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  #1  
Old 07-28-2002, 10:39 PM
rigsy rigsy is offline
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Default magnum crate jetting ?

from my sig you can tell my engine mods on my 360/380 crate,can anybody with a crate engine please share carb set up with me? eg, jetting,power valve combo's etc. our track is aprox 1000 ft above sea level and carb is a 750 vacuum with a brown spring in the secondary's. i need a rough idea to start from. thanx
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  #2  
Old 07-29-2002, 09:05 AM
mtrv8n mtrv8n is offline
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here's the best jetting advice you'll get...buy an edelbrock!
stick it on and run..
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  #3  
Old 07-29-2002, 11:55 PM
rigsy rigsy is offline
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i'll stick with the holley, haven't seen a fast car with an edeljunk on it yet.
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  #4  
Old 07-30-2002, 09:05 AM
mtrv8n mtrv8n is offline
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sorry6, just my experience..your car really needs a double pumper....
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  #5  
Old 07-30-2002, 02:01 PM
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cuda66273 cuda66273 is offline
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Without all the details....probably a Race Demon 825.

4.5 power valve, start with 86/88 jets, -10 line from the tank to the pump, -8 from pump to regulator and -6 to each end of the carb. Fuel pressure needs to be a minimum of 5.5-6 pounds at the stripe.

Hook up a vacuum gauge, it should read 0 at the stripe. If it has any vacuum at the stripe the CFM of the carb is too small.
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  #6  
Old 08-05-2002, 12:50 AM
rigsy rigsy is offline
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just came back from the track this weekend and did not have a chance to see your post but i will consider up jetting a little. My car ran a best of 12.98 @104.75, 0-60 was 1.822 and we were 1200ft above sea level, and temp was about 65 degrees. I chose a 4.5 pv 71/75 jets and the plugs were a medium brn in colour. timing was kept at 38deg on 110 race fuel.I was happy to be in the 12s with a 3460lbs car but i know there's more! please post any other suggestions. thanx
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  #7  
Old 08-05-2002, 07:10 AM
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If your plugs we're brown thats telling us that the idle and primary circuits are pretty close, you need to do a WOT plug check.

Read my post on 4 corner idle adjusting and Edelbrock Carbs chapter 1.

I still don't even know what you have for a carb so it's hard to tell you what to do next...

You might want to try moving that timing back to 36 just for grins and see what happens.
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  #8  
Old 08-07-2002, 10:04 PM
rigsy rigsy is offline
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sorry cuda66273 i topped the crate with the recommended 750vac secondary holley.The vac diaphram uses the second lightest spring (i believe it's white). also i was shifting moderatly at 6200 rpm.
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  #9  
Old 08-11-2002, 07:45 AM
Toddd Toddd is offline
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I went to a short track last weekend , but it was hard to gather any tuning tips for myself. I'm going to some 1/4 mile drags next weekend. We went back to stock jetting , as a Holley catalgue would specify the carb to have. I do know that the motor does like to rev. On the street I've been shifting at 7200 and it is still pulling. I will be working on the carb to get it right and will let you know. Hey one more question...How much air pressure do you run in your tires?. I tried 12 psi last week and I think it was too low. I've got Hoosier Quick time pro dot tires and they F''n hook. They were spinning on the rims. I'll keep you posted. Todd
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  #10  
Old 08-13-2002, 06:27 PM
rigsy rigsy is offline
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todd i was running 10 psi with the rims screwed and tubes the track we raced on is a shut down air port with no concrete slab and not much rubber laid down.. i didn't get enough runs before racing to play with shift points or jetting. in a month or so i'm going to a track were you can get 15 to 20 runs a day.i'll dial it in then
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  #11  
Old 08-17-2002, 09:34 PM
Toddd Toddd is offline
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Well I just got back from the race track. What a crappy outing. I have major fuel delivery problems. First run open headers..16.5 no kidding. Pull the plugs and they indicate very lean . Put the mufflers on and run 16.1 It's a little improvement but I'll take it. Third run (first run of eliminations) RE-set floats. Dial 16.1 car runs 15.6 in the heat of the day. I lowered my shift point to 6800, and it runs better. I'm going to put in an electric pump from the tank to the mechanical pump. I'd do it tonite to try to racwe tomorrow but it's too big of a project for me to do over night. Sorry I was hoping to have better news.
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  #12  
Old 08-18-2002, 09:20 AM
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When the air quality or density goes down and your et get's quicker it's a sure sign that your running lean.

