[Gach]

Originally Posted by mgarblik

Certainly a light rotating assembly is a help. We did this out of necessity and budget. No aftermarket forgings were available, only an old 990 crank if you could find one. Billet crankshafts were not an option for us in those early days. We ran what we had and we had 3-4 N cranks. With all the options we have today, I would never run a cast N crank to 1000 HP. But I wouldn't be at all concerned running one to 600-650 HP with nice steel rods and modern pistons.

That’s what I figured… understand it perfectly thats all we had. Yes agree on 600-650 hp.

[JLMounce]

Considering the reputation that Mile High Crankshaft has, and how close I am to them, I'll probably go this route. It may cost a bit more, but it sounds like that's probably the way to go.

[Johnny406]

Originally Posted by Gach

I tired calling that number, says no longer in service.

Crap, my dyslexia strikes again...

Here's a picture of his card...

[steve25]

I would not loose any sleep over using a factory crank at the 650 Hp level with a spot on balance, especially with lighter reciprocating parts, but what I would have concern over is the block.

Of course it needs to pass a mag test first off.

A block that’s drilled taped for 4 bolt but only using two bolt main caps is weaker then a block that is drilled and tapped for only 2 bolt caps.

If your not going to go thru the huge expense of adding 4 bolt caps then you have to install Allen head cap bolts into the 6 unused holes
These cap bolts need to be a tad shorter then the holes there going into, they only need to be torqued up to 45 ft lbs, but they need to be set in place with Blue Loctite.

Once the Loctite has set over night then the line bore needs to be checked.

I have never seen a shift in line bore from doing this mod, but it can’t be left to chance.

Note also that in two blocks I have had that where drilled and tapped for 4 bolt caps I have seen cracks in one outer wall of one of the bolt holes in each block.

Since these two blocks where only 2 bolt main 300 hp 2 bbl motors, the cracks must have been there from day one and due to core shift and the factory tapping and or drilling process.

In short inspect your block very closely before ordering any parts and or carting it off to a machine shop.

[Johnny406]

Originally Posted by steve25

I would not loose any sleep over using a factory crank at the 650 Hp level with spot on balance, what I would have concern over is the block.

A block taped for 4 bolt but only using two bolt main caps is weaker then a block that is drilled and tapped for only 2 bolt caps.

If your not going to go thru the huge expense of adding 4 bolt caps then you have to install Allen head cap bolts into the 6 unused holes
These cap bolts need to be a tad shorter then the holes there going into, they only need to be torqued up to 45 ft lbs, but they need to be set in place with Blue Loctite.

Once the Loctite has set over night then the line bore needs to be checked.

I have never seen a shift in line bore from doing this mod, but it can’t be left to chance.

Dang, my motor is going to come out soon for inspection. I was going to ask down the road if I should have those "extra" main cap holes weled up or a set screw?

[steve25]

Welded up did you say?

[Johnny406]

Originally Posted by steve25

Welded up did you say?

Filled in would be a better term than welded up, like with a rod on a arc welder but...I'm no welder so I really don't know if that's feasible.

[Dragncar]

For what you are doing a N crank that is not cracked will be fine. Molnar makes the rods you need and will always check out spec on size.
But if you have a extra 1000$ for a crank, go for it . Scat or Molnar only. Otherwise you might have to re grind a new crank.
Your 2 bolt block, studded have been good to 550-600 HP forever, as long as you do not spin them high.
Stepping up to billet caps on a PMD street engine is getting close to waste of money territory. You only get a 100-150 HP safety margin for a lot of time and money. And at that point, its not a street engine anyway.
Stud it ,and you do not have to align hone it just with stud change. Not to say its not a bad idea, but I studded my 4 bolt 455 many years ago and its lived a long life.
IMO aligning up the oil holes from the tab side of the block where they intersect with main bearings themselves is very important to a long life. If you have a round hole in the middle of the bearing, the shot of oil does not come from the middle hole in the block. It comes from the tab side of the block and a hole needs drilled through. If you don't, the oil has to hit the back of the bearing, move over and get to the crank. Bad for rod oiling at high RPM.
I BEAT on a N crank for almost 30 years and it is still OK.

[JLMounce]

Great information everyone, keep it coming.

