J head 1.88 vs 2.02

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Magiver

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I'm building a 360 to go in my 68 dart. This will be a street machine. I have no intrest in racing it.
Stock bore and stroke, a mild Comp cam kit summit #k20-212-2, performer RPM intake and J heads,
Long tube Heddman headers and 2.5" duel exhaust.
The heads are going to the machine shop soon to have the springs and seals installed. I have this urge to
have the 1.88 intake valves replaced with 2.02. I just don't know if the added expense is worth the gain of flow.
I just want close to the same horse power the my 69 roadrunner had with its 383. I think it was rated at 335 hp. Am I going to be close without the larger valves?
 
Not worth it in your case. The 1.88s will be fine.
 
RustyRatRod is probably right, but I got a super deal on 2.02"x11/32"x4.980"
part #HUG 1006E $5 ea) at Hughes Engine's. They are brand new from Edelbrock heads that they resize to 2.05's or something like that. My machinist install them for what I thought was a reasonable price (can't find the invoice right now). At any rate the make your heads more valuable if that is a factor.
 
What Rusty said. 1.88's will give better lower end response in a street-driver. 2.02's don't start to breathe until way upstairs.
 
QUOTE you have no interest in racing ? You'll never see the benefit of 2.02's til you sell them.
 
Also.....and I am SURE I will get argument here, but IMO, the larger valves are not necessary unless you port the heads. Those 1.88s can support everything the stock ports can do, because all the stock ports are good for is right around .500 or so lift.
 
If the 1.88 are sunk in the head then I would do it. But your machinest show be able to tell you what he thinks.
 
the mopar 1.88 sst int valve will flow better versus stock 1.88 valve. port velocity is way more with 1.88 valve. port velocity is far more important than big numbers! I have found, the lowly 1.88 will flow upstairs quite well.
 
Magiver said:
I'm building a 360 to go in my 68 dart. This will be a street machine. I have no intrest in racing it.
Stock bore and stroke, a mild Comp cam kit summit #k20-212-2, performer RPM intake and J heads,
Long tube Heddman headers and 2.5" duel exhaust.
The heads are going to the machine shop soon to have the springs and seals installed. I have this urge to
have the 1.88 intake valves replaced with 2.02. I just don't know if the added expense is worth the gain of flow.
I just want close to the same horse power the my 69 roadrunner had with its 383. I think it was rated at 335 hp. Am I going to be close without the larger valves?
Click to expand...

With the Summit 'High Energy' Camshaft

#K20-212-2
Lift ........................ .454"/.454'
Duration ................. 268*/268"
Duration @ .050" ..... 216*/216*
LSA ........................ 110*

With a 'Street Driven' 360, you will be better off with the 1.88" Intake in the
'J' Cylinder Heads.

The 1.88" Intakes will be 'perfect' for this application.

Bigger isn't always better all the time, unless your John Holmes {*** rated **** Star}
 
perfacar said:
the mopar 1.88 sst int valve will flow better versus stock 1.88 valve. port velocity is way more with 1.88 valve. port velocity is far more important than big numbers! I have found, the lowly 1.88 will flow upstairs quite well.
Click to expand...

Times 2

3 angle valve job, clean the bowl below the bottom angle cut!
 
Let's not get to carried away! The engineers put 2.02 valves in the 275 HP ( more like 310Hp in 71) 340's for a reason. On a healthy engine you will see more flow at low lift and low rpm with a bigger valve. If his valves and guides are fine and he can get away with just a seat regrind fine use the 1.88. But on a +.030 over 360 with headers, a good intake/carb, and a cam that has at least 224 @ .050 I'll take the 2.02 every time.
 
EL5DEMON340 said:
Let's not get to carried away! The engineers put 2.02 valves in the 275 HP ( more like 310Hp in 71) 340's for a reason. On a healthy engine you will see more flow at low lift and low rpm with a bigger valve. If his valves and guides are fine and he can get away with just a seat regrind fine use the 1.88. But on a +.030 over 360 with headers, a good intake/carb, and a cam that has at least 224 @ .050 I'll take the 2.02 every time.
Click to expand...


I can't argue with that much either............................


But my statement would still be the same either way.

3 angle valve job, clean the bowl below the bottom angle cut!
Click to expand...
 
Well now i'm going to have to wait until the wife calms down to spend more money on this 360. I am curently in deep dodo for spending over a grand in the last few weeks. I don't know what happened to her sence of humor.
 
Keep 1.88s to keep port velocity up. You will notice more low end response.
 
IMHO I would switch to the 2.02s now while things are apart. They will flow better and offer more potential. Then, if you decided to put in a bigger cam, manifold, carb, etc later, you would not have to pull the heads off and drag them to the machine shop. Can you get by very satisfactorily with the 1.88s? Yes, but I'd go with the 2.02s. They put them in the 340 for a reason. Again, IMHO.
 
the reason mopar went to 2.02 is because chev used them in their 327 and 350. called keeping up with jones's . the 1.88 flows very well, has better port velocity. the chev head 1.94 does same versus their 2.02 valve. port speed is what feeds the engine. in real world of stock and superstock, the 1.88 340 and 360 are damn fast. they are factored higher or about the same versus the 2.02 340 engines. horse power numbers sell cars!!!
 
Perfacar nailed it.... save your $$$. FWIW in our spare iron head race engine we run 1.96 small stem valves and even that engine will go 10.9's in Vegas on a nice day.
 
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