spazz

Hi,

Can someone tell me the size of a stock 4v inlet and exhaust valve?

Also what cc is a 4v Closed chamber head?
How much cfm does a 4v inlet and exhaust port flow in stock trim?

Thanks Spazz

davis

Usually, 4V CC heads came with 2.19" intake and 1.71" exhaust valves. There were some later model US-made 4V OC heads that had smaller valves, but this is probably not an issue for you.

The stock ports, with just a good valve job will flow enough for about 520-550 HP, but the camshaft requirements to get this much work done is rather wild. With a bit of head work, 600+ is not unreasonable. Above 600 and you're looking at high port plates and massive port work at least. It is a lot easier to simply purchase a good set of alloys.


:davis:

spazz

Thanks davis.

Do you know how much cc's in a 4v Closed Chamber head? (stock).

Thanks Spazz

davis

They range from about 64cc to not much more than about 66cc, typically. Your mileage may vary... :D

xbgs351

How about the runner volumes, lengths and minimum cross-sectional area?

XD_ESP XELR8!

4V(CLOSED) I 2.50 + 1.75<size of port
62.6cc E 2.00 + 1.74 <size of port
4V 100 .200 .300 .400 .500 .600
2.19 I 64 115 163 210 246 273<stock
1.67 E 66 103 133 154 169 178
2.19 I 65 107 162 208 245 268<stock
1.79 E 50 85 122 145 160 167
HOPE THAT HELPS YA MATE