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383 power questions

Pace performance sells vortec heads cheap, and cut around the valve springs for more lift. Remember that you need an intake, valve covers, a different temp sensor, and the bracket for AC wont fit even if the intake has the holes for it

Is the rotating assembly internally or externally balanced ?

Just a side note the flywheel on a one piece rear main seal is different that a 2 piece rear main motor. So depending on how the engine is balanced 400's came internal in the front and external in the rear, you will have to use a flywheel that is balanced for the rotating assembly, or not dependign on the setup.

I personally bought a internal balanced rotating assembly for my vortec headed 383, so I could put any flywheel on it (also running a sm465).
 
ive just gotta get it running thats the main thing. i figured vortecs would be a good flowing head for what i wanna do. and i can get a set of vortecs off a 99 suburban for 150 bucks from a buddy and have my machine shop clean em up and put new seals in for me. later if i need to switch to aftermarkets so be it but for now price is the big issue
 
I can give you the specs off of my cam if you want basically the same motor setup

Ha just noticed where you are located, I'm moving to Augusta in a month

Yeah just look at the other prices as well an edlebrock preformer is around 120.00 and center bolt valve covers are about another 100.00 or so.
 
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the_mule said:
Pace performance sells vortec heads cheap, and cut around the valve springs for more lift. Remember that you need an intake, valve covers, a different temp sensor, and the bracket for AC wont fit even if the intake has the holes for it

Is the rotating assembly internally or externally balanced ?

Just a side note the flywheel on a one piece rear main seal is different that a 2 piece rear main motor. So depending on how the engine is balanced 400's came internal in the front and external in the rear, you will have to use a flywheel that is balanced for the rotating assembly, or not dependign on the setup.

I personally bought a internal balanced rotating assembly for my vortec headed 383, so I could put any flywheel on it (also running a sm465).
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That statement is incorrect, ALL 400 SBC's are externally balanced at the FRONT and REAR. :deal:

Starting in 1986 when GM changed to the one piece rear main seal engine ALL of those engines are internally balanced on the front BUT externally balanced on the REAR.
 
Are you saying the 86 and up (one piece rear main seal) 350's are externally balanced in the rear?

And before this gets started I'm asking not arguing.
 
the_mule said:
Are you saying the 86 and up (one piece rear main seal) 350's are externally balanced in the rear?

And before this gets started I'm asking not arguing.
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YES, EVERY SBC from 1986-through the end of the Vortec engine regardless of displacement is externally balanced on the rear.
 
4X4HIGH said:
YES, EVERY SBC from 1986-through the end of the Vortec engine regardless of displacement is externally balanced on the rear.
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This is correct. The counter weight that was on the rear of the two piece seal crankshafts was removed from the crank in order for the one piece seal to be used. It wouldn't work with the weight in the way.

Martin
 
We just finished building a 383 for my car

If i was gonna do it again. I would buy a set of aftermarket heads to handle the lift like was said above. Buy the time I had got the heads machined, guides, exhaust seats, springs, retainers, etc I was well past what a set of aftermarket pieces would cost.
 
sweetk30 said:
and older holleys = blown power valves. now thay sell a restrictor to fix that or new ones for a long time now come factory with them.

and why build 383 with stock short 400 rods ? longer rod = more leverage = more power.
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I completely agree on the Holleys, they stopped blowing power valves 20 years ago, not an issue. And for a mud truck that probably won't be on big angles, you would want a holley for the power available.

However, I wouldn't worry about the rods for his engine. There is actually arguement, (and somewhat proven in the engine masters a few years back), that with pump gas, at lower RPMs(by low I mean 5K - 6K), a shorter rod can be better, because the piston is at TDC for a shorter time with the same stroke, lessening the chance of detonation. Also, there is the fact that the rod becomes perpendicular to the crank quicker, potentially causing more torque to be transfered to the crank. It's obviously a huge debate, and I completely agree longer rods are better for higher RPM, less piston angle, etc. But in his application I don't think it will matter much. I have a spreadsheet I made that calculates the piston movement, rod angle (relative to crank and piston), etc, with every degree of crankshaft movement based solely on the stroke and rod length if you would like to see it, and how much (or little, depending on how you look at it) it effects piston movement.

By the way, if you can afford it, I would step up the heads and cam if it's a mud truck. The heads and cam are going to be the life of the engine that will make the power, the bottom end just needs to be able to withstand it. Assuming your rotating assembly is strong enough and machined well, the heads and cam are where your money is going to get you the most power.
 
personnally I would only consider 062 vortecs (which do crack if you run the motor out of water, which happens alot since we all know vortec intake gaskets like to leak) 487s 441s, 993s or Bowties. Sure you can spend a lot more and buy aftermarket heads but I have flow benched and dynoed all these heads and Vortecs are by far the best flowing then bowties then the heavy casting smog heads. I built a dirt track 355 with 062s, a miss matched Team G intake and a 4412 (2 bbl) and it made 450hp on the dyno. They are great preformers.
 
folkenheath said:
I completely agree on the Holleys, they stopped blowing power valves 20 years ago, not an issue. And for a mud truck that probably won't be on big angles, you would want a holley for the power available.

