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Captainkirk

Captainkirk

Old School Mopar Warrior
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I've got two sets of heads I could use on my 340 build....the J's I was running before (which have been CC'd to lower the compression with the TRW pistons I'm planning on running) and a stock set of X heads. The J's are 1.88 intakes and I've been told the 1.88's will work fine on a street motor for building torque at a lower range. These heads have been ported and polished as well as CC'd and I would rather use them than molest a set of stock X heads, but since they will be going to the machine shop next spring, would it be a worthwhile investment to up them to 2.02's at the same time? I don't want to spend money recklessly and can live with the 1.88's if they won't buy me that much on a street motor. Your opinions?
 
You can definitely do fine with 1.88s on the street; the only thing I could see as a potential problem is when you get the seats cut for the rebuild, it'll set the valve deeper in the parent material and increase the volume a little bit. You can get 2.02s and they would sit high in the chamber and provide better flow with a fresh cut seat, but you'll be spending more for new valves...up to you though.
 
Stick with what you have,JMO. The 2.02 valve done correctly ,bumps low lift flow at the expense of intake velocity. Fwiw,the 1.88 intake starts stalling around .460-.480 lift unported.
 
Hebrews10:26 said:
I dont think there is a large enough valve that could steal velocity from a 360/340 head.
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This seems to be a point of contention amongst engine builders. My engine guy says the 1.88's will give me better low end torque below 5000 and with a flat-tappet cam and 6500 redline I should have no need for the 2.02's and that the 1.88's will actually perform better in my application. Just not sure if I buy it.
 
Captainkirk said:
This seems to be a point of contention amongst engine builders. My engine guy says the 1.88's will give me better low end torque below 5000 and with a flat-tappet cam and 6500 redline I should have no need for the 2.02's and that the 1.88's will actually perform better in my application. Just not sure if I buy it.
Click to expand...

I'd stick with the 1.88 J heads as they are already done port wise. I would also stay with the 1.88 valves as upsizing to 2.02 will require a moderate amount of port work to actually yield a benefit. Merely having the seats
opened to 2.02 without doing the complementary port work won't do anything for you and may in fact hurt. If your heads still have the factory valves, replace them with one piece stainless valves. This virtually always improves airflow and durability.
 
skrews said:
I'd stick with the 1.88 J heads as they are already done port wise. I would also stay with the 1.88 valves as upsizing to 2.02 will require a moderate amount of port work to actually yield a benefit. Merely having the seats
opened to 2.02 without doing the complementary port work won't do anything for you and may in fact hurt. If your heads still have the factory valves, replace them with one piece stainless valves. This virtually always improves airflow and durability.
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Where would I find stainless valves?
 
Try S.I valves,California. Or Competition Products, Wisconsin. Skrews dead on,in the airflow &durability improvement...
 
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