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Would the XE256 cause an E58 to have low vacuum? UPDATE
#427763
08/03/09 08:39 PM
08/03/09 08:39 PM
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Joined: Apr 2007
Posts: 2,327
Glendale, AZ
69L78Nova
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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
1969 Nova
454/M21/3.31
Mild mid-11 second weekend cruiser
1994 F150 XLT Super Cab 2WD
5.0/4R70W/3.55
(Daily driver)
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: 69L78Nova]
#427764
08/03/09 09:07 PM
08/03/09 09:07 PM
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Posts: 14,889
up yours
Supercuda
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Did you degree in the cam? Almost sounds retarded.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: gomangoRTSE]
#427767
08/03/09 11:09 PM
08/03/09 11:09 PM
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Posts: 2,327
Glendale, AZ
69L78Nova
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Thats what I was thinking. The balancer ring has quite a wobble as well. How likely is it the balancer ring could have spun? This thing has a ton of mid-range and top end, considering Im still running the small stock manifolds and exhaust for the time being. If I bring the stall up and hit it from a stop, it takes off like a 2bbl 318 until it hits around 2000rpm. Granted, I still have yet to adjust the air door and such, but the low idle in gear is whats puzzling. And forget turning the A/C on. Gotta "2 foot" it at idle to do that.
1969 Nova
454/M21/3.31
Mild mid-11 second weekend cruiser
1994 F150 XLT Super Cab 2WD
5.0/4R70W/3.55
(Daily driver)
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: 69L78Nova]
#427768
08/04/09 12:49 AM
08/04/09 12:49 AM
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Posts: 2,327
Glendale, AZ
69L78Nova
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Also, with the timing set at 12*, it is kicking against the starter when the engine is at operating temperature. That doesnt sound right for an 8.0:1 360
1969 Nova
454/M21/3.31
Mild mid-11 second weekend cruiser
1994 F150 XLT Super Cab 2WD
5.0/4R70W/3.55
(Daily driver)
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: 69L78Nova]
#427769
08/04/09 09:21 AM
08/04/09 09:21 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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I Live Here
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Quote:
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.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: patrick]
#427770
08/04/09 10:58 AM
08/04/09 10:58 AM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
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Az
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Agree with patrick in that it's a timing issue ( although I have never seen 30 degrees of mechanical advance in a distributor before ). It sounds as though you have too much timing coming in too soon ( curve is too fast at the bottom end ). You can try replacing the light spring with a heavier one, or to verify that's the case, set the initial timing @ tdc or even a little on the retard side and see if that perks up the low end. It will obviuosly kill the top end ( and the vacuum )but it's just a test to see if the initial curve is too fast. For your set up, I would run about 12 mechanical degrees in the distributor ( 24 degrees @ the crank ) with initial timing at 12 degrees for a total mechanical of 36 dgerees - Curve to start around 1200rpm and all in around 2800 rpm. I'd run about 14 degrees of vacuum advance. This would give you a total of 50 degrees at cruise - 2800 rpm or above. Very common set up for a streeter.
Fastest 300
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: Crizila]
#427771
08/04/09 11:17 AM
08/04/09 11:17 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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Quote:
Agree with patrick in that it's a timing issue ( although I have never seen 30 degrees of mechanical advance in a distributor before ). It sounds as though you have too much timing coming in too soon ( curve is too fast at the bottom end ). You can try replacing the light spring with a heavier one, or to verify that's the case, set the initial timing @ tdc or even a little on the retard side and see if that perks up the low end. It will obviuosly kill the top end ( and the vacuum )but it's just a test to see if the initial curve is too fast. For your set up, I would run about 12 mechanical degrees in the distributor ( 24 degrees @ the crank ) with initial timing at 12 degrees for a total mechanical of 36 dgerees - Curve to start around 1200rpm and all in around 2800 rpm. I'd run about 14 degrees of vacuum advance. This would give you a total of 50 degrees at cruise - 2800 rpm or above. Very common set up for a streeter.
all my degrees I mentioned were in crank degrees off of the damper, so the advance plate actually had 15 degrees in cam degrees, or 30 in crank. degrees.
