Slant Six Forum :: Advance vs. MPG

Well in my case the gauge is a fairly accurate(?) Auto Meter temp gauge. And my definition of "warm" should actually be "hot" because I am talking pegged at 250 degrees after 30 minutes on the highway and then not cooling down for about 20 minutes after getting off the highway(lower speeds). Last night it occurred to me: what if I have a missing or broken centrifugal advance spring ? This would surely cause over-advance at highway speeds correct ? dave

Is that a stock cam from 70-74?

what if I have a missing or broken centrifugal advance spring ? This would surely cause over-advance at highway speeds correct ? dave

Ok maybe I am overlooking something here (not uncommon for me lol), but if you were missing a spring in there wouldn't it cause the dist. to overadvance because the spring is not there to counteract the centrifugal force?

Quote:

Is that a stock cam from 70-74?

Nope.. Stock cam From '77 or 79 I really cant remember now as The oirginal engine lost a rod bearing @ 162,000 and I punched a 27,000 Mile 77 Engine in - But I dont remember which Cam is in there now.

Greg

70-74 was the best factory cam. Kind of like a MPG/RV type cam.

Any ideas for the best year vacuum advance pod to get?

Author:	GENT [ Sat Mar 07, 2009 1:35 pm ]
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Quote: Well in my case the gauge is a fairly accurate(?) Auto Meter temp gauge. And my definition of "warm" should actually be "hot" because I am talking pegged at 250 degrees after 30 minutes on the highway and then not cooling down for about 20 minutes after getting off the highway(lower speeds). Last night it occurred to me: what if I have a missing or broken centrifugal advance spring ? This would surely cause over-advance at highway speeds correct ? dave How long have you owned this car? I bought my 67 Dart and I noticed it over heating on the highway,and on the highway only.I poped off my thermostat housing and saw a 160 deg. thermostat from what looked like the 80's.Changed it out for a 195(winter;I switch to 180 when it warms up.) and the problem went away.

Author:	slanty6 [ Sat Mar 07, 2009 3:57 pm ]
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That is what is boggling me. It is a high flow 195 stat. The radiator andwater pump are about 4 years old and heater core is relatively clean. and this occurs in both the winter and the summer on the highway; so not really influenced by ambient conditions.

Author:	Greg Ondayko [ Sat Mar 07, 2009 7:20 pm ]
Post subject:
Quote: Is that a stock cam from 70-74? Nope.. Stock cam From '77 or 79 I really cant remember now as The oirginal engine lost a rod bearing @ 162,000 and I punched a 27,000 Mile 77 Engine in - But I dont remember which Cam is in there now. Greg

Author:	ceej [ Sat Mar 07, 2009 8:21 pm ]
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Quote: what if I have a missing or broken centrifugal advance spring ? This would surely cause over-advance at highway speeds correct ? dave No. If you have a missing or broken spring and set your base timing where it belongs, you will have far less advance at a given engine speed. And that can be a bad thing as far as temperature. But that is only one item. What is your timing set condition? Have you flushed the block, and what does the rest of your cooling system look like? Get a good dial back gun, or borrow one. It will tell that tale. I doubt it is timing related, unless something is really fouled up. If the engine runs fine running around town, economy is good, and power is OK, timing is likely not your issue. CJ

Author:	slanty6 [ Sun Mar 08, 2009 10:00 am ]
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Ok maybe I am overlooking something here (not uncommon for me lol), but if you were missing a spring in there wouldn't it cause the dist. to overadvance because the spring is not there to counteract the centrifugal force? Also, are all vacuum advance units the same for all the years? Do they have different curves to them ? Thank you all !

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Advance vs. MPG https://www.slantsix.org/forum/viewtopic.php?t=34041	Page 2 of 3

Author:	DusterIdiot [ Sun Mar 08, 2009 10:35 am ]
Post subject:	Yes and no...
Quote: Ok maybe I am overlooking something here (not uncommon for me lol), but if you were missing a spring in there wouldn't it cause the dist. to overadvance because the spring is not there to counteract the centrifugal force? 2 scenarios here: 1) if the heavy spring broke you'd have very quick advance on the low rpm side, maxxing out pretty quickly....enough to say that if you set the initial timing by that, your base timing would be very low... But I've never seen the big spring take a tank in an OEM dizzy yet... 2) The dizzy has two springs a ligth one and a heavy one (or if EI a heavy one with a slot/loop)... the light spring is there to moderate your low rpm advance, and once it passes beyond it's ability to govern the advance, the heavy spring will start in to keep the pins on the counterweights from bouncing off the ends of the governor slots (so even if you broke a spring you would just wind up to the max timing the slot allows). Vaccuum Advance Pods are different between points and EI dizzy's, and also there are different pods for different apps and years (manual vs. auto tranny apps, long mech advance vs the 1976+ short mech advance...crap loads of vacc. advance in the Dart Lite or Feather Duster cans for mileage....) cheers, -d.Idiot

