• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

440 still idles with screws turned in

Why don't we wait for the OP to try a few things, like advance the timing to 30 degrees initial, just for idle, do not drive the car, and see if the throttle blades shut and mixture screws work? I doubt it will but hope I am wrong, maybe Geoff could provide him a vac can part number that will fit his stock mopar dizzy and work with the low vacuum? I would add, measure the vacuum in gear also if it is an automatic, if he can get 10-11" in gear it is a new ballgame, 7-8"old ball game. If his dizzy is a stock mopar performance electronic he may have a ton of centrifical advance and some had reluctor phasing issues.
Yep, this is the first thing I'm going to try, tho still scared of that much timing, but I'll try. If it helps, then he probably will go for the FBO kit
 
Well good luck, you have an engine with timing issues, too small of a carb, and a cam that may be retarded, and an owner that does not want to buy the fbbo kit to make your life easier. That distributor should be limited to 20 degrees with tight enough springs too not bounce to at least 1000 rpm for testing to eliminate one problem first, you can change it later. Then do the 30 degrees initial, adjust the carb to get the 700 idle in gear, then give Geoff the vacuum reading and he can recommend a vacuum can that will work and fit your distributor. If the idle screws still do not work with 30 degrees at idle then you either change the carb or drill the blades.
 
Last edited:
6bbl,
Good advice but that is EXACTLY what I recommended to the OP back in post #5.
And if anybody else wants to simulate the improvement that MVA would make to their engine, do the 5 min test in post #5. Remember, the bigger the cam, the bigger the benefit will be.

Here is where my 284-484 mopar cam in at 108 idled with 18 initial, and 20 in the distributor. Geoff what vacuum can would fix this? More timing did nothing, and also how could it ever idle without more air added? I mean say 6" of vacuum vs 12" of vacuum do you not need a bigger restriction to get the same air. I did add about 10 degrees with the vac can at cruise speed, any more and it would miss, even with bigger idle feeds, just like the late engine did. Plugs were clean, pipes were grey inside, power brakes even worked, it ran pretty well got decent mileage, but was a 4-speed.
190 pounds compression within 5 pounds in every hole.

20181031_121828.jpg
 
Last edited:
6bbl,
Not sure if there part #s for adj vac units. I have only bought complete dists that include an adj vac adv. Hardly worth messing trying to swap cans when Summit have new dists for $140 & you get everything new.
Your engine would be the first one in 30 yrs for me where adding timing did nothing.

Some things do not add up. Hard to understand 190 psi cranking pressure with 5.5 " of vacuum. Are the gauges correct? Long duration/high overlap cams have a late closing intake valve that reduces low speed compression.
And your car must be the first one where the p/brakes worked with 5.5" of vacuum!!
So I do not have an answer until we clear up the above anomalies.
I presume a 440?
The best 'equivalent' for comparing idle vacuum I can come up with is a LSA test presented in the Hot Rod Camshaft book. A Joe Sherman 357 Chev engine 10.8:1 CR. The cam was a wild Isky SFT 262/266 @ 050; 290/294* adv. The 108 LSA cam, same LSA as yours. It had 5" of vac @ 1200 rpm idle. Two other cams, identical except for LSA were tested: 106, 110. Cranking compression for 106,108,110 was 180, 165, 155.
Lash for the Isky cam was 014/016" hot. That means to equate the 440 cam to a SFT you need to add 8-10*. So the 284 cam is 241 @ 050, would be equivalent to a SFT of 250 @ 050.
So let us look at the differences. Your engine is getting about the same idle vacuum as an engine that has 80+ less cu in. The cam in your engine has about 12* less intake duration & 16* less exh duration....which should increase vacuum.
So two factors should have given your engine more vacuum: more cubes, less cam duration/overlap. But not happening?
Now I realise there are some generalisations here, but to me something seems amiss. Are the valves adjusted correctly?
 
Here is where my 284-484 mopar cam in at 108 idled with 18 initial, and 20 in the distributor. Geoff what vacuum can would fix this? More timing did nothing, and also how could it ever idle without more air added? I mean say 6" of vacuum vs 12" of vacuum do you not need a bigger restriction to get the same air. I did add about 10 degrees with the vac can at cruise speed, any more and it would miss, even with bigger idle feeds, just like the late engine did. Plugs were clean, pipes were grey inside, power brakes even worked, it ran pretty well got decent mileage, but was a 4-speed.
190 pounds compression within 5 pounds in every hole.

