young, broke and stupid 440 build

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mopower440

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Back in my 20's i built a 1972 dart with a 440. I did just a totally stock rebuild on the 440 i pulled out of a '75 new yorker in the junkyard. I ran it for a while and decided i wanted to boost the compression a little and install a bigger cam. this was about 20 years ago and i didnt have a lot of money. I bought a set of .030 over sealed power L2355 'six pack' pistons very cheaply from a member on moparts at the time. So i took the block to the machine shop and had it bored for the pistons and new frost plugs and all and had the pistons installed onto the stock LY rods. The things i did NOT do are rebalance the rotating assembly and did not change the rod bolts. As everyone knows these pistons are so heavy that everyone thinks they are worthless. Fast forward to today and i get quite nervous 'hot rodding' around being i didnt rebalance or at LEAST install ARP rod bolts. Now, my not too distant plans are to get some trickflow heads and better cam to install on this bottom end, but when the time comes to get the new heads, i plan on removing the rotating assembly and having it balanced and changing the rod bolts so i will have peace of mind finally, especially with the better heads and cam. Now, Even though i built this almost 20 years ago, the engine probably doesnt have 1500 miles on it as i just cruise around every now and then and actually lost interest for a while so it didnt get driven much for a bit. I have run it up to 6000 rpm's a few times with no problem and it does run quite nicely but i cant get it off my mind that its not been rebalanced or the rod bolts changed so i constantly worry about breaking it. It may be close to a year before i take it apart to balance it and get the heads and i really would like to continue driving it and 'hot rodding' it until then. Im sure i am going to hear it for not at least changing the bolts, but have any of you done this back in the day and not had problems? I wouldnt worry about it if it had light pistons but these are HEAVY.
 
Does it run with out vibration? Many years ago when building a engine I never replaced rod bolts. I didn't have the money for such luxuries. 6000 RPM is a safe number to twist it. I tried to keep mine below 6500 on my junk yard builds.
 
SGBARRACUDA said:
Does it run with out vibration? Many years ago when building a engine I never replaced rod bolts. I didn't have the money for such luxuries. 6000 RPM is a safe number to twist it. I tried to keep mine below 6500 on my junk yard builds.
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No vibration that i can tell..it runs smooth, just the little shake that most engines with lopey cams have, but she runs quite smooth
 
Well you don't have to worry about missing a gear and something letting go. I would drive it until you can afford to go thru it again.
 
Sad thing is with the stupidly low miles on the build, if i would have just balanced it and installed new rod bolts back then, i could have just swapped on the new heads and cam i want to get and be done..but now i have to pull the motor and tear it all down again and do this. It is a nice , smooth running engine though regardless
 
What your wanting to hear is that it will be find just like it is. New rod bolts are overrated as well as balancing, Not needed. I would put the aluminum heads on it and a nice hyd cam and drive it like I stole it. Is that better?
 
SGBARRACUDA said:
What your wanting to hear is that it will be find just like it is. New rod bolts are overrated as well as balancing, Not needed. I would put the aluminum heads on it and a nice hyd cam and drive it like I stole it. Is that better?
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Damn, sure didnt mean to piss you off there buddy! Just making conversation. sorry
 
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No, i know better, thats why i made the post, maybe help someone else from doing the same thing and then regretting it later. If i thought it was ok, i wouldnt be worried about it.
 
if it was me and it ran smooth/well i'd swap the heads and cam and use/enjoy it. stop worrying about something you didn't do 20 years ago, it would've been a problem by now if it was going to be.
neil.
 
If it runs smooth, I would not bother balancing it for what you want. And I would not worry about the rod bolts one bit. Those rod bolts are not the new stuff being torqued past yield. I did a cheap rebuild, hone with torque plates (just enough to clean and straighten the bores), rings, bearings, seals, brass freeze plugs, 268 duration cam, valve job, and a double roller timing chain, reused the rod bolts, on a 60's 383 back in the late 70's. Put it in my 68 Formula S and ran it everywhere. Easily wound up to 6K many a time and put a lot of miles on it as a daily driver. Still runs fine. If your balance was off, you'd know it.
 
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The reason it doesn’t vibrate with the 6bbl pistons is....... they aren’t really that heavy.
In fact, the Speed-Pro catalog shows a .030 over L2355 is actually 4 grams lighter than a .030 over L2266 piston, which is .070” shorter, but has no valve pockets.
It’s the big rods used in the 70-up 440-6 that makes the motor externally balanced....... not the pistons.

I balanced my factory 1968 440 rotating assy many years ago.
The stock std bore pistons and pins weighed 1086 grams.
Std bore L2355’s and pins are listed at 1083 grams.
 
PRH said:
The reason it doesn’t vibrate with the 6bbl pistons is....... they aren’t really that heavy.
In fact, the Speed-Pro catalog shows a .030 over L2355 is actually 4 grams lighter than a .030 over L2266 piston, which is .070” shorter, but has no valve pockets.
It’s the big rods used in the 70-up 440-6 that makes the motor externally balanced....... not the pistons.

I balanced my factory 1968 440 rotating assy many years ago.
The stock std bore pistons and pins weighed 1086 grams.
Std bore L2355’s and pins are listed at 1083 grams.
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This is a 1975 cast crank 440 with LY rods and externally balanced, so the 2355 weighs less than the factory pistons? I didnt know that, thought they were heavier..?
 
I've got a 440 that we built in the early 90s and it was turned 7300 rpm with bushed polished stock rods, I always worried about the rods so I replaced them the last time I refreshed the motor with H beam rods, now with the cam I have in the motor I only turn it 6700 rpm and I still worry about the new H beam rods. Lol
 
so the 2355 weighs less than the factory pistons?
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They weigh basically the same as the early stock high CR pistons.

I don’t think I have any weight info for the low compression cast pistons, but I doubt they’re all that much different than the 2355’s.

If it was enough to really bother anything....... you’d feel it.

Someone likely has the weight numbers for a stock low CR piston.
 
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PRH said:
I don’t think I have any weight info for the low compression cast pistons, but I doubt they’re all that different than the 2355’s.

If it was enough to really bother anything....... you’d feel it.
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well that is some relief! What exactly would an out of balance engine feel like? always wondered..
 
If it runs well I wouldn't worry about the rod bolts. We have replaced them on some motors and not on others (not that we have built lots). The only one we ever had a rod problem with was the 383 we replaced the bolts on. Then again, my son was turning 7,000 rpm with the stock oiling system on a car that could handle...oil starvation was his problem, not the rod bolts.
 
What is important that ALL the pistons are close in weight. A few grams difference in another set of pistons isn't going to be big deal in a street driver.
 
Bewy said:
What is important that ALL the pistons are close in weight. A few grams difference in another set of pistons isn't going to be big deal in a street driver.
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It is a street driver but i do want to be able to run it up to 6000 without fear of rod bolt breakage.
 
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