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  #31 (permalink)  
Old 12-11-2012, 06:55 PM
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I talked to my brother and he said he didn't change the jets. We want to get a 650 but can't afford it right now(already had the 750 on a shelf). We had a 650(?) Holley given to us so he got a rebuild kit and popped that on(before we got the fuel pump issue squared away) seemed to make it worse. Probably because it was a Holley. =) Haven't tried it since getting good and consistant fuel pressure. It started way harder than the eldelbrock so I'm not overly excited about trying it.

I did however drive the truck to work and I acualy paid close attention to what was happening. First and second go good with no issues than as soon as I shift to 3rd and the RPMs drop below 1500 it backfired under heavy throtle. as soon as I top 1500 it gets better and at 2000 it pulled very well but is still "missing". The same goes with the other gears. anything below 1500 and it falls flat if i give it too much gas. If I lightly roll into the gas it is not nearly as bad and the higher the RPMs the more gas it will take.

So should I get and try larger jets?

Also I want to say we did put heavier weights on the distriburator(before the fuel pump issue) and I hav't messed with timing since. Might be till after CHRISTmas that I can get the lock out plates and jets. I'm not too worried about squeezing out as much power as it can give. I'm just trying to make the thing drivable without falling on its face.

thanks again for the help!

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  #32 (permalink)  
Old 12-11-2012, 07:11 PM
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Originally Posted by 89k1500 View Post
Also I want to say we did put heavier weights on the distriburator(before the fuel pump issue) and I hav't messed with timing since.
Heavier weights, or springs?

The earlier you can bring in the mechanical advance, the better. The advance should be all in by no later than 3000 rpm in most cases. If you used heavier springs, that's going in the wrong direction unless you were having detonation.

Did you read the link I gave you on timing? ANY good timing info will do, it doesn't need to come from here.

Get the timing sorted out first, THEN the carb.
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Old 12-11-2012, 07:42 PM
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I want to say it was heavier weights and lighter springs.

as for the link on Hot rodding your HEI Distriburator, I went there, read it, printed it off, and read it a few more times. Its good info I just havn't had time to implement said knowlege. Not to mention its cold as heck outside so my ambition level is low. =)

So should I do the timing before messing with the jets? (EDIT: Just read the last line of the last post, please ignore this question....lol )
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Old 12-11-2012, 08:09 PM
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Originally Posted by 89k1500 View Post
I want to say it was heavier weights and lighter springs.

as for the link on Hot rodding your HEI Distriburator, I went there, read it, printed it off, and read it a few more times. Its good info I just havn't had time to implement said knowlege. Not to mention its cold as heck outside so my ambition level is low. =)

So should I do the timing before messing with the jets? (EDIT: Just read the last line of the last post, please ignore this question....lol )
I get it- COLD! lol

The timing is easier to get in the ballpark. In a lot of cases when using a GM HEI distributor, two medium or one medium and one light spring w/the stock weights will be about right. Then it's a matter of finding the initial timing it likes (good idle, good vacuum, carb idling on the idle circuit and not into the transfer slot), followed by limiting the amount of mechanical advance to keep the total timing from being too high. The total timing being too high is always the case because the initial timing is always higher than what the factory setting called for.

The MSD distributor uses bushings to limit the mechanical timing.,With the stock HEI you have to use screws like you saw in the link. When you get to that stage, if you need help someone can give you a hand w/that.

Lastly, during the process of finding the right amount of initial timing, you will need to readjust the idle mixture screws as you change the timing. And you'll possibly need to lower the curb idle speed to keep the mechanical advance from creeping in, or raise the idle speed if it gets too low.
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Old 12-11-2012, 08:48 PM
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Change the plugs and check them for heavy black or burnt light brown look. After a short run.

Do you have the accelerator pump in its full on position where the lever has the greatest movment on the pump. That may help if it only help a little it will probably need larger jets.

If you run out first and second up to redline it runs fine? What if you go straight to third at redline in secnd so rpm does not drop will the engine take wot then. Also dont over do it trying just wanted to ask if you have tried it. Dont want to see you hurt it just to see. If wot is ok at high rpm then needles may need to be tweaked. Larger jet will be needed if wot throttle is not working in any gear unless its granny gear trans where third is the first long gear. Also does wot make any power or is it still lame in first and second.

My own lean rich test is simple does it run better when the air is cold or hot. Runs better in the cold then its too rich in the hot its to lean. If the colder it gets the worse it runs then you know its way to lean. Bigger jets or more fuel pressure are in order. Runs better in cold weather then its jetted to rich and fouling the plugs.

And yes timing is easier to check most of the time. I also would not try the holley a second time.
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Old 01-05-2013, 07:21 AM
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Just to update,

Pretty much we replaced everything! My brother bought a new ignition system for it ( with a digital controler box, new coil, and new distriburator) and I bought a new 650cfm edlebrock carb. After puting all that on the truck runs awsome! Before putting the stuff on, the problem got worse, and i'm pretty sure it was the distriburator. more specificaly the ignition module in the distriburator. By that point I was tired of screwing around and just wanted it fixed. =)
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Old 01-06-2013, 12:19 AM
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Very Involved Problem 400sbc

You are not the first person I have read about having problems like you had. Most of the time it turned out to be a distributor bought from ebay for $50. The distributor was probably a Procomp brand. Glad you have it fixed.
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