured they would be good people to ask about this. maybe if enough people email them and express an interest in 1.717 compression height pistons with the "d-cup", they might add it to their regular product line, and we could buy them at MUCH LESS than the cost of a custom piston...

you can contact them at:

tech@kb-silvolite.com

and maybe look at the post below if you're interested in this:

https://www.ford-trucks.com/dcforum/DCForumID12/1058.html

 

What kind of compression would you get by just bolting on an Aussie quench head to a 351C 2V block? (leaving stock-type pistons)
Mark


https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=5362&.jpg
Ford started it; Ford will finish it!

 

[updated:LAST EDITED ON 04-Aug-02 AT 00:23 AM (EST)]i'd guess that it'd be about the same as a 351c with 4v heads and the same pistons, but i don't know what the stock 2v pistons are like.

i have a theory that FORD designed the 400 with "below deck" pistons on purpose, so they could use the same pistons in the 351c and 400.

if both engines had the same heads, same pistons, AND same deck clearance, then the 400 would have WAY more compression than the 351, because you're shoving 400 cubes of stuff into the same size chamber as the smaller motor is shoving 351 cubes.

it looks like maybe they decided to make the RODS .041" shorter (than i would like them ) in the 400 so that the extra cubes would be offset by the extra room in the chamber, so the same pistons would work for both with similar compresssion.

that's fine if you have a 400 with open chamber heads - and since all 400's came with open-chamber heads, nobody (that i can find) thinks it's worthwhile to make a real 400 piston. but if you want higher compression, you need quench - and quench doesn't work unless the piston comes up close to the head.

 

ok enough on the compression height. just mill the block and the heads, its about .045 combined. it all works with flat tops and such. 4v heads are great on a 400.

 

milling the heads won't get them any closer to the top of the piston - it will just make the chambers smaller. to make it work by milling, it will all have to come off the block.

what's your setup?

 

its been posted alot. just remember .035

 

GT40 man... Do you actually own one of the GT40 kits? If so, does it have the 289 in it, 5.0, or 1 351W? (or is there another option with a kit car, and still use a ZF transaxle?)
Just curious, 'cause I love those cars! I want an MKI some day...settle for Mk iii
sigh...
Mark


https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=5362&.jpg
Ford started it; Ford will finish it!

 

[updated:LAST EDITED ON 04-Aug-02 AT 01:27 AM (EST)]i put my money on a era mk2 with a 427. but look like the market wont let me get it right now.

 

 

ok - so you're saying it IS safe to take .035 off the block deck surface?

that looks like it would work with the KB pistons:

10.297 (deck) - 0.035 (mill) = 10.262 (new deck height)

2.00 (stroke/2) + 6.58 (rod) + 1.67 (KB piston) = 10.25 (top of piston)

10.262 (new deck height) - 10.250 (top of piston) = .012 (deck clearance)

.012 (deck clearance) + .038 (gasket) = .050 piston/head clearance


with an .048 gasket it would be .060, which is about as far as you can go before quench starts to not work anymore - according to speed-pro & KB... but the .038 is listed as the stock gasket for a 400, so hopefully there are some of those around.

 

remember check with your engine builder before going ahead. always be safe.