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Did basic tuning on new build and still running meh. Help with advanced tuning?

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Old 02-13-2018, 09:40 PM   #41
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I am just throwing this out there because I am in the process of building my motor and learning a lot of things I never gave thought to. One is degree-ing the cam. The OP stated he installed a cam. Through all my conversations and readings, it is clear that a cam MUST be degree'd or you will chase your tail. Just a thought. I saw no mention of this.
Not everyone degrees (or knows to) their cam during a rebuild, but it's a good idea. You won't necessarily be chasing your tail. You degree it to "check it" so that you're sure the valve events happen as the cam company / grinder advertises. If it is off one way or the other, you then have some options to tweak (advance or retard) it one way or the other with bushings or keys. In probably 6-8 builds between my brother and I, all our cams have been right on or within a degree. Some others on here have found cams being several degrees off right out of the box.

It's a good assembly practice and sanity check, and the tools aren't a large investment.
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Old 02-14-2018, 12:40 AM   #42
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Back to basics. Back to square one. Look for errors, omissions, and stupid.
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Old 02-14-2018, 01:51 AM   #43
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Back to basics. Back to square one. Look for errors, omissions, and stupid.
That's where I'm at right now. I'm re-doing the whole process with my recently gained knowledge of timing mechanics and carb circuits. After more messing around I'm pretty sure I've got an excessively lean condition (Today I realized she backfires a bit off-idle when driven not fully warmed).

I am stumped in one spot though. I'm re-checking what power valve to use. Holley says to halve your idle vacuum and round it up. Lars says to just subtract 2. So Holley's instructions say I need a 5.5" PV, but Lars' documents say I need an 8.5" and that's quite a big difference.

As well, I'm a little stumped on the jets. There's a ton of contradicting info about jet sizing and confusing guides on how to choose the correct size. I have 65s in the primaries and unsure about secondaries (Haven't taken the secondary bowl apart yet)

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Old 02-14-2018, 09:45 AM   #44
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Next time you run it, let me know vacuum at idle.
I should have the dizzy worked out by Sat.
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Old 02-14-2018, 05:36 PM   #45
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Next time you run it, let me know vacuum at idle.
I should have the dizzy worked out by Sat.
Vacuum at idle is about 11-12

I just pulled the bowl off and switched back to the 6.5" power valve, checked my accelerator pump, and made sure there was no blockages or anything in it. I then switched to the Medium springs from the MSD recurve kit and then retimed the engine. I'm at 16 degrees initial w/ 34 degrees total (Confirmed with a dial-back light). I then re-adjusted my accelerator pump arm. After that I took a vacuum gauge and turned the idle mixture screws until I got the best vacuum. Then adjusted my idle to get around 1k in Park and is giving me 750 in gear.

I have less power than before I rechecked everything. She stumbles off-idle and is taking even longer to climb up to high RPM. Has very little torque. The idle is rough, but I think that's the nature of the cam.

I'll double check the floats and see if that changes anything

Edit: Floats are good

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Old 02-14-2018, 10:19 PM   #46
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Long story short. I dropped off the shaft to have ONE advance stop hole welded up. Going to drill a new one.
I picked it up and BOTH holes are welded up. Now I've lost my indexing.
I lost all my index marks.
NOW, I order another one to get on track. No biggie. I fix one, then transfer the cure to the other, and have two to sell.
I just received it, took it for a spin, and the rotor is phased at rest between towers.
This is the gear installed 180* off.
You are going to have to send it to me after I figure this out, or your going to go nuts doing this, or you need a different one.
Give me a couple days to iron this out with your vacuum at idle.
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Old 02-14-2018, 10:31 PM   #47
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Got that fixed. Spun it with stock springs. Starts to advance at 600 engine rpm. Full advance at 8000RPM. (The dizzy that keeps on giving).
Unless you can idle at 500RPM, this would hunt at idle like crazy.
All for tonight.
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Old 02-15-2018, 02:20 PM   #48
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Not everyone degrees (or knows to) their cam during a rebuild, but it's a good idea. You won't necessarily be chasing your tail. You degree it to "check it" so that you're sure the valve events happen as the cam company / grinder advertises. If it is off one way or the other, you then have some options to tweak (advance or retard) it one way or the other with bushings or keys. In probably 6-8 builds between my brother and I, all our cams have been right on or within a degree. Some others on here have found cams being several degrees off right out of the box.

It's a good assembly practice and sanity check, and the tools aren't a large investment.
I didn't degree the cam, but I'm too far into it to worry about that now it seems. I just gotta hope that isn't the issue since the engine is already fully assembled in-car. It definitely feels like I'm running excessively lean.

I was thinking and I do believe that rubber thing on the inside of the gas tank is collapsed and that maybe my fuel sock is clogged or something. When driving it feels like it's sometimes not getting enough gas (Backfires and stumbles, but very inconsistently). Sometimes feels alright and like it's running decently albeit with no power, but other times it'll feel incredibly lean. Maybe I'm not getting enough fuel flow due to clogging at the gas tank?

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Old 02-15-2018, 02:38 PM   #49
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Originally Posted by Shdggsdv View Post
I didn't degree the cam, but I'm too far into it to worry about that now it seems. I just gotta hope that isn't the issue since the engine is already fully assembled in-car. It definitely feels like I'm running excessively lean.

