Q. on installing non-lockup torque converter in lockup 200-4R?
 

I called Continental about installing a 3000 stall Jim Hand t/c, which is non-lockup, in my Bowtie tranny, which has a lockup t/c. The tech said I need to install a valve in the tranny to stop fluid flow through the t/c. He was a bit vague where this valve goes. Can anyone confirm this?

The tech also told me the 200-4R gets its OD just by locking the t/c up, which kind of made me wonder about the accuracy of the valve information:oogle: .

The non lock-up valve replaces the TCC apply valve in the pump. You also must remove the check ball in the front of the input shaft.

TCC function is independent of transmission gear changes. Some units are set up to lock the TCC as early as second gear, some in 3rd and OD, some just in OD......Cliff

He told me Transgo sold the valve. I just found it on their web site, part # 7-CCV, so I owe him an apology (except for the bit about the OD coming from the TCC lockup which was just plain wrong). So I have to pull the tranny and get a tranny shop to install/remove these parts? That complicates things a bit.

The transmission doesn't have to come out to install the valve, but it has to be pushed back some and the torque converter removed to access the check ball/capsule in the front of the input shaft.

He may have just been confused, as a lot of units are set-up so that the TCC doesn't apply until the transmission makes the shift into OD. This is usually accomplished by wiring the TCC solenoid through or grounding it with a normally "open" 4th gear pressure switch.

I've tried using a TCC for retrofits into older cars, and like the non L/U deal a LOT better. A high quality torque converter with efficient characteristics is required, but the whole deal makes using OD's in older vehicles much easier......Cliff

So Cliff, you would suggest then to go non-lock-up over a lock-up in a 2004R? I have to admit, the converter is the one thing on my BTO that I feel lacks, and have been considering changing it. One concern I have is that at @70mph on the highway, I'm only turning like 1800 RPM, and a non-lock-up would run hot or wear faster with any kind of a stall above that. Or am I missing something?

I tried both in my 67 Impala SS (4L60 with 3.31 rear gears). Started out with a custom L/U unit, stalled about 2400rpm's, rpm's at 70 were about 2200 with the TCC applied. I ran it that way for several months, then BOOM, lunched the converter and it pumped enough needle bearings thru the trans to require a complete rebuiding.

I used a ported vacuum switch/brake pedal switch/grounded on a 4th gear pressure switch deal to operate the TCC. It worked fine, unlocked at heavy/full throttle, and when coasting. I didn't really like it much, as it would "lug" the engine in 4th gear at low vehicle speeds, and clunked in and out like a factory TCC cruising around 35-50mph when we were on and off the throttle.

I replaced the L/U converter with a custom built 2400rpm with no TCC, and absolutely LOVED it. It was very well coupled for "normal" driving, and barely any rpm increase at any speed in 4th noticable over the L/U unit. Have some torque multiplication in 4th gear at lower vehicle speeds was a BIG plus over the L/U converter, which typically required enough throttle opening to unlock it to get the heavy Impala back up to speed without shifting back into 3rd. No switches, no wiring, no thumping/clunking in and out of L/U, better everyplace, IMHO.

I didn't even run a cooler with it, just in the factory replacement radiator. Ran it that way over 35,000 miles before selling the car, averaged 18-24 mpg's, and never once missed the L/U deal......FWIW.....Cliff

And who would you recommend for a 2004R non-lock-up converter? I too would like a 'tight' 2400-2600, and wonder what a good one would cost. I spray, so would prefer an anti-balloon plate.

Continental has been making all of the converters we sell. I've only sold half a dozen of their 10" units for non-LU OD applications, so far, no complaints, no problems......Cliff

I also don't like the l/u 2400 rpm converter he BTO tranny came with. 4th gear engages at a low speed. I could live with that, but it then immediately locks up (4th gear TCC switch) and the engine lugs.
So it sounds like I can install the Continental 3000 t/c with the TCC valve and check ball mods, without too much slippage and overheating when cruising at 2500 rpm.
Why do the mods have to be done? I have heard of people running a 200-4R with the TCC not functioning, ie no l/u, with no problem.

