Carburetor size Question

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go-fish

go-fish

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I have a 318 getting finished up and will be needing to upgrade my carb. Currently the engine is a stock 318 HD in a 1976 D100 that was ordered for Cal Trans. It has a 360 intake on it and I've always been curious if the HD designation had it built with 360 heads and intake in 1976 or if these were add-ons. The engine had reportedly had the oil pump replaced by the previous owner. After a few months of ownership and the truck running like **** I was tuning on it and decided to buy an Edelbrock AVS 500 cfm carb to use on the current engine. It ran much better with this carb.
The good times didn't last as it started knocking pretty bad and parformance dropped off so bad that I could barely get up the hill on my driveway. With the report of a previous oil pump replacement I decided to just have a different 318 built with a '73 340 cast crank I had laying around. Around this time Speedmaster was having one of their salse so I got a pair of bare heads and an air gap intake.
Specs on the new engine are .060" + for "328 cu in.", '73 cast 340 crank, Eagle SIR rods, KB167 pistons, GJ oiling mods, HFT 224/230 @.050 lift on a 110* LSA, Competition Camshafts adj. rockers, bowl blend on the SM heads and gasket matched intake. I am thinking about an FBO ready to run distributor. Fresh 727 with mild work, the shifts are a little firmer but nothing crazy that is annoying for street cruising. Stock converter, 3.23 gears. This is just a SWB, parts chasin'/run around town "sport truck".
Any ideas on HP and the main question of what carb? I really like the AVS. I was flirting with doing a Fi-Tech but leaning toward sticking with the AVS style since I was liking it in the 500 cfm form with the 318.
 
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KB107 are for a 360 with 4 inch and larger bore...and a 3.58 stroke.....

With a 3.31 stroke from the 340 cast crank they will be a 1/2 mile down in the bore .....if you can get the bore large enough
 
70aarcuda said:
KB107 are for a 360 with 4 inch and larger bore...and a 3.58 stroke.....

With a 3.31 stroke from the 340 cast crank they will be a 1/2 mile down in the bore .....if you can get the bore large enough
Click to expand...

They are different. KB 167 piston not the 107 . KB hypereutectics for a .060” 318. 3.31 stroke.

I was just typing off the top of my head and accidentally put the wrong number.

My apologies.
 
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well.,,you wrote KB107 which is hyper piston for a 360 which is 4 inch bore and larger....3.58 stroke
 
go-fish said:
Well, ok. Fixed it. Any advice?
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Stroke a 360....that is all.........over and out 10 4

I can only response to what you wrote ....not what is bouncing between your ears....
 
A stroked 360 is not the route I took.

If you’re just going to come in a thread and act like this why would you even comment?

Who pissed in your Wheaties this morning?

70aarcuda said:
Stroke a 360....that is all.........over and out 10 4

I can only response to what you wrote ....not what is bouncing between your ears....
Click to expand...

You can choose not to “response” too.
 
With a 9.5 to 1 go with what Rusty says. He's a good man.
 
RustyRatRod said:
A 650 DP would light it up.
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Thanks for the reply Rusty. How would a double pumper do in regards to economy vs. say a Demon or AVS style carb?
I would like to balance economy and performance. Gas prices are ridiculous and I want to drive the truck a lot.
 
go-fish said:
Thanks for the reply Rusty. How would a double pumper do in regards to economy vs. say a Demon or AVS style carb?
I would like to balance economy and performance. Gas prices are ridiculous and I want to drive the truck a lot.
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Maybe a spread bore would work best for you. I think they sell them in a 700 - 750 and that would work good too. Running on the small primarys when your foot is out of it.
 
go-fish said:
Thanks for the reply Rusty. How would a double pumper do in regards to economy vs. say a Demon or AVS style carb?
I would like to balance economy and performance. Gas prices are ridiculous and I want to drive the truck a lot.
Click to expand...

It's not gonna be enough of a difference to hurt you, but the performance difference will be really good. Had I not had such good success tuning this 450VS on my slant 6, it'd have a 600DP on it right now.
 
LO23M8B said:
Maybe a spread bore would work best for you. I think they sell them in a 700 - 750 and that would work good too. Running on the small primarys when your foot is out of it.
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I agree, if he wants more towards mileage. But the difference between the small DP and a spread bore for mileage IMO on a 318 will be minimal, so why not go with the better performance? Either will work well, though. I think the little 625 Street Demon would turn it on too.
 
go-fish said:
A stroked 360 is not the route I took.

If you’re just going to come in a thread and act like this why would you even comment?

Who pissed in your Wheaties this morning?



You can choose not to “response” too.
Click to expand...

Hey.,,,its your money spend it on what ever pulls your chain....
I was just pointing out the errors in your post....wrong pistons...

carb 650 double pumper
 
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My opinion: You own the 500 carb now and know that it works. Since your putting a new cam in the new engine, break everything in with that carb and use it. They are easier to tune than a Holley. (yes for flat out performance a Holley or similar is better) But your post states running around parts chasing fun sport truck...
I will question the 224/230 cam for the 318 though it seems a bit big duration wise for a running around parts chasing fun street sports truck, to me with a stock convertor and 3.23's.......
Sounds like a neat project though Good luck with it!
 
1966Post said:
My opinion: You own the 500 carb now and know that it works. Since your putting a new cam in the new engine, break everything in with that carb and use it. They are easier to tune than a Holley. (yes for flat out performance a Holley or similar is better) But your post states running around parts chasing fun sport truck...
I will question the 224/230 cam for the 318 though it seems a bit big duration wise for a running around parts chasing fun street sports truck, to me with a stock convertor and 3.23's.......
Sounds like a neat project though Good luck with it!
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I agree a bajillion and a half percent to break it in with a known good carburetor. That point cannot be driven home enough. Great point!
 
318 in a street configuration, anything bigger than a 625cfm is too much imo.

500-600cfm would be it. Wouldn't necessarily choose a dbl Pumper either.

So you took an external balance 340 crank and hung lighter than stock 318/340 pistons and rods on it.
You balanced it, right?
 
MOPAROFFICIAL said:
So you took an external balance 340 crank and hung lighter than stock 318/340 pistons and rods on it.
You balanced it, right?
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Yes. Cast 340 crank in a 318. It has been balanced. I had a 318 that had a stripped balancer bolt and I tossed the crankshaft. I had a ‘73 340 crank laying around. Parts I already owned. If I had to buy a crank I would have bought a 4” crank. I’m not trying to pull stumps or drag race this truck so I figured a low budget build would be in order. Intake and heads were cheap and I already had the block and a crank.
 
1966Post said:
My opinion: You own the 500 carb now and know that it works. Since your putting a new cam in the new engine, break everything in with that carb and use it.
Click to expand...

Excellent advice. Thanks.
 
LO23M8B said:
Do you know your true compression ratio?
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Just talked to the engine builder and he said it’s going to be more like 9.75:1.

Waiting on springs and to port match the intake.


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