However, I wouldn't worry about the rods for his engine. There is actually arguement, (and somewhat proven in the engine masters a few years back), that with pump gas, at lower RPMs(by low I mean 5K - 6K), a shorter rod can be better, because the piston is at TDC for a shorter time with the same stroke, lessening the chance of detonation. Also, there is the fact that the rod becomes perpendicular to the crank quicker, potentially causing more torque to be transfered to the crank. It's obviously a huge debate, and I completely agree longer rods are better for higher RPM, less piston angle, etc. But in his application I don't think it will matter much. I have a spreadsheet I made that calculates the piston movement, rod angle (relative to crank and piston), etc, with every degree of crankshaft movement based solely on the stroke and rod length if you would like to see it, and how much (or little, depending on how you look at it) it effects piston movement.

By the way, if you can afford it, I would step up the heads and cam if it's a mud truck. The heads and cam are going to be the life of the engine that will make the power, the bottom end just needs to be able to withstand it. Assuming your rotating assembly is strong enough and machined well, the heads and cam are where your money is going to get you the most power.
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can you please explain to me how a longer rod in a sbc is better at higher rpms than a shorter rod....piston speed and heat....lateral thrust? the complete opposite is true for Harley engines.

thanks
 
80' 427 said:
personnally I would only consider 062 vortecs (which do crack if you run the motor out of water, which happens alot since we all know vortec intake gaskets like to leak) 487s 441s, 993s or Bowties. Sure you can spend a lot more and buy aftermarket heads but I have flow benched and dynoed all these heads and Vortecs are by far the best flowing then bowties then the heavy casting smog heads. I built a dirt track 355 with 062s, a miss matched Team G intake and a 4412 (2 bbl) and it made 450hp on the dyno. They are great preformers.
Click to expand...

Arent the 487's different than the 487x's? Ive made good money selling the 441s and 487X's when I was buying lots of nova's back in the day.
 
4X4HIGH said:
Until they crack like they all do. :deal:
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Aren't there two casting numbers for vortec heads? I thought one was prone to cracks and bad ext valves and the other was prett much a good head.

I'll see if I can find that paper.
 
shovelbill80 said:
can you please explain to me how a longer rod in a sbc is better at higher rpms than a shorter rod....piston speed and heat....lateral thrust? the complete opposite is true for Harley engines.

thanks
Click to expand...

I don't know anything about Harley engines, I had a 2000 Buell Lightning 1200 for a few years that I changed some gaskets on, but other than that I have zero experience with Harley engines. So, what do you consider high RPM? That thing would redline at 6k, had about 110 horse and was a ton of fun. And what is the rod ratio of a typical Harley engine to start with?

I have some more questions for you by the way, since I bet you have the experience to know the results. How much difference in hp or torque have you seen with ONLY a rod length change, and how was it over the entire RPM range? Total power of that engine (thinking in percentage here to compare to a V8) I am very curious.

I am not the best person to explain it, but a longer rod will have less angle relative to the bore, for less side load on the piston and less friction, and more force from the piston is tranferred to the rod instead of into the wall. It will also leave the piston at TDC longer for better combustion, piston speed near TDC and BDC will be slightly slower, however, piston speed in the middle of the stroke will be slightly higher. So although the piston speed is slightyl higher in the middle, the transition when changing directions is softer. In the long run I think the heads and cam/intake are much better to spend the mondey and time on, because that's where the power is. Most people probably won't notice the difference in a rod length change, you can only fit so long or short of a rod anyway. I don't deal with this stuff every day, so I can't recall everything I have learned on that, but I am VERY curious to see what results you have seen in actual percentages on the dyno with rod length changes?
 
folkenheath said:
I don't know anything about Harley engines, I had a 2000 Buell Lightning 1200 for a few years that I changed some gaskets on, but other than that I have zero experience with Harley engines. So, what do you consider high RPM? That thing would redline at 6k, had about 110 horse and was a ton of fun. And what is the rod ratio of a typical Harley engine to start with?

I have some more questions for you by the way, since I bet you have the experience to know the results. How much difference in hp or torque have you seen with ONLY a rod length change, and how was it over the entire RPM range? Total power of that engine (thinking in percentage here to compare to a V8) I am very curious.

I am not the best person to explain it, but a longer rod will have less angle relative to the bore, for less side load on the piston and less friction, and more force from the piston is tranferred to the rod instead of into the wall. It will also leave the piston at TDC longer for better combustion, piston speed near TDC and BDC will be slightly slower, however, piston speed in the middle of the stroke will be slightly higher. So although the piston speed is slightyl higher in the middle, the transition when changing directions is softer. In the long run I think the heads and cam/intake are much better to spend the mondey and time on, because that's where the power is. Most people probably won't notice the difference in a rod length change, you can only fit so long or short of a rod anyway. I don't deal with this stuff every day, so I can't recall everything I have learned on that, but I am VERY curious to see what results you have seen in actual percentages on the dyno with rod length changes?
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i'm just on a coffee break so i won't go into detail.......but......let me apologize for typing while multi-tasking last night. my brain comprehended the rod/stroke point, but my fingers asked the wrong question.......i was right in the middle of a phone conversation about STROKE length and piston skirt height....... i do agree on the long rod being better for the stroke and will revisit this later.
for this motor at 5000 +/- rpms the rod won't make a difference imo.

sorry for the confusion......not hard for me to get that way :eek1:. later
 
we are setting the redline on my 383 which keep in mind is built for torque to turn 40s in the mud for 5500 rpms. i never intend on actually letting it get that high if i can help it but it will be there. using vortec heads with 1.94 valves what kind of cam should i be looking for to get the maximum power out of it
 
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