My 73 340 has a set of 051 heads . What is the best way to get more out of them. For what it would cost to buy a set of x or j heads would I be better off to put the money in the 051s?
73 340 with 051 heads
- Thread starter christmas53
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In general, no matter the head, they all flow pretty much the same and all port out very well. The best way to upgrade the head is starting with quality valves. 2.02/1.60 sizes are the best bet in most applications. Seldom do I see larger in these heads.
Once the larger valves are in, the next step is to bowl port them. The area under the valve needs to be expanded to allow the valve size increase to be effective. How far you port the heads there after should be in line with the power goals of your build.
Getting another set of heads to build while you drive with the old heads on is fine IF you don't mind another set of heads laying around and the extra cost of getting said heads. What ever they may cost.
Once the larger valves are in, the next step is to bowl port them. The area under the valve needs to be expanded to allow the valve size increase to be effective. How far you port the heads there after should be in line with the power goals of your build.
Getting another set of heads to build while you drive with the old heads on is fine IF you don't mind another set of heads laying around and the extra cost of getting said heads. What ever they may cost.
Just port whet you have..
fishy68
Tyr Fryr's Inc.
Rumble nailed it. Their all such similar castings there's no use in buying different heads unless you run across a screaming deal on some that you can trust. One of the biggest problems with any older heads is most of the time their so worn out when you get them that it'll cost nearly as much to have them rebuilt as it would to buy new heads that perform much better right out of the box such as the RHS X or EQ magnum heads.
perfacar
Well-Known Member
after much flow testing on 340/360 heads, the stainless 1.88 valve flows very good, the port velocity stays up. velocity is way more important than big numbers. a 4 angle seat and 3 cuts on valve face will get you good flow and port velocity. the port was designed for a 1.88 valve. I've found flow loss and loss port velocity when 2.02 valves are installed. same thing on small block Chevrolet heads. just food for thought.
Agreed on the loss on the lower rpm scale.
Once you start moving, it's all good and not an issue. Power increases everywhere.
Absolutely nothing wrong with staying with the smaller valve. However since the head is old and may have had work prior, I voted for the 2.02's. But if the 1.88's are what he wants to stay with and its the engines first rebuild, no harm or foul.
Once you start moving, it's all good and not an issue. Power increases everywhere.
Absolutely nothing wrong with staying with the smaller valve. However since the head is old and may have had work prior, I voted for the 2.02's. But if the 1.88's are what he wants to stay with and its the engines first rebuild, no harm or foul.
moper
Well-Known Member
2.02s mean the seats can be moved out too. IMO there's a difference in having to run the smaller valve for class reasons and looking to eek out that last iota of power or just being able to run anything. If there is wear on the 1.88, sinking it will add volume to the compression equation in addition to reducing flow at low lifts. with 340/360 heads I see no reason to keep 1.88s in anything if you're going through them anyway and there's not a rule saying they have to be in there.
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