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Old 01-31-2008, 03:28 PM
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Edelbrock or Holley Carb. for my street/strip Truck

I have a 1986 1/2 ton short bed Chevy truck. It has a 350 crate motor from summit part number NAL-12486041. I have an edlebrock air gap intake manifold and a 650 Holley double pumper vacuum secondary and electric choke which I installed straight out of the box. It has summit HEI distributor and a 6AL MSD ignition box. As for as exhaust I have 1 7/8 hooker headers to 2 1/2 inch exhaust and three chamber flow masters. The trani is a 350 lock-up with a shift kit and a 4.11 geared rear end (not posi). I have also installed an electric fan system and it has factory A/C. My best time is a 15.60. My next mods will be to get the heads ported and put bigger valves. I also plan to make the rear-end a posi and install a 2500 stall converter. I hope to run high 14's with these mods, will this be possible? Well I guess my big question is do I just need to tune the carb I have, but what size jets to go with? Or do I get an edelbrock 600 carb? Because in high school my buddy had a very similar set-up in a 69, minus the mods I am planning to do. He was running 15.30's in what im sure was a heavier truck. As far as I can remember the Edelbrock carb seemed better on the bottom end and had a quicker throttle response than the Holley. Is there anything else I can do without messing with the bottom end of the motor to get more power without putting it on the bottle, or forking out the money for a supercharger? Thanks for any positive feedback you might have, Anthony.

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Old 01-31-2008, 04:05 PM
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When you ran the 15.60ET, what was the MPH (from your track Time slip)?
what was the 60ft time?

Its either a DP or a VS carb, not both. The stock out of the box carb jeting is usually pretty good. the accelerator pump needs dialing in. Your 1-7/8" headers are way too big.
You're giveing up a lot of torque. 1-5/8" long tube headers are best for your vortec motor.

Timing should be 12 to 16 initial 32 to 36 total. Your HEI distributor likely needs a recurve.
A big old pick up truck needs all the help it can get launching out of the hole.
get a 3000+ stall converter, a posi and some sticky tires. Are you sure on the rear gear ratio? How tall are the rear tires.? Its all about maximizing traction and torque.

Start with the MPH from your drag time slips. (a good indication of how much horsepower your motor is actually making.) What is the weight of your truck ( with you and all your junk, in it.)

