I have a Holley 4011 650 DP spreadbore carb with mech. secondaries and man choke.

I have an Edelbrock Performer RPM that has always been used with this Holley carb.

I have a used Erson TQ20 towing cam that I first used with the carb and manifold for about 20K miles and then stored it when I tore the engine down for a rebuild.

I have used this carb and manifold on another 360 while the cam was stored having no problem with it.

Both engines had points distributors, one was a Mallory dual point with mechanical advance and the other engine used a stock single point distributor with a vacuum advance and I had no problems with either setup.

When the second engine got tore down about two years ago, the vehicle had been sitting for a couple of years and I put all the parts in storage for future use.

My Son got a 75 Dodge Maxi van and I gave him a TON of my parts stash including the Erson cam, the RPM and the Holley and it uses a magnetic pickup distributor and a vacuum advance. So we installed them onto his 360 and the thing just won`t act right no matter what I do.

I went through the Holley and cleaned it all out, replaced the power valves becausse one was stuck from storage. I checked the needle and seats and they worked flawlessly, float level was still dead on and all passageways were blown through to make sure it was all clear.

The cam had a little patina on it from storage, but it was light and cleaned right up.

This thing will surge at park idle as well as in drive while sitting still. Some of the time I can mess with the timig, and carb adjustments and get it to run without surging in park, but not in drive. It will rev up real nice, with no bog or lag, but it seems to top out a little early at the high end and sounds like turbulence. At idle it will either surge in park and in drive, or at times just in drive. Once I fiddled with it and got it to run without surging in both park and in drive, but the timing was set at 5 before BTDC and upon taking for a test it bogged when trying to accelerate, popped out the carb once and then felt likeit was being held back and didn`t have ANY legs to run with.

Back to the beginning and set the timing at 7 BTDC and it bogged less, the idle surge was a lot less and it didn`t pop out the carb at all, but the lack of power and same acceleration feel, or lack of it, took me back to the driveway.

Then I set the timing at 9 BTDC and the surge was all but gone in both park and in gear, rpm`s were almost steady and it took a lot less pedal to get it moving, but STILl the lack of acceleration was still exactly the same, rough and choppy like it is being held back.

So, I said to hell with the timing tight and set it the way I always have done on ALL of my old Vans, by ear and feel. I checked my adjustments with the timing light and it was 11 or 12 BTDC and the idle was very slightly surging in gear, but not park and when tested it ran fair but a little sputtery just putting around the neighborhood. It still felt a little choppy when accelerating and it was pinging under heavier acceleration. Damn !!

I have got out the vqacuum guage and got as much as 18 and as low as 12 depending on the timing and adjustments, but nothing makes it act any differently, the feel is always the same no matter how I work it. Smoothish idle, occasionally surging, in park it revs up nice with NO lag or bogging, but once driven it has a semi choppy idle and a choppy and held back feeling to the acceleration.

I have been used to the way this thing SHOULD feel for 20 years and this ain`t getting it at all, I`m missing HALF my ponies.

I wondered, if the tach is wandering up and down only 100 to 150 rpm`s with this surging, .... Could it be a slack timing chain ??

I`ve done everything but sprinkle magic Merlin dust on this thing to get it to smooth out, with ZERO luck. Anyone have any opinions of what might be the problem ?

Thanks for reading, I know this was a bit long. Guido

To speed things up I'd drop in the points dist/ballast & hot wire it up to see if it's an ign or a mixture (vac leak) prob & we'll go from there. Good luck & holler back.

Try initial timing of about 20-22 deg. btdc.

If you set initial timing this high you will have to limit the amount the advance weights move.
[ avoid pinging )

Set total timing between 32-36 deg. btdc.

keep the vac. advance disconnected for now

Current era pump fuels will not act the same as fuels of the early 70's.

I have had worn plastic timing gears jump a tooth.
But it usually wont run then. can't hurt to look.

Also electronic ignition is a good upgrade

good luck

On a Dodge van, you have to stick your head against the firewall and put your face on the battery to even see the 10 before and 10 after marks. Anything beyond that simply cannot be seen. It sucks, which is why I had always just timed it by ear and feel. I have no way to tell where 32-36 BTDC would even be.

My mech choke is pinned wide open so there is NO choke. In Phoenix it doesn`t get cold starts, it pops right off and just idles a little low for a bit, So.....

This is what I did this afternoon. I hooked up a vacuum guage to the carb and I timed it by ear to where I thought it felt the best and sounded good and the pedal responed crisply. Then just for shits and giggles I checked the timing with the light and the vac hose removed and it was set at 8 BTDC.

Then I adjusted the carb by the guage and got 17 to 18 vacuum depending on where I the idle was, which was between 1000 rpm`s half warmed up and 1100 once warmed up completely. So warmed up I`m pulling 18 in park and the tach is steady and there is no surging.

Then I dropped it into gear and the vacuum was 14 and slight surging of about 25 to 50 rpm`s on the tach as well as very slight surging on the vacuum.

