Feel like 360 should have more power

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standup303

standup303

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Good morning all, so I purchased a 69 Dart with 360 LA, 727, 8 3/4” with 4.10s. And I feel like the thing is a pig. When I first got the car I was strapped for time and I just wanted it running well so took it to a local “classic car”shop and they replaced a few plug wires that were burned, set timing, said they tuned the carb. I feel like it barely helped.

I did a compression check this weekend and checked plugs, below are those results and the only details I know of the motor mods. Also there is a pic of the plugs, all looked the same.

IMG_6175.jpeg


I found the #4 and #6 plug wires pulled right off the boot, so I’m getting a new set of plug wires and changing plugs while I’m at it. Also based on the plugs I’m going to richen up the fuel mixture a bit as well.

The car does emit a small amount of white smoke out of the exhaust, wondering if the rings are worn based on what I’ve read? If any of you have any tips to help me get this running a bit better I would greatly appreciate it, I’ve never tuned an engine up before.

360LA
Weiand intake
Edelbrock AVS2 650 cfm carb 1906
Long tube headers
2.5” exhaust
Stock distributor and ignition
MSD blaster coil

All taken with engine at 175 degrees, car had been sitting for 2 weeks

Cylinder #1 104
#3 108
#5 101
#7 106

#2 110
#4 110
#6 110
#8 106
 
Good morning!

Is the short block stock. The numbers suggest so, like a smog year, very low.
Yep! Those plugs show rich. Lean the carb out a step.
What is the ignition set at rod the intial?
 
rumblefish360 said:
Good morning!

Is the short block stock. The numbers suggest so, like a smog year, very low.
Yep! Those plugs show rich. Lean the carb out a step.
What is the ignition set at rod the intial?
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Previous owner did not know details on the engine or cam. And I’m not sure what initial timing is set at I need to get a timing light.
 
standup303 said:
Previous owner did not know details on the engine or cam. And I’m not sure what initial timing is set at I need to get a timing light.
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OK cool. Once you grab your dial back timing light, see where that initial is set at. You’ll probably find more power when you can advance the initial a good bit.

For a small cost, A - FBO distributor timing limiting plate can be purchased and installed. This will allow maximum initial timing with the ability to limit the total timing. Your OEM heads will like about 36*’s or more.

Check your plug gap. OEM says a .035 gap is what should be done. A little more opening can help. You’ll know when you went to far as power falls off.
 
rumblefish360 said:
OK cool. Once you grab your dial back timing light, see where that initial is set at. You’ll probably find more power when you can advance the initial a good bit.

For a small cost, A - FBO distributor timing limiting plate can be purchased and installed. This will allow maximum initial timing with the ability to limit the total timing. Your OEM heads will like about 36*’s or more.

Check your plug gap. OEM says a .035 gap is what should be done. A little more opening can help. You’ll know when you went to far as power falls off.
Click to expand...
Awesome thank you! I’m going to order a timing light this week and give it a shot
 
Harbor freight has a decent inexpensive dial back timing light.
 
With that low of compression it will be a pig. It's a low compression one for sure. It needs more initial timing and a faster curve as long as you don't get into detonation territory.
 
From the looks of the plug pictured, it's a fat pig. DO NOT richen it up any, lean it down some. When they "tuned" the carburetor, what exactly did they do? If the car sat for a long period before you acquired it, it may take a bit of run time for the rings to reseat in the cylinder bores.
 
With compression numbers that low, I don't think you are going to get much performance at all. You might be able to get it running decent (like a bone stock engine), but I would not expect too much power.
 
Demonracer said:
From the looks of the plug pictured, it's a fat pig. DO NOT richen it up any, lean it down some. When they "tuned" the carburetor, what exactly did they do? If the car sat for a long period before you acquired it, it may take a bit of run time for the rings to reseat in the cylinder bores.
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I’m not sure what they did, it as fairly vague.
 
What would be the remedy for the low compression? New rings or worst case bore over, new pistons and rings?
 
First things first, get a good tune up on it, get the timing in it's sweet spot and delve into tuning the carburetor. From there, give us a much information as you have, IE carb type and size, daily driver or weekend car. The more info you give us, the better we can help you out.
 
It looks like the cam might be too big lowering your compression how does it feel at higher rpms does it pull strong? Also is your trans shifting too quick and not down shifting into lower gears?
 
standup303 said:
I’m at 6,220.
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at that elevation, and that compression, you are correct, it will be a dog. Your gears help. But in the end, 140 psi per cylinder would be a huge difference. 125 psi minimum to have some "snap". We don't know about the cam or converter....??
 
318willrun said:
at that elevation, and that compression, you are correct, it will be a dog. Your gears help. But in the end, 140 psi per cylinder would be a huge difference. 125 psi minimum to have some "snap". We don't know about the cam or converter....??
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My first thought was cam and converter after he gave his compression numbers.
 
Ottmundr said:
My first thought was cam and converter after he gave his compression numbers.
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Yes, and the cam could be a factor in lowering the compression. The compression is pretty even across the board, which generally isn't just one or three bad valves or a couple of cylinders with bad rings. It would be kind of strange that all would be equally hurt. But, I know cars suffer at that elevation.
 
teringer said:
It looks like the cam might be too big lowering your compression how does it feel at higher rpms does it pull strong? Also is your trans shifting too quick and not down shifting into lower gears?
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He don’t know anything about the cam but I as well suspected this. The previous owner could have slid something in. His cylinder psi report (something 99% here don’t know or do) is pretty low but also pretty equal across the board.

I’m thinking this is a dead stock engine with bolt on parts and “The wrong Cam” installed or a super tired engine evenly across the board. That you don’t see everyday.
 
IMO, once he takes a few steps in the general HP tune department, I’d suggest a track run and see what it does.
Just for fun of course…
 
Add a few drops of oil to each cylinder and re do the compression test. If the numbers change drastically then you know you have a sealing issue. If not then it is what it is. I bet you’re just dealing with a low comp 70s smogger engine with some mismatched speed parts at 6200ft of elevation.
 
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