Piston and con rod dilemma

-
oliver

oliver

Well-Known Member
Joined
Jan 12, 2011
Messages
567
Reaction score
252
Location
Vallejo, CA
Not to sure what i should do about the pistons and rods in my .60 over 340. I currently have a set of l2316 forged trw's and stock bushed rods, i just found out the top ring lands in all the pistons are wore out and you can stick a 8 thou feeler in between the ring and piston :-x For fun i weighed the piston and rod combo and it was 1844 grams! :-s Wow crazy!

Think i should go to a set of KB hyper pistons and eagle or scat rods or hyper pistons and rework my old rods? I figure that its going to be 150 to resize the rods and 50 bucks or so for the arp hardware, scats are less than 100 dollars more and the hyper and scat rod combo would be only 1230 grams. The motor is going to be a 555 lift solid roller and plan to spin it to 7-7500 rpm's... Any input? Should i consider other pistons or rods? Im trying to keep this on the cheap and going to also have to pay around 300 for balancing the assembly. Ugh, this motor is a nightmare.
 
I think if you're looking for that high an rpm I'd go forged pistons. The hyper should work, but I think it will last better with forged. Otherwise, you have goood common sense. Lighter is better, and the cheaper I beam rods are fin as a stock replacement with a light piston. I would not run H beam rods with that rpm.
 
Agree with Moper that forged pistons and aftermarket rods are good choice for your motor but I still would have some concern over your 340 block which is already bored.

.060 is the largest over bore that pistons are readlly available for the 340 block so checking the bore sizing will be critical in this case to see if you can still use a .060 over piston especially since your current pistons are worn out.
 
The motor is going to be a 555 lift solid roller and plan to spin it to 7-7500 rpm's... Any input
Click to expand...
What duration? Cam manufacturer? What HP level/range?

If your looking to step up, depending on what arena your driving in, the choice of new rods is probably impossible to beat over reworking the old rods.

Hyper-U slugs are fine for street and strip performance. A forged slug is top dog and will take alot more abuse at the track for a longer period of time.

If your doing a "primary" street engine, then a set of inexpensive Eagle or Scat rod thatare good till 500 HP will do you well coupled with a set of Hyper-U slugs.

IMO, I doubt you'll need to spin the engine to 7grand to make max power. Highly doubt it.
 
With steep gears--4.10 or so--7,000 comes on pretty quick. True you can run a rev limiter at 6,800 and use hyper pistons all day long expect like was said, if pistons are worn out how is the bore?
 
You can not compair the SCAT I beam to an Eagle I beam, not even close to being the same rod. The Eagle I beam and Stock rod are compairable, and I would use a worked over stock rod before an Eagle I beam.

The SCAT I beam is lighter, stronger with its 4340 forging, and has 7/16 ARP rod bolts, you can even get them with ARP 2000 bolts. They have proven to me that they are the best I beam rod out there for the price.

You want to run 7500rpm for cheap. Ok, but dont expect it to last forever. The cheap way is SCAT I beams, KB 243 pistons. You will see an increase in compression going to the KB pistons over the Speed Pros you have now.
 
What would you suggest would also have to be done to increase the engine durability when being revved like that? IMO, revving a 4bbl SB that far, especially stroked like I may build, is way past peak power.

Does make for a cool burnout though.
 
if money id not an issue, id go with oliver connecting rods and diamond pistons, My dad has this 1968 dodge power wagon with a 1200 horse power 540 wedge. I know im compoaring apples to oranges here but id go with the oliver rods cause thats what im doing this winter in my big block dart and same with diamond pistons. if you spend a little bit more money up front then you wont have to later on, and id use a new crank, also just for insurance
 
think building a small block is a nightmare, try a procharged 540 that makes 1205 horse power on motor on pump gas, and try to not blow parts up and try to make it driveable, ya thats a nightmare
 
MRL Performance said:
You can not compair the SCAT I beam to an Eagle I beam, not even close to being the same rod.
Click to expand...

Just incase this is towards me, I didn't mean to even try to do that. Compare them as equal or similar.
However, a set of inexpensive rods they be. You can name more inexpensive choices if ya like.




The SCAT I beam is lighter, stronger with its 4340 forging, and has 7/16 ARP rod bolts, you can even get them with ARP 2000 bolts. They have proven to me that they are the best I beam rod out there for the price.
Click to expand...
Ooo, this is good to know since your building them alo (Engines.)


You want to run 7500rpm for cheap. Ok, but dont expect it to last forever.
Click to expand...
Amen!
 
rumblefish360 said:
What duration? Cam manufacturer? What HP level/range?

If your looking to step up, depending on what arena your driving in, the choice of new rods is probably impossible to beat over reworking the old rods.