you have it backwards. retarding the distributor will hurt low end, and move the powerband higher in the rev range, because at low RPM's the peak cyl pressure will occur after TDC with it retarded.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: patrick]
#427772
08/04/09 01:09 PM
08/04/09 01:09 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
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Az
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Quote:
Quote:
Agree with patrick in that it's a timing issue ( although I have never seen 30 degrees of mechanical advance in a distributor before ). It sounds as though you have too much timing coming in too soon ( curve is too fast at the bottom end ). You can try replacing the light spring with a heavier one, or to verify that's the case, set the initial timing @ tdc or even a little on the retard side and see if that perks up the low end. It will obviuosly kill the top end ( and the vacuum )but it's just a test to see if the initial curve is too fast. For your set up, I would run about 12 mechanical degrees in the distributor ( 24 degrees @ the crank ) with initial timing at 12 degrees for a total mechanical of 36 dgerees - Curve to start around 1200rpm and all in around 2800 rpm. I'd run about 14 degrees of vacuum advance. This would give you a total of 50 degrees at cruise - 2800 rpm or above. Very common set up for a streeter.
all my degrees I mentioned were in crank degrees off of the damper, so the advance plate actually had 15 degrees in cam degrees, or 30 in crank. degrees.
you have it backwards. retarding the distributor will hurt low end, and move the powerband higher in the rev range, because at low RPM's the peak cyl pressure will occur after TDC with it retarded.
10-4 on the degrees patrick. Peak cylinder pressure ( flame front at its peak )in normally asperated engines should occur around 12 degrees ATDC ( best angle of attack between the piston / rod / crank). If you light the fire too early, this peak flame front pressure will occur too early ( before the 12 degree crank angle ) in the cycle and torque will drop off. If you are lighting the mix too earily ( especially at low rpm's, the motor will be flat. An easy test to verify this is to just retard the distributor ( sets the hole curve back ) and see if it feels better a low speeds. Again, you could also install heavier advance springs - or switch the heavy and light springs - temporarily.
Fastest 300
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: Crizila]
#427776
08/04/09 04:33 PM
08/04/09 04:33 PM
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Joined: Feb 2008
Posts: 992
Simi Valley, CA
MoparJ
super stock
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super stock
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Simi Valley, CA
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Hell, my stock internal rebuilt 73 318 with a XE268, headers, along with 600 cfm Edde carb on a performer intake runs great for what it is. I have a 904 with a TF2 kit and a Hughes 2500 TC, with 3.23 gears. The dizzy is a MP piece with a MSD blaster coil. I have as much timing as it will take before it pings somewhat under load, but I have never encountered starter kickback yet. I think my balancer and tape is off, so I may have to just move up and run 89 fuel (as I am running 87) and see how it runs again by advancing the timing.
It has run anywhere from 14.6 to 15.2 in the quarter, depending on day and gets 16-19 mpg on the hwy.
2016 Ram 1500 Crew Cab: 5.7, 65RFE, 4.56 gears with locker, Hemifever tuned, AFE intake, 87mm throttle body, JBA headers, 3" Flowmaster exhaust, split to dual 2.5" exits. 13.57 best ET so far.
Searching for new A or B Body Project!
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: Paul_Fancsali]
#427777
08/04/09 05:36 PM
08/04/09 05:36 PM
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Joined: Apr 2007
Posts: 2,327
Glendale, AZ
69L78Nova
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Quote:
gear the car at least 3.90s and that car will be fast enough for you.
Im not trying to make the car as fast as I can. Thats what I have my Barracuda for. Im just trying to get this car to run as good as I can, and have it set up properly since I drive it every day. Just to let everybody know, Im not a burnout crazed teenager...just found it odd that it wouldnt break the tires loose. Im going to examine my ignition timing, and possible slippage of the harmonic balancer ring, and go from there. When I put the motor together, I double and triple checked the cam timing this time. Crizila can vouch for my past cam problems. He was a great help the last time. Anyway, Ill try some things and see what happens. Thanks for all of the replies so far
1969 Nova
454/M21/3.31
Mild mid-11 second weekend cruiser
1994 F150 XLT Super Cab 2WD
5.0/4R70W/3.55
(Daily driver)
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: 69L78Nova]
#427778
08/04/09 10:58 PM
08/04/09 10:58 PM
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Joined: Apr 2007
Posts: 2,327
Glendale, AZ
69L78Nova
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Well, I just got done messing with it. I tried the timing everywhere from TDC to 25* initial. The engine vacuum went up the farther I advanced the timing, but couldnt get any more than 17.5* or so at 1000rpm. I cheched the timing in gear as suggested and it is the same as it is at 1100rpm. I sprayed around the perimeter of the manifold, carb base and all of the vacuum fittings and plugs on the intake. When the timing is up around 20* base, the engine is very snappy and responsive at both idle and in gear, but it drags the starter when at operating temperature. The stall of the converter seems to vary as well. This is a reman unit that went in with the rebuilt engine, and sometimes it will stall at 1600 or so, and other times 1200-1300. Im thinking the starter is not the culprit either, as I had this starter on my Barracuda at one time and it is running 11.2 to 1, and turned it over just fine.
