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  #76 (permalink)  
Old 01-25-2010, 05:28 PM
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Quote:
Originally Posted by red65mustang
now that we know the low cruise Hg reading is correct,,,

the most likely reason for the low cruise reading is lack of total timing at 65mph rpms operating on just base plus cent added...
(if the dist has strong centrifugal springs,,,it may well only be adding say 2-4 cent at 65mph 2k rpms and the total timing 36* is not all in till 3800+ rpms which is needed on some applications to prevent ping due to a heavy load)

once the tach is installed you can know how many rpms to reach the 36* cent total "all in" actually is...

once you know what the 65mph rpms actually are from the tach you can use the linkage idle rpms screw to set the motor rpms to the cruise rpms value and read how many centrifugal degrees is actually added...

the idle reading in the last video was fine,,,again,,,idle on the Edie is a seperate function,,,at idle is only idle functioning on a Edie if that makes sense...

it's that 10-12Hg at 65mph reading on the video that needs your attention....

it will help you understand better by knowing and seeing how a correct operating car displays on the second vac gauge...
just a $3? long piece of small diameter wiper washer hose(?) snaked up thru the hood gap and gauge taped to the cowl of a different car so you can read it driving is all it takes...

LOL, 10-12hg cruise = did you look in the rear view mirror to confirm you weren't pulling a 30' boat when you shot the video????
"that" would cause 10-12 Hg cruise
Ok here we go!!! Last night I readjusted the mixture screws. Idle was a little better. I also set the idle by sound sine I did not get my tack hooked up till this afternoon!. Actually I installed it just a few minutes ago. The warm idle is 800-850 ;-) and the vacuum is 13.50-14". I also plugged off the vac adv until I can get a new one. I also routed my vacuum to the manifold and plugged both the ported and manifold ports on the carb.

Today we had a high pressure system coming through so the winds were about 15-20mph. The ride to work and home gave bad readings. Remember a Jeep is like driving a barn door!

However, here is what I felt, heard and noticed. Idle was fine. Slow, typical traffic acceleration is ok but not smooth. Cruise was not too bad but acceleration seemed better with the mixture adjustments. I guess a little more fuel was getting to the spark.

All in all it sounds like my problem is the total lack of the vacuum advance for a daily driver.

I now have the tach on so I will take tach/vacuum readings tomorrow and start from scratch. It ain't over yet but thanks to you guys I now have an understanding whats going on!

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Last edited by Blue84JeepCJ7; 01-25-2010 at 05:41 PM.
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  #77 (permalink)  
Old 01-25-2010, 05:38 PM
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Oh...and another thing...!

I did check the total timing with the tach. 36deg mark I made was on the "0" on the timing tab at 2,000rpm. The 36deg mark also advanced to the 4deg mark at 3,000rpm.
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  #78 (permalink)  
Old 01-25-2010, 05:39 PM
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Quote:
Originally Posted by Blue84JeepCJ7
All in all it sounds like my problem is the total lack of the advance vacuum.


It'll feel like a different engine.
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  #79 (permalink)  
Old 01-25-2010, 07:24 PM
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tomorrow driving to work note the actual 65mph rpms on the tach and check that specific rpms timing total with a light...

(sorry for the mis-communication)I was using 2k rpms only as a example number...

depending on your tires diameter it cound be as low as say 1200rpms on the tach at 65mph with 44" mud boggers...

by knowing the 65mph mech total,,,(say it is 36) that gives you a initial target for setting the new vac adv unit (about 10* added for 46TT) (TT=b+c+v)
then adjust the vac adv with add or subtract hex turns till you find the minumum TT needed to have the highest 65mph Hg reading (it can be anywhere from 40 to 54TT needed)(having more than needed does nothing for performance)

agree it is a brick wall to the air but it is also relatively light total car weight for a 350 cube motor...

one more try:
leave the idle screws alone,,,they don't change the "while driving" performance

with 16 base you are at 40 total "all in" at 3000,,,(the 36 plus 4 at 3k)
so your dist has 24*'s of centrifugal (40t-16b=24c)
do just check to confirm it doesn't go any higher with more rpms,,,some pick up truck oem dist's do have 28 cent not all in till around 3500- 3800...

with the vacuum advance helping it should drive much better and have better all around performance even with the base at 14b for a 38*t "ping insurance cushion" on WOT blasts....