I was thinking and I do believe that rubber thing on the inside of the gas tank is collapsed and that maybe my fuel sock is clogged or something. When driving it feels like it's sometimes not getting enough gas (Backfires and stumbles, but very inconsistently). Sometimes feels alright and like it's running decently albeit with no power, but other times it'll feel incredibly lean. Maybe I'm not getting enough fuel flow due to clogging at the gas tank?
I posted this previously, but installing a wideband O2 sensor will give you the information you are looking for regarding your suspected lean condition. I was disappointed after my rebuild due to lack of power too, but realized I was idling at about 18:1 and and was aroud 15:1 when accelrating. Worked through my quadrajet and I now idle between 14-15:1 and when accelerating I am around 11:1. These changes made a huge difference and after them I felt the money I spent on the rebuild was worth it.
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Old 02-15-2018, 02:40 PM   #50
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Originally Posted by Shdggsdv View Post
I didn't degree the cam, but I'm too far into it to worry about that now it seems. I just gotta hope that isn't the issue since the engine is already fully assembled in-car. It definitely feels like I'm running excessively lean.

I was thinking and I do believe that rubber thing on the inside of the gas tank is collapsed and that maybe my fuel sock is clogged or something. When driving it feels like it's sometimes not getting enough gas (Backfires and stumbles, but very inconsistently). Sometimes feels alright and like it's running decently albeit with no power, but other times it'll feel incredibly lean. Maybe I'm not getting enough fuel flow due to clogging at the gas tank?
Been watching and reading this thread since there's lots of good information flowing from it.

Not that this is your problem, but something I ran into with my 383 build that had similar symptoms to yours. At an idle my fuel bowls maintained proper levels per the glass sights. What i couldn't see that was causing sluggish feeling was how the fuel level was dropping through the RPM range while driving. I'm using the stock fuel lines with a return style regulator and mechanical fuel pump. What i didn't realize was my vent tube that was originally going to the charcoal canister was crushed and not allowing the tank to vent in turn making the carb starve for fuel during high demand times. Once i fixed the vent line, that issue went away.

Just food for thought
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Old 02-15-2018, 04:50 PM   #51
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Originally Posted by sstopczy View Post
I posted this previously, but installing a wideband O2 sensor will give you the information you are looking for regarding your suspected lean condition. I was disappointed after my rebuild due to lack of power too, but realized I was idling at about 18:1 and and was aroud 15:1 when accelrating. Worked through my quadrajet and I now idle between 14-15:1 and when accelerating I am around 11:1. These changes made a huge difference and after them I felt the money I spent on the rebuild was worth it.
Oh yeah! Forgot to respond to your comment, but I ordered an AEM air-fuel gauge due to your suggestion. Should have it really soon!
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Old 02-15-2018, 04:52 PM   #52
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Originally Posted by Darinm View Post
Been watching and reading this thread since there's lots of good information flowing from it.

Not that this is your problem, but something I ran into with my 383 build that had similar symptoms to yours. At an idle my fuel bowls maintained proper levels per the glass sights. What i couldn't see that was causing sluggish feeling was how the fuel level was dropping through the RPM range while driving. I'm using the stock fuel lines with a return style regulator and mechanical fuel pump. What i didn't realize was my vent tube that was originally going to the charcoal canister was crushed and not allowing the tank to vent in turn making the carb starve for fuel during high demand times. Once i fixed the vent line, that issue went away.

Just food for thought
My vent tube is actually disconnected. I thought it only really applies to preventing vapor lock in high heat scenarios?
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Old 02-15-2018, 05:13 PM   #53
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My vent tube is actually disconnected. I thought it only really applies to preventing vapor lock in high heat scenarios?
I didn't think it would matter either, but the proof was in the pudding.
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Old 02-15-2018, 06:23 PM   #54
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My vent tube is actually disconnected. I thought it only really applies to preventing vapor lock in high heat scenarios?
Where do you live again?
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Old 02-15-2018, 09:59 PM   #55
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Where do you live again?
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Originally Posted by Darinm View Post
I didn't think it would matter either, but the proof was in the pudding.


Vegas!

Was actually planning to figure that out later with one of those fuel filters with a vapor attachment thing before summer.
Like this Like this

It's still only like 60ish out so I wasn't too concerned about vapor lock.

Might just order one and try it out to see if it helps my issue at all!

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Old 02-15-2018, 11:59 PM   #56
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Your drawing vacuum in the tank. Vapor lock is bubbles in the fuel lines.
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Old 02-16-2018, 04:39 PM   #57
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Get your tank vented while I work on this. That is definitely an issue that will cause those symptoms.
Yesterday my vacuum regulator died. I spent part of the day rebuilding the regulators on both Sun machines.
Today the strobe went out. Installed a new capacitor on the strobe, and it fired right up.
Can't wait to see what happens next.
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Old 02-16-2018, 07:01 PM   #58
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Thinking to get this torque converter: https://www.summitracing.com/parts/s...02-1/overview/

Being that I'm aiming for around 400-440hp w/ 10:1 compression and a power range of 1800-6000 stated by comp. They recommend 2200+. I believe I have 3:55 gears and my car should be around 3400lbs. I think this should be a good fit?
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