360 con. rod bolt sizes

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360moparjunkie

360moparjunkie

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Currently have my 360 block at the machine shop. Bored the block .030 and went with the advise from many members and puchased the .030 keith black 107 pistons with advertised "zero deck" and valve reliefs.

My machinest is strongly recommending that I increase rod bolt diameter from 3/8" to 7/16". New rod bolts would be ARP.

This as well as re-size all con. rods.

What "out of round would be acceptable on my existing rods?

If I elect to continue dumping $ into my block; is this $ well spent?

For the record, I am going to spend the $ and have the rotating assy. balanced while it is there. Obviously, I need to make a decision on what to do with the rods if they are going to balance the assy.

Current rod bolt size is 3/8. How much extra should it cost to have the rod bolt holes enlarged to accept the 7/16 ARP's.

Appreciate the ongoing support :cheers:
 
It all depends on what your plans and expectations are with this 360.

With those pistons i would not run over 6500 rpm.

I would do some checking into aftermarket rods. I was told a few weeks ago by my machinist he could get me a set of aftermarket rods for a few more dollars than reconditioning stock rods. By the time you resize the big end and put new bolts in thats close to same price as an aftermarket steel h beam.

Was honing plate used on the final bore? Just cuious. I have seen a lot of engine talk on here but have yet to see anyone mention anything about a honing plate being used. I feel its an absolute must in engine building.

Hope this helped.
 
Tell your machinist he's everthinking it and replace the factory bolts with ARPs. The big ends will need to be re-sized after this replacement. He wants to drill the rods, loosing strength in the largest stress point, then install heavier bolts? I'd tell him no thanks...
 
Tell your machinist he's everthinking it and replace the factory bolts with ARPs. The big ends will need to be re-sized after this replacement. He wants to drill the rods, loosing strength in the largest stress point, then install heavier bolts? I'd tell him no thanks...

This is what I understood him saying.
So, just new ARP bolts and I should be fine?
Thats what I'll do then.

As to the bigger bolts...tell him:thebirdm:

So far the machine shop I'm using seems to be fair. I want a good relationship with them as I also want quality work on the internals of my engine. Just hoping they can be a little flexable on the pricing.
Looks like I'll probably have the following done on the s. block(boring already complete as well as piston / chrome molly ring ordering)

Bored .030
KB-107 pistons
Re-size rods / ARP 3/8" bolts (after checking price difference w/new rods)
Turn my crank down (Shop says my crank is at the max amount of wear just before turning would be mandatory.)
Purchase external balancer from them
Balance rotating assembly
Press on new pistons

Thanks Moper. As usual weighing your opinions heavily.
 
go with the 3/8 bolts..ARP sells 3 version of the rod bolts...

sort of good...better...best...

best are around 80 dollars for a set...

hate to say this ...but at some point it might be cheaper or at the almost the same price as buying Scat I beam rods with 7/16 rod bolts....
 
moper said:
Tell your machinist he's everthinking it and replace the factory bolts with ARPs. The big ends will need to be re-sized after this replacement. He wants to drill the rods, loosing strength in the largest stress point, then install heavier bolts? I'd tell him no thanks...
Click to expand...

mopa713602 said:
It all depends on what your plans and expectations are with this 360.

With those pistons i would not run over 6500 rpm.

I would do some checking into aftermarket rods. I was told a few weeks ago by my machinist he could get me a set of aftermarket rods for a few more dollars than reconditioning stock rods. By the time you resize the big end and put new bolts in thats close to same price as an aftermarket steel h beam.

Was honing plate used on the final bore? Just cuious. I have seen a lot of engine talk on here but have yet to see anyone mention anything about a honing plate being used. I feel its an absolute must in engine building.

Hope this helped.
Click to expand...

602,
Hello and thanks for the input.
Not that I'm planning on spinning this motor into the 6500rpm range, but why do you not recommend these pistons for up in that rpm range. Just got done changing my new pistons from std. to .030 partially cause the pistons sucked. (.1092" in the hole as well as a couple of worn holes up on top)

Very good point being brought about the honing plates.
This was one of my first questions when scouting out a machine shop to do my work.
The owner of the shop set me to rest on the idea that with the LA360 block design having only 10 head bolts per side that distortion would not be an issue like there is with the small block chevrolets. Expecially when compared to s.b.400 chevy where the bores are so close together in conjunction with many more head bolts influencing the bore.
Hope he's right, don't want my pistons getting stuck in the holes.

BTW, another local shop has these plates and charges additional 104.00 to add prior to honing.

I'll be looking into pricing for the new rods.

Thanks.8)
 
hone/torque plates are nice but not a must.

As in they came about in racing r&d, and not all shops have them,

they 'might' be worth 2 hp in your average street mill.
 