Something to do with fluid flow to the converter and possibly the transmission internals. I never took time to study an oil flow diagram for those transmission, we just install the valve when we build them, and have had zero issues in any area running them without a TCC.

We have even set them up with low stall converters for trucks in towing applications, without overheating problems. Some builders/shops speculate that the units will overheat if the TCC doesn't apply when towing. I can't see that happening up you use an efficient converter in the first place, designed for heavy load/low stall applications.....Cliff

So do I call Continental direct for a quote on a 2600-2800 non-LU w/ anti-balloon plate? Or is that something you can quote? (By the way, your PM mailbox is full).

Cliff's comment regarding a lock up converter - "I didn't really like it much, as it would "lug" the engine in 4th gear at low vehicle speeds, and clunked in and out like a factory TCC cruising around 35-50mph when we were on and off the throttle."

I have a similar situation. My 200-4R is set it up so the converter will only lock up in overdrive. Also installed is a electronic torque converter lock-up controler made by Ron Francis Wiring that I can switch on and off. This system locks up the converter at a set speed and unlocks it when the signal generator senses the vehicle speed is below lock up speed or when the brakes are applied. This unit is set to lock the converter at 42-47 MPH and can be adjusted if necessary. At 70 mph out on the open highway at about about 2100 rpm when locked up, all is fine and if I want to accelerate some with the amount of torque from my 505cid combo its not a big issue. However when I get much below 55-60 mph or so I can now feel it "lug" around a bit, and it will have that tendency to clunk like a stick car with my big cam. My motor makes its peak torque at 4400 rpm. So I find myself driving around at lower speeds with the unit not locked up, it's sure a lot smoother and the additional 200 or so rpms it adds has not presented a cooling issue for my set-up. That said, I have a large 19-row stacked plate design transmission oil cooler installed.

As of late I seem to have an issue with what seems to be slipping during the 2nd to 3rd gear shift. My car is currently in John's shop having a new exhaust system frabricated and installed so we are going to pull the 200-4R trans out and have it checked. While at the transmission shop I'm having it converted to a non-lock up unit. And he is exchanging the lock-up converter for a similar stall non-lock up type. Since I have already paid once for a converter I'll give it a try from him, if I don't like it I will give Cliff a call and make arrangements to get a converter from Continental. Cliff supplied a Continental non-lock up converter for a local friends 200-4R transmission and he is very pleased. And I have had previous experiance with a Contential unit before on my TH400 transmission with fantastic results, like so many others.

My new BTO 200-4R would slip on the 2-3 shift under WOT acceleration. I fixed it by adding a pint of fluid. I figure the fluid level was a bit low, letting the pump suck air under hard acceleration.

Actually, mine slipped on the 2-3 shift from being low too initially. I bought another dip stick & tube, closely measured it all out, and it went away.

Well, I'm going to look hard at the non-lockup converters, and will probably go to one in the near future. I'm needing to get this thing on the road for a number of reasons, mainly to make space for other projects. I'll drive it a bit more, and if I get fed up with it, certainly will switch the converter out sooner than later.

Thanks all for the input, appreciate it. Amazing what I've picked up here on the forums!

