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rebuilding my 400 SB's and wnat a bit more revs

  
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rebuilding my 400 SB's and wnat a bit more revs

 
kainhall kainhall
V-6 Camaros rule! | Posts: 38 | Joined: 05/10
Posted: 11/30/12
12:04 AM

one has a blown head, the other has been sitting in a field for 12 years and leaks like crazy...so, this summer im going to rebuild them. the one that goes in my truck is going to be kept stock...mabey a slight cam, as its a 6200 pound truck...its not fast!

the other, goes into my 68 impalla... now, i know you really cant rev these engines stock (dont realyl liek to go over 5000 RPM) because of the stroke externaly ballancing, and weak crank ETC blah blah

how can i make it rev like a 350? would internaly balancing it help any? i heard something about gettign shorter rods, and pistions with a lower wrist pin location?

im going to put a decent cam, a nice set of heads, and a better exhaust on it anyway... but a few more RPM would definatly be nice. would also stop me from worring about it flying apart when the stop light goes green!

thanks.  

68scott385 68scott385
I have an SS396 tatoo | Posts: 325 | Joined: 07/09
Posted: 11/30/12
09:01 AM

You need to have both engines disassembled and inspdected first. Then worry about what parts go inside. A stock crank in good condition will be fine for your truck. Depends on what you expect from your car as to what you put inside the motor.

Assuming the truck will be used to haul, not race, the stock parts will be fine. Personally I would go with 5.7/350 rods w/pistons to match...longer rods with higher wristpin location...better rod/stroke ratio amoung other things. Internal balancing is expensive and not really necessary unless the motor is a serious high performance unit.  
68scott385 68scott385 68scott385

kainhall kainhall
V-6 Camaros rule! | Posts: 38 | Joined: 05/10
Posted: 11/30/12
08:42 PM

ya.. the truck is used for getting threw the snow, and pulling people out of hte ditch... stock with a mild cam.

the 68, i want it to be turn key, 87 octain pump gas, tire roaster.

im just worried about reving that 400. the weak spots are the crank twisting, and rods i assume... the engine probably has 75,000 miles on it, well kept up (when it was not sitting), so its probably going to be just the normal rebuild...rings, bearing...possibly a bore or hone...the seals just kinda got dry and leak a ***  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 12/01/12
12:34 AM

Build a 383 or 388 and as Scott recommended stay away from long rods for the street. They have NO Horse power advantage. If you where building a Mechanical Roller Cam that was spinning 8,000RPM+ okay with the long rod.

  Getting back to what your looking to do with you truck, you want torque, torque. Torque gets the truck rolling and Horse Power keeps it moving. You can use a stock torque convertor, But you need atleast a 3:70 to3:90 Rear Gear depending on how tall your tires are.

  CompCams P/N 12-208-2 Grind #265DEH Engine 350 to 400Ci.
Very strong mid range,Lopey idle,use with a stock exhaust, and torque convertor.
The Cam Specs.   .211/.221 dur @ .050  .442/.465 lift. 1500 to 5750 RPM range.
                110* Lobe Seperation and 106* Intake Center/Line Grin  Cool

Bob  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 12/01/12
12:54 AM

Make sure you use aleast the Older Z-28 valve springs, or what CompCams suggest for valve springs. that will get you there for you cam lift. They will also fit into the valve spring pockets for you stock heads.
 
  One other thing make sure you follow the cam manufactures Break in procedure for a new cam. I would really suggest a Hydraulic roller cam. Then you wouldn't have to worry so much about cam failure! The cost for setting up a cam is around $800.00.
Use they're lube and follow the procedure I can't stress that enough! It is a little long, but it needs to be done exactly as they say. Grin  Cool

Bob  

Ravoll Ravoll
V-6 Camaros rule! | Posts: 85 | Joined: 02/12
Posted: 12/01/12
03:27 AM