Mopar 360 rods are plenty strong with just arp 3/8's bolts, they can take 450hp with just good bolts, I would not go to bigger size bolts in your stock rods drilling it out would weeken it. if your going over the 450HP mark, just get some good aftermarket rods
 
70aarcuda said:
go with the 3/8 bolts..ARP sells 3 version of the rod bolts...

sort of good...better...best...

best are around 80 dollars for a set...

hate to say this ...but at some point it might be cheaper or at the almost the same price as buying Scat I beam rods with 7/16 rod bolts....
Click to expand...

Want to say about 40.00 for the ARP set he's selling.
I'm going to flog this motor when installed. It needs to hold; however, I've never scattered one before. Everything done right on this one and I should feel good about my right foot sticking out infront of the radiator while under power.

I think moper is a scat dealer hope he logs back on soon. He'll shoot a price right over I bet.

Kidding aside, I am looking to save $ wherever I can without coming back to bite me. Hence the new pistons, bore, balance decision so far.
Turning into what looks like turning the crank as well. Whoo! adding up fast.
 
1wild&crazyguy said:
$12 each for resize and bolt install, $45 for the bolts=$141

thats the price where I'm at, used to be $9 each.
Click to expand...

1wcg,
COOL,
Comparing apples to apples here. Thats in the ballpark of what I've been quoted. Heard recently that re-sizing rods is not too difficult with the proper equip. Wondering if this is an area I can use to negotiate a better cost with him at. (since it sounds like they can do the re-size in about an hour or less)

Thanks, and getting closer.
 
basically you take .003 off the cap and .003 off the rod, then hone them out to spec, I don't know about an hour in a working shop cause you're usually doing multiple things at once to keep up with business.

If you are going press pin then add a lil $ for that, rod heater and press the pins in w/ pistons.
 
EL5DEMON340 said:
Mopar 360 rods are plenty strong with just arp 3/8's bolts, they can take 450hp with just good bolts, I would not go to bigger size bolts in your stock rods drilling it out would weeken it. if your going over the 450HP mark, just get some good aftermarket rods
Click to expand...

E340,

450hp would seem a little un-realistic for me since I am going to have to keep the head work down to a minimum. Using my current "J" heads with the 1.88" intakes I believe will be my limiting factor (as well as my new compression constraint, thought about the kb190's but it was raising eyebrows at the m. shop) I've never ported a set before either. These will be lucky to even get gasket matched.
Stock rods w/ new ARP bolts will probably be the call.

Thanks
 
1wild&crazyguy said:
I'd rev with those pistons past 7000rpm no problem.
Click to expand...

You woud, or you have? There is a differece. :bootysha:

I ran them for for many years with no problem when i was running the 284/484 turning 6500. I tore it apart freshened it and put in a cam same as what my 340 was i dont remember exacts of cam, but it was a .650 lift. i was shifting at 7600. It made it 3 days of racing a total of 17 runs before #7 rod went through the top side of the intake. Along with a big mess and nothing but the carb and valve covers salvagable.

I did a quick search for rods, and least expensive i found were scat with bolts for 250.

If your machinist is selling you off on not needing a honing plate i would find a new one! He is correct it may not have the distortion of a chevy, but it still does have distortion.

It is not an absolute must. your motor will run with out using it. But it wont be as good as one that did have it. I dont have any idea of what the hp gains are, i would guess 20 hp maybe more?

The reason for it is so after its all assembled and heads are torqued down the cylinder is still truely round and straight.

If i were to only do one motor i would pay the 104 to use their plate. When i bought mine, local machinist didnt have one, and werent going to pony it up to get one. So i bought my own. They arent cheap and they are expensive to ship. I think it was almost 600 bucks for the plate by the time it was here. But worth it in the long run.
 
mopa713602 said:
You woud, or you have? There is a differece. :bootysha:

I ran them for for many years with no problem when i was running the 284/484 turning 6500. I tore it apart freshened it and put in a cam same as what my 340 was i dont remember exacts of cam, but it was a .650 lift. i was shifting at 7600. It made it 3 days of racing a total of 17 runs before #7 rod went through the top side of the intake. Along with a big mess and nothing but the carb and valve covers salvagable.

I did a quick search for rods, and least expensive i found were scat with bolts for 250.

If your machinist is selling you off on not needing a honing plate i would find a new one! He is correct it may not have the distortion of a chevy, but it still does have distortion.

It is not an absolute must. your motor will run with out using it. But it wont be as good as one that did have it. I dont have any idea of what the hp gains are, i would guess 20 hp maybe more?

The reason for it is so after its all assembled and heads are torqued down the cylinder is still truely round and straight.

If i were to only do one motor i would pay the 104 to use their plate. When i bought mine, local machinist didnt have one, and werent going to pony it up to get one. So i bought my own. They arent cheap and they are expensive to ship. I think it was almost 600 bucks for the plate by the time it was here. But worth it in the long run.
Click to expand...

