About to put my head in the machine shop and was curious what my option were. Dont know much about heads but anxious toget some education on them. I am buying larger valves for the six and wanted to know if its OK to put the bigger valves with the Chevy 250 rockers and a mild can without damaging the engine by the valves hitting the pistons? Or can I put that with a stock intake and one barrel carb? Or do I nee d to get the Clifford right away to have it run right with the mods done the upped half of the engine ? Was going .030 over as well Might be a stupid question. Not an expert on heads at all. Been planning my dream 300 for a while and finally going to get it.

 

Suggestions: Have the head shaved only as much as necessary to clean/true it up...probably not more that .010. The Chebby rocker trick is usually done with a stock cam. If you want more lift, obtain a cam with the higher lift built-in. I have yet to see any problem related to valve/piston clearance in a 300.

Sit back and do a whole lot more reading of this Forum and here too: FORDSIX PERFORMANCE ? Index page

 

You can read here on FordSix.com where I asked if I would be safe to use 1.75 Chevy rockers. That thread and any other research I had done had steered me away from it. You'll be okay, but it will put more stress than necessary on the valvetrain, especially with the pushrods being 10" long, but more importantly if you're at the point of having a head at the machine shop you're better off putting in a camshaft than you are installing bigger rockers. Do some math and figure out what your total lift would've been with your "mild cam" and your taller rockers and then go find a camshaft that will give you that lift with factory spec rockers. I highly recommend Crower or Iskendarian as they're both made in USA. I just recently got my Crower cam, lifters, springs, and roller rockers in the mail. You'll find that a lot of people go with the Comp 268 cam but Comp has the highest lobe failure rate of any flat tappet camshaft manufacturer...

What size valves are you buying? I bought 1.94/1.60 valves from SI. Made is USA and as far as I can tell, made properly. Be warned that the exhaust valves are on a long back order right now.

You got a timing set yet? Get the Cloyes kit. You're welcome.

There's no point going for a bigger camshaft with bigger valves and then using the factory manifolds and carburetor which will only choke up the engine and waste your money. Spend the money on a carb, intake, and exhaust.

 

x2

Your money would be better spent on an intake, carb, and exhaust. Those things will very much wake up your whole engine and give you ample gains. The headwork and cam only add to those things.

The stock intake and carb are already restrictive enough that the engine can't fully utilize itself, so opening it up more while still using the stock fuel delivery will not amount to much.

 

Ditto the above, though you really should have said what you're after (daily-driver? street performance? other?).

If this is your dream engine, and you haven't started assembling it, read up on squish (google it, or go to www.speedomotive.com) and ask your machinist about it (it involves you or him doing some test-assembly and measurement, and him milling the top of the block). This is a win-win for any engine which has a squish area in the combustion chamber, for any purpose, no downside.

Use something better than the Ford 300 pistons, which crack.