Hi Guys.
When I read "i heard something about gettign shorter rods, and pistions with a lower wrist pin location?" it dawned on me that there is a considerable amount of misunderstanding with the subject of piston stroke.To get more revs you have to shorten the stroke/travel distance of the piston.
Changing piston stroke is done at the crank,not the rods.All that's accomplished by changing the only the rods is you change the travel "area" of the piston in the cylinder,but not the "distance". Longer rods move the piston higher in the cylinder,causing the piston crown to be up a little higher at TDC.This will raise the CR a bit but does not change anything as far as the travel "distance" goes.A shorter rod does just the opposite,lowering the piston crown at TDC,thus lowering the CR.It will also cause the piston skirt's to be pulled down out of the cylinder farther at BDC,but no rev change,(Unless you break the skirts off,boom clack clack, and the revs can change to zero).

You have to think of it like this.If you have a crank shaft with a 3.500" stroke,the piston travel "distance" in the cylinder is 3.500". It don't matter if you have 5.700"or a 6.00" connecting rod,your piston travel "distance" is still only 3.5 inches.Only difference is you've moved the piston 0.0300" higher or lower in the cylinder depending on which rod you use,and you are only changing the travel "area"and CR.


To change the stroke you have to change the crank throw,then you change the rods to get the piston back close to the correct travel area in the cylinder.Of course by changing the crank throw you change the travel "distance",and the "area"
Longer travel distance = lower rev,more low end torque.
Shorter travel distance = higher revs,torque comes in a bit later.

So for more revs ,de-stroke the crank,install longer rods or pistons with lower pin locations to get back within the travel "area".

Creating a longer stroke improves low end torque,but actually lowers the rev capabilities.Shortening the stroke reduces low end torque but allows higher revs.




The reason I got on this thread is I see this all the time.Over here, everybody wants a stroker but some are only engines with shorter rods and lowered compression with piston skirts in the oil pan,nothing has been done as far as the crank goes.

Oh Yeah almost forgot.Why would a 400 not rev like a 350? All my data on the older motors shows 350's and 400's using the same crank stroke.Only difference is the 400 main journals are larger in some cases.  
The older I get,the faster I was.

kainhall kainhall
V-6 Camaros rule! | Posts: 38 | Joined: 05/10
Posted: 12/01/12
04:05 AM

its all about angles... the rod does not have to get close to the wall.. or, sence the rods are shorter, they are stronger. also less weight rotating around at 6500 RPM!

and i dont want to raise compression or lower it (i do want to raise it a *** the rod and piston combo will be the same over all lengh, due to the different rist pin location.

to get a stroker engine.. you have to change the crank.. but i dont wnat a stroker...i think the only thing you can do with a 400 is but a 327 or 350 crank in it to make it a 377.  

kainhall kainhall
V-6 Camaros rule! | Posts: 38 | Joined: 05/10
Posted: 12/01/12
04:13 AM

shoot, doubble post, but!

i have worked with my dad on a few engines... namely his 440 in his 72 plymouth satilite..heads, cam, exhaust, intake, carb, crank...everything has been tweeked. so i know the came break in and using a zinc aditive (my dad rounded a lobe by not adding the zinc the first time we put a cam in it) ETC. we do all our own work...its not a back ward shop either... roy has a buessness hauling sand and water for the oil rigs in norhteast montana/north dakota.

however, i dont know everything, im only 18!

and to who ever sugested a 383 stroker... HP sells engines, tourque wins races. a 400 SBC has enough HP to keep it moving and a *** ton of tourque! it beats a 7.2 L ford deisel engine in foot pounds! (400+ vs 3 soemthing)

and im not doing mutch with the truck... it has some low rear end gears... the speedo was slow (at 55 on the speedo i was going 75) and i put the needle past the 100MPH mark and still had a few thousnad revs to go!! its its jsut got a th350!  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 12/01/12
11:21 AM

I suggested a 383. Did you suggest any engine size?
  If the 400 engine was so great GM would have built them as they did the 350's. That's why we use them in stroker kits. They have No Place in a truck. If you don't know how to modify it it will blow head gaskets as soon as you put a load on it.
  Tell me why you want to use a long rod? Ravoll didn't we go through this once before. A 6.0 rod No Advantage on a stock or near stock engine.

