360 is slow now, please advise.

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TomSchichtel

TomSchichtel

73 Duster
Joined
Jul 3, 2010
Messages
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Location
Newcastle, CA
So all I know about this motor is: I pulled it from an RV about 4 years ago, and it has run great. Has J heads, headers, edel dual plane intake, new 600 cfm edel carb, and a new complete tune up. The car is still doggy and slow. The timing is correct because my friend who only drives and deals in old school mopars timed it, and has done so before with amazing results. I am the student, so if you have a very technical question about my motor I may not understand. But my tach needle jumps at idle more than it has in the past (like a couple mm up and down when it used to be constant always). I'm wondering if that sounds like a stretched timing chain? Or a bad cam. So I'm determined to get this running right, and I wouldn't mind replacing both of those parts, but I would like a little advise on lift and duration, lifters, new springs maybe, and double roller or not... I would like mild performance a little more than stock, nothing crazy because this is my daily driver. I have a 3.23 posi in the rear, I'm sure that is something I will be asked if I don't type it in. Anyways thank you for reading my novel and if you have any advise that would be awesome! I would ask my mopar friend but he is in the middle of moving farther away and is very busy...
 
yes..3.23 with stock converter is not going to help you set the world on fire...

one thing is to check the advance curve on the distributor..just because the timing is set does not mean the distributor is curved.....electronic distributor??
 
The tach needle jumping has nothing to do with the timing chain. It is possibly mis firing causing the tach to be unsteady. How old are the plugs, dist. cap and plug wires? 3:23 gears should work decent with a stock cammed low rpm engine. I've ran them before with good results. A buddy of mine has a 69 Cuda with a bone stock 75 360 with just a 600 Holley 4 barrel and performer intake added and stock exhaust manifolds. He runs 3:23 gears with a stock converter and his car ran a 14.40 so they work ok when the engine is tuned correctly. Ignition timing is a huge factor and as Tony said it may be timed right at idle but what about the advance. Good suggestion by needsaresto too as it could be as simple as the carb not opening all the way.
 
I think it may be the carb. I'm going to have my carter thermoquad rebuilt because I don't think the vacuum secondary on my new edel 600 is not working right. I've had many guys who know what they are doing check it out, and that has not been sorted out.
 
if it is an eddy afb ....it is an air door that has weights on it....

can not do much to adjust it......
 
On the engine running bad, have you tuned it up since your bud last touched it? Did the distributor come loose?

Tune up will be plugs, wires, cap and rotor. You can do it yourself. LEarn to time the engine and jet a carb. You'll be miles ahead of the game that way.

Heres what I did, http://www.forabodiesonly.com/mopar/showthread.php?t=10508
You will have to use a different cam company since Crane is out of biz.
It ran 15.14 @ 89 mph with a low compresion (1979) 318/904 with 3.21 gears on a stock tire. There was more in her, but I never got there.

It is a simple build. Purchase valve springs with the cam and lifters and a double roller chain is also nice. A small AFB and a intake with headers is all that was really done.
 
I did the complete tune up, cap rotor, plugs, wires, air filter, fuel filter. I'm going to slap a rebuilt thermoquad in a day or two, whenever I can get my hand on one. The distributor did no come loose, and my bud timed it with the vacuum advance. Plus its electronic so I don't have points to worry about. I hope a new carb does the trick even though my eddy is only about six months old. Thanks for all of the tips so far everyone!
 
I don't know about all this fancy stuff but back in the day (....yeah, I know, I'm old) I use to just run it up to 2K and advance the dist. to peak the RPM then back it off "a tad bit". Worked back then but I'm sure the "new" methods are better.
 
MVRCorp said:
I don't know about all this fancy stuff but back in the day (....yeah, I know, I'm old) I use to just run it up to 2K and advance the dist. to peak the RPM then back it off "a tad bit". Worked back then but I'm sure the "new" methods are better.
Click to expand...

Me too in the old days. If you learn to time it by ear you can do nearly as good as anybody can with a fancy dial back light. I gotta admit I do love my Snap-on digital dial back light. Makes things a lot easier and I know exactly what the timing is.
 
I just talked to him and he told me that the vacuum advance was plugged when he was timing the motor, then connected afterwords...
 
A tune up on these engines is not just setting timing and bolting on new parts. From what I read, it sounds like you might be a little new to these cars. The "magic" of a good running carbureted car is in the carb tuning. From what you describe, it sounds like that might be all you need. A Thermoquad's a great carb but you'll have more issues with a mass-rebuilder T-Quad than a 6mth old Edelbrock. You need to know what your buddy did with the timing first. Like, what did he set initial timing at and what was the total he found with that.
 
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