modulator under dash

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70xlt
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modulator under dash

Post by 70xlt »

I'm having big trouble getting 302 to run smoothly after rebuild, brains storming everything, what is the modulator under the dash with vacuum lines run to from distributor? what is it purpose and if bad will it cause a problem is retard in distributor?? The distributor is a dual port too? two new carbs, new distributor, all new firing parts, runs rich and not smooth if any at high rpm. mild cam, bored .30, new valves, new intake. please forward any info for me to tell mechanic.
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colnago
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Re: modulator under dash

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Well, I just replied to your other post, so I'll try not to repeat anything.

If you have a dual-port distributor, then I believe it's for emissions. I'm not familiar with an under-dash modulator, unless it's part of the emission setup. At some point, Ford used a modulator of some sort to control which vacuum source (ported or manifold) to use for the distributor. I don't know the details of this (I believe it was temperature-controlled), or how a dual-port distributor was used. If you don't have to smog it, I'd suggest using a single-port vacuum can, or capping off the second port on your current can, and getting rid of the modulator. On my '67 with a 352, I have the single port running to the ported vacuum on my Edelbrock. While yours is a 302, it shouldn't be much different.

Joseph
"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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Re: modulator under dash

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Not sure if this will help, but I found this the other day:
Distributor Advance Specs Boss 302.jpg
Joseph
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"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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Re: modulator under dash

Post by 70xlt »

Thanks colnago, your advice is appreciated. My mechanics are not old school so I'm resorting to the net for advice. I will try your advice today and hopefully it will help.
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Re: modulator under dash

Post by DuckRyder »

Can you show us a picture of the modulator (lot could happen since 1970)... but it is probably this:

http://www.fordification.com/tech/image ... ator01.jpg

There was also transmission regulated... just go out to the main diagrams and schematics page and they are pretty much all there.

http://www.fordification.com/tech/schematics.htm

All of that said, I agree I would bypass it and run the advance directly to a source. I’ve never tried to verify, but I’ve been told that capping a vac retard can cause problems because it seals the chamber.
Robert
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70xlt
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Re: modulator under dash

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Hey Robert, it looks like part #9E718. I'm basically searching for anything to help with the running, I've read where the dual port vacuum dist could be the problem, more less now eliminating items. I do know on the rebuild the door switch for this modulator was disconnected so no trouble shooting to see if whole modulator is bad, etc. thanks and any info greatly be appreciated.
LT
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Re: modulator under dash

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As an experiment, you should be able to pick up a single-port vacuum can from AutoZone, NAPA, etc. Swap that onto your distributor, and see if your engine likes it or not. You should be able to leave everything else alone. Heck, you don't even need to pull the distributor; the vacuum can is held in place with two screws at the front of the distributor (you will have to take the top of the distributor off, to put the arm of the vacuum can on the advance pin, but this is no biggie). If you do the swap and simplify things, hopefully you can get the idle to smoothe out, and go from there.

Joseph
"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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Re: modulator under dash

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Joseph, I tried plugging the back port, changed some of the vacuum lines around and plugged too. I also disconnected the electrical plug for the speed control on the modulator diagram. I don't think it's nothing left to change or unplug but the modulator inside the cab. It almost sounds like it's got the wrong firing order?? My mechanic is using the 1 5 ...7 8, etc firing order. Still no luck, going to google some more. It's still struggling to run and then spits gas and flames out of carb.
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Re: modulator under dash

Post by sargentrs »

Points or electronic ignition?
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1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
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Re: modulator under dash

Post by 70xlt »

I had the access electronic points, but having so much troubles the mechanic asked to buy new distributor with points and with start back base line. It has a small erson cam, I just pulled plugs, they were heavy with gas. I googled erson for firing order of E210111.

thanks
LT
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Re: modulator under dash

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Flames out the carb? Eep! I had that prior to my rebuild, and really low compression on #1 and #3. With low vacuum, I figured that I had two stuck/burnt intake valves. But I think you said that you just rebuilt your 302, so that shouldn't be an issue. My next thought is retarded ignition timing. Try this:

- Turn the engine to 10 degrees BTDC on #1
- Pull the #1 plug, leave it connected to its wire, and lay it on the block with the end near (but not touching) the block
- Is the distributor pointing to the #1 plug terminal?
- Turn on the ignition, but don't crank the engine
- Turn the distributor slowly back-and-forth
- When you see the #1 plug spark, stop turning the distributor, and tighten it down
- See if the engine starts

