I have the 5.7 rods in my 400. The shop that built the engine suggested it right from the start. It runs like a champ and I've had no problems. I'm not sure but I think it has something to do with the piston to rod angularity or something. I'm sure someone with more experience will be able to give you a more exact answer. I am also running Dart Iron Eagle 215cc heads and a Comp Cams XE284 cam.

 

I have the stock rods in mine and it runs great. Unless you are building a race engine the stock bottom end with good bolts will hold together just fine. Build it for low end torque and it will be fun to drive on the street. The big change on mine were the heads and cam. It really made the 400 come alive. Very dependable, with good power and decent fuel mileage.

 

The stock crank is a nodular iron, still a cast crank but a bit stronger. Longer rods cause money to be spent on machining the block for clearance, special cams in some cases depending on the rod used and possible machining of the rod to clear the cam. It puts the piston rings into the wrist pin area and the shorter piston has a shorter skirt. I weighed the cost versus the benefit and chose to use the parts the engine was designed with, mine had 120k miles on it when I bought it with no problems other than a worn timing chain. The money saved was spent on the AFR 195 cylinder heads that boosted performance a lot more that a connecting rod that was 0.135" longer. I have not regretted the decision to build it this way.
I did machine the block to a .010" deck, bored the block .030" over size, used dished pistons, a Lunati cam, ARP bolts and studs and quality gaskets. It is by no means a budget build.
You need to decide where you want to go after hearing the pros and cons. I was never one that used any part just to say I had it. If the cost out weighs the gain I pass. There are no polished, billet or chrome goodies on the engine either, they do not make it run better and cause more work keeping it all shiny
To compare numbers the computer dynos put mine at 452 hp @6000 rpm. Torque peaks at 464 lb ft @ 4000 rpm, but is over 370 lb ft @ 2000.
It never sees 6000 rpm, but the torque is awesome feeling when powering through the gears.

Well said Philip! :thumbsup:

Many of the "nervous nellie's" out there with blank checks falling out of their pockets will do anything to change something because somebody else said it should be done.

My original Oddy built 406 utilized the stock crank and the stock rods. Now these parts were massaged but they still were GM parts and they worked very well. No, you're not going to spin them to 7000 rpm but Pandora's Box still went 7.90's in the 1/8th on street tires and that wasn't too shabby for a street car.

Many 400/406 combinations are out there running stock cranks & rods, they have for years and they have done well.

Is it the "best", no but anything can be improved on all you have to do is get out that "Blank Check"!

 

thanks for the reply philip. My intentions on my nova is a weekend tire kicker muscle car. Im know the 400 will perform very well stock but the 400 i have already has to clean up .30 atleast and since im changing the pistons i figure why not add a few little goodies while im in it. I've also heard some nice things about the longer 5.7 rods. I know a 400 ain't the toughest engine out there but i just wanna get a nice performance engine while im building it because once i drop it i hope it the last one i drop in it for a long time.

 

i have 5.7 rods in my 400 also... but then i added a 3.480 stroke crank to the mix and went the opposite way a lot of you guys choose to go. i destroked it...

i know pretty much all of our engines rev up in rpms, but my 377 just likes to stay up there and scream. it revs differently is all i can say. now i'm not really the torqueyest engine but i think i can live at a higher rpm for longer time than the .750 strokers will... never actually dyno'd but they ran whatever the sophisticated desktop dyno and it's right around 495/475 hp/tq.

torque is different so don't ever discount it. it is what pulls or pushes you to go fast. i just like stayin' there longer. the cost of pistons, rods & cranks these days the sky's the limit almost on different stroke/rod length engines. you can almost get lost in thinking about them all...

my concern when building my engine was i wanted it to live all day at 8000rpms. never intend on doing it but that was my thought.