I checked the vacuum advance with a brake bleeder tool with a guage on it and I pumped it up to see where the vac advance begins to move. It starts to advance at 12 or 13, possibly even 14, it`s hard to look at the mechanism and the guage at the same time.
When in drive if I give it some gas, the vac drops down to 10 and even as low as 5. Quicker throttle and it drops to zero momentarily.

My vac advance is adjustible (lucky me) but I`m not sure which direction I should turn it or how much a single turn or a half turn will do to the adjustment.

If my "in gear" (drive) vacuum is almost the same as where the vac advance begins to advance, then I guess this must be where my surge is comming from and it is "all in" way early which would make acceleration crappy at best ??

I have had a half dozen of these vans, most of them very fast for their weight. One that was a 1971 bone stock 360 2bbl ambulance with headers, one was a 1976 318 2bbl with just headers, one was a 1984 short box with a bored 360 and these parts with a 4 spd, one that was a 1972 with that same engine bored again and with more cam and headers. All of these ran great no matter what I put on them, and I have NEVER had this particular problem so it is all pretty foreign to me and relatively mind boggling.

"Oh, and I didn`t want to slap the stock points distributor into it becausde of the wiring hassle and also because it too has a vacuum advance and I would end up having the same problem, ... or most likely anyway". I also didn`t want to hook up the Mallory dual point with mechanical advance because of the hassle of dual points as well as the wiring to install it. It would be nice to have the mechanical advance at THIS point, but it would still be a total drag to deal with putting it in, dialing in the gaps etc etc. so I figured I`d work through what is on it now and attempt to cut the gremlins head off by tuning the diaphram to what my engine is doing so I can hopefully get it to act "Normal?"

Anyone have any idea`s based on the new info ?? I`d sure appreciate the input. I`d have already pulled out all my hair, ....but I`m already BALD !

Thanks, Guido

The two setups I have had this carb on were the same block, one was 30 over and the next was 60 over. The factory jet size was fine for both. this current engine is a stock one with stock heads and it doesn`t make any sense to me to make the jets bigger on a lesser setup.

When I measure clockwise on the damper to make the 35.5 degree mark, where will I view this from ? Would it be the usual place on the timing cover, with my head pressed up against the firewall and my face on the battery in order to see the factory timing mark reference spot? And IF I would view this 35.5 degree mark on the factory location on the timing cover, should it show up at zero? Or somewhere else, like 10 or 8 or whatever BTDC ???


I am going to go try to adjust the vac advance setting by turning it clockwise a couple turns to make it advance at lover vacuum and see what happens to the surging as well as the shitty acceleration and I`ll check back here after a bit.


Thanks for all the tips and advise, you guys are saving my ass right now.

Guido

First and foremost timing needs to be set spot on before carb adjustments. When dialing in the carb with a gauge it needs to be in gear. You're vacuum needs to be connected to ported vacuum.

A new update

1. Vacuum guage reads 18" in park, and 14" in drive
2. Drive idle was still surging.
3. Vacuum advance begins at about 12-12.5

Questions

1.Which way to would I turn the vacuum advance adjustment to make it unload at a lower vacuum?
2.What is a normal amount of vacuum when the diaphram begins to unload.
3. What is normal vacuu, for when the diaphram is done unloading?
4. what is normal vacuum while in gear?

Thanks in advanced,
Guido II

Set the timing in park. I am referring to the carb adjustment with a vacuum gauge, should be done in drive. Set you're mix screws to give you the most vacuum in gear.

Well, I spent all afternoon trying to get it tuned right and it just didn`t work out.

I measured the 2 1/4 inches on the balancer and made a mark. Then adjusted my idle all the way up, but it only went up to 2500. I can`t hold thge gas pedal and read the timing light at the same time, so I went with 2500 and set the 35.5 degree mark to zero on the timing cover. Then I plugged the vac hose back into the Dist and dropped it into drive and adjusted the carb. I got 18 inches of vacuum in park and 14 in Drive and the surging was pretty much gone. I did notice a slight surge, a micro surge if you will, happening about one time every 30 seconds up to a couple minutes apart. These miniature surges were not timed or rhythmic in nature, they were here and there. The kid (Guido II)said it seemed much better and he was glad the surging and roughness was gone, it accelerated fine in park and ran smooth in park as well as in gear, so he said he was fine with it. I had reservations about that timing location, I didn`t like the way the key kicked and the sound it made when cranking, I figured it would ping like hell so I told him I`d probably have to re-time it again. Well, just to see what it would do, He drove me for a spin to the store. He putted out to the main road and I noticed it ran a little rough, not like it had been, but it was still there in miniature form. Then when we got to the Blvd he tromped on it, it kicked down (for a change) and then acted like it wanted to haul ass, sounded like it wanted to as well, ... but it didn`t. The get up and GO factor was about the same as all prior tests and adjustments and the biggest difference was the amount of PINGING.

