Edelbrock 1406, new distributor, trans shifting, seems weak

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TommySpell

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https://photos.app.goo.gl/pwD9WfEXYP72UXPB9

Trailered home.
Installed NIB Edelbrock 1406 carb
New plugs wires and distributor.

Changed metering rods to 1459 and jets to 1429 , so somewhere between 18 and 19 on graph. Accelerator pump is set in middle hole
Removed vacuum advance set timing to 36° at 3500 RPM.
Slid detent as far in as crappy bracket would let me on th350
Pulling 13-15 pounds vacuum at idle.
Lopes around almost like she has a little cam.

Don't know how to verify but I have a sneaking suspicion it is a small block 305.

Has dual exhaust and tube headers.

In the video we are to the floor. 1-2 shift is at 45 2-3 shift is at 75 then trudges along to 85. The whole process seems lackluster as if I was just going on a grocery run and seems like I'm missing a gear (4 speed right?).

Any guru that can tell me the error of my ways or something I missed? Thanks for the help
 

75gmck25

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Stock transmission for an '81 would usually be a TH350, and that's a 3 speed automatic. Its a good solid transmission, but no overdrive.

When you install the carburetor you need to adjust the TH350 kickdown cable. The small square black plastic retainer that snaps into the kickdown bracket has two pieces. You slide/pop/push up the top piece (I usually need to pull it up with pliers), move the carburetor linkage to full throttle, and then snap the piece back down to lock it. This sets the full throttle position and makes sure the kickdown will work on the TH350.

There is also a vacuum modulator on the TH350 that can be swapped out or adjusted to change shift points. However, I've read that the modulator affects part-throttle more than full-throttle shifts. There are also aftermarket modulators that allow you to adjust the shift points with a screw. The modulator is mounted on the transmission case, and relatively easy to reach.

I'm not sure why you removed the vacuum advance, since its primary purpose is fuel economy and low speed driveability. It usually doesn't really help or hurt full throttle performance.

What did you use for base timing? Most stock SBCs run well with about 12-16 degrees base and 20 degrees mechanical. I would try to get all mechanical in by about 2000 rpm if you want better performance. This means you would have about 32-36 degrees by 2000 rpm.

Bruce
 

TommySpell

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Thanks Bruce, will set timing to be all in by 2000rpm and see how that does.

I only removed vacuum advance to set timing and hooked it back after.

We have been messing with detent but it is so old and nasty I couldn't get it to slide right. Will sprayed some pb blaster on it and try and get it right.

Thanks
 

TommySpell

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So adjusted it all, runs lots better but not a monster by any means. Trying to clean back there and see if I can't find the block number to verify it's a 305. I don't expect 13 second quarters. It resembles the difference in 4.8 vs 5.3 world I'm coming from.

Long story short, she runs much better now and sounds great!! That's all that matters right now. So much so that I went all the way to town and filled her up safely.Thanks for the help
 

75gmck25

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Every time I adjust that TH350 kickdown cable I'm waiting for one of the plastic pieces to break, but so far its worked okay. It doesn't help that its so far back in the engine compartment and you are at full arms length to reach it.

Good luck with the block number, since it is another area that's hard to reach. And even after you find it you will probably have a number that matches multiple engine options based on the year. For example, everyone seems to think 3970010 is a great block, but depending on the year it could be a 302, 327 or 350.

Its also common to find a number that indicates a replacement GM crate engine, but not be sure whether its the old Targetmaster crate 350 replacement, or the current GM crate 350. The old Targetmaster apparently had a spotty reputation for quality, but the current crate 350 seems to be quite solid (although still a low performance engine).

Bruce
 

HotRodPC

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Stock transmission for an '81 would usually be a TH350, and that's a 3 speed automatic. Its a good solid transmission, but no overdrive.

When you install the carburetor you need to adjust the TH350 kickdown cable. The small square black plastic retainer that snaps into the kickdown bracket has two pieces. You slide/pop/push up the top piece (I usually need to pull it up with pliers), move the carburetor linkage to full throttle, and then snap the piece back down to lock it. This sets the full throttle position and makes sure the kickdown will work on the TH350.

There is also a vacuum modulator on the TH350 that can be swapped out or adjusted to change shift points. However, I've read that the modulator affects part-throttle more than full-throttle shifts. There are also aftermarket modulators that allow you to adjust the shift points with a screw. The modulator is mounted on the transmission case, and relatively easy to reach.

I'm not sure why you removed the vacuum advance, since its primary purpose is fuel economy and low speed driveability. It usually doesn't really help or hurt full throttle performance.

What did you use for base timing? Most stock SBCs run well with about 12-16 degrees base and 20 degrees mechanical. I would try to get all mechanical in by about 2000 rpm if you want better performance. This means you would have about 32-36 degrees by 2000 rpm.

Bruce
Glad to see someone else agrees, the detent cable on a Th350 DOES in fact make a difference on the shift points and shift quality. But yep, I'd agree, with the carb swap, you need to readjust that detent cable and get a bit more pull on it. If you're still not satisfied, get even a little more on it. You can only get to much if it's shifting late then you need to back it off a little bit.
 

TommySpell

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Well to update... Got it all pressure washed and big as anything gm 5.0l stamped on it.
 

HotRodPC

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Well to update... Got it all pressure washed and big as anything gm 5.0l stamped on it.
So there you go, It's a Wee O Five !!! It'll grow up someday, with a little help of course, to a Tree Fitty !!!
 

TommySpell

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I still look cooler than most on my grocery runs. I want one with a 454
 

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With 13-15" vacuum at idle, you either have a somewhat bigger than stock cam or a vacuum leak.
 

TommySpell

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Well where should it be? I keep having the sneaking suspicion that I should have more power than what it does but my brain just says it's a tiny little baby 305 and I have to be gentle with it.

I am running my idle while setting my timing and RPMs and checking vacuum at roughly 850 to 890 RPMs
 

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