SO CLOSE! Just a little more help please

[moparleo]

Are they supplying the pistons? If not, it is best to have them bore and hone the cylinders to fit the individual pistons you are using. Believe it or not, it can make a substantial difference in the individual fit of the pistons. Learned that a long time ago.Had the machine work done first and then bought the parts later. When fitting the rings and installing the pistons in the bore, you could feel the difference between the tight and looser fitting pistons. Lesson learned. There are small differences in the diameters.

 

[DetMatt1]

Sounds like a reasonably priced shop and I agree with Leo, you should have the internals on hand for this. Does your crank need any work and is the crank you are using the one that was removed from the engine? If so the Hone on the mains probably isn't neccessary. Did you already by an engine kit?

 

[moparguy]

No i did not give them the pistons. My mistake I guess but what you gonna do. It is the stock crank but its a forged steel model. No i have not bought an engine kit. I looked at them but I already have purchased most of the things included in that kit I am getting a new cam as well. The rings are brand new and I actually have a double set of them incase anything goes wrong. Also I am not sure if I mentioned I am rebuilding this engine with my dad who is a chevy guy but works on engines out of necessity ever since my age. He's really good with timing and stuff like that but we are both wondering about balancing the engine. I am not trying to eek the last bit of hp that I can from the engine but I am trying to moderately strong at about 500 lb/ft at the flywheel which isnt too optimistic I dont think with the headers and the overboring and the cam. Is it entirely necessary to balance the engine at a shop or will it run smooth enough with the mods to crank that mopar put on it in 1970? If so would I need to make any changes to the harmonic balancer?

As always thanks,
Colton

 

[moparleo]

Is balncing necessary? do you balance tires ? I am not trying to eek the last bit of hp,only 500lb/ft at the flywheel? Haven't bought the parts yet ? Even a Chevy deserves more planning than this is getting. Talk about putting the cart in front of the horse. I am not going to say something that might hurt someones feelings, unbelievable. I'll just watch what happens and give no more advice. Don't use it anyway.....

 

[DetMatt1]

I am a bit suprised that the machine shop didn't require you to provide your pistons and rods. That makes me wonder. I would say fitting your new slugs to the bores would be more important then balancing the rotating assembly. You also may not realize that it's not cheap to make 500 ft. lbs of torque at the flywheel, let alone 500 horse. What are your plans to accomplish this?

 

[Juan Veldez]

Colton, PLEASE STOP! Listen to moparleo and DetMatt1. Man oh man, this has disaster all over it. Seriously, I know money is tight, but you really could be wasting it by not doing a few of these items and steps previously mentioned. The last thing you want is to get this motor all together to find out it's not gonna run right and have to pull it out and re-build part of it again. Especially since you think you will be in the 500 ft/lb range, balancing will allow your engine to last longer, idle smoother (excluding cam spec's), and spin up quicker - do it! There are some short cuts or money saving items that may be acceptable to some of us, but I think most here would agree not having the pistons on hand for the honing job is not an option.

Also, please note that the harmonic balancer is different for a forged vs. cast crankshaft!

 

[moparguy]

Well sorry but didn't mopar rate the engine at 490 lb/ft stock without accessories (alternator water pump and ac etc.)? This is the big performance 4 barrel model with the 725 carb (from mopar: 375 horse and 490 lb/ft.). Doesn't seem too far fetched to be able to gain 10 lb/ft from new headers, bigger cam and ported heads. Is the stock rating incorrect? I wasn't interjecting I was just asking. Also I am aware that the harmonic balancers are different. Also I am not looking for anywhere near 500 horses just would like to bring it at least back to stock specs. Also Leo I am not understanding your post. I have been using your advice and I do appreciate it but the ship has kind of already sailed on having the shop bore exactly to the pistons (which I do already own) because I had already handed off the engine to them before I read the thread that you said. And I have parts coming to me right now. (new water pump, starter,oil pan, gaskets, plugs, crank bearings, and soon I'm gonna pick up some new valve covers) I do have it all planned just still asking questions while I wait for the block to come back from the shop.