If I'm not buying a $1500.00 crank, there's room to do 4 bolt caps and a line bore. Splayed would obviously be ideal, but since the block is already drilled for 4 bolt caps, would run a steel stock type. Like a ProGram Engineering or similar.

[Gach]

Originally Posted by Johnny406

Crap, my dyslexia strikes again...

Here's a picture of his card...

Join the club…LOL

[PunchT37]

Originally Posted by JLMounce

Great information everyone, keep it coming.

If I'm not buying a $1500.00 crank, there's room to do 4 bolt caps and a line bore. Splayed would obviously be ideal, but since the block is already drilled for 4 bolt caps, would run a steel stock type. Like a ProGram Engineering or similar.

I wouldn`t sweat that at all. Use your factory caps. Get some 4340 rods, a good set of full float pistons, AND a good balancer/flexplate. All balanced, of course.

[JLMounce]

Originally Posted by PunchT37

I wouldn`t sweat that at all. Use your factory caps. Get some 4340 rods, a good set of full float pistons, AND a good balancer/flexplate. All balanced, of course.

Yeah I think that’s probably the way I’ll still go. I have a brand new Nitemare prepped BHJ balancer that will follow to the new build once I have all the parts.

[blueghoast]

I have been running my 455's @ 600-650HP and 275-325 shot of nitros
for years and the factory N cranks have held up fine, Thats over-under
A 1000HP so I wouldn't be afraid to run a factory crank at all.

GT

[PunchT37]

Like Gach said, good parts are needed for higher rpm`s more than hp levels. Pontiac engines will actually run forever if used as designed for lower rpm`s. Even with higher hp levels. Problem is, higher hp levels usually come with higher rpm`s. I had an old 455 that I sold with cast rods and heavy TRW pistons. Still running today at 470 to 500 hp. That thing has been beat on for a long time. BUT, I had a 5600 pill.


My new 463 has a factory crank, but has good rods and pistons. This thing has been to 6400 more than a few times now. All good so far.

Oh, and don`t run your clearances too tight. Mid 2`s to 3 is good.

[Formulas]

Originally Posted by mgarblik

Certainly a light rotating assembly is a help. We did this out of necessity and budget. No aftermarket forgings were available, only an old 990 crank if you could find one. Billet crankshafts were not an option for us in those early days. We ran what we had and we had 3-4 N cranks. With all the options we have today, I would never run a cast N crank to 1000 HP. But I wouldn't be at all concerned running one to 600-650 HP with nice steel rods and modern pistons.

With aluminum rods its not just about weight, the aluminum material also cushions, dampens the hit from the combustion process especially during detonation, big reason they are in top fuel

[HWYSTR455]

I've had a factory 455 crank break on me, so I'm in the other boat, replace it.

If you're doing rods and pistons, adding a stroker crank may not be as much as you think. It might even come out cheaper if the crank needs machine work. Price it out.

As for cast/forged, do it right, do it once. You never know if down the road you will want more power, and you will sleep better at night with a forged.

I say always cut rings for up to a 250 shot of spray, too. Even if you never plan on it, it will give you some added cushion, and not cost in any power. The additional blow by is unmeasurable, contrary to popular belief.

Same for the mains, studs help. On the sleep-well-at-night scale, obviously the 3 center caps upgraded to 4-bolt will add comfort. And it will make more of a difference in a stroker build.

If you're in there and you're doing it, do it right. Shouldn't even have to ask, especially if you're not trying to cheap out.


.

[Gach]

Originally Posted by HWYSTR455

I've had a factory 455 crank break on me, so I'm in the other boat, replace it.

If you're doing rods and pistons, adding a stroker crank may not be as much as you think. It might even come out cheaper if the crank needs machine work. Price it out.

As for cast/forged, do it right, do it once. You never know if down the road you will want more power, and you will sleep better at night with a forged.

I say always cut rings for up to a 250 shot of spray, too. Even if you never plan on it, it will give you some added cushion, and not cost in any power. The additional blow by is unmeasurable, contrary to popular belief.

Same for the mains, studs help. On the sleep-well-at-night scale, obviously the 3 center caps upgraded to 4-bolt will add comfort. And it will make more of a difference in a stroker build.

If you're in there and you're doing it, do it right. Shouldn't even have to ask, especially if you're not trying to cheap out.


.