 

lol flyer. what kinda torque you pushing with the destroke? I have heard of that before adding a 350 crank to a 400. I might just need to stay stock on the rods and invest in a nice forged crank? The mods you gotta do to make one thing work or the other can get complicated sometimes, but then again thats why some love to build them to see what they can mix and match lol....

 

The stock crank is a nodular iron, still a cast crank but a bit stronger. Longer rods cause money to be spent on machining the block for clearance, special cams in some cases depending on the rod used and possible machining of the rod to clear the cam. It puts the piston rings into the wrist pin area and the shorter piston has a shorter skirt. I weighed the cost versus the benefit and chose to use the parts the engine was designed with, mine had 120k miles on it when I bought it with no problems other than a worn timing chain. The money saved was spent on the AFR 195 cylinder heads that boosted performance a lot more that a connecting rod that was 0.135" longer. I have not regretted the decision to build it this way.
I did machine the block to a .010" deck, bored the block .030" over size, used dished pistons, a Lunati cam, ARP bolts and studs and quality gaskets. It is by no means a budget build.
You need to decide where you want to go after hearing the pros and cons. I was never one that used any part just to say I had it. If the cost out weighs the gain I pass. There are no polished, billet or chrome goodies on the engine either, they do not make it run better and cause more work keeping it all shiny
To compare numbers the computer dynos put mine at 452 hp @6000 rpm. Torque peaks at 464 lb ft @ 4000 rpm, but is over 370 lb ft @ 2000.
It never sees 6000 rpm, but the torque is awesome feeling when powering through the gears.

 

Longer rods cause money to be spent on machining the block for clearance

Your not very knowlegable on engines I can tell. But tell me why a 6 inch rods need block clearancing over a 5.7 rod. It depends on the rods your using as a Eagle 5.7 or 6.0 rod need clearancing because of the bolt used in those rods. Go to a callies rods or Lunati pro mod rods the have alot of cam clearance and pan rail clearance over the Eagle rods.

It puts the piston rings into the wrist pin area and the shorter piston has a shorter skirt.

And what wrong with that as its been done for years with out any issues but I use Mahle pistons which use no spacer rings. Having the wrist pin higher in the piston is not a bad thing as it takes alot of thrust of the skirts. With 5.7 rods you have to much skirt hanging out of the bottom of the cylinder at BDC

5.560 and 5.7 rods with a 3.750 stroke has to low of rod ratio and most 5.7 rod cranks need to be extrenally balanced.

Benefits to the 6 inch rod

Better rod ratio

Lighter pistons

Internally balance

Less friction

Less piston hanging out of the bottom of the bore at BDC

Here is a real engine that was actually put on a dyno with 6.000 rods and AFR 195 heads it made 501 on torque and 459 horse. Just a hyd. flat tappet cam.

http://www.chevelles.com/forums/showthread.php?t=106715

 

That was well said Philip and some times myself and probably a lot of us have to remind our self about that. A lot of times we just want a part just because the name and to say we have it. You guys are helping me think about my build and knowing what needs to be touched and what's already good enough. Thanks

 

I used 5.85" rods in mine...because they were free!
It makes 615 H.P. and over 500 Ft.Lbs. from 3500-6300 RPM.

 

Philip,
That sounds like an awesome mill! That stock rod length combo sounds like it really simplifies the build. Also your response to the origingal post was based on personal experience in your Nova, and I like that.

 

Here is a neat little combo
http://www.yellowbullet.com/forum/showthread.php?t=447197

5.7 or 6.0 rods, either way will work as long as it is matched to the piston. For what you are doing, the stock rod would work.

Personally I would buy a matched set of pistons and rods rather than piece meal from ebay, at least for the main rotating assembly. Get a price from your engine machinist for the rotator - the price may be the same or better than a Summit at the end of the day.

As far as p-v clearance you will need to check regardless of the direction you go, never assume you wont hit. Check bearing clearances, pushrod length, cam to rod clearance, ring fit to piston, etc. Just takes some time and patience, but bottom line don't skip the important stuff. Good luck with your hot rod and bottom line -> enjoy what you are messing with!