Mine does exactly the same, you can add timing till end of times...lol.
But the vacuum does not get better, well tell a lie..it does get better because idle rpm goes up as you are moving to the MBT point, lowering the idle speed gets you back at the same vacuum as before and throttle is still too far open. Mine was that far open that it was always pulling vacuum on ported vacuum (Holley 750 DP and 780 Street Avenger (vac sec) and both did the same thing. My cam has 238/244 @ .050" .572/.576" and 108 LSA, it does 283/291 @ .008" so the real duration is even longer than that. Some cam manufacturers also take advantage of the .904" lifters and have a higher rate of lift so it is not just duration, there is also more lift over longer time.
The engine requires the air as per it's displacement at idle, that volume cannot be given by the carb alone as it is too restrictive so commonly one adjusts the curb idle screw to open them more...and then the problems start. (also keep in mind that due to the low vacuum there is poor fuel distribution and atomization as with high vacuum it shears the fuel when it passes the throttle blades.)
Idling pig rich, smoking, greasy plugs and the obvious stumble at some point.
The carb is too far open, not responding on the idle mixture screws and is rich as it is on the transition slot and when taking off it stumbles as you run out of transition slot before the boosters start flowing fuel, I had it all.

You need to get the carb to do its work on basic settings and let it provide what it can, add bypass air and provide the extra fuel with the idle mixture screws to enrichen the mixture.
Setting the carb back to basic idle settings and getting an alternative air source that you can control and find the point where it is running good.
I had a short piece of hose on the carb PCV port with a small plug with a hole in the center, I had 3-4 of them with different size hole and tried all. Fixed orifice.
After I got a Wagner PCV and set that to fixed orifice mode and now it has become an adjustable orifice.
When you go to far it will be same as when you have a vacuum leak so you are notified when you go to far.
After that you will find the idle mixture screws work and you set them accordingly.
From there on you will see where your idle is at, since you got the fuel and air sorted you can now make final idle adjustments.
  • Increase rpm with more ignition advance. (yes a adjustable vac. can)
  • Decrease rpm with air/fuel or retard ignition
This is how I got somewhere with mine, was a long road and lots learned!

Edit: I unfortunately found that using the vac. can just causes it to ping, a lot of vac. advance made it ping when driving off, a little vac. advance made it ping at light throttle to increase speed during driving.
18* initial and 18* mech advance, all in around 3000 and runs fine.
Now even better with Sniper Stealth EFI.
 
Last edited:
6bbl,
Not sure if there part #s for adj vac units. I have only bought complete dists that include an adj vac adv. Hardly worth messing trying to swap cans when Summit have new dists for $140 & you get everything new.
Your engine would be the first one in 30 yrs for me where adding timing did nothing.

Some things do not add up. Hard to understand 190 psi cranking pressure with 5.5 " of vacuum. Are the gauges correct? Long duration/high overlap cams have a late closing intake valve that reduces low speed compression.
And your car must be the first one where the p/brakes worked with 5.5" of vacuum!!
So I do not have an answer until we clear up the above anomalies.
I presume a 440?
The best 'equivalent' for comparing idle vacuum I can come up with is a LSA test presented in the Hot Rod Camshaft book. A Joe Sherman 357 Chev engine 10.8:1 CR. The cam was a wild Isky SFT 262/266 @ 050; 290/294* adv. The 108 LSA cam, same LSA as yours. It had 5" of vac @ 1200 rpm idle. Two other cams, identical except for LSA were tested: 106, 110. Cranking compression for 106,108,110 was 180, 165, 155.
Lash for the Isky cam was 014/016" hot. That means to equate the 440 cam to a SFT you need to add 8-10*. So the 284 cam is 241 @ 050, would be equivalent to a SFT of 250 @ 050.
So let us look at the differences. Your engine is getting about the same idle vacuum as an engine that has 80+ less cu in. The cam in your engine has about 12* less intake duration & 16* less exh duration....which should increase vacuum.
So two factors should have given your engine more vacuum: more cubes, less cam duration/overlap. But not happening?
Now I realise there are some generalisations here, but to me something seems amiss. Are the valves adjusted correctly?

Geoff we agree, something about this cam.
My buddy had a 296/.557 in at 108 solid cam in basically the same engine, same heads and it idled nice with stock 6bbl carbs, my carbs on his 3700lb car ran 11.70 at 117 with exhaust manifolds.

