Thread: 6" con. rod in 383?

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In particular Ryan's Example 56 shows that the case of a cam with a longer duration exahust pattern still benefits from the use of 1.6 rockers only on the exhaust valves.

Don Shillady
Retired Scientist/teen rodder[/QUOTE]

Well the whole idea of split angle cams was so that they could get more flow out of the stock exhaust ports. This was mainly when we only had the old stock heads to work with. With the plethora of modern well designed good breathing heads on the market today you will see that the cam designers are coming back to a straight design of camshaft the timing events on the exhaust are exactly the same as the intake because the exhaust port flow designs ahve caught up with the intake flows.

Originally Posted by southerner

In particular Ryan's Example 56 shows that the case of a cam with a longer duration exahust pattern still benefits from the use of 1.6 rockers only on the exhaust valves.

Don Shillady
Retired Scientist/teen rodder

I am not sure what happened to the first post.

Originally Posted by erik erikson

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Well the whole idea of split angle cams was so that they could get more flow out of the stock exhaust ports. This was mainly when we only had the old stock heads to work with. With the plethora of modern well designed good breathing heads on the market today you will see that the cam designers are coming back to a straight design of camshaft the timing events on the exhaust are exactly the same as the intake because the exhaust port flow designs ahve caught up with the intake flows.

On what heads has the exhaust caught up with the intake???

Weren't the long rods originally supposed to be a longevity deal to correct the rod aspect ration on some of the sroker engines???? Ran a long rod Windsor with a two ring piston and buttons on the dirt track, made good power and seemed to outlive the short rod version of the same engine displacement. Only problem was keeping the rings sealed, about 10 shows and the leakdown got a bit high.....

This year i built a long rod 383 with TS Gapless rings. I currently have over 40 shows on the motor in my Mod. Leak down is still almost nothing, and oil pressure is good. so i dont know. I do know this is the most i have ever gotten out of a dirt track motor without a freshen up.

Don't know if it was the rod or the two ring piston that caused the problems.... Curious what others thought..... 40 Shows is excellent on a circle burner!!!! Engine program for next year isn't dialed in completely yet, but I think we'll be freshening about every 20 shows......

Originally Posted by erik erikson

On what heads has the exhaust caught up with the intake???

Well, figure of speech, I should of said that the newer head designs, edelbrock, airflow reasearch, dart, et all. flow a darn sight better out the exhaust than the stock chevy 1955 to 1986 head.

for next year a Dart Block 427, flat top pistons, 6" rod, 49cc dart heads and a big fat Roller cam. Santa might just bring me the block and rotating assembly for Christmas!! I need to get rid of a couple Motors first though. Running out of places to put them right now. :P

Originally Posted by Dave Severson

Don't know if it was the rod or the two ring piston that caused the problems.... Curious what others thought..... 40 Shows is excellent on a circle burner!!!! Engine program for next year isn't dialed in completely yet, but I think we'll be freshening about every 20 shows......

Dave,the biggest problem we have is still the valve springs.
We have ran up to 25 night's on a couple engines and found springs that we a little weak for our likeing.
20 nights is a safe bet.

Erik, What kind of RPM do you run on your motors? Mine stay in the 7400 range. Valve springs have yet to be a problem for me. but i guess there is always a first time. I normally build these things and only run them one season. There is a good market out there for a well built Circle track motor. I get my use, someone else gets a good deal on a nice used motor. Although i always freshen them up before selling.

Originally Posted by mod67

Erik, What kind of RPM do you run on your motors? Mine stay in the 7400 range. Valve springs have yet to be a problem for me. but i guess there is always a first time. I normally build these things and only run them one season. There is a good market out there for a well built Circle track motor. I get my use, someone else gets a good deal on a nice used motor. Although i always freshen them up before selling.

The 380 with a mech. cam turns to 7,800

I know some of the sprint guys around here get in the 9000+ RPM range. they are constantly changing valve springs. Normally not a problem in the Modifieds.

We will be so limited with the cast iron non-ported heads and the 4412 carb, I would imagine rpm's would be in the 7200 to 7800 range, hopefully. This Super Stock class is really going to be a challenge with all the engine limitations.... Back to chassis set up and driver skill..... Greg realizes what a steep learning curve he is going to have, might even send him to one of the late model driving schools...... Any good ideas for some lightweigh 1.94's and 1.60's valves???? lol, no, we can't run titaniums!!!!!

Oh yeah, any good ideas for a steel stock stroke crank with a GM part number???? Can't be a GMPP piece, either......(sigh) I hate 50 pound cranks!!!!

Originally Posted by Dave Severson

We will be so limited with the cast iron non-ported heads and the 4412 carb, I would imagine rpm's would be in the 7200 to 7800 range, hopefully. This Super Stock class is really going to be a challenge with all the engine limitations.... Back to chassis set up and driver skill..... Greg realizes what a steep learning curve he is going to have, might even send him to one of the late model driving schools...... Any good ideas for some lightweigh 1.94's and 1.60's valves???? lol, no, we can't run titaniums!!!!!

Oh yeah, any good ideas for a steel stock stroke crank with a GM part number???? Can't be a GMPP piece, either......(sigh) I hate 50 pound cranks!!!!

Dave,take a mic. and check the stem in other words look for under-cut stems and also weigh your valves.We have found a lot of difference in valve weight over the years.

i have heard of hollow stems, but still SS and look normal. but of course thats just what i have heard...