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Discussion Starter #1
All right guys I need a little help here. All of my previous engine builds have been stock bottom end basic builds. I was going to do the same for this one but I have got behind on things due to colder weather and being sick. To make up some time I am buying parts to get a long block built so once it warms up I can more quickly swap out the motor. The end game is a 306 motor that will make around 500whp(with a supercharger) for street and strip duty.

I bought a stock block and it's at the machine shop now getting align honed,decked,bored and honed.
I have stock rods with some Silv-O-Lite pistons.

Now I need a crank but I have a few questions. First off I already plan to buy an SFI approved balancer and flexplate. I can get a stock 50oz crank that is ground/polished and with bearing on eBay for around $225. I have heard that many people dislike the 50oz cranks, so is it worth it to upgrade to a 28oz? I can get an Eagle cast steel for the same price and bearings aren't that expensive. I have also found a forged crank for $325 but is that overkill for what I want? If I get a new crank,balancer and flexplate do I still need to have it balanced? Cost isn't really an issue but I don't want to spend unnecessary $$ either. So what is the best overall option for my needs? Thanks for any help.
 

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If cost isnt an issue I would have gone with a 3.250 or 3.400 crank. But you would need different rods and pistons. With a stock block you could use a Scat cast crank, plenty strong enough at 500 HP. They are 28 oz imbalance and yes you need to balance the assembly.

Stock rods and those pistons are not likely going to last a week with a blower at 500 HP (block is suspect too), so use the cheapest crank you can get......
 

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Stock rods and those pistons are not likely going to last a week with a blower at 500 HP (block is suspect too), so use the cheapest crank you can get......
It is all in the tune. Get the tune right, keep the rpm's under 6K and the stock block can handle a lot more than 500 hp.
 

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At 500 whp it's grenade with the pin pulled. I'd spend as little cash as possible on a crank because the block will fail before almost any crankshaft, the factory rods or any aftermarket forged piston. The likelihood of the block surviving for an appreciable amount of time is low. As mentioned the tune is really important. It may be more important than the crank or anything else in the engine.

My opinion, for what it's worth (and it's probably not much), is always run an internal balance crank. If that's not an option due to cost/availability/etc... then run a 28oz crank. It you already have the 50oz crank run it. Because stock blocks think they are amoebas and try to split by fisson.
 

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500 RWHP, as you specified, is alot for any 302 (close to 600 at the crank or so, depending). You need lots of rpm to hit that target, even with a blower. A bit easier, meaning less rpm, when you are dealing with a 331/347.

RPM is much of what kills stock 5.0 blocks. Stock rods at that level are toast anyway.
 

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Discussion Starter #8
Regardless of which crank you buy, they all need to be balanced. Spend as little as possible for the crank in a stock 302 block
I guess that settles it. When I said the cost isn't an issue, I meant for the given options. An aftermarket block is way out the question unless someone want to sell me one for under 1K

It is all in the tune. Get the tune right, keep the rpm's under 6K and the stock block can handle a lot more than 500 hp.
At 500 whp it's grenade with the pin pulled........................
As mentioned the tune is really important. It may be more important than the crank or anything else in the engine.
That is another item of confusion for me, where to really draw the line on power output. Above are two different opinions, my bases for the number is from an article I read by
another member here @Decipha where he stated max for stock block is 550whp. I am hoping to find a good tuner for it so that won't be the problem.
 

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The issue with a cut crank is you are left with very little options to adjust bearing clearance with bearings. Just because it comes with bearings means nothing at all other than they are .010 or .020 bearings. They will physically fit but that's all that is assured
 

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I guess that settles it. When I said the cost isn't an issue, I meant for the given options. An aftermarket block is way out the question unless someone want to sell me one for under 1K

That is another item of confusion for me, where to really draw the line on power output. Above are two different opinions, my bases for the number is from an article I read by
another member here @Decipha where he stated max for stock block is 550whp. I am hoping to find a good tuner for it so that won't be the problem.
I've seen them break at 200, I've seen them live at 625.

