[retrojoe]

Ok, I have a question about which set of heads to use. I will be rebuilding a 67' 400 to place in my 66' Lemans,to replace the ever lovely H.O.65' 326. My question is, I have a set of 455 4x heads, a set of 400, 143 heads, and access to a set of 6x heads. Which would be the best set to use on the rebuild? I do not plan to build a "massive" motor , just something that will stick your booty to the seat, and be fun to drive without "tuning" every weekend to run. The only strange thing about the 4x heads is that on one of the exhaust ports the center divider has a strange casting flaw. It does not meet from top to bottom as a perfect divider between ports. It has a small gap between the two center exhaust ports. Is this norm? Which heads should I concider?The rear gears, are a massive 2.56 at this time! I would like to lower them to somewhere around 3.08-3.55. Any tips would be great!

[retrojoe]

Ok, I have a question about which set of heads to use. I will be rebuilding a 67' 400 to place in my 66' Lemans,to replace the ever lovely H.O.65' 326. My question is, I have a set of 455 4x heads, a set of 400, 143 heads, and access to a set of 6x heads. Which would be the best set to use on the rebuild? I do not plan to build a "massive" motor , just something that will stick your booty to the seat, and be fun to drive without "tuning" every weekend to run. The only strange thing about the 4x heads is that on one of the exhaust ports the center divider has a strange casting flaw. It does not meet from top to bottom as a perfect divider between ports. It has a small gap between the two center exhaust ports. Is this norm? Which heads should I concider?The rear gears, are a massive 2.56 at this time! I would like to lower them to somewhere around 3.08-3.55. Any tips would be great!

[David Holmberg]

Joe don't use the 455's 4x heads. They have large chambers and compression on a 400 will be way too low.

I would go with the 6x heads, 6x-4's would be preferred (around 8.? comp but you can mill them to get what you want).

[Gooatee]

Ditto to what David said! With the right cam you could have a nice street car! A little more gear would do the trick like 3.73's!

[retrojoe]

Thanks for the help! I guess the 4x heads would be great for a blower motor! Are the 143's any good? Also can I fit 373's in my 10 bolt rear? I've heard that you can only go to a certain size ring in those rears.

[cpetrice]

hey joe. I was in the same boat with the 143 heads question. they are small valve,press in studs heads. if you want to make them screw in studs for performance aps,it would be cheaper to get better heads,as I did. I took the 143 heads to the shop,to have them get a valve job,valve seals,new valves,milled a little,use the factory springs and valves,press in studs converted to screw in studs,would have cost me a little over $600. instead,I bought a pair of 670 heads,larger valve,comp springs,teflon sealed,milled,stainless valves,already screw in studs,for $450.

[retrojoe]

Thanks for the tips! I will see how much my buddy wants for the 6x heads, or see if he wants to trade for the 4x heads. I could use the 143's for a door stop in the garage! [img]/infopop/emoticons/icon_biggrin.gif[/img]

[larry davis]

6X all the way!