I have been building 200r4 and 700r4 transmissions since the early 90's,as far as "speculation" as to a non-lock up torque convertor damaging a transmission when towing,the success of a non-lock up convertor depends on alot of variables. I have seen PLENTY of overdrive transmissions with melted geartrain from attemting to run a non-lock up clutch on the street and I have other customers where it has never been a issue. First you have to understand the oil flow,oil goes thru the torque convertor (yes-the transgo valve is a must along with removing the input check valve) and this is where the most heat is generated. It then goes thru the cooler and then flows directly to the return port which flows to the planetary gears/sprags etc. A nice tight convertor that doesn't generate much slip over stock with a giant oil cooler combined with low rear end gears is the ideal set-up. On the oppposite end of the spectrum,a heavy car with tall rear end gears with a stock cooler will almost always end in destruction especially with a high wind load,low cruising speed,towing use,large vehicle frontal area etc. What happens is the vehicle goes down the road at lets say 55-60 mph,with a 3.42 or even lower numerical gear it would cruise at 1500-1800 rpm's in overdrive IN LOCK UP,without lock up the torque convertor will stall closer to its rated stall point,lets say 2200-2500,the oil temp starts to creep up slowly on a long,steady drive until it reaches a point where it no longer provides a good lubrication film/lubrication boundary to the overdrive gears/overdrive sprag and the parts start to overheat and self destruct. I steer my customers away from non-lockup set-ups for these kind of applications-high profile vehicles like trucks,suvs etc, cars that are driven alot for highway cruising with less then a 3.73 gear,convertors that are rated any higher then a typical 2000 stall unless just driven occasionally around town (I think your typical 2400 stall continetal convertor is built from a factory 2000 stall core like the grand nationals,vettes,4.3 vortecs etc use-the stators in them will typically give around 2400-2500 stall behind most v-8's). If you do choose to run this set-up on the street and you have a heavier vehicle not running 4.11-3.73 etc gears,do yourself a favor and install a transmission temp gauge,preferably in the pan,Smitty

Well, the car in question, is my daily driver, stop & go traffic, and I take several 1000+ mile trips a year. Many daily trips and weekend trips see 30-45 min of 70+. It's @3850 lbs, 3.73 rear, aluminum rad with cooler, plus the largest stack plate cooler B&M makes. Would you say this application is 'safe' for a non-lockup? I need at least 2400 stall, due to the cam selected, prefer 2600-2800.

since putting my car back on pump gas ,lower compression ,milder solid roller, 200 4r 3.50 gears nonlockup 3200 stall continental convertor,10.3 compression,it run cool temps ,160-170 engine, 150 transand desent highway mileage,13-15mpg. got the convertor fromcliff,could not be happier.

IMHO the converter clutch is the most important benefit of installing an OD in a performance street car.

If you aren't going to use it, install a TH400 w/ a Gear Venders unit, it makes no sense not to.

Depends on what kind of temps the trans ends up running,you are probably safe,you don't want to see trans temp over 250 degrees,preferably225 or less cruising,Smitty

With the 3200 stall what kind of rpm do you see in overdrive vs 3rd gear? I could see your car benefiting from the lower first/2nd gear but I would expect your convertor to slip at about the same rpm in overdrive that it would run in 3rd gear ( calulating a 26" tire at 60 mph gives you a 2750 cruise in 3rd gear,1850 rpm cruise in overdrive). With the .67 overdrive ratio and 3.55 gears you end up with a final drive ratio the same as a 2.34-1 ,no matter how effiecient your convertor is if it stalls to 3200 and your overdrive gearing puts your rpm's at 1850 cruising at 60 the convertor will just constantly stall somewhere between,I would even expect the convertor to be slipping slightly in 3rd gear. Now,would lock up make it run better,probably not because it would hold your rpm's solid at 1850 cruising which would probably stifle your motor and make your car lug miserably,Smitty

The key to success is to use a good converter with efficient characteristics.

Folks also tend to associate stall speeds with coupling efficiency, thinking that a 3200 stall speed converter will slip excessively at rpm's lower than that for "normal" driving.

This is true if you buy "low end" off the shelf stuff. The Continental 10" units that we use are very, very efficient for normal operation. They act and drive much like stock converters. There is very little slippage at light throttle and light load conditions.

Even on the brakes the 10" unit in my car will start spinning the tires at apprx 1800rpm's. Yet is flashes to near 3500rpms on full throttle starts at the track. We have used and provided scores of non-LU converters for applications where the cruising rpm's in OD was quite low, and have had ZERO complaints or issues related to transmission failure from overheating.

