High Compression Head

Smitty

Smitty

Well-known member
Are there any negative aspects to using a high compression head over a stock head? Is it all gain or are there trade-offs?
Most folks running high compression head these days?

Thanks, Steve
 
I have been running a Brumfield 5.9 for 10 years. Not the first hint of a downside yet. Also running a Brumfield 5.9 in the speedster for three years with no negative side effects.
 
Some of the heads are not recessed for piston clearance like the originals so you need to check clearance from head to top of piston. I don't think this is a problem with the Snyders or Brumfields.

Charlie Stephens
 
I have heard that it is important to not run too much advance when the engine is loaded up such as going uphill. Savvy operation of the advance lever can help prolong babbit life.
 
I run a 5.5 and have had no trouble. In fact the engine runs sligtly cooler with it than with the standard head.
 
I have a high compression head on both of my A's. I haven't noticed anything negative after about 3000 miles of use on each car. What is very noticeable is the difference in performance. There's a long hill of about 1/2 mile near my house. With a stock head, I had trouble maintaining 35mph on the hill. With the new head, 45mph is now possible, and I can keep up with most of the traffic.
 
I have about 1500 miles on a Snyder's 5.5 head and have had no problems but enjoy the increased performance.

dusty
 
I have been using both Snyders and Brumfield heads with no apparent problems. I have found that the Brumfield, at 5.9, does have a tendency to detonate under load. backing off the throttle and/or retarding the spark stops it. Once learned, it is easy to anticipate the problem and avoid it completely.
 
Due to the compression pressure (running cylinder pressure), turbulence and air flow characteristics, all of which combine to make the Brumfield Heads a real power and torque producer, the Brumfield Heads have a faster flame speed and do not require as much timing advance for a paticular speed and load. If you hear any pings or knocks then you have the timing too advanced. Retard just enough to make the noise stop and that's it.

For those who really want to fly, i.e., race track speeds along with other mods, a high compression head with a faster fame speed allows more room for timing advance, if needed, when revved to the highest RPMS.

Larry Brumfield
 
Just had my old head resurfaced ,runs good but wish I had went to a higher compression head,lack a little power but not knowing the background on my A motor thought it may Crater under more pressure.
 
You shouldnt have any problem running a high compression head....unless if your head is aluminum (then you might run into some problems)

people who use their model A's as daily drivers and what to put an aluminum head on there will run into the problem of a blown head gasket because of the heat.
 
I have an aluminum Weiand 7:1 and it runs cooler than the stock head. No gasket problems. A reprint of an old Hod Rod Magazine article out of the 50's says to retorque an aluminum head hot, and a cast iron head cold.
 
Rebuilding a B engine, read on a recent thread (can not find ) that a B head stock C stamped was about 4.4 and an A head was higher, would you but an A high compression Head on the new B engine??? Bruce
 
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