440 cu in standard bore shortblock never apart, 6bbl intake, every part and orifice in the carbs matched the holley master book
65 psi hot oil pressure with any oil, tried 10w-40 nothing ever changed so stuck with 30wt
.020 preload on every valve
Johnson hydraulic lifters
Correct mopar valve springs for that cam
Vacuum gauge is correct, that reading is at 700 rpm, usually ran it at 900, since it was a 4-speed
Brake booster was a bendix dual diaphram as they tolerate low vacuum, a single would not have worked.
More timing did increase vacuum and rpm, but once you adjust the idle back down is was back to 5.5" at 700, and about 8" at 900.
I bought the Alex Walordy holley tuning guide my problems were over and I was no longer afraid to drill things. I still have this engine as it is the numbers matching one, I could throw it on the run stand someday, always wanted to advance that cam and see what happened, but doubt I ever get to it. I have also assembled many others with up to .650 lift cams, none idled as bad as this one. Pretty much just like Wietse, I was always told you are doing something wrong. For the automatic guys the $1000 torque converters are worth it, you drop it in gear and it idles, you drive and it slips less, jump on it better hang on. Anyway just trying to help the guy, not argue.


6bbl,
Not sure if there part #s for adj vac units. I have only bought complete dists that include an adj vac adv. Hardly worth messing trying to swap cans when Summit have new dists for $140 & you get everything new.
Your engine would be the first one in 30 yrs for me where adding timing did nothing.

Some things do not add up. Hard to understand 190 psi cranking pressure with 5.5 " of vacuum. Are the gauges correct? Long duration/high overlap cams have a late closing intake valve that reduces low speed compression.
And your car must be the first one where the p/brakes worked with 5.5" of vacuum!!
So I do not have an answer until we clear up the above anomalies.
I presume a 440?
The best 'equivalent' for comparing idle vacuum I can come up with is a LSA test presented in the Hot Rod Camshaft book. A Joe Sherman 357 Chev engine 10.8:1 CR. The cam was a wild Isky SFT 262/266 @ 050; 290/294* adv. The 108 LSA cam, same LSA as yours. It had 5" of vac @ 1200 rpm idle. Two other cams, identical except for LSA were tested: 106, 110. Cranking compression for 106,108,110 was 180, 165, 155.
Lash for the Isky cam was 014/016" hot. That means to equate the 440 cam to a SFT you need to add 8-10*. So the 284 cam is 241 @ 050, would be equivalent to a SFT of 250 @ 050.
So let us look at the differences. Your engine is getting about the same idle vacuum as an engine that has 80+ less cu in. The cam in your engine has about 12* less intake duration & 16* less exh duration....which should increase vacuum.
So two factors should have given your engine more vacuum: more cubes, less cam duration/overlap. But not happening?
Now I realise there are some generalisations here, but to me something seems amiss. Are the valves adjusted correctly?
 
The first time I opened the cam gear cover to have a visual and see if I could find out what cam was installed, I found the cam gear installed 1 tooth off center.
Being on purpose or a mistake, I don't know.
IIRC that put the cam 14*!!!! advanced, cylinder pressure was 200 psi (with "906" iron heads) and, guess what..vacuum was also **** at that time. lol.
At this point this thing would not even burn the tires, it would rip the wheels clean off at any rpm in any gear.
I reinstalled it back to where it supposed to be with the ICL at 105*, which is with the 3* advance that is ground in the cam.
Vacuum barely changed even after that, though my cylinder pressure went down to 160-165.
I was actually considering advancing it again 3* with the crank gear key slot, but I decided to go with the Rhoads variable lifters.
The plan is to take out 10-15* with the lifter adjustment, which will give me more cylinder pressure again and some more low-end tq.
Those lifters, combined with a 3K stall converter will set thing in place a lot better and once done I am going to see to get the Vac. can operational.

Brake booster was a bendix dual diaphram as they tolerate low vacuum, a single would not have worked.
For that reason I also still have functioning power brakes with 6"In/Hg and with the Bendix booster.
 
Post 104. I talked about cam test 106, 108, 110 LSA. I probably should have elaborated more because some people are probably wondering what the test was testing.
The test was to see the effect of LSA. Note that there three cams, identical except for LSA. It was NOT one cam installed at 106, 108, 110 ICL.
Peak power was in the 580 hp range, with max HP from the 110, 583.6 hp @ 7000. It was just 3.4 hp better than the 106. How often are you at 7000 rpm?
The average change through to 7000 was that the 106 made the most tq, 23.7 ft/lbs more than the 110.
The average hp through to 7000 for the 106, 8,10 was 525.5, 514.2, 506.
I know which one I would pick!
 
