[1980jr]

I just picked up a fresh 1970 455 bored 40 over it has factory rods and bolts 2bolt main caps and factory N crank I'm not sure if the pistons are cast I have edelbrock 87 cc round port heads with crane 1.65 roller rockers, a comps cam 274h cam dougs headers and and edelbrock rpm intake and a 770 Holley street avenger fired off by an msd pro billet distributor.


Now my question is should I swap out the rods for some eagle forged rods and add studs to the main caps and can I do this work without sending the engine to machine shop? The engine is going to be street driven but I want to be able to bash on it when I want this engine is going in a 1980 trans am with a t56 magnum trans and a 9"rear with 3:89 gears I want this car to be fast and I want around 550hp without blowing the guts out the pan

[Nicks67GTO]

I would stick the forged rods in it but in it but its going to have to go to the machine shop for a balance/clearance check. I have a feeling that if you dont put good rods in it and balance it, you'll have a picture window out the side of that engine in short time.

[rad400]

I would either add the stump puller roller cam or the ol faithfull cam as well.

[MescaBug]

Needs to go to the machine if you change rods. And might needs an align/hone job if you switch to main studs. Torque ratings are different than bolts.

Some say its not necessary but why not do it proper.

What kind of pistons you have in there?

[1980jr]

I'm not sure what pistons I have I'll have to remove them to see what kind of rods I need to order. Any ideas on the cost of balancing and assembly they might as well put the short block together while its there. I don't want to change the cam out because I just put it in new last week. I may just be looking at adding forged rods and pistons and main studs.

[MescaBug]

Originally Posted by 1980jr

Any ideas on the cost of balancing and assembly they might as well put the short block together while its there. I don't want to change the cam out because I just put it in new last week. I may just be looking at adding forged rods and pistons and main studs.

Depends on the shop.. My shop charges 250$ (often less if its a small job) for a complete rotating assembly balance; crank, rods, flywheel.

If you change the pistons, you'll need new rings. With new rings, the cylinders needs a hone to get rid of the 'ridge' from the top of the cylinder, and remove surface wear and imperfections so the new rings seals.

You also need to check clearances with new pistons.

[1980jr]

This engine has 0 miles or run time never been fired will I still need to hone the cylinders?

[MescaBug]

Sorry, my bad... I read your first post too fast.

No hone needed. But check the clearances just to be sure.

[72LuxuryLeMansLa.]

Originally Posted by 1980jr

I just picked up a fresh 1970 455 bored 40 over it has factory rods and bolts 2bolt main caps and factory N crank I'm not sure if the pistons are cast I have edelbrock 87 cc round port heads with crane 1.65 roller rockers, a comps cam 274h cam dougs headers and and edelbrock rpm intake and a 770 Holley street avenger fired off by an msd pro billet distributor.


Now my question is should I swap out the rods for some eagle forged rods and add studs to the main caps and can I do this work without sending the engine to machine shop? The engine is going to be street driven but I want to be able to bash on it when I want this engine is going in a 1980 trans am with a t56 magnum trans and a 9"rear with 3:89 gears I want this car to be fast and I want around 550hp without blowing the guts out the pan

I'm no expert but my opinion is this; you need forged rods and pistons but your power levels are no place close to requiring a forged crank or four-bolt mains. The hone may be required if you use a different ring type and tension so leave this to the machinist. The balance job is as said earlier only in the 2-300.00 range. You can save a little money tearing it down yourself but really I think it would be best to let the machinist do this so that he can keep all of the bearings and such in order to make checking clearances easier and they can be used again. Then add another couple hundred to assemble the short block and finish the build at home if you have the tools.
I also agree with the post recommending the "Old Faithful" HR cam. An added expense but a great choice for your car. Why spend all of that money on a Pro-Street build and go cheap on the cam only to change it later.

Karl

[screamingchief]

I guess I'm the voice of dissent here,I'd leave the shortblock together and just throw a better cam in there.

Probably something like the #60310 or #60311 Crower SFT cams.

I'd just be real sure to put a rev limiter on it and keep it below say 5500 or so RPM.

Never seen a main cap bolt fail in my life,so I see no reason to convert to studs for a build like this,the 455 block will fail (crack) long before the main cap bolt will fail.

And while the cast rods are'nt ideal,in a street application like this,I dont see that being a real problem,and w/o knowing what pistons are in that shortblock,the rods would'nt worry me like they seem to be worrying others.

I'd spend the money you'd spend on improving the shortblock on other things like a good oil pan for improved oil control and such,as most rod failures are typically caused by oiling system problems.

This is one of those deals where project creep starts coming into play,one or two small changes end up forcing others changes,and next thing you know it's years & many $$$$ later and all you wanna do is drive the d@mn thing.

Nah I say just get the rest of it together and enjoy it now.

You can always start building a better 400 block based stroker shortblock w/all the "good stuff" while you're driving around in this one.

FWIW

Bret P.