 

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Here's some good reasons not to use the stock short 400 rods.

• They are much weaker than regular 5.7" rods.
• If you are re-using the rods that were in the engine, consider the fatigue life. Most 400 rods have probably well over 50% of fatigue life used up. Resizing and new rods bolts will help but it will cost nearly the same as a new set of new and better metallurgy forged rods.
• You can buy "stroker" rods with that minimize or eliminate block grinding
• Rod angularity. Argue all you want about long rod vs short rod, but increasing rod angularity does increase thrust wear at mid stroke.
• Longer rods allow a lighter piston because the CH is less. Lighter pistons reduce reciprocating mass which helps acceleration and reduces load on the rotating assembly.

Here's the only reason to use the stock 400 rods.

• Might save a couple bucks.

 

Paul

Thanks for posting

As you can tell some guys here don't have a clue or understand how an engine works or what it takes to make it run properly!!!:no::no: and some base all there info on just one engine LOL

 

If your going to purchase pistons, a 5.7 rod even stock is a better choice.

Also, you will not find any performance piston with a stk 400 rod.
I wonder why???


The answer of "THIS IS WHAT I HAVE" is not the answer to the question.

 

Hi Al,

I may be wrong, but I get quite a few performance style pistons that have compression height dimensions that will work with a 5.565" rod. I "think" its the same piston as is used with a 4.125" (nominal) bore and a 5.7" in rod with a 3.48" stroke to get a 377 cid (4.155" bore I think?).

I have seen quite a few 5.565" rod 400s go very fast over years especially in stock and super stock applications.

I would prefer nowadays to use a 6" rod for piston weight and ease of balance.

In my opinion for an average street type car about any rod/piston combo 400 performs pretty well if its built right.

I actually prefer a 5.565" rod in some combinations, but thats just me. Its not very respected and/or popular, but it does what I desire.

As far as the stock crank goes, I would have it checked out (including a simple hardness test) and if its OK, I would not hesitate to use it in a mild external balance application.

Have your machinist buddy pay special attention to the steam holes and head bolt holes in the deck for cracks, if he hasn't already, but I bet he was anyway. Its a common problem with 400s (starter boss issues as well, and it may need a hole drilled and taped?).

Oh well good luck,

Jeff

 

Carl you are correct I am not an engine guru, I do however respect opinions of the engine builders that helped with mine. The machinist that did the work on the block, crank and rods had 400 engines in his daily driver and race car, the person that assembled it builds 800 + hp custom big blocks for those that can afford his services and has a short rod 400 in his Chevelle. The combination I have performs well, it runs on pump premium with no detonation or over heating issues and can be driven anywhere I need to go.
As stated it is not a race engine but a very good performing street engine. All of the expensive parts you and the other engine builders like to use are fine, I chose not to and if I won the lottery and had it to do over again it would be built the same way.
It would be nice if the respect work both ways, but you and Al and Paul seem to think the GM engineers got the design so wrong that every 400 has to be stuffed full of after market parts to be built correctly.

 

but you and Al and Paul seem to think the GM engineers got the design so wrong that every 400 has to be stuffed full of after market parts to be built correctly

The GM engineers built a 180 horse engine that was only made for a few years does that tell you anything. I highly doubt the engine you are talking about is 180 horse. And what did that stock engine turn for RPM????????

The 400 block is the poorest block GM ever designed by the those engineers and rod ratios externally balanced is not the hot set up and look at those mickey mouse rods they used.

If that was a good engine GM would still be making it. HMMMMMM

I know I can make a 400 Cubic engine run better then what GM did back 35 years ago.

 

I respect guys like Jeff, Stock z/28, he has no doubt built a crap load motors than I have, who advocates the useability of the factory rods, as I do many others here all listing valid reasons to go to the longer rod.