I don't know if its the way i've been writing or how its been interpreted but I do respect all you guys advice and experience. Its just some of you guys have been cross-checking each others info. DeMatt said I probably dont need any work done on the crank and Leo said I definitely do. I'm not understanding who to follow here.

No hard feelings though,
Colton

 

[Juan Veldez]

A 440 with a six pack or 2 fours and around 10.2 - 10.5:1 pistons is rated for 490 ft/lbs. in a few years offered, so using a similar (or better) cam, heads, exhaust, etc., will get you there. I had to go back to previous threads to verify you are rebuilding a 440, not a 340 - that may have been the confusion from others as I wasn't sure myself.

I think you are correct, the way we interpret what you write may be creating the pucker factor from our side. I feel a little better after reading your last thread.

IMO, the crank (if not brand new) at the very least should be gone over to verify no cracks, wear & for straightness. Double check bearing sizes, even if new. I've bought brand new stuff only to find out it wasn't exactly right. The shop should have done this for you if you gave them the crank, or at least asked you.

Again, IMO, pistons are mandatory for the honing job, not as much for the boring, assuming you are using brand new pistons. Ideally, yes, it's better to have ALL your internal parts (some external) on hand to get a more precise fit and balance.

And it doesn't take much to weigh the pistons and rods individually with a proper scale to balance them. My rods were a little off and some grinding off of the cast marks got them dialed in dead nuts. Didn't cost anything but my time and some grinding stones and polishing sandpaper wheels liked used to port/polish heads.

I am more of a back yard mechanic and will accept more tolerances in a street car motor. Others here are more professional and are sticklers for exact perfection. If funds are unlimited and your not in a time crunch, go with the pro's recommendations, well, because they are pro's!

And pro's, if I'm WAY off base on any of my comments here, please tell me and Colton.

And there are no hard feelings on my end. We all want the best obtainable for you!

 

[DetMatt1]

I appologize in that I didn't see where you had provided the pistons. My thoughts on the crank are that if it has been spinning in that block for 40 years or so that there would be little or no benifit to a main hone. It does go without saying that you need to have your crank inspected and polished at the very least and plasti-gauged upon installation. Balancing the rotating assembly is a good idea but again, if you're putting the original rods back in you should be ok. I'm not saying that they are perfect from the factory, because they are probably not. It is also not a matter of making sure that all the rods weigh the same but making sure that all the big ends weigh the same and same for the small ends, big ends being more important.
What are you using for heads?

 

[moparguy]

Im using the stock 906 heads that I sent into the shop to have cleaned up and are doing a valve job on. Down the road I think I will have them ported. And ya you guys could definitely see my confusion if you thought it was 340.:happy8: Dematt - I have a brand new set of connecting rods (but still the stock type) already attached to the 30 over pistons. Do you think it would be worth changing them out with the older rods I took out of the block just for balancing purposes.

And yes Juan I am using a bigger cam, much bigger exhaust, and the stock high hp heads. with the 725 carter. :3gears: I believe Steve told me with the pistons he gave me it should make about 10.1 compression. Do you think that will pull the torque out that I am looking for? Also haha ironically I am building this engine in my backyard, but in this nice shed that me and my dad built just for rebuilding this engine and future engines. (When I get done with the 440 my 10 year old brother wants to rebuild a 383, hes also a big Dukes of Hazard fan haha and wants to build a 69 charger when he gets to be old enough) hopefully I will have some advice to share with him.

PS: If any of you guys know Steve Wann, he races a 68 cuda I believe, well he gave me the overbored pistons and rods when I bought the engine from his buddy. He is a diehard mopar man and that is why I plan on installing his rods unless anybody says otherwise.

Glad I could clear up all the confusion and I'm sorry if I got off on the wrong foot with anyone.

As always, Thanks a million, :wave:
Colton

 

[DetMatt1]

Hopefully the guy you got the pistons and rods from balanced the rods. You might be able to see evidence of some non factory grind marks on them. What kind of pistons are they? With an open chamber head you will need a particular piston to get the compression you're looking for.