[Blued and Painted]

Originally Posted by screamingchief

leave the shortblock together and just throw a better cam in there.

Probably something like the #60310

This is one of those deals where project creep starts coming into play,one or two small changes end up forcing others changes,and next thing you know it's years & many $$$$ later and all you wanna do is drive the d@mn thing.

Bret P.

X2
Probably could use the same springs.
double check for spring locators.

[Skip Fix]

X3! Lots of cast piston motors hammered on that live. Some for factory rods assuming they put new bolts in them. I ran stock rods new bolts in my first 455 with RAIV heads spinning to 6000 all the time and autocrossed the heck out of it.

Keep a mild cam and you will be fine.

Then start collecting the parts for a better shortblock -rods,pistons etc.

One last thing that always worries me about a balanced assembled short block-what flywheel did they use a neutral balance or one with the factory external balance?

[ta man]

Leave it alone...my current shortblock is factory crank,prepped factory rods..hasn't blown up yet.I keep the revs under 5500 rpm...It doesn't make much power either only mid 11's at 118mph...

[Tim Corcoran]

If you are serious about having a true 550 hp then I would agree you should have stronger rods and forged pistons. If the stock rods were re-sized and new bolts installed they will be stronger than most people believe but would not use them for 550 hp. If the engine is not approaching detonation and kept in proper tune cast pistons will hold up just fine up to a point and 550 hp is beyond that point.

[CROCIE JR]

That combo is good for 490-500hp at 52-5300 rpm. Rev limiter at 5500. Not enough cam to go past 5500. Keep the tune safe. 38-39 degrees total timing and AFR in the 12.4-12.7 range WOT. It better be less than 10.5:1 if its on pump premium. On a side note. Some of you are recomending that the machine shop assm or dis assm. the engine. Machine shop guys are not engine builders. I only know of one guy in the country that has a machine shop (primary business) that I would let or attempt to put an engine together. "one bank of lifters is clatterin" How many times have you heard that? "Did he get the rear seal right" The list goes on and on. Find a guy that has built a few Pontiacs that dont leak and are still together, thats your guy. Just sayin'

[CROCIE JR]

That being said, run it and enjoy. Besides, if it pops, it was just stock stuff anyway!

[rexs73gto]

If you have all the money in the world & don't care if you blow up an engine, go ahead & leave all the cast parts in & run it any way you want. But if you care about this engine & want it to stay together for a long time then pull it apart get some good forged rods & pistons, have it balanced & put in the studs & align hone the crank. If you do it right the first time then you won't have to woory about the NEXT engine your going to need. Or if your just doing this engine for pratice then just leave it along because 1 bad tank of gas or the oil gets low you'll get the chance to put a second one together. Build it once build it right & have a great time with it & then you won't have to worry about the next engine your going to build. But hay if you have more money then sense leave it alone, beat on it & you'll get your chance to build thaat next engine the right way. Right now your going to spend about $ 600.00 to $ 1000.00 on new parts & machine work, but your next engine will cost probeley cost you around $ 5000.00 to $ 7000.00. Because if you do it right now then you can have that exrta money to do something else on the car that may need it to.

[Nicks67GTO]

Originally Posted by rexs73gto

If you have all the money in the world & don't care if you blow up an engine, go ahead & leave all the cast parts in & run it any way you want. But if you care about this engine & want it to stay together for a long time then pull it apart get some good forged rods & pistons, have it balanced & put in the studs & align hone the crank. If you do it right the first time then you won't have to woory about the NEXT engine your going to need. Or if your just doing this engine for pratice then just leave it along because 1 bad tank of gas or the oil gets low you'll get the chance to put a second one together. Build it once build it right & have a great time with it & then you won't have to worry about the next engine your going to build. But hay if you have more money then sense leave it alone, beat on it & you'll get your chance to build thaat next engine the right way. Right now your going to spend about $ 600.00 to $ 1000.00 on new parts & machine work, but your next engine will cost probeley cost you around $ 5000.00 to $ 7000.00. Because if you do it right now then you can have that exrta money to do something else on the car that may need it to.

This

[CROCIE JR]

There are plenty of bone stock 455s running E heads and small cams. Key word being rev limiter. Oil system upgrades have been mentioned. Does it need forged internals for the rpm and cylinder presures associated with 500HP at 5200rpm, no. Would it be nice to have a pontiac engine builder go through the current combo. Yes. $$. Would it be nice to have at least forged rod$$ Forged piston$$ Forged crank$$$. A reputable machinist to perform the machining$$ How about correct some of the other important parts$$ Yes. These are just internet opinions, here, there is no right or wrong.

[1980jr]

Thanks for all the great input I made up my mind with your help I contacted an engine builder locally who said he could swap out the rods align bore the mains and put in studs ill use the factory crank he gave me a quote of 1200 including parts. So ill be dropping it off to him in the next few weeks I want to build this engine once and one time only. This quote is minus a new set of pistons btw so I figure for 2 grand I can have a nice solid foundation for an engine that I can revv and beat on.