Wietse,
You are the right track. You are probably in the same position as me, not living in the US parts are expensive to buy & ship, & sometimes not easy to get.
If you have not bought Rhoads lifters yet, you can modify stock lifters to work like Rhoads. Done it many times.
 
I was always told you are doing something wrong.

That's the frustrating part, "there is something wrong", vacuum leak, cam still not installed correct, etc.
People try to help, though it is never easy on the other side of the monitor to get the full pictures of what is going on.
I blocked off my crankcase and checked pressure build-up from blow by to proof the sealing between intake and crankcase, pressure tested my heads/intake with rocker shafts removed to proof my intake had no leaks to atmosphere, had the carb off 100's of times for setting the transfer slot back to basics, changed jets, power valves, replaced drilled throttle plates.
Even the "simple" verifying the cam valve events and confirming the ICL as intended by going with the dial gauge over it was part of it all, I had never done that before but with help and patience from quite some people here I got to know and see everything.
I learned a ton out of all that and in the end I got it to run decent with the cam and it's poor vacuum.

Geoff, yes getting parts and materials is a challenge, specifically for the wallet.
I did purchase the Rhoads lifters already and they should be on the way soon, recently received a box full of goodies from Summit incl. the new converter.
I am setting up a new garage with a car lift, that I need to finish first before I will get to the converter.
 
I thought Geoff might have known of a vacuum can that would work on a mopar distributor at 8" or below but it sounds like no and he would recommend a new style distributor with the Chevy style can. I can't say if that would work, it did not for wietse with an msd,or me with a crane adjustable vac can back in the day.

We sound like brothers wietse, everyone always said vacuum leak, cam in wrong, motor is worn out, but the pvc would suck paper down to the breather opening, even while burning the tires in first gear, until the 6bbl kicked in. It was not the engine.

Rhodes lifters, they did not work well for me but I think I had too much oil pressure at idle, the adjustable plug for the oil pump 440 source sells, and the right oil would help you be successful. I was 19 and did not know any better, but nobody I asked did either.

One other issue with the rhodes lifters, or any of these newer shitty loose clearance lifters on a mopar big block. When the lifters bleeds down, like when you go to start it after it sits 6 months, some rockers will kick a pushrod out. Some combos will do this after sitting while hot for an hour. Put one lifter in the block with no oil in it, install your valve gear, adjust the valve, then depress the lifter and see if the pushrod can fall out. If it can you need to fix it, Chevy guys do not experience this because of guide plates, they also do not understand why we have to run .020 preload, not a turn and a half like they can, our lifters do not bleed down, or adjust to the middle, like everyone says. So picture this, a 245 at .050 hydraulic cam, a lifter that will not bleed down, and a cam ground to take full advantage of that .904 lifter.....kinda make sense why they idle so bad, and a bigger solid lifter cam idles better. Now you know the real reason common tuning magic does not work with these. People get deep in the 10s with a mopar 292-.509 cam for a reason, they are not small cams. Anyway I want your Rhodes deal to work, preoiling the motor with an accusump will eliminate the pushrod problem, deep pushrod cups, limited travel lifters would be the best fix. I wish we could buy a .100 disc to drop in the lifter to limit the travel.
Look up limited travel lifters, even gods gifts to mankind, the gen 3 hemi, ls motors and coyote motors have these available. Hope this helps.
 
I bought the adjustable Accel GM style vac can but after a few time adjusting it it seems the screw fell out of the spring plate and was a goner..... maybe I did something wrong I don't know.

Who is the manufacturer of your cam? Mine is from Hughes Engines, it is an older/obsolete model and used the Engle K-grinds which are "Real Mopar" grinds as per their wording. (I.e. a Comp cams grind will work on Mopar, Chevy, Ford, and are not utilizing the bigger lifter but rather a 1-size-fits-all.
I have high oil pressure and use 20W50 oil so there is some trial and error to come I think with the lifters, I did mention it but Jack from Rhoades did not mention anything about it.
If what I could try the adjustable pressure regulator for the oil pump, which is a high volume type.
Regardless, their variable lifters are designed to work based on time. Thicker oil or higher pressure could aid in reducing noise, I think it could make them a bit more "spongy" and reduce the effect a little when the oil is still cold. Once getting warmer and thinner they will just do their job as intended.

