just wondering what u guys think of the 308 heads i find they maky great power when ported
308 heads
- Thread starter jimjimjimmy
- Start date
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Agreed. The ol'iron head is preety good and a bargin if found cheaply/done cheaply. Excellent head for the street. No to bad for the strip ethier. Fully done up, the should be less than a Edelbrock head, but the flow can not complete with a apple to apple port job on the heads. Still, for about half the total cost and some good broad flow numbers............Hummmmmmmmm
I like the 308's. I have a set with 2.02/1.60 valves and ported, flow numbers look like this (compared to stock 915's on the same bench)
Lift Stock 915's 308's
0.200" N/A 165.78
0.250" 154.63 184.36
0.300" 178.42 202.20
0.400" 199.97 243.84
0.450" 197.00 258.70
0.500" 193.28 263.91
0.550" 193.28 257.22
0.600" N/A 252.76
Sorry for the formatting, site keeps correcting it. Anyway, my ported 308's flow 264 cfm at .500" of lift, which should flow well enough to support over 500 hp. The design of the exhaust port is a big improvement over the J and X heads. The only issue with the 308's, like other smog heads, is that they tend to crack between the seats because of the way the seat hardening was done. Not the end of the world, and I found a set without cracks.
That said, the new RHS X heads will outflow a set of ported 308's with 2.02/1.60 valves and no porting. Plus, they're a closed chamber design. So, it depends on what you're looking for. I probably saved a little money by having the 308's ported, but not a ton. Now, if you can do your own porting, then its a different story. I also chose to go with the open chamber design of the 308's because they were going on my 340, and since it's a '68 the pistons are .018" over the deck, so closed chambers can get sketchy with valve clearance.
Lift Stock 915's 308's
0.200" N/A 165.78
0.250" 154.63 184.36
0.300" 178.42 202.20
0.400" 199.97 243.84
0.450" 197.00 258.70
0.500" 193.28 263.91
0.550" 193.28 257.22
0.600" N/A 252.76
Sorry for the formatting, site keeps correcting it. Anyway, my ported 308's flow 264 cfm at .500" of lift, which should flow well enough to support over 500 hp. The design of the exhaust port is a big improvement over the J and X heads. The only issue with the 308's, like other smog heads, is that they tend to crack between the seats because of the way the seat hardening was done. Not the end of the world, and I found a set without cracks.
That said, the new RHS X heads will outflow a set of ported 308's with 2.02/1.60 valves and no porting. Plus, they're a closed chamber design. So, it depends on what you're looking for. I probably saved a little money by having the 308's ported, but not a ton. Now, if you can do your own porting, then its a different story. I also chose to go with the open chamber design of the 308's because they were going on my 340, and since it's a '68 the pistons are .018" over the deck, so closed chambers can get sketchy with valve clearance.
i hope they work as good on my new 340 with a 4"stroke as they did on my 340 im hopeing for close to 500hp . oh ya my cam is 540and 555 lift and 255 and 260 at 50 comp cams im going to use this setup . it worked good with the 340 do you guys think this will work real good with the 4" stroke thanks
sorry solid lifter and hold from laughing a port o sonic intake
The Port-o-sonic is a good intake.
You should have said it was a stroked engine. Now the head choice takes on a new twist. This is a surprise, something I hate to continually adjust for/on. If you tell us what your doing, you'll get better advice and proper parts.
Is this also supercharged/Turbocharged?
You should have said it was a stroked engine. Now the head choice takes on a new twist. This is a surprise, something I hate to continually adjust for/on. If you tell us what your doing, you'll get better advice and proper parts.
Is this also supercharged/Turbocharged?
im using all my old 340 set up . ported 308 heads solid comp cams 273 solid rocker shafts portosonic intake ported to match ohhhhh 202intake valves fforged pistons i use this now in my 73 duster with a 4000 dynamics converter thermoquad carb it runs 11.90'sall day with a stock rear suspension i was wondering if i stroked it 4" how this would work . the cam is. intake lift 540 . dur at 50 is255 .exhaust lift 555 dur at 50 is260 e thanks my typing sucks
LOL, my spelling sucks.
IMO, skip the 308 heads in favor of a higher performing head. The 308's are good OE iron and would require some serious porting to get ya going. You would be better off performance wise going to another head.
Iron, W2
Aluminum, Edelbrocks would probably be cheapest, Brodix is another option.
IMO, skip the 308 heads in favor of a higher performing head. The 308's are good OE iron and would require some serious porting to get ya going. You would be better off performance wise going to another head.
Iron, W2
Aluminum, Edelbrocks would probably be cheapest, Brodix is another option.
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