3782461 cylinder heads

[brumbach]

Well I finally found set of 461 heads with the correct casting dates for my 65 327/350 engine. Unfortunately they are 1.94/1.50 and not 2.02/1.60. Any thoughts to what I can expect to pay to them changed over? Any recommended shops to do the work in the Knoxville Tn or Lexington Ky area? Since I'm going to have them reworked, I'll probably have the hardened seats applied too. Thanks--Bill

 

[allcoupedup]

Check the archives on this subject. The benefit of opening up the valves is hardly worth the extra cost and risk of cracking. If you just HAVE TO modify something and install hardened seats, go with the seats on exhaust only and have the exhaust only opened up to 1.6.

You don't even need to do the hardened seats unless your current seats are recessed. There are those that insist on using octane boosters and hardened seats and then there are the rest who get along just fine without.

The heads that I am running happen to have hardened exhaust seats but I would never pay to have it done unless it was necessary.

Brian

 

[JohnZ]

Well I finally found set of 461 heads with the correct casting dates for my 65 327/350 engine. Unfortunately they are 1.94/1.50 and not 2.02/1.60. Any thoughts to what I can expect to pay to them changed over? Any recommended shops to do the work in the Knoxville Tn or Lexington Ky area? Since I'm going to have them reworked, I'll probably have the hardened seats applied too. Thanks--Bill

Enlarging 1.94's to 2.02 (and the 1.5's to 1.6) AND adding exhaust seat inserts requires VERY careful machining in order to stay out of the water jackets on the exhaust side, PLUS making the necessary unshrouding cut in the chamber wall adjacent to the intake valve, or the 2.02's will flow less air than the 1.94's did. I'd make sure the shop knows exactly what they're doing, or you could wind up with two pieces of properly-dated scrap.

 

[brumbach]

Not that I'm a teenager anymore and have the need to blow the doors off the guy next to me at the red light but would the performance between the 1.94 and and 2.02 be that different? Are we talking 300hp vs. 350 hp?

Enlarging 1.94's to 2.02 (and the 1.5's to 1.6) AND adding exhaust seat inserts requires VERY careful machining in order to stay out of the water jackets on the exhaust side, PLUS making the necessary unshrouding cut in the chamber wall adjacent to the intake valve, or the 2.02's will flow less air than the 1.94's did. I'd make sure the shop knows exactly what they're doing, or you could wind up with two pieces of properly-dated scrap.

 

[Kid_Again]

Put this one back up to the top......I'd like to know also. Anyone know of magazine reviews on the issue? As far as valve size goes, GM currently uses 1.94's on a large number of crate engines. Of course, the flow characteristics of the old and new heads must be substantially different.

 

[studiog]

Not that I'm a teenager anymore and have the need to blow the doors off the guy next to me at the red light but would the performance between the 1.94 and and 2.02 be that different? Are we talking 300hp vs. 350 hp?

Maybe John Z will revisit and answer this question. I'm curious myself.

 

[JohnZ]

Unless you're looking for that last elusive tenth of a second, I'd leave the 1.94/1.5 setup as is, rather than take the chance of damaging a really nice pair of heads. The exhaust seats are the biggest risk, and they're not necessary unless you're road-racing or towing a trailer at 100mph all day long.

The 2.02/1.6 conversion isn't a big risk, but will show zero improvement unless the required double unshrouding cut is made in the chamber wall (see photo of a factory-machined 461 2.02 chamber below); any machine shop worth their salt knows this, and has the proper tool to make the cut. If they go "Huh??" when you ask about the unshrouding cut, grab your heads and take them somewhere else. :eyerole