what can i expect 318 with x heads

[roaddevil]

i like to bring my 66 barracuda back to the road and have a good running 318 left and also a set of good x heads and a tight budget . My 318 has a breathing problem so i thought i go with a mild cam , put my x-heads on it 4bbl carb (650 ? ) and a set of spitfire headers which i am allready have. What do you think can i expect from this ? Around 250 hp ???

 

[1wild&crazyguy]

lower compression=lose of throttle response and low end torque.

if you cc check and mill accordingly to 62-64 cc you be alright, but still might/will lose just a lil off idle response till 3000 rpm, just a guess

 

[RustyRatRod]

Consider adjustable rockers, too. If you mill that much, you will likely need them. Lifter preload with a performance engine should be somewhat less than a stocker. I like to run no more than .030" preload and like it around .020". It will likely be much more than that with milled heads and stock valve gear. You can use shims under the stock shafts, but it's not as accurate as adjustable valve gear.

 

[roaddevil]

hmm milling the engine would be a way to make more power of course ,but why do you think i will loose comp. with the x heads? ar they have more cc? sorry for mybad english

 

[1wild&crazyguy]

it's .0048 for every cc, they might be around 72cc now- -8cc [.038] then figure in a .039-.041 aftermarket head gasket and the push rod worry pretty much go's away.
Stock gasket is around .019 thick, so you changed/increased it around .020 pre load.

in that instance he would have the 68cc that those 318 heads are, so no cyl psi loss
though it would not make the 65cc mark and help the low end/response...unless he stayed with the thin shim or mill another 4cc off for a total of 12cc to make up for that .039 gasket and really get 65cc psi
who knows what the pre load is now with worn parts then on the other side..worn seats sunken valves...

good idea rob.
better check it out.

 

[1wild&crazyguy]

hmm milling the engine would be a way to make more power of course ,but why do you think i will loose comp. with the x heads? ar they have more cc? sorry for mybad english

usually have 70-72 cc's stock, from what I've measured.
the stock 675 318 heads I have measure 68cc's

 

[roaddevil]

usually have 70-72 cc's stock, from what I've measured.
the stock 675 318 heads I have measure 68cc's

ah okay i did not know that:-(

 

[66fs]

i like to bring my 66 barracuda back to the road and have a good running 318 left and also a set of good x heads and a tight budget . My 318 has a breathing problem so i thought i go with a mild cam , put my x-heads on it 4bbl carb (650 ? ) and a set of spitfire headers which i am allready have. What do you think can i expect from this ? Around 250 hp ???

If done right, i would think more. Get a good valve job, mill both sides of the heads, and get matching valvesprings for your cam. 340 intake and carb, or equivalent. Should be pretty strong.