The Rhoades lifters have com a long way now days, you are still on about the old original style lifters which were set from top position of the plunger.
Now they do the V-Pro and V-max lifters, which are adjusted from "bottomed out" with the lash you want between the rocker and valve stem.
So if you run .015" that is the maximum slack it will ever see, even after bleeding down for 6 months this .015" will not let the push rod fall out of the cup.
When you start it, or let it idle the lifter is getting bottomed out during the time the lifter is on the lobe, only until 3-3,5K rpm there is no longer sufficient time for them to bleed off and you are back at full duration and lift.
Anything below that the "slack" you gave it will be absorbed until bottomed out, so you have a .015" "delay before the valve opens, .015" earlier closing and .015 less lift.
 
Nice, sounds like that will work well for you, my cam was a mopar purple, but who knows who ground it, I guess they used several vendors.
 
Gents,
Comments on the last few posts.
- was not recommending a GM HEI style with adj VA. I was referring to a Ch dist that I bought from Summit that came with adj VA unit.
- the Accel & Crane adj units. I mentioned this in an earlier post. The ones I have used for GM dists have a sleeve inside the spring; if there is one for Ch, probably has the same. It SEVERELY limits adjustment & can lock up the unit. Most stupid idea, do not know what they were thinking...
Maybe this 'feature' limited the adjustment capability on your combos.
I prise the cover apart & remove the sleeve & they then work perfectly. The cheap Chinese dists [ which I found are well made & work perfectly ] do not have the sleeve & the VA works out of the box.
- Rhoads. Mate had set & I stripped one. It is a U groove on the inner piston, which provides the bleed down. I measured the width & depth of the groove to get the area. I can then file a flat on the piston to match the area & duplicate the operation. That is the arc of a circle so I calculated the chord length of the arc to remove the right amount of metal.
My understanding is that Rhoads has an ongoing patent on their design so other companies 'variable rate' etc lifters rely on select fitting of the piston to the body to get the bleed down rate. Never as reliable/consistent as the Rhoads groove.
- Comp cams has 0.904" lobe designs available, not sure if they have shelf grinds. I have had many, many CC custom grinds; accurate, good service, reasonable price.
- pretty sure Crane ground the MP cams
 
I know you did not recommend that vac adv. unit but that is the only style that would work on the MSD distributors.
At the time I did not come across any other vac cans that were adjustable and would fit my application.
I do remember the instructions that came with it were unclear to me and I went to figure it out myself.

I know there is a trick to get a general hydr. lifter to become a variable lifter like Rhoads but I am not to keen on a trial & error to see if I can sort that out myself.
I stick to the safe side and let them do the machining. :) Yes, it will cost me around $450 incl. shipping and taxes...and then I still require new push rods.....
 
I have only come across one type of MSD dist that came with VA & the VA unit was non-adjustable. That was the R to R MSD dist. I did try to fit/adapt an adj VA unit, but it was unreliable & would bind in operation. I persuaded the owner to use a HEI dist, which I can get here for $80. Comes with Rynite cap & rotor, steel gear for use with roller cams; weights & centre plate. chromed to prevent corrosion. Have used heaps of them & have been trouble free. Since the owner drag races the car, runs low 11s on street tyres, 3.31 axle, I upgraded the module to the MSD # 83647, which switches 7.5 amps & has an adjustable built in rev limiter. Dist also comes with adj VA unit that can add 30*. I know with the very big cam it idled @ 53*, now it is back in the 40s.
 
Will that fit a bb mopar? What about the restoration cars that need a stock appearance? Give us a part number that works on a bb mopar that will work at 8" of vacuum or less, otherwise he will need to go the high initial, vac can for cruise route. You keep giving examples that do not pertain to this cam/engine, give him a tune you have used on a car/cam/ distributor/carb like his.
 
Lose the attitude. I have more than covered the VA units.
Here are some Summit part #s & these are just the cheaper ones:'
SDM-PCE376-1052
PRO-440-432
SUM-851008
SUM-851018
PRO-6694
AAZ-30-3816
 
I have only come across one type of MSD dist that came with VA & the VA unit was non-adjustable. That was the R to R MSD dist.
Correct, that distributor is exactly what I have, the vac. can is like the GM style and the Accel adjustable version should be able to replace the standard non-adjustable one.
I only had a short time with playing with this Accel unit as it broke on me very fast, it could have been binding up on me as well and therefore I was struggling around with it and was in the bin shortly after that.
Maybe the stroke of the cans are different?
 
Lose the attitude. I have more than covered the VA units.
Here are some Summit part #s & these are just the cheaper ones:'
SDM-PCE376-1052
PRO-440-432
SUM-851008
SUM-851018
PRO-6694
AAZ-30-3816

No attitude.....just was hoping you knew of something that would fit the stock distributor.
 
Auto Transport Service
Back
Top