What are the typical L-98 rod lengths in the 383's?

SR or Steatlh Ram up top, new cam probably LPE flat tappet cam, headers and stroke to a 383. Just looking for a car to be in the high 12.xx's or very low 13.xx's.

 

the easiest way to do this is a $200 383 scat 9000 or eagle crank {i prefer scat} $200-$300 6" rods, eagle or scat again...preference here is the same as the last, the scat rods are stronger, eagles are cheaper. now all you need is a piston made to run the 3.750 stroke and 6" rod. wiseco makes one that even comes with moly rings in the $400 range. {forged} speed pro also does & you can set them up fairly tight as well.

 

Typical...

5.565
5.7
6.0 inch lengths.

 

just remember, the longer you make those rods the higher up on the piston the rings get, the shallower the piston skirt and the thinner the tops of the pistons get. My understanding is that "most" people would go for 5.7" and use the more standard piston sizes. Not sure about price difference (if any), especially since you're going forged, etc- or if it's even an issue. But if you're thinking about higher HP, blown or juice-fed applications, it might be something to consider. The 5.7" versus 6.0" rod lengths seems to be a pretty subjective issue (there are even a few books on the subject referenced in previous posts), so perhaps it boils down to which vender/gearhead you talk to and the type of piston you want to buy. With the afore mentioned issues revisited, I have faith that the more opininionated forum members amoung us will chime in and aid in your decision!

:cheers:

 

Which rod length you use in a 383 is controversial as he said above. I plan on 5.7" rods when i do my engine someday. Its all about a good rod length to stroke ratio, higher is better, but 6" rods might be a little too expensive where the 5.7 will do just as good for most applications.

You should also consider the material of the rods, and their weight as more important than length. Id do a 5.7" forged rod before id do a 6" PM rod for example.

 

The choices in rods all have drawbacks and benefits.

As was said above, the longer the rod, the thinner the ring grooves and piston decks. The difference made by shorter rods is you can use stock rings, which last a very long time. If you use a longer rod, you will have to use thinner rings, which typically don't last long at all ( you will be smoking at high rpm in less than 40000 miles ).

The benefit to a long rod is less cylinder wall side loading, longer dwell time at TDC and BDC, and slightly less piston acceleration speeds. This might make a difference at 7000 RPM or so, or it might just make you feel better about spending more money, because the block is not going to crack from side wall loads anyway.

If it sounds like I am opinionated, well, after running two long rod 383's for years, I can tell you I wish I had built a short rod motor. It only took a few years of driving to notice it looks bad smoking at shift rpm's.

 

Rod length vs performance is something most people are vary mislead about. I've only built two identical engines with the only difference being 5.7" vs 6.0" rod length and pistons appropriate to each, and dyno results showed little if no advantage or disadvantage. If you want to talk to some one that has done significant engine build, graph plots, dyno testing in researching the effect of rod length, contact the guys at REHER-MORRISON RACING ENGINES in Texas phone # 817-467-7171. They will tell you that rod length is absolutely not important when looking for a performance gain! The graphs they plotted on a BBC using rod lengths of 6.135", 6.385"(+.250"), 6.535"(+.400"!) to show piston movement through crankshaft movement, when layed on top of one another it is virtually impossible to see a difference! At 10* ATDC, a point at which the most pressure is present in the cylinder on power stroke, the difference between the shortest rod combo and the longest rod combo is a mere 0.0004 of an inch!!! They have aslo built these BBC combos as test engines to prove thioer results. They built a small block dyno mule to test the different SBC rod lengths with the same results. The results showed ZERO GAIN WITH LONG RODS PAST 1,500 RPM! In simple terms, the rod connects the piston to the crank. There is nothing more to it so don't waste your time or your money on rod length combos. I know there will be plenty of guys that will disagree with me, but CALL REHER-MORRISON, THEY ARE PROFESSIONALS WITH MANY< MANY HOURS OF R&D ON THIS SUBJECT. I would recomend this, 383= 5.7 rod, forged "off the shelf" piston, and spend the saved money on port work, camshaft, or gearing....something that will result in a positve gain for your money. Ok, let the bashing begin... :lol: :cheers:

 

Well this is basicallyy what I have read, I dont want to start a major debate for sure :nono:

Stroking is where I decided to start with the rebuild and I got rid of the iron heads as many had suggested. I will likely stick with the 5.7 rods and pick up the Scat 9000 crank.

The motor will be bored out in in a few weeks so I guess I am down ot the choice of pistons and then a cam. :smash: