Ok, here’s my quandary. I am getting ready to build up my 1978 400 to go into my F-250 4x4. I want good power and throttle response but still want it to be a daily driver and be able to run it on regular, hence the conservative 9.5:1 c/r. The parts selection process is going great except for one thing – the heads. I can’t decide if I want to go with the Aussie heads or to just shave and build up my stock ones. Now I work in a machine shop so machining costs are not a factor. I know I can pick up a set of Aussie heads for $200-300, and, as previously stated, the cost is not a factor. My question is, are they significantly better heads? I am going to put bronze liners, new seats, port and polish, gasket match, 3-angle and all the other good stuff in my stockers (or if I bought the Aussie’s, I would do all of this to them, too). So if I do all this to my stockers and then machine them to get my desired c/r, is there really going to be a huge difference between my stockers and the Aussie’s? Are the flow figures significantly superior to my stocker’s? Are these figures going to translate to a noticeable difference in power or efficiency? I would like to get the Aussie heads, but I don’t want to go to all of the trouble of getting a set and needlessly spending $300 if building up my stock heads will do the job just as good. One other thing that troubles me is that once I machine the heads, if I ever have to do it again (i.e. overheat them) then I will have to get a new set. Also, I have heard a rumor that decking the heads significantly weakens them. Is this true? I am probably just going to get the Aussie’s, but it’s not too late if you guys think I would just be senselessly blowing money on a set of heads that will marginally outperform some built stockers. Thanks in advance for all the great advice you guys are going to give me.

 

Get the Aussie heads there's less porting needed on them, compared to the U.S. ones ( Emission Bumps )And you'll have a better flame path and better burn with the aussie closed chambers with flat top pistons.

 

Don't forget to account for the reduced chamber volume when you order pistons.



Bear Tracks

 

Ok where do I get the "flat top" pistons? I can't find any for a 1978 400 and wouldn't they make my c/r like 10.5:1 with Aussie's anyways? I don't want something that high because I am going to be driving it almost everyday. And I don't want to have to put premium in it. I would say the max c/r I want to go with is 10:1. I have heard that with stock pistons and Aussie's your c/r is right around 9.5:1, which is where I want to be. Is that correct? If it isn't, what am I looking at with Stock Pistons and Aussie's? Thanx again

 

if you want 9.5, use stock pistons. the -13.75cc dish should take it to 9.5. flattops will take you to 11:1.

 

>if you want 9.5, use stock pistons. the -13.75cc dish should
>take it to 9.5. flattops will take you to 11:1.

I know that flat tops on a 351C with Aussie heads will get you around 11:1, but wouldn't a 400 be well over 11:1 due to the larger cylinder volume?

 

This sight makes it easy to calculate compression. http://www.fordmuscle.com/calculator/compression.shtml

People claim anywhere from 54-62cc for the AU 302C heads. When you get them, cc the combustion chambers to be sure.

With a 62cc chamber, .040 gasket, .055 deck clearance and a -13.75 piston volume, I get about 9.6.
A -4cc P.V. comes to 10.6

 

Remember, the closed chamber heads give you a quench effect, which allows you to run higher compression than you would ever be able to with the open chamber heads.

 

Ok, you were talking about some 400 pistons with a -4.00 cc piston volume. Where do I find these pistons? Does Badger make them? So with those pistons I would be running about 10.6:1 c/r with Aussie's? And that will be fine for pump gas? Help me find some pistons because if I can get my c/r that high and still run on pump gas I would be really happy!

 

this is answered in another post.

 

[updated:LAST EDITED ON 15-Jun-02 AT 08:37 AM (EST)]>this is answered in another post.

Are the 9:1 pistons flat top?

 

Try here.
http://www.broncotech.com/cgi-bin/ultimatebb.cgi?ubb=do_search&search_in=ALL&search_ forum=ALL&search_words=badger&match_all=yes&search _date=ALL&search_user=&File=temp-2452441-143633-2rBq.cgi&Total=&StartAt=15

 

OK I am real sorry to keep bugging you but I am having a hard time with this whole piston ordeal. I work in a machine shop and we can order pretty much any part out there. I was looking in the dynagear catalog and it seems as though Badger is the piston division of them. As stated earlier, the 400 pistons come in 2 flavors - 8:1 and 8.4:1. I am going to call them tomorrow to see if they have any other pistons but I don't think that 8.4 is going to be enough. But thanx

 

>Try here.
>http://www.broncotech.com/cgi-bin/......

Can't if you are not a registed user of that site. What were you pointing us to?