If you're getting flames out the carb, you have an open intake valve at the same time a cylinder is firing. The above sequence should get you in the ballpark for proper timing (maybe not exactly where you need to ultimately be, but a good starting point). If you never see the plug start, double- check that your distributor can turn to point to the #1 terminal. If it can't, you'll have to pull the distributor, turn it, and seat it again (kind of a PITA, because it has to line up with the shaft for the oil pump, so you might have to turn the engine by hand to line everything up) Also, recheck the firing sequence. The distributor turns counter-clockwise on these engines.

Where are you located? Maybe a fellow board member can come give you a hand.

Joseph
"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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Re: modulator under dash

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I just had a thought that your harmonic balancer might have turned over the last 45 years, and taken your timing marks with it! Have you ever used a piston stop? Basically, a bolt goes into the #1 plug hole. Do this:

- Remove the plug on #1
- Make sure you're on the compression stroke on #1. Some people put their thumb on the plug hole, so they can feel it being pushed off. If it doesn't push off, you're on the exhaust stroke, not the compression stroke.
- Install the piston stop
- Turn the crank slowly until it stops. Mark the balancer.
- Turn the crank the other direction until it stops. Mark the balancer
- Mark the balancer exactly half-way between the first two marks. This is your new TDC mark (which may line up with the original mark, but it's good to verify on these old girls).
- Tune from there.

Joseph
"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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Re: modulator under dash

Post by 70xlt »

IMG_3867.JPG
thanks Joseph, 1st I aint an engine mechanic so I'm repeating what I think I saw. Saying that I first question if I put it back correctly such as under dash and engine compartment. I did video(s) and used colored tape/labels for each fitting/connection.

I saw the machine shop guy put the harmonic balance back on, its a reputable machine shop. I witnessed both my Ford Mustang guys check TDC numerous times, used timing light to make sure #1 cyl was pinging and too had a firing adapter they put in line to show fire. Used the thumb in cyl too for rush of air. They both say it resembles 180 out but their experience says not. All new electrical parts under the hood, my only concern is if I put something backwards under the dash? They too feel it resembles a timing or vacuum issue. The first carb dumped so much gas in the break in oil I had to change engine oil, presently took it back and got another brand.

I've replaced 95% of the vacuum lines, going today to get new single port vacuum canister, new vacuum line for tranny. I've read where dual port vacuum canisters can throw engine timing out of sorts.

engine builder put new intake on, I put the vacuum tree on behind the carb (tranny and carb vac), I put in the center of manifold same as the old ford intake position, could this be the problem?

thanks for your help, I'm trying to cover all I did in case it is a rookie mistake.
LT


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frame off restoration, engine bored, cam, intake
lowered 4"
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colnago
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Re: modulator under dash

Post by colnago »

70xlt wrote:... I put the vacuum tree on behind the carb (tranny and carb vac), I put in the center of manifold same as the old ford intake position, could this be the problem?
I seriously doubt it. My vacuum lines are like this:

- Brake booster to rear of carb
- Tranny modulator to intake manifold (my intake has a port on the passenger rear)
- PCV to front of carb
- Distributor to ported vacuum on Carb
- Manifold port on Carb plugged

But I've seen others do it differently. The big thing is that tranny, brake booster, and PCV go to some source of manifold vacuum. Some use manifold vacuum for the distributor, some use ported. For now, I would suggest you use ported. Another thing you can try (if the engine idles at all) is to spray carb cleaner around the carb and intake (but not into/around the air intake). If the idle changes at all, you found a vacuum leak. Plug or patch it before going forward on anything. You can also get a selection of rubber caps from the auto store. Use these to cap all inputs to the carb (disconnect everything, and cap off the ports).

You said the carb flooded? That could either be that your fuel pressure is too high, or your carb floats are not adjusted properly. If you don't have the 1405 manual, you can download it from the Edelbrock site, find it on Google, or I can e-mail you a copy. You'll need some Torx drivers, but it's pretty easy to work on Edelbrocks.

Joseph
Last edited by colnago on Sun Mar 25, 2018 3:16 pm, edited 1 time in total.
"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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Re: modulator under dash

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Whoops! Double post!

Joseph
"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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