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I just rebuilt the 360 in my 78 Fury. It is a totally stock rebuild (rings, bearings) with the exception of an XE256 cam. I know the E58s had an actual 7.something to 1 compression ratio, but this cam was suggested by many people, including people on Moparts. My dilemma is, this thing is absolutely gutlass off idle, and is very lazy. The converter is the stock piece and will stall at about 1600. It wont even turn the tires doing a brake torque! The timing is set at 12* initial, and the idle is set at 1100 in park/neutral, but it drops down to about 550 in gear. Vacuum in park is about 16-17, and in gear drops down to about 11-12. Ive tried the timing everywhere from 8* to 15* initial, but fuel economy and performance seems to be best at 12*. Im running a "pre-emissions" Thermoquad, and a standard electronic distributor with an orange box. It pulls like a bat outta hell for what it is once ya get into the secondaries. Is this just not a torquey cam or what? The RPM range for the cam is listed from 1000-5200. Any ideas? This baby is my daily, and Id like to get it running right. Thanks in advance



you might have a balancer issue, I don't know. when assembling an engine I usually toss the balancer on with the heads off to check the TDC mark with actual TDC of the #1 piston, just to verify.

anyway, I was running a comp XE262 in a stock long block 360 that was rerung, and used the standard .054" gaskets that come supplied in the fel-pro tear down kit, so my actual compression was in the 7.8:1 range. my car had lots of low end with this cam. the key is setting up the distributor correctly.

your issues tell me that it is the mechanical advance that needs to be tuned. the 500+ RPM drop when putting it in drive tells me that.

what's happening is you're already up on the mechanical advance at 1100 RPM. when you put it in gear, the idle drops, pulling out timing, which drops the RPMs further, which pulls out more timing, until you get to the true base timing and the idle stabilizes (in this case, ~550 RPM). check the timing in gear, I'm guessing it'll be significantly less than your 12 degrees at 1100 RPM.

my 360 is a '79. the dizzy that came with it had 30 degrees of mechanical advance, and it started advancing at about 650 RPM. there were 2 springs in it, a very light, and a very heavy spring, so it advanced ~20 degrees very quickly, before 2000 RPM, and the last 10 degrees very slowly, so it wasn't all in until over 4k RPM. I used a dial back timing light on the engine to determine the total amount of mechanical advance the dizzy had by disconnecting the vaccuum advance, and running the RPMS up until it didn't advance the timing any more.

then I pulled the distributor out, and disassembled it. I measured the length of the slots in the mechanical advance plate & the diameter of the pin that rides in the slot. I subtracted the two numbers to get the total travel in the slot, and divided it by 30 to get the travel per degree advance. my car idled best with no starter kickback with ~18 degrees base timing, so I wanted 18 degrees mechanical advance, and I needed to remove 12 degrees. so I took my travel per degree calculation, multiplied by 12, and that was how much I had to shorten the slots up. I welded up the slot from the INSIDE some, and then used a small file to fine tune the slot length. welding up the inside of the slot will increase the preload on the advance springs, raising up the RPM they start allowing advance.

I played around with a advance spring kit I got from a friend, who ended up locking out the mechanical advance in his MSD distributor (for an EFI app) and the stock light spring from my dizzy to come up with a spring combo (I think it's got the light stock spring, and one of the lightest MSD springs in it) that gives me an advance curve that starts advancing at 1200 RPM, and was all in by 2500 RPM. I have 18 degrees initial, 36 total, and with the 600 eddie carb, I was idling in park at 950 RPM with 17" vaccuum, in gear at 800 RPM with 13" vaccuum, and about 700-750RPM in gear with the AC on and 11-12" vaccuum.

you may have other issues (vaccuum leaks, balancer thats off, etc), but you'll never get it to run right without setting up the dizzy for that cam. I'd probably look at as much initial as you can get without starter kickback (I'd expect to get at least 16 with that cam), and 36-38 degrees total mechanical advance, all in by 2500 RPM or so.

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