Hyper-U slugs are fine for street and strip performance. A forged slug is top dog and will take alot more abuse at the track for a longer period of time.

If your doing a "primary" street engine, then a set of inexpensive Eagle or Scat rod thatare good till 500 HP will do you well coupled with a set of Hyper-U slugs.

IMO, I doubt you'll need to spin the engine to 7grand to make max power. Highly doubt it.
Click to expand...

288/288 adv duration, 244/244 at .050" lift. Comp magnum 288r. HP range is going to be 420-450 HP. The cam is advertised to make power from 3k-6500, should spin up to 7k no problem.
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=684&sb=2

Im going to be running 3.91 gears and a 4 speed in a 3k pound car. The heads im using flowed 260 at .500, using a single plane torker II 340 or edelbrock rpm with a 750 cfm carbbie. Im not going to be spraying the motor and it it going to be mostly a street/strip car with maybe 20 runs down the track ever few months.

This is why i figured that maybe light is the way to go, a set of kb hypers and scat I beams would weigh almost 600 grams lighter than the stock setup.
 
dodge freak said:
With steep gears--4.10 or so--7,000 comes on pretty quick. True you can run a rev limiter at 6,800 and use hyper pistons all day long expect like was said, if pistons are worn out how is the bore?
Click to expand...

Im thinking that this motor should hold together at 7200 fine if it has a good balance. The bores are good, just had it hones and checked. Block sonic checked good and the top ring lands are all worn out and even the rings wore... 3 pistons had broke upper rings. This motor was spun to 7k all the time by the previous owner.

67 prostreet gt said:
if money id not an issue, id go with oliver connecting rods and diamond pistons, My dad has this 1968 dodge power wagon with a 1200 horse power 540 wedge. I know im compoaring apples to oranges here but id go with the oliver rods cause thats what im doing this winter in my big block dart and same with diamond pistons. if you spend a little bit more money up front then you wont have to later on, and id use a new crank, also just for insurance
Click to expand...

Oliver rods? Didn't know i made con rods! :happy3:

67 prostreet gt said:
think building a small block is a nightmare, try a procharged 540 that makes 1205 horse power on motor on pump gas, and try to not blow parts up and try to make it driveable, ya thats a nightmare
Click to expand...

Tell me about it, just finished building a 512, everything on that motor had to be machined, clearanced, shimmed, checked, shaved. LOL
 
MRL Performance said:
You want to run 7500rpm for cheap. Ok, but dont expect it to last forever. The cheap way is SCAT I beams, KB 243 pistons. You will see an increase in compression going to the KB pistons over the Speed Pros you have now.
Click to expand...

I don't expect it to last forever, the motor is already at .060 over. My trw's are .025-.030 out of the hole already and cc'ed at 8cc's. The KB's are going to be more outta the block? This is on a stock deck too.
 
rumblefish360 said:
Again;


Lighter is better for performance.No doubt.

MRL spell a few things out well. His is IMO a preety good idea.
Click to expand...


That was what i was thinking too, but i really think its going to take 7000rpm's to make max power.
 
LOL, OK, dyno it and let us know.

Ask MRL's opinion. He works on MoPar engine s ALOT! I would certainly respect is thoughts on this.
 
rumblefish360 said:
LOL, OK, dyno it and let us know.

Ask MRL's opinion. He works on MoPar engine s ALOT! I would certainly respect is thoughts on this.
Click to expand...

Maybe he will chime in. So it looks like the consensus will be the KB hypers with the scat I beams and give it a damn good balance. Should be a hot little street machine.
 
yeah, this motor at first we had to wear breather masks just to be within 20 feet of the thing, it was so rich then we switched carbs then we switched ingition, all in all we spend a good chunk of change in just replacing stuff and now it sits because ive got my dart to get ready for the nationals and my dad is gone alot, who knows maybe well get it done, course is it ever done? i think its not but thats just my opinion
 
The KB pistons have a 6cc volume, 2cc less than the TRWs. so you will se a slight bump in compression. They both have a 1.840 ch, so your good there.

Your peak power is going to be under 7000rpm with that cam. You would need a minimum of 250* @.050" to get it to peak at 7000rpm or above. You can take it to 7000rpm, but you will really need to play with shift points. If you go to high, and bypass the torque you wont go any faster.
 
I'm using the kb 243 in my 340 expect I had a 72 340 that had all original stuff so I re used the rods and had new apr rod bolts install and big end resized. Got a old factory forged crank that cleaned up at .010 under.

It has 3,000 miles now in its first year, seems as tight as when new. My rev limiter is set at 6,500 thou. Needs a larger cam but got other stuff to do
 
You must log in or register to reply here.
-

Back
Top