My thoughts exactly

[Cliff R]

I've seen the limitations of the factory 455 blocks. Had one 455 block that we just kept upping the power level on over the years and it finally gave up just shy of the 700hp mark. It showed us signs of not liking the improvements around 650hp as there were two main cap dowel pins in the oil pan on the last tear down before going to heavily ported Edelbrock round port heads and BIG solid roller cam up near .750" lift and 276 @ .050" duration.

The writing was on the wall but we continued with the upgrades and 13 runs on the new build it let-go at 6400rpm's in the lights and about all we could do was pull the intake off and scrap the rest of it!

As far as main caps I'd stick with the factory bolts. The factory bolts are bulletproof so going to studs is not an upgrade, just an additional expense and they don't have a "shoulder" to help keep the caps aligned.

EVERYTHING improves when you go to light rods and pistons as spinning and reciprocating weight combined with high RPM's is a KILLER on the long stroke engines as mentioned. Factory "N" cranks typically do well in high performance 455 builds, but like anything else it's a cast part and once in a while one cracks and ends up failing. A good forging is simply insurance and a good idea at higher power levels, but you still have a relatively "weak" block in the lifter bore area which is where our 455 failed when we tried getting "big" power out of it.......FWIW......

[mgarblik]

Originally Posted by Cliff R

I've seen the limitations of the factory 455 blocks. Had one 455 block that we just kept upping the power level on over the years and it finally gave up just shy of the 700hp mark. It showed us signs of not liking the improvements around 650hp as there were two main cap dowel pins in the oil pan on the last tear down before going to heavily ported Edelbrock round port heads and BIG solid roller cam up near .750" lift and 276 @ .050" duration.

The writing was on the wall but we continued with the upgrades and 13 runs on the new build it let-go at 6400rpm's in the lights and about all we could do was pull the intake off and scrap the rest of it!

As far as main caps I'd stick with the factory bolts. The factory bolts are bulletproof so going to studs is not an upgrade, just an additional expense and they don't have a "shoulder" to help keep the caps aligned.

EVERYTHING improves when you go to light rods and pistons as spinning and reciprocating weight combined with high RPM's is a KILLER on the long stroke engines as mentioned. Factory "N" cranks typically do well in high performance 455 builds, but like anything else it's a cast part and once in a while one cracks and ends up failing. A good forging is simply insurance and a good idea at higher power levels, but you still have a relatively "weak" block in the lifter bore area which is where our 455 failed when we tried getting "big" power out of it.......
FWIW......

The PMD engineers obviously were aware of the limits and weakness in some areas of the 455 block. Working on my first SD-455 block now and every time I look at the block I see more small improvements I had missed. In addition to all the cross-bracing in the lifter valley, the lifter bores themselves are thicker. The cam bearing bores are 1/8"-3/16" wider with more material around them. The main webs are much thicker on the outboard ends where the outer bolts go. The factory dowel pins are much taller sticking out of the block than a regular 455. The engineers really did their homework trying to improve the block for more HP. And all this work was to safely make 300 Net HP. (factory rating 290).

[Gach]

Originally Posted by Cliff R

I've seen the limitations of the factory 455 blocks. Had one 455 block that we just kept upping the power level on over the years and it finally gave up just shy of the 700hp mark. It showed us signs of not liking the improvements around 650hp as there were two main cap dowel pins in the oil pan on the last tear down before going to heavily ported Edelbrock round port heads and BIG solid roller cam up near .750" lift and 276 @ .050" duration.

The writing was on the wall but we continued with the upgrades and 13 runs on the new build it let-go at 6400rpm's in the lights and about all we could do was pull the intake off and scrap the rest of it!

As far as main caps I'd stick with the factory bolts. The factory bolts are bulletproof so going to studs is not an upgrade, just an additional expense and they don't have a "shoulder" to help keep the caps aligned.

EVERYTHING improves when you go to light rods and pistons as spinning and reciprocating weight combined with high RPM's is a KILLER on the long stroke engines as mentioned. Factory "N" cranks typically do well in high performance 455 builds, but like anything else it's a cast part and once in a while one cracks and ends up failing. A good forging is simply insurance and a good idea at higher power levels, but you still have a relatively "weak" block in the lifter bore area which is where our 455 failed when we tried getting "big" power out of it.......FWIW......

Perfect Cliff !! I can see we’re on same page.