I've come to dislike using a TCC for retrofitting, unless the needed time and funds are spent to make sure that it operates much like factory set-ups.

This requires the solenoid be grounded on a 4th gear pressure switch, and the voltage to the solenoid routed thru a vacuum switch hooked up to ported vacuum. The insures that the TCC can only apply in high gear at part throttle. Any coasting, heavy/full throttle, etc, will lower the vacuum enough to disengage the TCC. This insures that the clutch doesn't get overloaded, and the engine doesn't "lug" at heavy throttle openings/low vehicle speeds in OD.

I've seen a lot of units set up with direct wiring, toggle switches, sometimes using a 4th gear pressure switch, sometimes routed thru a brake pedal switch, etc. The LAST thing one should have to do is look for a switch to operate the TCC, especially in todays driving situations.

The TCC needs to be set-up to lock and unlock under a variety of situations, just like factory units. If not, it can/will lug the engines, or overwork the clutch.

As mentioned earlier, I ran my 67 Impala SS both ways, and came to quickly HATE the TCC. After going to a non-LU converter, we enjoyed over 35,000 miles of trouble free operation from the transmission and converter, and didn't use any cooler other than the one in the factory radiator.

We've set up plenty of these transmissions over the years, and in almost all cases use a TCC if the vehicle came that way from the factory. For all retrofitting, we go non-LU, and help the customer choose the correct rear gearing, tire diamter, etc, in addition to providing a correctly prepared transmission with a good torque converter......Cliff

smittyseng- Have a temp gauge on it, and I'll keep an eye on what it is running at now. That will give me a baseline when/if I go non-lockup.

Cliff R- Due to time constraints, as I mentioned earlier, I left the LU in there. So for now, I'd like to try the vacuum switch setup your talking about, and wonder if you have a source for those? Typical auto parts store stuff? Would imagine this would be wired with a relay in conjunction with the brake switch? Some info on this would be helpful, avoid having to do the research from ground up....

I still haven't talked to my GN buddies, about the LU / non-LU topic, would like to hear their' input. Obviously, they have cars that were designed from day 1 to use a LU, but would still like to hear their' side. I know a number of them, the guys who spend a lot of time at the track, have all gone to TH400s, so not sure what their' memory is going to be like on the 200s

I'm installing a painless wiring kit this week, I'll report back on it's operation. I have several things to do on this car so hopefully it's driving late in the week.

It's a tad pricey @ $150, but it should save some time not seeking out and buying individual components.

It includes a vacuum switch (haven't checked it's # value), brake switch, internal wiring, 4th switch, solenoid and all specific connectors.

I've never bought a Normally Open vacuum swith separately from any of the kits, so have no source of supply for one.

Maybe a Google search will help?.....Cliff

at 70 mph ,275/60-15 nitto drag radials i'm turning2300 rpm on level ground. on highway trips in warm weather trans temp runs 140 to 160. hot lapping at the drag strip temp rises to 200.

Looked at the Painless kit, and wonder why they include new solenoids? Are they different than what's in there now? Reason I ask is that the TCI kit is half the price, and doesn't include them. The TCI kit has a combo vacuum/Brake switch, the Painless has two separate switches. Wonder which would be better?

Cliff R- Which kits do you usually use/recommend?

It's just a new replacement TCC solenoid and harness. It's actually a Fitzall brand solenoid with a full harness rather than 3" pigtails w/ screw connectors.

I wasn't aware TCI used a vacuum switch, good info.

The first pic is the TCI kit, the second the Painless. The TCI kit has a combo vacuum/brake switch, the Painless they're separate. Anyone have any opinions on the TCI combo switch? I know the Painless is more expensive, but the switches being separate seems to me they may be of better quality and last longer?