What else should I check? I really cant think of anything else. When the timing is at the 12* I had it at, driveability was good, and MPG was good...but off the primaries, it was just lazy. Taking off semi-hard off of a stoplight, it would almost stumble. The carb had been completely rebuilt right before the engine rebuild and ran like a top. Could it be maybe a little lean now with the addition of the cam? Other than adjusting the metering rods 1 turn up to eliminate part throttle miss at cruising speed, it is as it was with the old motor. Im not sure what else to check without going back into the motor.
1969 Nova
454/M21/3.31
Mild mid-11 second weekend cruiser
1994 F150 XLT Super Cab 2WD
5.0/4R70W/3.55
(Daily driver)
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Re: Would the XE256 cause an E58 to have low vacuum?
[Re: 69L78Nova]
#427779
08/05/09 07:05 AM
08/05/09 07:05 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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the only additional info I can add, is when I initially put together my 360 with the comp XE262, I had an eddy performer 750. it ran like a scalded cat above 3k RPM, but I could never quite tune the low RPM bog out of it, and my car felt kinda soft on the low end, it wouldn't light the tires up romping on it, you'd have to deliberately powerbrake it. I switched to an eddie performer 600, and I gained a ton of low RPM responsiveness, as well as 2" idle vaccuum. stomp on the gas and the rear would light up and start to walk out on you, and if I did lose any high RPM performance, it wasn't noticable.
the huge neutral-drive RPM drop you mentioned initially makes me think there's still something wrong with the timing, or possibly with the torque converter, but I suppose it could be carb tuning.
when you were messing with and checking the timing, you did have the vaccuum advance disconnected and plugged, right?
Last edited by patrick; 08/05/09 07:06 AM.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Would the XE256 cause an E58 to have low vacuum? UP
[Re: 69L78Nova]
#427780
08/05/09 07:24 AM
08/05/09 07:24 AM
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Joined: Jan 2003
Posts: 5,443
Indiana
YO7_A66
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Indiana
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""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""
Since your timing at 1100 N is 12 degrees is the same as the timing in gear, then this might be a carb idle circuit problem which might indicate that the carb is lean in D. (I wonder if your springs are fluttering in D which would make it rich?) Try tuning the carb once you have the motor up to running temp and since it is an auto, then tune the car with the tranny in D and the emergency brake applied. Then you can readjust the carb for the highest vacuum while in D at the desired rpm. Tuning an auto car for best vacuum while in N is fine to get you close, but an auto street driven car needs to have the final tuning done while in D with the brake applied to simulate actual driving conditions.
Note: I have had 6 carbs on my 340 and the worse performing carb by far was the Edy Performer 750. The Edy Performer 600 was a much better idler/performer carb.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Would the XE256 cause an E58 to have low vacuum? update
[Re: YO7_A66]
#427781
10/23/09 09:27 PM
10/23/09 09:27 PM
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Joined: Apr 2007
Posts: 2,327
Glendale, AZ
69L78Nova
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I know Im bringing this thread back from the dead, but I have been messing with this car off and on for a while now. I have done a compression test, and all cylinders are averaging 135 across all eight. Squirting oil in the cylinders doesnt make any difference at all. I also swapped intake manifolds from the stock cast iron TQ manifold to a Performer for testing purposes. The vacuum is still what I consider low, but rock steady (16-17 in park at 1000rpm, and 12-13 in gear at 600rpm) I degreed the cam and it is in at 106*, which is what Comp says. I changed the converter and now its stalling at 1600 all the time. This motor has all of about 4000 miles on it, and has never smoked or had one bit of blowby. I cant understand why the compression test would turn up such low numbers. The only thing I can think is the cam.
Ive been looking at some of Summits cam and lifter kits. I have heard many good things about them for the price. I am not looking to build a racecar out of this boat, but I would like to have some low end torque since 99% of the driving I do is city.
I dont want to start throwing parts at it, but since the Summit cams have a fairly good reputation for what they are...would the K6900 or K6901 be a better choice for a heavy car like this?
1969 Nova
454/M21/3.31
Mild mid-11 second weekend cruiser
1994 F150 XLT Super Cab 2WD
5.0/4R70W/3.55
(Daily driver)
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