360 tuning advice needed

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TylerW

TylerW

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Hey guys:

We have a vehicle with a late 70's 360 in it and I guess we need some tuning tips.

The engine is fairly fresh, with Performer intake, 600 Edelbrock carb and LT headers. We didn't do the work.

The problem is a pretty severe stumble that lasts about 1000 rpm up the band.

It's not a tip-in stumble. You hit the pedal and it'll take off for 50 feet, then starts to hesitate and stumble, then finally pulls itself out of it and goes.

It had a #1411 750 E-brock on it and we initially thought that was the culprit since that's a too-big carb and those haven't had a good track record.

The 600 is known good, and it cleaned up the running a lot(leaner), but still has that low-midrange don't wanna go thing even after the carb swap.

The engine seems lazy even when it's not acting up, and the issue is predictable....it cuts up the same place everytime.It starts and idles fine and it doesn't seem to run bad at cruise speeds.

The place we haven't touched yet is the distributor, so you guys think something might be amiss in there?
 
Work on the timing. My 360 we put a 600 and 750 eddy carb with stock points dist. We changed it to a 770 holley street and a pertronix dist. It helped a lot and it did need more timing.
 
Is the vacuum advance hooked up??, you need that for a street motor, make sure there aren't any open vaccum lines, what is the total timing at at 3000 rpms?? what is it at idle with the vacuum advance line plugged??
 
do you have a timing light? whats the initial and total timing? and whats the timing do in the range where you have issues?
What had been done to the motor? IE intake,cam,headers,

I think you should see if your mechanical advance is working properly in the distributor. Is it sticking? anything out of the ordinary in there? are the slots the weights slide in screwed up? is a spring missing? stuff like that.
 
The 1411 carbs are sold lean from the factory. They are for non-performance factory engines like the 454 and 460 truck engines. You need a stip kit for the 1407 carb and tune it. Prob will need the step up springs and rods/jets changed.
 
Hey guys, just wanted to update :

I've finally slowed down at work enough to get back on this. My timing light ended up being junk, so I picked up a new dial-back light and checked the timing.

Initial timing was about 18 degrees with the advance unplugged. Somehow I forgot to check the total timing while I was at it, but I did reset the initial to 11 degrees.

That helped the idle quality out, so it idles great now. However, it still had a lot of that low midrange gutless stuff. I got my hands on a step-up spring kit and popped in the heaviest springs, which are the natural(no color) pair.

That helped the most of all. It's not perfect yet, it still sounds and feels lean at certain spots..you know when the exhaust gets that slight sick sound...but it's running a lot better, so I'm on the right track at least.

I also went to the richest setting on the pump stroke and that also helped. I guess my next step will be to richen the rods/jets up a step or two, but I need to do some studying on that first. That calibration kit is about $70.

Are these Edelbrocks really THAT lean out of the box?
 
It depends on the combo, but I find I usually have to richen them and swap the step up springs. What distributor is in this thing?
 
moper said:
It depends on the combo, but I find I usually have to richen them and swap the step up springs. What distributor is in this thing?
Click to expand...

4145604, has 2 harnesses instead of 1, and has a vacuum advance unit.

The whole thing looks like a reman, it's very clean.
 
moper said:
The 1411 carbs are sold lean from the factory. They are for non-performance factory engines like the 454 and 460 truck engines. You need a stip kit for the 1407 carb and tune it. Prob will need the step up springs and rods/jets changed.
Click to expand...

Given the timing is set properly, the above is what i recommend as well.
 
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