Author:	Aggressive Ted [ Sun Mar 08, 2009 10:36 am ]
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slanty6, Not necessarily. ...... What is your base/initial timing? and what governor do you have in the distributor? Example: if you have a 7R governor, max mechanical would be 14 degrees. If your base/initial timing is at 5 degrees, with full mechanical (14) total would be 19 degrees even with a broken spring. Not nearly enough timing. Best mpg and power is 30-32 degrees. Yes, there are a variety of cans available. The arm is stamped with a 7R, 9R, 11R etc...double that number for the max timing the can will provide and add it to the total initial and mechanical. A total of 55 degrees will provide good punch and excellent mileage.

Author:	slanty6 [ Sun Mar 08, 2009 12:58 pm ]
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OK. I got you, the actual notch would limit the centrifugal mechanical advance to certain fixed point. Understand completely now. Would anyone want to give me an off the cuff recommendation for a year of a vacuum advance unit ? Car is a stock 74 Satellite that sees mostly low speed use currently and does some towing. Should I go w/ a stock 74 unit or is there something more suitable to me ? Thanks again for being patient...

Author:	Aggressive Ted [ Sun Mar 08, 2009 3:46 pm ]
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slanty6, DI has his preference, however I am working with a VC208 11R unit for 22 degrees of advance at the moment. I am running a 2.76 8 3/4 posi in a 74 Swinger, 3600 lbs. with a full tank and me in it. P225 60R BF Goodrich T/A's. Not too heavy and not too light. How heavy is your car and what is your rear end gear ratio?

Author:	slanty6 [ Sun Mar 08, 2009 8:12 pm ]
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Ted, the car is fairly heavy; call it 3700-3800lbs. with me in it. The rearend is an economy gear. It is either a 2.91 or 2.94 8.25" rearend. Would this require something with lots of advance or a bit less ? thank you.

Author:	Rug_Trucker [ Mon Mar 09, 2009 8:20 pm ]
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Quote: Quote: Is that a stock cam from 70-74? Nope.. Stock cam From '77 or 79 I really cant remember now as The oirginal engine lost a rod bearing @ 162,000 and I punched a 27,000 Mile 77 Engine in - But I dont remember which Cam is in there now. Greg The reason I asked was tha 70-74 was the best factory cam. Kind of like a MPG/RV type cam.

Author:	slanty6 [ Wed Mar 11, 2009 10:53 am ]
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Any ideas for the best year vacuum advance pod to get? I was gonna try to do it this upcoming weekend, now that the flood waters have receded. lol

Author:	rock [ Wed Mar 11, 2009 12:37 pm ]
Post subject:	slanty, if it works, the cheapest one you can find is fine
slanty. use a hand or powered vacuum pump and see if it works. If so, the cheaper the better. Not quite like RAM chipsets. Look up a post I made a while back with the relationship of advance onset to number of turns out for the common cans. Depending on when you want your advance to come in, you probably can use any of several cans. VC208 is a good one, so are others. rock '64d100

Author:	SlantSixDan [ Wed Mar 11, 2009 1:41 pm ]
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Quote: 70-74 was the best factory cam. Kind of like a MPG/RV type cam. That's not so. 225 from '60-'64 and 170 from '60-'65 had a cam with specs 232Â° intake duration, 228Â° exhaust duration, 0.37x" lift, and 8Â° overlap. 225-1bbl from '64-'70 and 170 from '66-'69 (+'70 export) and 198 in '70 had a cam with specs 241Â° intake duration, 236Â° exhaust duration, 0.39x" lift, and 16Â° overlap. 225-2bbl (export only) from '67 on and 225 (domestic) from '71-'80 and 198 from '71-'74 had a cam with specs 244Â°Â intake and exhaust duration, 0.420"/0.414" lift, and 26Â° overlap. There was no particular cam used in '70-'74 (that year range includes two different factory cams). The '71-'80 item is considered the best of the stock cams.

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Author:	SlantSixDan [ Wed Mar 11, 2009 1:45 pm ]
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Quote: Any ideas for the best year vacuum advance pod to get? They don't really go by year, specifically. See here for the different pods and their specs. 1972+ distributors can use early- or late-type pods. 1971 and earlier distributors can only use the early type.