I just dropped a shortblock to my machine shop and without even looking at the crank prior to hot tanking and inspecting my builder wants me to get a new crankshaft(Eagle). The crank I have is out of a F2 70 BB with "N" stamped on it and the question I have is if am looking to get around 525 hp and 600 ft/lbs torque can I just have the journals turned on crank. I ask because I would rather spend the extra cash on a hydraulic roller or is the machine cost to magniflux, heat treat, shot peen and chamfer oil holes just as much as buying new crank

 

Did he give any reason for replacement?
Might he just have one 'laying around' he'll give you a 'super deal' on?
Tell him 'no'!! Check yours - you're paying the bill!

 

Your power goals would be easier to make using a long stroke Eagle crank. BTR Bill sells a CP piston stroker crank kit pretty reasonable. I would not just swap it out in stock stroke form unless it checked out to be bad.

 

No the only reason he gave is the Eagle Cast crank will be stronger and if anything fails it will be the factory rods or crank because of age/fatigue and not knowing how they were being used for 40 years. He also suggest Eagle H-Beam Rods, I assume this is all for added security. I plan on getting the Edelbrock alum heads, forged pistons and 10.25:1 compression.

 

The Eagle crank is not any better of material than the factory N-crank.The Eagle cranks are cast,not forged,so you power output capabilities won't be any greater by switching cranks.
If you are going to purchase aftermarket rods,then I would get a BBC rod,and either offset-grind the N-crank,or get one of Eagles 4.500" stroke cranks,which have the BBC rod journal.You can get a complete Eagle stroker rotating assembly,for that matter.If you do get the Eagle crank,I would have it checked before assembly.I know they advertise those as "ready to install",but they rarely are.They will require some sort of finish work,whether it be a final polishing,or a possible grind.Been there done that with a variety of aftermarket cranks for different makes of engines.

 

How much $$ wise am I looking at to prep the crank to receive BBC rods vs. new crank? Also do you have a part or kit # for the rotating assembly your mentioning?

 

You can get the complete Eagle rotating assembly through Summit,or call Eagle themselves for more info.
When I did the crank in the 507,I had about $400.00 or so,with the offset grind,and widening of the journals,for the BBC rods.I would say that $500.00 should do it,to get your existing N-crank done.There are a few ways that you can do the crank for the BBC rods.The BBC rods are wider than teh Olds rod,so you can take all off the difference off the crank,all of it off the rod,or split it between the crank & rods.I split it.The width of the Chevy rod has a slight offset.That was removed,to make the rod centered,and the addtional material was removed from the crank.I believe that Eagle does it all on the crank,so the rods are not altered.

 

X2, expect to have to grind the crank, they're normally all over the place.

What's the rest of your combination? Usage, street, track, both?

 

I want to go with a max street setup. I will be going with the Edelbrock Alum Heads, probably SRP Flat top forged pistions, comp cam hydraulic roller cam(have not made selection) custom grind, 350C tranny, 3.73 posi, 2200-2400 stall converter, have a torquer intake but once cast complete most likely going with Edelbrock RPM Air Gap dual plane and either 800 Edelbrock Thunder Series or 770 or 870 Holley Street Avenger

 

http://www.realoldspower.com/phpBB2/...ic.php?t=74636

some info on stroker crank post from rop.

 

Check out my comments on this thread, this was my latest build. Maybe I can help.
https://classicoldsmobile.com/forums...455-build.html

 

I'm sorry but I think having the stock "N" crank shot peened and turned will be just fine. I don't think there is any problem with stock crank and rods up to 600 hp. Just have both shot peened and use ARP studs and either billet main caps or billet straps to reinforce the stock caps. The cost is going to be less than using the aftermarket Eagle crank because you're gonna want to shot peen that as well. Use what you've got, invest in the heads...that's where your power is going to come from.

Also, check out the Keith Black IC886 flat top forged pistons. They are light and strong.

 

You can use the stock crank at that hp level but I wouldn't use the stock rods. Buy the aftermarket stuff, it's not that much more and a lot stronger.
Jmo

 

Agreed

 

You can also get a BBC rod that is the same length as a stock Olds rod,except it has the smaller bearing diameter,and the .990" wrist pin VS the Olds .980 pin.
I figure that if you are going to get an aftermarket rod,you might as well improve the rotating assembly.The stroked 455's make great street/strip engines.More stroke,longer rod,and a short,lightweight piston at the end.Sick torque & a low-rpm powerband.The 496" stroker assemblies consist of a 4.500" stroke crank,7.100" rod,and a piston with a 1.250" pin height.You could use your crank,and get the rod & piston.I think the pistons in the Eagle kits are Mahle.You can also get a CP piston from BTR.493" with a +.030" bore,or 496 with a +.060" bore.
Regardless if you go with more stroke or not,if you are going to make the power that you are thinking about,you will need something other than the stock caps & bolts.I just have the straps,but there are plenty of other options out there now.

 

With all you guys info and research I did I will definately go with the stock crank magnafluxed, heat treated, shot peened and have oil holes chamfered. I was just given the impression by builder that by the time all this work is done including turning and cross drilling journals I would be near the cost for a new crank and given the response from 507 olds he spent $400-500 where a new one runs around that cost.

Anything else need to be done on the bottom end such as ARP main studs and moly straps?

 

A main girdle is cheap insurance. Fwiw I wouldn't cross drill the crank, just do the other stuff mentioned.
Where are you located?

 

I'm in the St. Louis, MO area.

I also ordered the Mondello Oldsmobile V-8 Engine Technical Reference Manual to see if it is any helpful info in there.

 

Dool, there is a ton of good info in that manual...most of it is for an experience machinist so that he may learn the quirks of an Olds 455. But for the layman you will find good info on what to look for in an Olds engine. It is a great learning tool to get you started on your first build and will serve you well for many years, especially if you have trouble remembering things between engine builds every 10 years Just think of it as you would the Bible, every time you read it you will see something you missed previously.

If you are going to assemble the engine yourself pay close attention to the engine sealing section. The principals discussed are used by most engine builders today. Also, if you have a dremel tool and are relatively handy you can do the block de-burring and oil passage smoothing yourself. I would stay away from any critical areas though, once you take material off, you can't put it back on. Good luck with the build! If you have any questions don't hesitate to ask.

 

Engine shop gave me a quote for align and hone of block without even checking. Is this required when blue printing the engine for tight tolerances?

 

You normally start with the main saddles, make sure they're to size and straight, then to the decks making sure they're parallel to the crank.
Then if you really want to do it right you get yourself a BHJ Bor-Tru plate, bore it with that then hone with a torque plate.

That's the way it should be done imo.

 

Hey Dool, I think I know what you're asking. You wanna know how they're giving you a quote without looking at the block to see how bad it is? They can give you the quote because whether they bore .020, .030, .060 it doesn't matter, it's going to cost the same.

They will give you the quote and then inspect the block when you bring it to make sure the work can even be done. If they magnaflux it and it's bad they'll let you know and find you another block.

 

Any of you guys have any luck with alum connecting rods?

 

The aluminum rods of today are much better then the ones of the past.The GRP pro-material aluminum rods can withstand the hot-cold cycles of a street engine.I have them for my new engine,and plan on putting in my others.

 

Are they installed on ur motor or u intend on installing? Looks like u have more a strip app and they would work better. U know anybody used them on street machine?

 

I drive this car 45 minutes back & forth to work,and in parades.I plan on doing the same with the new engine,and others already have with their engines.