what does the guage read when you do put it in drive (no load=14Hg at 800),,,in drive brake on = ?Hg and ?rpms

cobalt,
I was having a bad day yesterday (wife pushed my buttons to almost the blow my top point all day long),,,did not intend for that power window post to be read as criticizm (probably did in my mood)

Last edited by red65mustang; 01-25-2010 at 07:38 PM.
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  #80 (permalink)  
Old 01-25-2010, 07:44 PM
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Quote:
Originally Posted by red65mustang
what does the guage read when you do put it in drive (no load=14Hg at 800),,,in drive brake on = ?Hg and ?rpms
I will double check but I think it drops to about 12", maybe 11"
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  #81 (permalink)  
Old 01-26-2010, 10:07 AM
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need to also know how much the rpms drops also...

in park = 14Hg at 800
in drive = ? and ? rpms

what you are measuring is the actual motor power output at idle (with only mech timing) versus the "fixed value" torque convertor added load/resistance in drive by comparing the readings....

it gives one more clue for what duration the cam is...
and gives a first clue for stall rpms rating on the convertor....

performance ign tuning can add 20HP/20TQ+ at any/all rpms,,,but it isn't a miracle cure for severely mis-matched drive train parts...

ex: my then teenage son just had to have huge mud tires on his stock 4 banger 5 speed ranger "to look cool",,,,truck drove like a total dog to the point it wasn't safe!!!
I gave him the option,,,lose the tires or spend the $800+ to correct it (much deeper rear gears set and racing clutch due to added tires weight),,,he shelled out his hard earned Taco Bell money and kept the tires...
Joke was,,,the friend he sold it too hated the tire noise and put on reasonable size tires,,,,came by one day and remarked: "wow what the heck did you do to that 4banger it screams and winds up like like a V8 for power"
(my son forgot to tell him the gears were changed)

???? I missed it?
what does the Hg read in 3rd gear at around 60-65 (and what does the new tach read for rpms in 3rd)



PS: when the vac adv is working,,,hooked to manifold,,,the new idle timing will be b+v (around say 26) and both the idle rpms and idle Hg will increase quite abit (idle will jump to 1,000+?)...
Lol,,,so leave the idle mix screws alone,,,it is a wasted effort
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  #82 (permalink)  
Old 01-26-2010, 04:43 PM
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Just a reminder I have a 700R4 "K" case transmission with a manual lock-out switch. The front and rear have 3.37 gears! Tires are 32"....1:1 with the speedo.

1. Idle (engine cold) = 1,000rpm @ 15"
2. Idle (engine nice and warm) = 850rpm @ 14"
3. In drive but not moving = 650rpm @ 11.5"
4. 4th gear, lock-out engaged @ 65mph = 1,800rpm @ 8"
5. 4th gear, lock-out engaged @ 55mph = 1,500rpm @ 7"
6. 4th gear, lock-out engaged @ 70mph = 2,000 @ 10"
7. 3rd gear, lock-out disengaged @ 55mph = 2,400 @ 15" ?
8. 3rd gear, lock-out engaged @ 55mph = 2,100 @ 11"
9. 3rd gear, lock-out disengaged @ 70mph = 3,000rpm @ 12"

SHIFTING typical traffic acceleration
At 2,000rpm shifts from 2nd up to 3rd w/lock-out engaged, 25mph shift, rpm drops to 1,000 and vac drops to 5"

At 2,000rpm shifts from 3rd up to 4th w/lock-out engaged, 55mph shift, rpm drops to 1,600 and vac drops to 10"


Vac Adv ordered and should be here tomorrow or thursday!!!!!!

Last edited by Blue84JeepCJ7; 01-26-2010 at 05:55 PM.
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  #83 (permalink)  
Old 01-27-2010, 08:40 AM
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Blue,
good grief my brain is shot!!!!

it never even crossed my mind that it "could be" a 4x4!!!!

I was going totally nuts trying to figure out what the hell can knock down that cruise Hg so darn much,, even experimented with my car looking for clues.....

seems posting on this board to "excercise" my brain is not working...

everything we have discussed and the tuning articles links are based on a 2 wheel drive vehicle!!!!

