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Discussion Starter · #1 ·
I have a 3970010 high nickel 350 2 pc, 4 bolt main block that i am taking to the shop to setup for a 383 CID.

I have decided to go with Comp Cams XR270HR retrofit camshaft, RPM range 1600-5400, LSA .495/.502, 218 intake/224 exhaust LSA 110.

I have decided to go with the Edelbrock Air Gap RPM Intake, Edelbrock Performer RPM cylinder heads 64cc with 185cc intake runners.

The bottom end will all be Scat Rotating assy with ARP bolts including its Forged steel crank, forged steel rods, 5.7 rods, Flat tops with 2 valve reliefs, the piston head is 5.00cc floating wrist pin. Forged Aluminum pistons...

Edelbrock Carb 650 thunder series AVS

i really dont want no more than 9.5 to 10.1 compression for this setup but i will be running a fully built 700 r4 for the transmission, 3.42 gears and its going into a 1978 chevy silverado big ten.

I am looking for a good street motor that i can have fun with, that is strong, reliable, sounds nice, i can cruise on the highway or get down on it on the highway if i wanted too. I dont intend on this motor EVER going to the strip or drag racing...

So how does my set up sound for a street motor? is the edelbrock heads flowable enough for the 383? Is the camshaft a good one for my combination? should i find the camshaft with a lower rpm range such as the xr258hr, 110 lsa, .480/.487 , rpm range 1000-5000 or the xr264hr with .487/.495 with a rpm 1200-5200..... let me know your opinions
 

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Discussion Starter · #3 ·
yes i was thinking it would get me close to 400hp with equal amount of torque if not more but i just want a vehicle that can tow, rpm pretty good as well as cruise... i'd like to smoke a few fords who try me! lol
 

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Discussion Starter · #5 ·
You think the edelbrock 750 is more streetable than the 650? honestly, im really leaning towards buying both carburetors to see which is best.... maybe the 650 is better for the street and 750 is more for the highway and getting down on it.
 

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Discussion Starter · #7 ·
hmmm i have a question, which camshaft would you pick out of the three i listed? With the 258hr im sure it would come out the hole faster but also lose its power faster than the 264hr or the 270hr. I'm really trying to decide which is better and i really dont see myself going past 5500rpm.
 

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Discussion Starter · #9 ·
so you think the 3.42's that are in it isnt steep enough? i was figuring the 3.42's would give me a good highway cruise and with the power of the 383 it would help some.... you think the OD will have my rpms way too low for this? i'd be willing to bump it up to a 3.73 with a posi... If you know a way to keep the gas mileage pretty decent .. wow there are alot of factors to consider here.. your input is very much appreciated
 

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I have a similar motor

Demarques. I just finished a 9.5:1 383 and had it dyno'd this afternoon. I went with AFR 180 Street heads, Comp Cams XR270HR, but with a 600 cfm Edelbrock 1406 and a Performer Air Gap. We had to change the jets, rods and springs in the carb to get the right air/fuel mix, but the results were great. 422HP at 5200 RPMs. 463 Lbs TQ at 4300 RPMs. Still had vacuum at WOT so a larger Carb will get you more HP. The motor is a Torque monster.

I have a 700R4 with a WOT Shift point of 5100 RPMs. You shouldn't need a new Converter. The more powerful motor will create a higher stall in your stock converter.
 

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Carb size

I built in escalation. Everyone says, "once you get used to the HP, you want more." I factored that into the build. Now when I get bored of the power - new carburetor starts the cycle all over.
 

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I think it depends on what kind of highway cruising your doing. If your highway cruising is 70-75, then the 3.73 would be fine, but if your highway cruising is 55-65 then 4.10 would be better for mileage and driveability.

Here's what I found with your setup :
3.73 at 60 mph = 1800 rpms
4.10 at 60 mph = 2000 rpms

3.73 at 70 mph = 2100 rpms
4.10 at 70 mph = 2300 rpms

If fuel economy is the concern and cruising speeds are closer to 70, then the 3.73 are fine. Personally, though, the 4.10 will be more fun at all rpm ranges and shouldn't kill your fuel economy too much because your running relatively tall tires.

Now, if fuel economy isn't a concern, and your going to change the gears anyway, which you should, and you want it more snotty, then 4.56's would be even better yet and it would still be driveable at low speeds :
4.56 at 60 mph = 2200 rpms
4.56 at 70 mph = 2550 rpms

Just my opinion, for what its worth. Have fun.
 

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Economy

If economy is important to you, I would recommend a dyno tune. Otherwise your timing could kill your mpgs. I've known people who gained 30% better mpg's by having the right timing.
 

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64nailhead
could you show me the math? I dont even see a tire height?

ROAD SPEED vs ENGINE SPEED CALCULATOR

My math is in the road speed calculator I use. I use the one in the link above. I always confirm odd tire sizes by going to either Cooper Tire's website or tire rack.com and verify the size that comes up on the road speed calculator.

I've used this for several years and it has always been accurate. Also. you can see the formulas that are being used.

EDIT
Vinnie, I might have misunderstood you. Marques said he was using 265/35r22 tires on the previous page.
 
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