The one question I haven't seen asked here is, what is the difference cost wise to prep a set of 100K mile stock rods, add good bolts, resize ect... Versus a new set of 5.7 or 6.0 I beam rods from scat or Eagle.

I know you can get a set of aftermarket 5.7 rods for way under 200.00.

Figure $60.00 for new rod bolts for the stockers, plus machining? For a weaker rod with tons of miles on them? Maybe you save $30-40.00?

Doesn't add up for me.

Am I too high on the recon $$ of the stock rods?

 

I respect guys like Jeff, Stock z/28, he has no doubt built a crap load motors than I have, who advocates the useability of the factory rods, as I do many others here all listing valid reasons to go to the longer rod.

The one question I haven't seen asked here is, what is the difference cost wise to prep a set of 100K mile stock rods, add good bolts, resize ect... Versus a new set of 5.7 or 6.0 I beam rods from scat or Eagle.

I know you can get a set of aftermarket 5.7 rods for way under 200.00.

Figure $60.00 for new rod bolts for the stockers, plus machining? For a weaker rod with tons of miles on them? Maybe you save $30-40.00?

Doesn't add up for me.

I totally agree that with you that you can buy an aftermarket rod with with some type of enhanced quality rod bolt for probably "less" money than you would have in properly prepared stock set. That is why I am not recommending using any rod stock or other wise. All that I am trying say is that a lot of engines have been very successful with a 5.565" rod, stock or other wise.


I don't expect anyone to agree with me, but when it comes to aftermarket rods, there are a lot of the "budget" import rods that I am not impressed with, in fact I would prefer a "stock" rod in a lot of applications. Not a lot of quality control in my opinion.

Just to clarify my thoughts- I would not be afraid to use a stock 5.565" rod in a moderate hp 400 for a typical street car. I have used these rod quite a bit and (knock on wood) never had one break, and to the best of my memory no bearing issues either, but I am very particular in their prep..

 

i've always felt good that i could sit amongst friends and talk and learn and have it be a friendly exchange... i can't claim nor have i ever claimed to know everything, let alone anything about the principles of bore/stroke. it's always been nice to relate experiences as a layman to other laymen and to also have the benefit of other's experiences and knowledge... hey, we're all kickin' it in my/your/their shop shootin' the breeze. :yes:

one thing i did learn long ago, there is more than one way to do things...

it depends on what ya want...

 

I agree, many different ways to get there. I could care less who built what, names don't mean anything to me. I have built all my own for around 37 years now and so far haven't ever had to redo my stuff. If I want to go fast I will make it go fast. It all depends on what and how far you want to go. One big happy family.:yes::yes::yes:

 

we used to mag then polish, install bolts, resize, balance & shot peen the rods...
good rods cost considerably more then compared to now, cranks too...

quality of rod bolts have gone up too...

 

Never used the 400 rods in anything, but my old 14.5-1 iron headed 406" had a stock cast crank and stock 5.7" rods that saw the wrong side of 8000 RPM many, many times. It wasn't making a ton of power back then, but it ran 10.80's, went on a couple Power Tours, and went 9's with a shot of nitrous. The rotating assembly is still in my shop, and the crank still checked good the last time I used it. Of course, it could all go to hell on the next pass, but if I had a decent .030" over 400 block...

 

Gents?

There is a well spring of knowledge on this site that we can all benefit from.

Hell, just reading the posts that have been posted on this thread has supplied me with some very useful info.

Let's try and keep it civil. I know that it can get maddening when you have a setup that has worked great but, as mentioned, there is more than one way to skin a cat.