Before you go to all the expense of converting your fuel delivery system you might want to put a fuel pressure gauge on it and see if your holding a minimum of 5.5 at the top end.

If your going to redo your fuel delivery I would recommend a -10 from the tank to the electric pump, -08 from the pump to the pressure regulator and -06 to the carb. This should give you the volume you need to build up to 500 HP.
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  #13  
Old 08-18-2002, 11:12 AM
mtrv8n mtrv8n is offline
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maybe your shift point is still too high, by about 500rpm. Rated specs for a hyd cam engine, specially this one, under 6000 rpm. You'll get valve float above that unless you go to solids. Check out your speed through the traps with a lower shift point.

Also, you're winding real fast with 4:10 gears, so you may be shifting later than you think.
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  #14  
Old 08-18-2002, 07:49 PM
Toddd Toddd is offline
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Question shift point?

We were out one night after the first race and decided to " wind on it" and see where we noticed where it was over revved. When I shifted I hit the recall on the tach and it was 6800 rpm. We never heard or felt valve float, it was pullin hard and the light for the first to second shift was very soon. So we figured the problem was solved. It seems everyone that "Came by the pit" had an opinion..Some almost got my fist cramed down their throat...some had a car.....at home though..... I can fix this problem and will. I had one guy, who hates to lose, tell me the motor will never rev that high..I hit the recall button and shut him up "numbers don't lie Al".




I shifted where "It sounded like it needed " to be shifted at. I tried shifting under 6000 rpm the thing ran even slower. I'm going to change the fuel system and then go back to the short track, and see if any thing changes. Until then . Toddd
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  #15  
Old 08-18-2002, 10:27 PM
rigsy rigsy is offline
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todd, when i purchesed my magnum it was from a pro racer around these parts that bought 2 crates just to see what they
would run stock and then modified. 1st engine was untouched, shifting the engine at 7400 rpm for three races with a best et of 12.40@108mph. the second engine was built with MP race ported cyl heads and roller rockers and some other tricks, that ran 12.29@109.5mph. when i purchased the bone stock crate i had dissassembled the mill to check it all out because it sat for about 1 year uncovered. the heads were sent out for porting,and the valves were slightly bent from overrevving. Stock valve springs were too weak to handle this rpm, he purchased the slightly stiffer springs and gave them to me to install.I then installed the roller rockers and windage tray. as mentioned i ran a 12.98@104mph shifting at 6400rpm. i know there is a lot more power left in this engine with some proper tuning. my cuda weighs 3460 without me and i'm 170lbs. my friends cuda weighed 3700 with him inside, but he was also running different gearing, different trans ratios. good luck! and hope the fuel system works out.
forgot to mention i'm running a stock 5/16 fuel line with carter mechanical pump.
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  #16  
Old 08-18-2002, 11:58 PM
Toddd Toddd is offline
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I have the same fuel line , The stock one eh?, and I think/know that this is the bottle neck. Good luck. Toddd
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  #17  
Old 08-19-2002, 01:59 AM
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"forgot to mention i'm running a stock 5/16 fuel line with carter mechanical pump."

WHAT!???...come on now you know better than that!
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  #18  
Old 08-19-2002, 11:05 AM
Toddd Toddd is offline
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:shock:

I kniow better now. I got "Ridiculed" from some friends at the track for the same thing. Everyone wants to see the car scream, and wants to help that is the nice thing. Thanks for your input. Toddd
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