So when we got home I peeled off the doghouse cover and set up the timing light and started to re-time it by ear. I advanced it until it got choppy and wanted to die and then backed it off a ways, .... but the idle didn`t come right back at the sweet spot, it stayed a bit choppy. So I turned the Distributor until the idle went way down and then slowly started to turn it back the other way and then right where I thought it would/should be, I hit the sweet spot again and thr RPM`s went up quickly. Hmmmmmm, I thought, why such a delayed response from the distributor???

So, I did this a few times and each time I advanced it too far and it got choppy, then turned it back to where it was, it stayed a bit choppy until I retarded it enough to drop the idle, and then on the way back to the sweet spot it would finally give me results. Over and over again this was done and again and again the effect was the same.

This sluggish responding distributor effect plus the fact that I had tried every timing location and carb adjustment under the sun and none of it made ANY difference to the way it ran out on the road, combined with the fact I had already been through the carb completely, as well as the fact that I had used this intake and carb on a 360 previously that had a vacuum advance and had no problems with any of them working well together, I came to the conclusion that the only thing that would create that scenario was, .......







Wait For It, ....



Drum roll Please, ......



A sloppy timing chain !!!

So, just before dark my Son and I tore into the grille and bumper and radiator support, took out the radiator and peeled everything off the front of the motor.
I`m looking at the timing chain already and it appears pretty sloppy. I havent measured the chain play yet, but I will if anyone is curious to know how sloppy it really was.

Lckily, in my parts bin of stored and unused goodies was a nice new Edelbrock double roller timing chain and a Mancini`s brand timing chain tensioner. I think I`ll keep the tensioner though ;-)

We might have it all back together by morning, you never know.


Thanks foir all the vacuum advice and timing tips, I`m sure it will all come in handy after I get the chain in and I`ll chime back in to let yoou all know how things are turning out. Guido

It was hard to push and pull sideways on the timing chain while holding a tape measure steady, but I measured roughly a little over 3/4 of an inch of slop on the timing chain.

I`m not sure how much slop makes for a crappy running engine, but when I looked at the right side of the crank pulley, the chain was hanging away from the cogs and saggy. That can`t be good, but I wonder, how sloppy can a chain get and still run sort of normally ???

Would 3/4 to 7/8 chain slap have the kind of effects on an engine that I was experiencing earlier ? No acceleration, rough idle in gear while driving, failure to maintain a constant idle setting or even failure to mauintain a decent timing setting ? If so, what other kinds of symptoms can be caused by a slack timing chain ?

Oh, we got it all tore down Sunday night and had it all just about put back together by Minday mid-morning. 7:00pm to 10:am with lots of breaks for frivolous stuff like eating dinner, taking an iced tea break, taking a go inside where the air is on break hahahaha. It is still real hot in Phoenix righ tnow and we sweat all night on this pig. But still, we had to tear the whole front of the van off to make it easy to get at the cover and the chain and all the peripherals, so I don`t think we did to bad for a little over half a day, or 15 hours. All that is left is a radiator support, brace that has to be hooked up and a spark plug that has to be put back in and we`ll be ready to fire it up Tuesday. We took the rest of Monday off to sleep, it has been a REALLY long weekend with not much sleep at all, so the kid and I were like walking zombies by Monday afternoon.

I`ll check back for any info I can gleen about sloack timing chain symptoms and any other helpfull info.

Thanks everyone for helping us out, Moparts is the place where all the superhero`s hang out, ... No Bull.


Guido

After all this tinkering, adjusting and pulling my hair out, wondering if it is the can, the carb/intake, timing chain etc. He tells me that it had always surged and run that way. Crap ! And all this time I was looking at stuff I had Just put onto it rather than the old stuff that already Was on it.

Swapping out the timing chain helped a lot, but it still just didn`t have the balls I remembered it having, so aftet the NEW info, we yanked out the distributor and gave it a good hard looking over. It had at least an 1/8th inch of end play on the shaft, it had side play at the pickup that would pinch the gap mostly closed and altered the shape slightly of the center points that spin past the pickup. Oh, and the Vac advance had a very small leak that I didn`t notice until I compared it to a new one. We re-gapped all the plugs, threw the new distributor in, timed it by ear like I always used to do, tuned the carb with a vac guage and then took it for a test.
The Kid bombed up an onramp to the freeway and we hit 100mph in the old 1 ton Maxi Van before the on-ramp ended. Now That`s what I was looking for, .... and the Kid was grinning from ear to ear.

He drove it back to Iowa the next day, I thought it was too early, untested and not trusted, but he took it anyway. He got a flat tire or two (must be a lot of schrapnel on the backroads) and a small fuel tank leak where a patch had been and the carb began to drip a little from the accellerator pump shooters and that made it idle a lot lower, but all in all, it made the trip ok.

So, it idled right, the surge was gone, the power was back, .... and in the end all it took was a $44 Distributor.
Ugh !!