Hot Rods Angle milled heads, timing?

Here is a question for you smallblock Chevy guru's, ( I know I call the "mouse) motor a rodent engine but am occasionally required to work on them!)...anyhow I am working on a standard bore and stroke 350 with EXTREME angle mill and it ran like a sick pig , ran 250 degrees water temp at 36 degrees total spark advance, it even sounded flat and he spark plugs looked lean...fast forward to yesterday when we determined the angle mill must have shrunk the combustion chamber enough to slow the flame travel, bumped advance up until it sounded correct, had no idle water temp issues and were at 44 degrees total advance...anybody have experience with this issue? Is it worth trying?...we are not afraid to experiment but don't realy want to be embarrassed again if it still can't pull a sick hooker off of a hopper!

 

I've had mine angle milled as much as possible without what you are experiencing. It was a race only engine but it seemed normal in all respects. I'd go back thru your cam timing, sounds like it is retarded.

 

What fuel are you using....

 

Race only engine,( oval track, north east modified style car, economy- sportsman class engine 110 octane vp racing gas, I don't currently know about cam timing, I am not the guy that assembled it .just trying to help tune it but I will ask builder about it...thanks for any and all info and help guys!

 

We angle milled hundreds of Chevy double hump heads in the '70s. No one ever had a heating problem.

 

What are you using for an intake? How does it fit? If the spark plugs look like it is lean and you have to have a lot of lead to make it run you may have an intake sealing issue which is common even if you are using an intake built for the heads (not all angle milling is created equal).

As for cam timing I commonly run my [personal] motors with the valve timing a little slow, they don't run hot and unless I am running one really slow (seldom do that) they are not sluggish and I don't have to run tons of lead. For a circle track car unless it was a short track motor I can see retarding the cam to be advantageous, a few more Rs on the back stretch could be a good thing.

 

Are you sure your timing marks are correct?

 

good question, I will check that ....thanks again guys for all suggestions !

 

For a quick check pull the valve cover and watch the valves on number 1 as you turn the engine. When the exhaust is closing and the intake starts to open and they are both open the same amount you should within 2 or 3 deg. of TDC. If not you have a bad damper or mismatched parts.