cheap rebuild options...

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sledger46

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I am thinking I need to pull my stock 360 for a "freshening". I already have plans for a new cam, lifters, double roller timing chain, and mildly ported "J" heads. I will add those part to my existing M1 dual plane intake and 3310, 750 vac secondary Holley carb, and 1 5/8" long tube headers.

The 360 is a low compression LA engine from the late 70s with unknown miles and leaky gaskets. The leaky pan and rear main gaskets are the main motivator for pulling the motor.

Enough background, onto the REAL question: Would it be cheaper to offset grind the crank to get the stock pistons close to zero deck or buy new pistons and have the block bored?

I was originally thinking re-ring and re-bearing with a new oil pump, but might be willing to go a bit further if the price is right.

Your thoughts?
 
Cheaper to offset grind. Just remember that the pistons have no valve reliefs - so getting them up a ways might get you into trouble with piston to valve if you're running a larger cam.
 
moper said:
Cheaper to offset grind. Just remember that the pistons have no valve reliefs - so getting them up a ways might get you into trouble with piston to valve if you're running a larger cam.
Click to expand...

I was planning on running a cam with 220 ish .050 numbers and .470-.480 advertized lift. I want a small cam with a tight 107-108 lobe separation. I might have to notch the pistons for the intake valve.
 
moper said:
Cheaper to offset grind. Just remember that the pistons have no valve reliefs - so getting them up a ways might get you into trouble with piston to valve if you're running a larger cam.
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Wont there be a limit to the amount of offset as far as bearing selection though?
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Why i asked the question above is, with most 360's having the pistons average .070 to .100 in the hole, a simple offset grind with the available thicker bearing shells will get you no where near zero deck. You either have to grind the existing pin too far (smaller) and that requires a aftermarket or some other brand of rod......or the crank pins need to be welded up to allow grinding the pin back to a standard size allowing the use of the stock rod.

I hope i'm not forgetting or missing something about this process as i haven't really thought about it much in a while, but in my opinion, i'd just get a set of KB hypers with the proper pin height and be done with it. And it will need balancing either way.
 
That cam will probably be fine but mock it up to check for piston to valve before you clean and final assemble.
Bearings make nodifference. the journal is still the same size. They only move the centerline. You are correct - you cannot move it enough to get zero deck. But for the cost of a crank grind you can get the piston up to around .040 in the hole. Rebalancing IMO (and basing it on "no budget") is not necessary unless you get new pistons. The "right way" would be new pistons but that means cleaning, boring, honing, balancing, mount and dismount of rods, and new block hardware and cam bearings... Much more cash required for the best result.
 
instead of paying for grinding the crank, you could get a forged crank... they go for about $600 though
http://www.ohiocrank.com/mopar_cranks.html

but you could pick your stroke and just get pistons to match whichever stroke you go with.

if it was me i would much rather pay $600 to get a forged crank with stroke than pay $250 for an offset grind on cast crank. something to consider.

however, a stock 360 crank if you are running under 500hp you should be ok... in order to keep your costs down you could just have the crank cleaned up as needed, use stock stroke & pistions, have the block/heads milled slightly to get your comp ratio up to 9.5 or so. it depends on the condition of your crank/pistons/etc.
 
If it can take a home and re-ring, go for it.
If it is worn out and needs a bore, grab the piston to fit the bill and new rods rather than rework old rods.
These are your roads.
 
OldmanRick said:
with most 360's having the pistons average .070 to .100 in the hole, a simple offset grind with the available thicker bearing shells will get you no where near zero deck. You either have to grind the existing pin too far (smaller) and that requires a aftermarket or some other brand of rod......or the crank pins need to be welded up to allow grinding the pin back to a standard size allowing the use of the stock rod.
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I assumed you were asking about the crank you already have and since we like pics, i made one of my thoughts from my quote above........

#1) Use a .030 under bearing and cheat the grind to the high side, shaded area, resulting in minimal gain.

#2) Weld up the high side and grind to the stock big end diameter to use the stock rod.

#3) Grind only to a smaller pin diameter, but will require a different rod.

View attachment 003.jpg

My thoughts......

Best bang for the buck.....Rering & bearing then cam, custom if necessary, to help build cylinder pressure with your existing combo.

Most aggrevation.....the offset grinding route.

Somewhat costly, but the easiest.....get KB's with the 1.675" pin height.

Sorry moper, i know were talking inexpensive here, but i'll still take mine balanced.....:D.


P.S. If there are other ways of accomplishing this, please let me know. I had to dig into the cobwebs for this one....:D:D:D.
 
lol.. no sweat Rick - I internally balance everything I do. But in the interest of the OP's "low buck", it's option 3 and there is no need IMO to balance for the change in stroke.. The pistons and rods are so far off in factory form that a slight geometry adjustment isn't going to be noticed. It's not the right way, but if we were doing it "right" it would all get balanced with the new pistons.
 
you wanna do it cheap just get a master rebuild kit thro in a new used cast crank and have it over 1000.00 $ other wise pull out some jing and let her buck
 
Piston are the right way to go, but you could mill the block and heads and a thin gasket to get CR you need.
 
moper said:
lol.. no sweat Rick - I internally balance everything I do. But in the interest of the OP's "low buck", it's option 3 and there is no need IMO to balance for the change in stroke.. The pistons and rods are so far off in factory form that a slight geometry adjustment isn't going to be noticed. It's not the right way, but if we were doing it "right" it would all get balanced with the new pistons.
Click to expand...

Great point. Now that you got me thinking about it, the factory balance did leave alot to be desired.......
 
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