Haven't installed the Painless kit, but I like the looks of the vacuum switch much better. We had a couple of the TCI switches act up, and had to replace them. They seem to not have much of a range of adjustment.....Cliff

I like everyones input on this subject,I'm glad to hear you have found tq convertors that work well running a non-lock up set up. I will look at the continetal 3200 stall convertors for future performance packages. I have used TCS convertors-"The Convertor Shop" in lake havasu with some success,they custom build very high quality pieces,I have also used Coan,Dacco and a few others. Setting a 200r4 up to work well with a "stand alone"lock up kit is difficult,the early 700's were a breeze because they had internal control that you could use a stiffer lock up control spring in combination with any cheap kit like the tci. I have used the tci kit and also used the factory 82-84 chevy truck vacuum switches with 200r4's and it is very crude and there isn't much adjustability. The problem with 200r4's and 87 and newer 700 r4's is the lock up was computer controlled and there isn't much in the trans that helps the lock up timing,they basically had a switch for 4th gear and sometimes 3rd that grounded the computer letting in know it was in that particular gear,as soon as it shifted to that gear. When you control the lockup with these switches it pretty much goes instantly into lock up as soon as it shifts and a vacuum switch will only delay it momentarily if your into the throttle. Something that came out recently that I used that is actually very cheap and offers a nice adjustment range is the superior vacuum switch but you will need to come up with wiring and a 4th gear pressure switch (not that hard to find though). here is a link to the superior switch for anyone interested
http://www.superior-transmission.com...lvers/k052.htm.
They also have a few other nifty products that combined with the switch can be made to work well,a lock up "delay box" to keep a vehicle from slamming into lock-up then un-locking repeatedly which causes some of the complaints we are discussing
http://www.superior-transmission.com...nics/PR290.htm.
They also offer a std lock up pkg to retrofit 200r4's,I think all 3 kits cost less then a typical kit from summit or jegs
http://www.superior-transmission.com..._high_gear.htm
Any local transtar or dacco transmission parts branch should be able to get these for you,I hope this may help somebody out.
Cliff,you are definately right also,just installing a manual switch is a disaster,the first time someone forgets to turn off lock up they will damage the lock-up clutch under a hard throttle run,Smitty

We've also seen a lot of shops simply direct wire the TCC by grounding it on a normally "open" 4th gear pressure switch. Then you get a shift to 4th and immediately the TCC engages.

The problem with this set-up is that it will not unlock when coasting and any heavy/full throttle driving.

The best set-up I've used in a vacuum switch hooked to a ported source, then to the solenoid, then grounded on a 4th gear pressure switch. One can also route the voltage thru a toggle switch if the operator wants manual control at any point.

With all that said, I'm still not very fond of using a TCC for a well set-up retrofit into an older vehicle. If a good converter is used, the vehicle simply shifts 3 times, and still has some torque multiplication for heavy throttle situations without having to shift back to third gear.

I ran my Impala SS with both set-ups, and I could barely detect any rpm difference cruising on the highway above apprx 50 mph. The tach would move maybe 50-100 rpm or so when climbing a steep grade in OD when additional throttle was applied to maintain speed. I couldn't measure any differences in fuel economy either. I did all this WAY back in the early 1990's. These transmissions weren't all that popular at the time. I bought the first torque converter from Daaco, and blew it to BITS shortly after installing it. I'm pretty sure we bought the custom non-LU unit from Precision Performance. It was a very well built converter, with decent flash stall and very, very well coupled for "normal" driving.

The combination of 3.31 gearing, stout 327 engine, good converter, and the 4L60's 3.06 first gear gave the old Impala a whole new outlook on life. That car was amazingly quick from a stoplight.

A big Pontiac with a 400 or 455 would be even better, and one wouldn't need steep rear gears, 3.23's or even down to 3.08's would be fine......Cliff

Yeah, 4L60 would be nice, though for now I have the 200! And a LU!

smittyseng- Thanks for the links, I will certainly look into that, and gives me an option over the 2 I posted. I like the delay box thing, which from some of my reading seems to be a point of concern (slamming in & out).