Kainhall. Do you know what dwell time is when your using a longer rod then stock!You have it backwards. Torque moves the car or truck Horse Power gets it to the big end.  

kainhall kainhall
V-6 Camaros rule! | Posts: 38 | Joined: 05/10
Posted: 12/01/12
05:46 PM

wiat.. your saying for a truck... made for towing, running around in the 140 inches of snow we get... you want i high HP engine, insted of tourque? MIND = BLOWN! and a 350 is a 5.7L not a 6.0... 400 is a 6.6L.

tell me why i know a dude (recently died) with a vega with a 400 SBC...he told me it was making over 600HP... and this old dued was not the type of person who puts a crome thermostat housing on it and clames a 25HP gain.

im use it would be easyer to drop in a 350 like every other person out their... but, you cant beat displacment. im gaining more HP and toruque than you with the same upgrade and msot 350 upgrades also work for a 400. GM stoped making them because they are almost a full LETER bigger than a 350... that requires a LOT more fuel. now, if you remember right... 1970 oil embargo, then requirments for higher MPG and lower emitions. and heat problems.. mines runs at 185 just like everything else.

this probably does not help my case...but my 400 in my truck does have a blown head/gasket, but it still will lift a front tire off the ground... the 400 in my 68 tears motor mounts (gone threw 2 cheap ass carquest ones).

i jsut heard that a long rod improves the geometery, their for improving other things. i cnat go ask the old man with a 600BHP 400...because hes dead. he did however mess with the q-jet on my truck...and god damn.

i dont have a 350 or 383 just lying around... we have a L6 with twin, twin screw superchargers...but thats going into a rat rod.

give me a few summers.. im in college, i cnat put 4 grand into an engine... drive your 383 up to montana, and let teh flag drop.  

kainhall kainhall
V-6 Camaros rule! | Posts: 38 | Joined: 05/10
Posted: 12/01/12
05:46 PM

it some how posted twice... damn IE

and a vortech head upgrade (need to do soem digging to see if vortec heads really make a difference), cam, exhaust, intake, piston, and CP upgrade is not a stock engine.

you like the 383..i like the 400. dont tell me my engine is trash... tell me what i wnat to know.

how do i make a 400 SBC rev higher?  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 12/02/12
12:35 AM

I agree there is NO replacement for Displacement! You had better know the modifactions for that 400 block. Or it will blow a head gasket the first time you put a load on it.

You have all the answers, and yet all you do is quote the same crap to this forum If you know so much then why are you on a Chevy forum looking for answers. Please don't try and insult any of the guys on this forum.

Why don't you know how to get a 400 to rev higher? You don't know everything so ask you question don't debate people.

I am not going to debate you because your fudged HP and TQ numbers are fiction.

Also what is the 5th cycle in a 4 cycle engine?  
You didn't answer my simple question. What is the difference in Dwell time of a 5.7" rod and a 6.0". I have never seen GM use a 6.0" rod in any production small block engine. It's we the Gear Heads that wanted to make these combos work.  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 12/02/12
01:02 AM

Icon QuoteRavoll:
Hi Guys.
When I read "i heard something about gettign shorter rods, and pistions with a lower wrist pin location?" it dawned on me that there is a considerable amount of misunderstanding with the subject of piston stroke.To get more revs you have to shorten the stroke/travel distance of the piston.
Changing piston stroke is done at the crank,not the rods.All that's accomplished by changing the only the rods is you change the travel "area" of the piston in the cylinder,but not the "distance". Longer rods move the piston higher in the cylinder,causing the piston crown to be up a little higher at TDC.This will raise the CR a bit but does not change anything as far as the travel "distance" goes.A shorter rod does just the opposite,lowering the piston crown at TDC,thus lowering the CR.It will also cause the piston skirt's to be pulled down out of the cylinder farther at BDC,but no rev change,(Unless you break the skirts off,boom clack clack, and the revs can change to zero).