4x4 is a totally different animal!!!
ex:
just the TQ force needed to rotate/accelerate those tire's "mass" has to be a consideration...
the 1406 carb factory rods and jets are for best mpg in a typical "car" application...
it's not a light weight vehicle....

thanks for all the numbers,, I need to dust of some cobwebs in my head (and think abit) to give a decent reply
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  #84 (permalink)  
Old 01-27-2010, 11:09 AM
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blue,
these numbers (from my older than dirt engine analyzer software) following are only a illustration of what happens to the low rpms TQ output with a performance cam

stock 8.0CR 350 with a typical 196/204 oem cam with a 600cfm carb WOT:
500=85 ft/lbs TQ at the flywheel
1000=209
1500=279
2000=305
2500=312
3000=309

14Hg at 850 rpms idle says your cam is around a 220/230 grind,,,with no other motor changes the TQ output is:
500=0 ft/lbs TQ at the flywheel
1000=84
1500=184
2000=235
2500=267
3000=277

the difference doesn't look like much until you multiple it by the tranny ratio and by the rear gears ratio to find the actual total ft/lbs applied to the tires....

picking the 1500 rpms #'s for the example:

stock cam 1500rpms=279ft/lbs from the motor x 1.0 tranny 3rd gear x 3.37 rear gears=940ft-lbs of force on the tires...
stock cam in OD =279 x .70 x 3.37=only 658ft-lbs available at the tires

220/230 cam 1500rpms =184ft-lbs x 1.0 (3rd gear) x 3.37=620ft-lbs available
220/230 cam in OD=184 x .70 x 3.37=only 434 ft-lbs available to keep the 4,000 lbs car weight moving!!!
YUP a head wind will for sure knock down the Hg!!!!!

LOL, that is about like asking one Shetland pony to pull the Budweiser beer wagon at 60 mph!!!
he'd be huffing and puffing same as your motor is doing,,,lowHg=rich carb= the motor is "trying" as hard as it can to make enough power to maintain the speed...

sorry, the vac adv isn't going to do much because you are so far out of balance for TQ at the tires versus weight...

the gears are no where deep enough in OD to get your cammed motor to the rpm-TQ output needed so the motor isn't huffing and puffing at cruise....
the illustration numbers show your motor needs to be at 3000rpms=277ft/lbs to produce the same TQ that the stock cam does do at only 1500rpms=279ft/lbs of force which a gears swap will do....

rather than swap 2 sets of gears I would change the cam and never use OD...
ex?:
a "RV" grind is designed to help make the most/best TQ possible "at" normal driving rpms range with just normal pedal...
they are excellent for quickest 0-60mph WOT which is what you do want on the streets for fun....

PS/fyi
the jeep doesn't like 55mph because the carb is teetering on the Hg/TQ/rpms point where the springs on the rods do move them up to the richer position....
(at cruise they are normally down because the Hg is higher than the spring rating)
richer rods and/or a springs change would fix that...
BUT only 8Hg at 55 is telling you don't use OD,,,,you are "lugging" the motor

edit:
park and in drive values are normal/typical for a roughly 220/230 cam and stock 1800rpms? stall convertor....

Last edited by red65mustang; 01-27-2010 at 11:37 AM.
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  #85 (permalink)  
Old 01-27-2010, 11:43 AM
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Quote:
Originally Posted by red65mustang
blue,
these numbers (from my older than dirt engine analyzer software) following are only a illustration of what happens to the low rpms TQ output with a performance cam

stock 8.0CR 350 with a typical 196/204 oem cam with a 600cfm carb WOT:
500=85 ft/lbs TQ at the flywheel
1000=209
1500=279
2000=305
2500=312
3000=309

14Hg at 850 rpms idle says your cam is around a 220/230 grind,,,with no other motor changes the TQ output is:
500=0 ft/lbs TQ at the flywheel
1000=84
1500=184
2000=235
2500=267
3000=277

the difference doesn't look like much until you multiple it by the tranny ratio and by the rear gears ratio to find the actual total ft/lbs applied to the tires....

picking the 1500 rpms #'s for the example:

stock cam 1500rpms=279ft/lbs from the motor x 1.0 tranny 3rd gear x 3.37 rear gears=940ft-lbs of force on the tires...
stock cam in OD =279 x .70 x 3.37=only 658ft-lbs available at the tires

220/230 cam 1500rpms =184ft-lbs x 1.0 (3rd gear) x 3.37=620ft-lbs available
220/230 cam in OD=184 x .70 x 3.37=only 434 ft-lbs available to keep the 4,000 lbs car weight moving!!!
YUP a head wind will for sure knock down the Hg!!!!!

