Engine.

[Prm78Big10]

New here, I have a few questions for fellow C10 owners. I'm building a 383, but currently have an L31 in my truck. Both are carburated. What I'm wondering is... Is this the right place for engine discussion, or is it only fuel related?
I'm really looking for someone who has run their truck down the 1/4, because mine should do a little better, and looking for some tips. Thanks in advance, and if this is the wrong place for performance please let me know.

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[bucket]

Do you suspect you have carb issues that are holding it back? What's the specs?

 

[Prm78Big10]

Do you suspect you have carb issues that are holding it back? What's the specs?

670 Avenger. Air fuel ratios are good. 12.8 at WOT. This 350 with 9.6 compression, Vortec heads, and Comp 276 hr, should be producing around 375 at the crank.
The only problem is, I can only squeeze out 13.9 in the 1/4. 1.9 60ft, no spinning. And barely 94 mph.
Truck has 3.9 rear, 2800 stall converter, and a 28 inch tall drag radial.
Wallace calculator is telling me I'm only pushing 265 ponies!
I know these things are big and heavy, but we are missing something here.
Truck weighs 4020 with me in it.
What gives?

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[78C10BigTen]

Nice to see another 78 big ten!!!

 

[bucket]

I wouldn't put too much trust in a calculator. Your times seem reasonable to me? Your truck has a lot of work to do to push it's way through the air, so that is hurting just as much as the weight, imho.

What trans are you running and what's your rpm across the line?

 

[4WDKC]

670 Avenger. Air fuel ratios are good. 12.8 at WOT. This 350 with 9.6 compression, Vortec heads, and Comp 276 hr, should be producing around 375 at the crank.
The only problem is, I can only squeeze out 13.9 in the 1/4. 1.9 60ft, no spinning. And barely 94 mph.
Truck has 3.9 rear, 2800 stall converter, and a 28 inch tall drag radial.
Wallace calculator is telling me I'm only pushing 265 ponies!
I know these things are big and heavy, but we are missing something here.
Truck weighs 4020 with me in it.
What gives?

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calculator I used... are you sure you dont have convertor slip?

Car weight: 4020


Flywheel horsepower 375




60 Foot Elapsed Time = 2.03

1/8 Mile Elapsed Time = 9.16

1/4 Mile Elapsed Time = 13.5

1/4 Mile Trap Speed = 106

 

[C10MixMaster]

670 Avenger. Air fuel ratios are good. 12.8 at WOT. This 350 with 9.6 compression, Vortec heads, and Comp 276 hr, should be producing around 375 at the crank.
The only problem is, I can only squeeze out 13.9 in the 1/4. 1.9 60ft, no spinning. And barely 94 mph.
Truck has 3.9 rear, 2800 stall converter, and a 28 inch tall drag radial.
Wallace calculator is telling me I'm only pushing 265 ponies!
I know these things are big and heavy, but we are missing something here.
Truck weighs 4020 with me in it.
What gives?

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frankly a square body with a a sbc running 13.9 / 94 is pretty respectable. if your pushing for 12's it going to take more than a cam and headers. the vortec heads stock or gm performance racing? stock l31 heads you have probably maxed out thier flow.. going fast usually requires trial and error or alot of money lol.

 

[Prm78Big10]

calculator I used... are you sure you dont have convertor slip?

Car weight: 4020


Flywheel horsepower 375




60 Foot Elapsed Time = 2.03

1/8 Mile Elapsed Time = 9.16

1/4 Mile Elapsed Time = 13.5

1/4 Mile Trap Speed = 106

I like your calculator much better! I'm running a 10 inch converter now, but it does about the same as a 12in that I had in it before. Both drove normal until you leaned on the accelerator, then they would flash out to about 3,000 RPM.
The thing runs really good on the street. I'm pretty sure it puts down over four hundred foot pounds of torque for a good while. At least from 3000 RPM on up. I know it is a brick trying to move air oh, that's probably why I can't get up over 96 miles per hour on the big end!

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[Prm78Big10]

frankly a square body with a a sbc running 13.9 / 94 is pretty respectable. if your pushing for 12's it going to take more than a cam and headers. the vortec heads stock or gm performance racing? stock l31 heads you have probably maxed out thier flow.. going fast usually requires trial and error or alot of money lol.

Yes, I'm pretty sure I have the stock Vortec heads maxed out with Beehive Springs and a .510 lift cam already.
I have a 383 I'm building right now with some Dart Platinum clones goin on it, and a Chris Straub cam!
Should be producing close to 500 horsepower and the same for torque all in under 6500 RPMs.
It's really nice to hear that I'm doing good with what I've got, because I thought I made a serious mistake with this motor I have in it now being way underpowered. But it's turning out that I really do have the 375 hp. I was looking for in the beginning!
Thanks for the words of encouragement. Looking forward to keeping you guys posted with my new build.
By the way, trans is in the shop right now getting a stage 3 upgrade. Supposed to be good for 650 horsepower, so I'll be ready for the Stroker motor...

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[Prm78Big10]

I wouldn't put too much trust in a calculator. Your times seem reasonable to me? Your truck has a lot of work to do to push it's way through the air, so that is hurting just as much as the weight, imho.

What trans are you running and what's your rpm across the line?

700r4. I will have to look at the tachometer next time I'm doing 95. But I'd say somewhere around 4500 RPMs, right in the fat part of my 276 hydraulic roller! The thing really pulls pretty good on the highway, I was wondering why couldn't at least run some low 13s.

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[bucket]

700r4. I will have to look at the tachometer next time I'm doing 95. But I'd say somewhere around 4500 RPMs, right in the fat part of my 276 hydraulic roller! The thing really pulls pretty good on the highway, I was wondering why couldn't at least run some low 13s.

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If you are still in the meat of the powerband and have some rpm to go as you cross the line, it could use a little more gear. But if there's a new engine going in soon, it might like the current gearing.

 

[Rusty Nail]

Well..

You can't run low 13s because you don't make enough horsepower.

Previously having scratched my own head trying to go faster down a 1320 with a built sbc in a car I thought oughta go faster, it boiled down to gearing.

Trust me dude, run, don't walk - to 4.56s.
After you get the stroker installed your truck will be stupid.fast....if you run 4.56.

A prior move to the gear swap may have kept you from building an expensive engine..I do not believe THAT sole change will yield the results you desire because - you STILL won't have enough GEAR to go fast - with a small block in a 4,000 pound truck that's shaped like a brick.

Just sayin..

 

[Prm78Big10]

If you are still in the meat of the powerband and have some rpm to go as you cross the line, it could use a little more gear. But if there's a new engine going in soon, it might like the current gearing.

Thanks guys, I like the 3.90s. The truck rarely sees track time, I just go to gauge how I'm doing on my build, and tune. The truck absolutely destroyed 2 gov-loc rear ends on the street, before I went Eaton Tru-Trac. So I knew it was putting down some grunt.
I am really glad I met my goals for this L31 build, but now I'm setting the bar higher for my 383. I have the 700r4 getting upgraded to stage 3 right now at a shop in Raleigh. So as soon as I get it back in there I'm going to go back to the track and have some fun!

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[Prm78Big10]

calculator I used... are you sure you dont have convertor slip?

Car weight: 4020


Flywheel horsepower 375




60 Foot Elapsed Time = 2.03

1/8 Mile Elapsed Time = 9.16

1/4 Mile Elapsed Time = 13.5

1/4 Mile Trap Speed = 106

Which calculator is this?

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[4WDKC]

Which calculator is this?

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https://robrobinette.com/et.htm