I just purchased a 455 engine, code 396021F, with E heads. I think it's a 1970 engine?...Is a 1971 engine as good? Are these good heads? I've heard the E's can have different valve sizes? Should I put in larger valves? I'm missing the exhaust manifolds, are the 350 exhaust manifolds the same? I plan on going through the engine, conservatively, what hp numbers can I expect on a mild build?

 

Hi DanP. I have the same questions. Starting the same (1971w/G heads). let's keep in touch. please let me know what you learn and i will recip! Thanks. Bill. wfg4u@aol.com.

 

1970 455(E heads) will have a higher factory compression than a 71(G head) motor.
There are big and small valve heads in each casting. For 1970, pull a valve cover and check for a double valve spring, 2.07 heads used doubles, 2.00 heads used single springs.
On Any other head, you have to pull the head and measure the valve, no external clues as to valve size.(except some mid 60's 442 motors)
Yes changing to bigger valves will help flow.
Machining the small valve heads to big valve is a better route, as the machinist can change the crappy factory valve angles to a better, more perfromance orientated angle.

Prepping iron heads can get relatively expensive rather quick if yours need everything(valves, seats, guides, springs, retainers, related machine work, porting), so keep in mind that you can buy a decent set of aluminum heads all set up for about $1000 from BMRE(Bernard Mondello)

 

Just a answer to the last post, the compression differenc between 70 and 71, is not the heads. It is the pistons. Also the G and E heads came big and small valves. The main difference between 70,E and 71 G, is the G have harden seats