John

 

the 347 fuud people are prolly laughing pretty hard at somebody complaining about a 5.565 rod

 

:doh: :no: :no: :no:

That is pretty funny though! :yes:







opcorn: opcorn: opcorn: opcorn: opcorn:

 

Wow has this post grew? What's with the arguing? Everybody knows there is more than one way to build an engine. This **** starting to sound like a political debate here lol. Anyways my main question was what all had to be changed in order use the 5.7 rod? Yes I would like everything to be the best of the best but unfortunate I am on a budget and I am going to have to stay stock on a lot of things. If I could afford to put the best parts and the best of everything in this engine then I would just say the hell with it and buy a turn key...lol thanks for the help and info on the 400.

 

Only the piston needs to match the rod length and the stroke of the crank or it will come up to short from the top of the deck or it will come out past the top of the deck. I have the 5.7 rods in my fresh 383 with Probe pistons and the Scat 9000 3.75" stroke crank. Good luck with yours.

 

what makes the 400 rod 383 so much fun ,, is that you do not have to spend an arm and a leg on this motor and it still performs very well ,,, take a set of 350 flat top pistons for a stock 350 rod ,, 1.560 comp height , 400 rod , 400 crank turned to fit ,, you can have a rotator for under 350 bucks if you use a cast piston ,, i think thats half the fun in this ,, to see what you can do without spending a ton of cash ,, if a person likes to spend money ,, well go spend it ,,, but you don't have to ,, if you want a 450-500 hp motor

 

Just to add a little additional info, I have built a lot of 5.565" rod 383s and actually prefer the shorter rod, but its hard to do with most import cranks as the counterweight is somewhat different in shape than the OE 400 crankshaft, and there is a very good chance there will be interference with the piston at or near BDC.


I still modify the original 400 cranks to build this combination even though its a lot more practical to just buy the $129.00 import 3.75" crank.


Its just my preference for this particular combination, and I am not trying to sell anyone on it, but it does seem to work well in a lot instances up to about the 5000 RPM range. If a realistic operating point was above that I would probably go the easier Chinese route.

Jeff

 

you can buy TRW forged 350 stock replacement pistons ,, and build a solid 383 with the 400 rods ,,, i'm sure all the nascar engine builder strikers won't like them ,, but that combo does very good ,, so ahead ,, spend more if u want ,, depends on what you have when you start and what you want to do ,,, 500 hp , i'd use the 400 rods IF i had them ,, i've seen too many of them built ,, and last when they're getting ran hard for years ,,, drag racing , circle tracking ,, they do a decent job

you can get 350 replacement pistons for around 100 bucks if u shop around ,, so , it is cheaper to go the 400 rod route ,, saw 'em do good ,, ,, 6500 rpm ,, they do fine

the one we did for my brother ,, he had a 400 that the start boss broke off , so , we had the crank and rods ,, its still running with over 10 years of use ,,

my neighbor had one in a pick up he ran for 5-6 years ,, 400 rods ,,, i can't dislike them cuz i've saw too many to a fine job ,,

 

Another general thought:

When I hear the anecdotes about really fast "low budget" engines, my first impulse is to wonder if the owner would sell for the price claimed. In every case, the owner declines because he has a lot of time in skilled modifications, scored some one-of-a-kind "nearly free" parts, or after everything is accounted for, really has more money into it than "advertised".

There should be an Internet "claimer" rule. If someone brags about an engine having extraordinary performance for a ridiculously low price, someone else should be able to buy it from you at that price. If you won't part with it at the price you stated it cost you, it's obviously worth more than the price you claimed.

Also, "bench racing" should always be civil, but it also should be accurate. These kind of controversial threads seem to always go out of control when someone gets mad and starts jabbing.

Baiting someone with smack talk just to get a rise out of them is not productive to the conversation. Everybody is entitled to an opinion. It's a discussion, not a fight to the death battle.

 

Paul,

I would have to say that when I talk "cheap" I mean cheap.

If it were "easy" to use a say a 327 piston with 5.565" rod x 3.48" stroke I would have done it. It would have to be easy to duplicate.


As far as resale value goes, in my opinion, Internet or not in the USA you are entitled to compensation for your efforts?