LOL, that is about like asking one Shetland pony to pull the Budweiser beer wagon at 60 mph!!!
he'd be huffing and puffing same as your motor is doing,,,lowHg=rich carb= the motor is "trying" as hard as it can to make enough power to maintain the speed...

sorry, the vac adv isn't going to do much because you are so far out of balance for TQ at the tires versus weight...

the gears are no where deep enough in OD to get your cammed motor to the rpm-TQ output needed so the motor isn't huffing and puffing at cruise....
the illustration numbers show your motor needs to be at 3000rpms=277ft/lbs to produce the same TQ that the stock cam does do at only 1500rpms=279ft/lbs of force which a gears swap will do....

rather than swap 2 sets of gears I would change the cam and never use OD...
ex?:
a "RV" grind is designed to help make the most/best TQ possible "at" normal driving rpms range with just normal pedal...
they are excellent for quickest 0-60mph WOT which is what you do want on the streets for fun....

PS/fyi
the jeep doesn't like 55mph because the carb is teetering on the Hg/TQ/rpms point where the springs on the rods do move them up to the richer position....
(at cruise they are normally down because the Hg is higher than the spring rating)
richer rods and/or a springs change would fix that...
BUT only 8Hg at 55 is telling you don't use OD,,,,you are "lugging" the motor

edit:
park and in drive values are normal/typical for a roughly 220/230 cam and stock 1800rpms? stall convertor....
Thanks for the info. Let me digest it for a while....lol Certainly makes sense!
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  #86 (permalink)  
Old 01-27-2010, 12:21 PM
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Ok, so what you are telling me is that I have a drag, top end, cam that needs 3,000rpms or better for TQ?

So what I need is a low end cam like the old 69 chevy trucks had for towing?

If I am correct this is what I would have needed in the Chevy engine that I was going to get for my airplane. Direct drive to the propeller max,(cruise) rpm @2,700.

BTW here is a video of the type airplane I was building with a 383 Stroker. fyi, in the video is another airplane that is loud and sounds like a sewing machine! Note the "Hawk" airplane is actually quiet!!

TURN THE VOLUME UP!!!
http://www.youtube.com/watch?v=YTtGkrEbqZU
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Old 01-27-2010, 12:52 PM
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Yup,
it is a chunk to try to digest,,,,
but does boil down to simply the available TQ power to weight ratio at whatever rpms...

hope this makes sense:
I could have swapped a stock 302 into my son's 4 banger Ranger to gain signifigant TQ at all street rpms for the (I think 34") bigger tires and stock 3.73 gears but that was way more than he could afford...
so I stuck some 4.56 gears (I think?) in it so it behaved a tiny bit better than original tires and gears performance with the 34"s...
with 27"? tires it scooted pretty darn good for a 4 banger...

as always in Hot Rodding: ALL the parts need to match for the rpms you will use to actually gain performance....

LOL,,,the price for my labor was I got the Ranger wheels and they are still on my 65 Fastback,,,look and fit good
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Old 01-27-2010, 01:19 PM
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blue,
both cams do reach peak "max" TQ possible within about 500 rpms of each other....
(above that rpm point you have to speak HP values because TQ will fall off)

it's the TQ/rpms graph plot curves at low rpms difference that is inherent with a performance cam....

yes you are on the right track,,,

a truck cam does put more A/F into the chamber at lower rpms so it can/will make more power because of the valves timing and lift better suits the (slow) piston speed air velocity...

at the TQ peak rpms the cylinder is getting a 100% A/F charge fill so TQ won't go further up...

you can shift the TQ peak rpms by about 500rpms up or down by advancing or retarding the cam installed position...
for the airplane you would have installed the truck cam advanced to it's limit to get best power at 2750rpms...

Last edited by red65mustang; 01-27-2010 at 01:31 PM.
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Old 01-27-2010, 04:06 PM
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Need a quick response.

I got the vacuum advance today and was going to put it on anyway. However, when I pulled the old one off, I checked it and it works. Turning the screw all the way left gives me an off like position. All the way, 8+ turns to the right gives me about 5" of vacuum to get it to advance.

Now, the problem is that the tab inside the distributor, when I try to move it...it does not move at all...as if the "pick up plate" is froze!

What to do now?
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Old 01-27-2010, 04:51 PM
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contact accell tech help....

http://www.accel-ignition.com/TechSupportHome.aspx
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