WETTE VETTE

Please don't run stud mounted rockers with a .700"+ lift cam!! Run Jesels or T & D shaft rockers. If your buddy was running studs in a drag car with big lift and RPM it doesn't surprise me that he pulled a stud!! Was he even running a stud girdle?

JimV

42MTI

I found the new Dart cataloge. If the 370's that you are refering to have a 119 cc chamber it's problaby the 24 degree head. I don't like recommending anything I personaly haven't tried but I'd stick my neck out on this one. The 16875050 18 degree would be worth looking into for big inch motors. Interesting it has a 2.350 intake and a 1.840 exhaust valve.

Mr Gadgets

Jim,
any more research on the flow with an exhaust header? Did you get any info on the 18* Darts?
I have a sheet on a 383cc CNC Oval port. PN 16800000; 102cc chambers. The numbers are good at the high lift, but it was tested on a 4.500" bore. Put it on a real motor with 4.605" bore and a 4.875" stroke and it might just work?? What do you think Jim?

Dick

JimV

Very impressive numbers on the 18 degree heads. I got some numbers from Dart at the trade show. I should have some flow numbers with a header next week.

PatriYacht

Jim V is finished with my heads but apparently he's too busy to post the numbers. So I'll put them up for general info. Remember they were cnc ported AFR 335's.

After exhaust and chamber port

intake exhaust
.200 154 143
.300 236 206
.400 301 251
.500 350 279
.600 380 289
.700 391 295

Adding the cheater pipe to the exhaust brings it up to 347 at .700. The heads flow like real race heads now. Jim really knows his stuff. However, for the amount of money I have in these heads now, I would've been better off buying a set of hand ported Dart 320's from Jim in the first place. I'm hoping to get these on the dyno in the next month or so.

Tinkerer

That is why I just buy the heads direct from JIM in the first place.

KAAMA

Lookin' good Ian. JimV really did a nice job on those exhaust port flow numbers. Those heads ought to give your engines a real kick in the britches this year. We'll all be looking forward as to the dyno results----keep us posted. Thanks

JimV

Thanks guy's

Sorry for the delay. Dick you asked for some numbers with a full header. Flowing the header allowed me to clear the paperwork off my bench in a hurry.

.2...............138
.3...............180
.4...............211
.5...............232
.6...............241
.7...............243
.8...............246

It choaked it pretty good. Interesting though the 6" 2.1/8 pipe outflowed the 6" 2.1/4 pipe at the head. I slipped the 2.1/4 pipe over the 2.1/8 and it increased another 3 percent with a total lenth of 12 inches. Maybe there's something to those stepped headers.

Mr Gadgets

Jim,
what brand of header did you use? Was it a CMI and did you use the whole header or was it a partial? I can see it choked it down, but what were the original numbers? There have been so many numbers in this thread it is hard to tell whats what. Can you hook your flow bench up to the computer and just let it report the numbers straight to OSO?? Then we would be flying.. LOL!
I have a CMI lower if that is a help. Also have my modifed uppers from the 25' Checkmate if you want to do any more chokin of the flow..

Dick

PS. almost moved into the new shop, hope to get your upper assembled soon.

WETTE VETTE

No scavenging is taking place by testing just one port with a header bolted up. The benefit of exhaust scavenging is one of the main reasons for running a true header. To further complicate things the benefits of scavenging doesn't really start to show up until about 5500 RPM and above on most motors. This is why some manifolds actually do as well, if not better than headers at lower RPM's, and the headers do better as RPM's get high. Personally I think testing the exhaust port flow with a pipe is somewhat bogus. Subtract 7% from AFR's reported exhaust flow numbers to get a better comparison with other heads. Just my .02!!