Last edited by F-BIRD'88; 01-31-2008 at 04:18 PM.
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Old 02-01-2008, 05:43 PM
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Well Iím working out of town right now and my time slip is somewhere in my truck my girlfriend looked for it but no luck so I will have to get back to you on that. In the meantime she did give me the info on the tires. They are BF Goodrich radial T/A P275/60 R 15ís. As for as the rear end its either a 4.11 or 4.10 whichever GM goes by. When I bought the truck the owner told me he had them put in because he used the truck for towing. I want to say my mile per hour was around 87 to 89 mph. As for as the weight of the truck the title said 3900 and if you factor in me and my junk your probably looking at 4100 pounds considering the weight on the title is an accurate one? Oh and the carb is a 650 VS with electric choke, and I am pretty sure the timing is already set right in that range. The motor is suppose to make 330 hp at 5000 rpm and have 380 ft-lbs of torque at 3800rpm. Thanks for the advice you have already been a big help I hope this information will give you a better picture of what Iím working with and you might be able to help me out a little more, thanks again.
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Old 02-01-2008, 06:26 PM
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Get a Holley 750 model 3310 w/vac secondaries and you will be happy with it.
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Old 02-01-2008, 06:30 PM
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You don't think that is too big? I will consider it thanks, for the input.
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Old 02-02-2008, 07:03 AM
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It is pretty hard to over carb with a vacuum secondary as the secondaries open in response to engine demand.If the engine wants 600 cfm thats how far the secodaries wil open.I would try changing secondary springs on the one you have keep going lighter till you feel a bog then go back stiffer one step.The stock spring in your carb probably is not letting the secondaries fully open due to the rpm range you are in.
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Old 02-02-2008, 12:18 PM
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Based on your estimated weight (4100lbs) with 330hp you should be able to go 95MPH in the quarter. With good traction (tires+posi) and a hard launch (torque converter stall, carb+ignition tuning+headers that make low end torque etc) your et should range from 14.26 to 14.73.
This is all based on a true weight of 4100lbs. If the truck in fact weights more than this, expect less MPH (with 330 hp) eg: If it weights 4600lbs, 330hp is only good for 91.5 MPH
So the thing to do before you go dumping money into it is to establish its true weight to see if the motor is performing correctly as it stands now (quarter mile mph) Your gearing is just about right. I would get some shorter diameter tires that have a lot lot of traction (like a 8.5x26" ET street or P235-60-15 drag radial) to increase the effective gear ratio and traction. Then get a torque converter that will launch the truck at the rpm just below the engines peak torque. Should be around 3500 to 4000rpm. So you want a converter with a stall of 3000 to 3500rpm. (10" th350 converter)
Your carb is fine but probabily needs tweeking and dialing in.
The large tube headers seem a little big for this motor.
Have you run it thru open exhaust (uncapped) to see how efficient the exhaust system is or isn't? there is lots of et in messing with the exhaust tuning. All this and you haven't even added 1 hp to the motor yet.
But all this is essential to getting the most out of what you have now.
Get that 60ft time down in the 1.7sec range.
From there, More engine hp with be a bonus once you've gotten some traction and engine torque to the ground.
I would not wimp out on the torque converter stall speed if you plan to hop up the motor (cam etc etc) as this will move the engines torque curve up in rpm for sure, where a high stall is required.
Don't waste your time with a "2500stall". If you're going to buy a new converter get a 10" "3500stall"
You can, raise the compression ratio (shave the heads,thin head gaskets)
You want to get up to around 10:1 cr.
Port the heads (the intake side is good as is (unless you go to a full on port job with larger valves) The exhaust side needs work reguardless)
re-cam the motor for more hp.
remove weight: It's free horsepower.
What would be the chances of weighing the truck?
You'll have to decide for yourself how much you want to "hot rod" this truck up as your fuel mileage will go down a bit.
Say you hot rod the motor up from 330hp to a true 400BHP.
The potential performance in a 4100lbs truck is 13.37@101.7 +/- a few tenths et.
Once you budget that all out, a super charger added to your low compression motor starts to look pretty good.
(you'll still want the converter and traction mods)
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Old 02-02-2008, 09:17 PM
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Amthony, there must be a grain elavator near Midland. Just go there and ask them to weigh your truck. I've done it several times and it's always been free and easy.
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Old 02-02-2008, 11:58 PM
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Iím glad to hear my carb. isnít too big. Thats was why I was thinking of going to a 600 edelbrock in the first place. I will definitely play around with the secondary springs and see if I am able to get some better performance out of it, thanks. On the note of getting it weighed. I was planning on taking it to the city dump, because I know they have a scale there as well, but thanks for the input on that! To F-Birdí88 I will definitely get it weighed and do my best to find my time slip when I get home. As for as the tires I am going to have to wait a while. If they cost anything like the ones I have now, i dont think I can justify to my live in girlfriend on buying another set when these probably only have 10,000 miles on them at best. I am definitely going to take your advice on the head work, stall converter, smaller diameter headers, and the posi rear end. You have been a great help. I feel like I should be paying to speak to someone this knowledgeable! Wait a sec, I better not give these people any ideasÖÖ..Thanks for all your help and I will get back to you when I know the true weight of my truck, and find my time slip.
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Old 02-21-2008, 09:45 AM
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Well i had my truck weighed the other day and it weighs 3875 pounds, and if you add me your lookin at about 4050 total weight. I also found my time slip leaving the line at 1500rpm with a little tire spin;
60ft time 2.29
330ft time 6.57
1/8 mile 9.99 at 72 mph
1000et 12.99
1/4 mile et 15.60at 86 mph
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Old 02-21-2008, 10:08 AM
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The Edelbrock carb is an upgrade of the old carter AFB I have a couple Edelbrocks on the shelf in the shop /// I always liked the old afb's better than the holly's there are about 10 holly's in there including a nascar 3 barrel one thing was the rebuild kit setup instructions did not alwaqys work right, I had to tweek everything to get choke lock out . secondary kick in and wot to be right
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Old 02-21-2008, 10:41 AM
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The 60ft time is very slow. Any reduction off the 60ft time, reduces the ET by the same amount. So say you were to get some sticky tires, a posi trac and add a 3000-3500 stall converter and reduce the 60ft time to a 1.80sec. The ET would be 15.1.

The quarter mile MPH seems low relative to the 1/8th mile mph.
Did you let off before the last MPH light? (66 ft after the end of the quarter)
Could also be a aerodynamic problem. (usually the truck tail gate creating wind turbulence at high speed) Possible fuel pump volume problem. Did the truck seem to "nose over" (loose power) at the end of the track?
Was it very windy that day? (cross wind, head wind)
Your MPH should have been 91MPH. Indicates about 290 horsepower.

Quarter mile MPH should be = to the 1/8th mile mph x 1.27
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Old 02-26-2008, 12:03 PM
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15.1 huh thatís almost where I want to be. with that and the head work i want to get done i should be in the mid 14's i hope. thinking back to the light you know i might have let off a little early. i asked someone where the end of the track was and they pointed to some light at the end of the track this was my second time out there the first time was when i got the truck and after putting exhaust it ran a 17.0. oh yeah speaking of the exhaust i do have 1 5/8 headers not 1 7/8 like i told you before. To me the truck did seem to lose power at the end this was my reason for asking about the carbs to begin with. i had taken the tail gate off that day to counter that problem as for as the wind it was probably in the neighborhood of 10 to 15 mph that day as far as the direction i cant recall. now that i think about it i am pretty sure the fuel pump is stock what kind would you recommend for an upgrade for the set up i have? only 290 hp huh, thatís a bit of a disappointment when im suppose to have 330 hp hopefully im just losing power somewhere like the crab or amount of fuel Iím getting. i plan on going to the track either this weekend or the next so i will have some more feedback then thanks again for the help and great advice.
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