RPM, tune, and the nut behind the steering wheel.
 

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Discussion Starter #12
I personaly find the old flat tappet blocks , are less money and pretty robust .
I'm lucky I guess, in my area the 5.0 roller blocks are easily found for $100 or less. I can get complete Explorer motors for $250 at a u-pull lot. He had 15 to choose from last time I checked. I paid $75 for the block at the machine shop now.

I've seen then break at 200, I've seen them live at 625.

RPM, tune, and the nut behind the steering wheel.
At 200??? something was done way wrong.
There ain't no loose nuts here. At 54, I know the difference between performance driving and abusive driving. I am trying to do this motor right so I can get some longevity out of it. I would be happy at 450 if that's really what it takes. This will be the last time for this Mustang, if it has issues quickly I'm done and going back to my really old cars.

Last question here, what about balance? Would an internally balanced assembly be best as suggested above? Sounds logical to me.
 

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Cast crank will live longer than the block..

I have a 347 that runs fine I just pulled after putting 35-40k on it all supercharged around 550hp (498 uncorrected for altitude) that I've beat on hard. The trick is to keep the damn thing under 6k and don't get greedy with timing/compression. It's got a cast crank, light weight I beam forged rods and Probe SRS pistons. You don't need a stroker to make power to split the block. But if your going to spend the money anyway just stroke it and get the extra torque.
 

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. You need lots of rpm to hit that target, even with a blower.

RPM is much of what kills stock 5.0 blocks.
You are right and you are wrong. RPM does kill the block, but it does not take a lot of RPM to make that kind of power. There are quite a few people who make well over 500 whp with stock blocks. One guy runs mid 8's in the 1/4 mile with one, but he never spins it more than about 5,800 rpm or so.
 

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I'm lucky I guess, in my area the 5.0 roller blocks are easily found for $100 or less. I can get complete Explorer motors for $250 at a u-pull lot. He had 15 to choose from last time I checked. I paid $75 for the block at the machine shop now.


At 200??? something was done way wrong.
There ain't no loose nuts here. At 54, I know the difference between performance driving and abusive driving. I am trying to do this motor right so I can get some longevity out of it. I would be happy at 450 if that's really what it takes. This will be the last time for this Mustang, if it has issues quickly I'm done and going back to my really old cars.

Last question here, what about balance? Would an internally balanced assembly be best as suggested above? Sounds logical to me.
Yes....at 200. I've been building Fords for over 60 years.......not much left that I haven't seen. Incidentally, my beard is older than you....:p:p
 

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I have a 347 that runs fine I just pulled after putting 35-40k on it all supercharged around 550hp (498 uncorrected for altitude) that I've beat on hard. The trick is to keep the damn thing under 6k and don't get greedy with timing/compression.
This.

I remember when the word on the street was to avoid 347s because of "sidewall loading", a term which was repeated so often that the myth became "conventional wisdom". Until a few years passed and someone asked the question "has anyone who actually owned a 347 have it fail due to sidewall loading?" And another myth was debunked.

The "500hp grenade" myth was another one that came and went.

My recommendation is that anything you build should consider whether you want to daily drive, drive on weekends, or race. Do you want the car to idle without overheating and not die in parking lots? Do you plan on doing the tune yourself? Keep in mind that most shops will tell you that your car will be perfect in every way once they tune it, so you pay, and most likely the thing will have all sorts of problems and they will tell you that it's your fault because Ford designed the sensors all wrong (which is BS).
Do you have a reputable shop that you're certain knows how to tune this car?

To your original question, years ago I knew a guy with a 95 cobra and blown 306 that was dynod at 505 rwhp. LOL, the car looked totally stock and once I saw a camarobird driver make the mistake of trying to show him up. That cobra MOVED!
 
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