You have to think of it like this.If you have a crank shaft with a 3.500" stroke,the piston travel "distance" in the cylinder is 3.500". It don't matter if you have 5.700"or a 6.00" connecting rod,your piston travel "distance" is still only 3.5 inches.Only difference is you've moved the piston 0.0300" higher or lower in the cylinder depending on which rod you use,and you are only changing the travel "area"and CR.


To change the stroke you have to change the crank throw,then you change the rods to get the piston back close to the correct travel area in the cylinder.Of course by changing the crank throw you change the travel "distance",and the "area"
Longer travel distance = lower rev,more low end torque.
Shorter travel distance = higher revs,torque comes in a bit later.

So for more revs ,de-stroke the crank,install longer rods or pistons with lower pin locations to get back within the travel "area".

Creating a longer stroke improves low end torque,but actually lowers the rev capabilities.Shortening the stroke reduces low end torque but allows higher revs.




The reason I got on this thread is I see this all the time.Over here, everybody wants a stroker but some are only engines with shorter rods and lowered compression with piston skirts in the oil pan,nothing has been done as far as the crank goes.

Oh Yeah almost forgot.Why would a 400 not rev like a 350? All my data on the older motors shows 350's and 400's using the same crank stroke.Only difference is the 400 main journals are larger in some cases.


Alan
  You never told me how you made out on those 305 heads? It's a lot of work hah? Did you ever finish them? I saw a set that a guy did he used a 416 cylinder head, and was only able to get a 1.94 intake valve in it for a 305 engine. Crazy Dave is going to dyno the engine when the guy gets some money. It will be interesting as to how they work. How's the Vette running? Haven't heard from you in awhile.
  I read an article in a trade magazine, they said the guys using flat tappet cams are wiping lobes off at a rate of almost 1-1. 50% thats sad when you think of how our Government controls us.
  I think by the end of this decade the word flat tappet will not be in our vocabulary any longer. The hydraulic roller cams do a lot of things right. The expense is great and when your selecting a cam you better be right.
  Why and when would you run a 6.0" rod in a small block?
Crazy Dave and I have done a lot of dyno work. A 6.0" rod will start to affect horse power and torque above 6500RPM. In fact there are times they work only when you have a poor flowing head. That reason is the Dwell time.  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 12/02/12
01:43 AM

kainhall
If your in college take a spelling course first. I don't know what half those misspelled words are.  

kainhall kainhall
V-6 Camaros rule! | Posts: 38 | Joined: 05/10
Posted: 12/02/12
03:22 AM

dwell.. when you throw a ball up in the air... and it looks to stop at the higest point. in an engine..TDC and BDC. that was not googled...know this from physics class... it actualyl does nto stop moving...earth is moving and spining ETC, but that does not matter.

how have i insulted, or quoted the the same stuff on this form? i know a bit..but like i said im 18... i dont know everything.. nor does my dad, roy, or anyone for that matter.

http://67-72chevytrucks.com/vboard/showthread.php?t=521583  5th post. i got my numbers (mines said 235HP IIRC) from a 1977 service manuel for K10 trucks...my truck is a 77 k10. these a NET figures... with the AC, power steering, ETC so actual power is a bit higher.

http://www.thedieselstop.com/forums/f24/how-much-horsepower-does-2000-powerstroke-have-227780/ 2nd post.

6.6 chevy damn near equals a 7.4 ford. *** you saying i make numbers up.

5th cycle in a 4 stroke... theirs not one, its a 4 stroke. unless your devinding 1 stroke into 2.

and a 400 does NOT use hte same crank as a 350.. journals are bigger... stroke is bigger. a simples wiki search will tell you a 400 uses a 4.125 inch bore with 3.75 stroke... 350 has a 4 inch bore with a 3.48

and im not just changing the rods like your quote suggets.. im THINKING ABOUT changing rod and wrist pin... same compression ratio... if it does anything.  

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