[CNC BLOCKS NE]

From what we have seen on the 6.200 and 6.250 rods is they make better horse power at a little bit higher RPM and don't fall of like the 5.7 rod engine and like I said it will require a special cam as the engine breathes different with the longer rods. And on the longer rod engines the torque is not as good as the 6.0 or the 6.125 rod engines.

And as far as cam clearance there should not be an issue on some of the high end flat tappet engines we build we go to the BBC cam tunnel in both the 010 blocks and the Bowtie blocks and 3.500 cranks and there seems to be no issues so far.

Ond on some blocks we machine them for 50MM roller cam bearings and still no clearance issues.

[johnsongrass1]

Originally Posted by engineczar

3.48 x 4.125 is 372 CuIn.

I do agree with JGrass on using thin rings with horizontal gas ports. As far as clearance issues, going with the stock stroke but using the longer rod length won't cause interference issues in the bulkhead area. The angular difference at the rod journal is nill. The problem with too much rod length is the wrist pin occasionally has to be located into the oil ring groove which means a spacer is needed to support the ring package.

Thanks, I was thinking the 3 1/3. I assumed they would check this with a whistler and it would be close enough for tech. Most dont work too well. The operators I mean

[briscoe]

bonuts,I ran a 3/8ths asphalt track for several years,enjoyed my best success when I went to 6.00 rod lenth,from 5.7.I did have to pay for lot of dyno time,my engine builder was experimenting with camshafts,but it was worth it,with this change,and a little bit of head work [something about acid dipping]I gained 24 hp on the dyno.I hope this encourages you to stick with your plan.Briscoe

[Lonestar]

Originally Posted by johnsongrass1

If the only thing I might say about it. DO NOT build your circle track engines like street engines. They are a whole nother animal all together.

Them words is priceless...

We only took the time to install the longer rods on the roundy-round cars...although we did put the 6 inchers in a 400 for streep / strip and found it wasn't worth the hassle. In fact, that engine wound up in the circle track car also.

[bonuts]

Hey thanks guys. Johnson, thats what I was trying to say when I was told not to run a long rod set-up. It is a race car, not a street car. I have talked with most of the guys who run NW tour engines and at the tracks we run most of them are running around 7900RPM, with one guy who is up in the 8k range.

As for the carb, we are told 650cfm, no other restrictions. The tour motor guys have to run 390's. They are teched.


bonuts

[CNC BLOCKS NE]

Here is a link I dug on long rods.
http://www.stahlheaders.com/Lit_Rod%20Length.htm

[johnsongrass1]

Sometimes I wonder why they make those rules.


Instead of allowing any carb, probably stock 850's, they call it 650 only and force you to spend twice as much to compete.

PM for a good carb guy.