First off 602, many thanks for the advise I do appreciateand thanks for the parts research.

But, DAMMN! 20 HP! Really?
Other member is saying 2 HP. That's a 100% difference in hp quote between yours and his.
Feeling a little locked in w/ this shop thus far. I want them to do good work and at a good price. Not sure what hp target is realistic as my $ will ultamately dictate my end hp. Feel like I'm spending $ where needed on the block thus far. 100.00 x-tra for plates when they've done it for years w/o them is tough for me to throw $ at. Not that it doesn't work, but I'm on a budget. Savy?:-D
Don't know if you read previous head statement, using 1.88" with my J's. Non ported. 20hp. in the 7,000 range may be accurate. In my world the engine would only see those R's running wild out of gear @ W.O.T.
My guess (and I'm no engine builder, just trying to build an engine) is that I could be leaving 10hp give or take on the table by not plating prior to honing. You agree?

Thanks again
 
I have, but not in my car.

I have also run KB243 hypers in my 340 and touched 7400rpm, 7200rpm more frequently.

I notice your mooning thing...you want me to put something there?

i've seen stock pistons go over 6500rpm...

and btw... gee ?.650 lift? what compression? 12.5?? i bet a sht load more than his
 
and btw...hone plates can only come close in simulating the distortion, but not perfect.

a cyl head is way thicker and structured diff.

chevys are garbage, when you check the decks during rebuild, they have high spots around each hole...paper thin junk.
 
1wild&crazyguy said:
I have, but not in my car.

I have also run KB243 hypers in my 340 and touched 7400rpm, 7200rpm more frequently.

I notice your mooning thing...you want me to put something there?

i've seen stock pistons go over 6500rpm...

and btw... gee ?.650 lift? what compression? 12.5?? i bet a sht load more than his
Click to expand...

Good enthusiasm...1wcg, is that Obama cleaning Palin's shoes?......Good one!

Just my opinion....the 6500 and up rpm club is grenade territory imo.
I just don't have the $ for that type of valve train.
Priced it. Looking close to 2000.00 for valve train. Not looking for divorce, just a very healthy small block.
 
360moparjunkie said:
Good enthusiasm...1wcg, is that Obama cleaning Palin's shoes?......Good one!

Just my opinion....the 6500 and up rpm club is grenade territory imo.
I just don't have the $ for that type of valve train.
Priced it. Looking close to 2000.00 for valve train. Not looking for divorce, just a very healthy small block.
Click to expand...

What is included in this ''$2000 valve train'' sounds like too much.

You could go roller cam and roller rockers for less.
 
1wild&crazyguy said:
and btw...hone plates can only come close in simulating the distortion, but not perfect.

a cyl head is way thicker and structured diff.

chevys are garbage, when you check the decks during rebuild, they have high spots around each hole...paper thin junk.
Click to expand...

Ever measured the bores in a SB Mopar before and after installing a torque plate? I have. There is a lot more distortion than you think.

It's all about sealing the combustion chamber as best you can. Remember, the rings & cylinder are the bottom of the combustion chamber. Striaght, round bores are key to making a good seal. The best way to do this is to use a torque plate. Yes, it's not exactly the same as having a cylinder head on the block, but I don't know of any special hone that will hone a bore with the head installed. ;)
 
lilcuda said:
Ever measured the bores in a SB Mopar before and after installing a torque plate? I have. There is a lot more distortion than you think.

It's all about sealing the combustion chamber as best you can. Remember, the rings & cylinder are the bottom of the combustion chamber. Striaght, round bores are key to making a good seal. The best way to do this is to use a torque plate. Yes, it's not exactly the same as having a cylinder head on the block, but I don't know of any special hone that will hone a bore with the head installed. ;)
Click to expand...

don't confuse my stance on torque plates, for what I'm doing they are used, but I punish my sht and rev it higher than the average person.

Did the factory do it?

I'm saying... for what he's doing he need not worry or spend an extra $100 for the plate.
but it's his decision, which if he would just make up his mind we could move on.

do or don't.
 
1wild&crazyguy said:
What is included in this ''$2000 valve train'' sounds like too much.

You could go roller cam and roller rockers for less.
Click to expand...

Would love to go roller!
The parts just keep adding up. By the time you get nice rocker arm assy., valves, push-rods, roller lifters, solid billet roller camshaft your looking at 16-1800.00 plus. Thats just valve train stuff! More stocker type components will probably serve my purpose. Just hope I'm right. (Other members feel free to sound off if it sounds screwy)

Since other members out there have built more of these motors than I, where is the best deal on roller components?

I already have new lifters in the box. Sort of throwing $ away if I don't use them.

Providing the right new components reveal themselves I could still go roller.
Not sure that the x-tra $ would be well spent though.
 
i thought this topic was about connecting rod bolt sizes..???
 
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