Both instructions for the TCI & Painless kits state that if 'slamming' is experienced, to use a GM vacuum delay to a full-time vacuum source (as apposed to the ported), and that part number is GM 14020691. What the heck does that thing look like? Or what's the 'auto parts' application & name? Maybe in combo with all the other devices, I'll get the best possible scenario with a LU?

Cliff R- No chance I'll wire it to 4th as you mentioned, I've experienced the 'poor' drivability as stated. I currently use one of those B&M adjustable lockup controllers, which, with a vacuum switch maybe, would be ok, but the darn thing hasn't worked right from day one. I'm guess it is similar to the delay box from Superior, but just a guess. The B&M unit has a transducer that attaches to the speedo cable, and the box has an adjustment knob for MPH. Anyway, in testing the box, to make sure it WAS the box, I had a switch to lock up directly, so I know exactly what you mean.

smittyseng - You wouldn't happen to have an online source for those Superior parts would you? The DACCO place over here closed down, closest one is 1.5 hours away...

The B&M speed sensor unit is the hands down best unit we have ever used for TCC installations. We have one in the yellow 72 Formula (Avatar pic) for many trouble free years now. The simple control unit mounts under the dash and the driver can select the speed at which the torque convertor locks up.

We leave it at the max setting all the time in case "an opportunity" comes up alongside us. But for cruising on the highway, set the speed (usually @ 50 mph for us) and forget it. Any speed below that setting will automatically unlock the TCC and we wired the whole thing through a later model brake pedal switch.

We originally tried a vacuum switch in the late 80's but found them to be too tempermental. Then went the route with the 4th gear pressure switch. Problem with that was the TCC was always locked when the trans is in OD no matter what.

The B&M Speed Sensor lockup kit is an easy install too if you must have a lockup converter. However I agree with Cliff that a high quality non lockup converter is ultmately the way to go. And our next unit will be just that.

Overkillphil- I'll buy that, worked pretty good for me, when it worked! The speed sensor crapped out within the first 100 miles, had it replaced, and I have to send the control unit back for repair, but, unfortunately, I can't find the receipt! Here's a scenario though that it wouldn't work well without a vacuum switch: Over 50 rolling into the throttle without a downshift. Or am I missing something?

Anyway, after listening to all, I thought about it, and I decided to go with a combination of all the above, the B&M controller, the adjustable vacuum switch, the brake switch (of course), the electronic delay, and a GM vacuum delay unit I listed the part number for. I found the Superior parts on eGay, at the OregonPerformanceTransmission store, and the GM vacuum switch at RockAuto.

I'll set the MPH on the B&M unit to like 50, add about a 3 - 5 second delay (for starters) on the electronic, and start with the vacuum switch around 5 inches of vacuum, which I'll connect to manifold vacuum, with the vacuum delay between. I may start out first without the electronic delay, see how it works.

I figure the vacuum delay and the electronic delay (if used) will prevent the 'cycling', the vacuum switch will unlock on heavier throttle, and since it's a 4th gear pressure switch setup, the B&M will keep it from locking under 50 mph. Sound like it makes sense? Opinions?

Now, if I could do a throttle position sensor or something, and have it unlock on coasting, that would be optimum. Maybe reverse a full throttle switch?

Sounds like you are taking the idea to the next level. You'll have to report back on your findings. Sounds interesting. I always thought those vacuum switches I used would have worked fine had they been adjustable like a Crane distributer advance unit. Maybe they exist now but not when I was playing with them 20 years ago.

Funny you had a problem with that unit. A good friend of mine had the same problem with his after we put a 200-4R in his 81 Bird. His lasted a little while though before he had a problem. He also had a problem with the speedo cable hookup coming apart. But then he put over 350k miles on his Bird too.

I have observed that scenerio of lockup/downshifting but deal with it by not using the lockup feature unless I am on a long steady highway. If I find myself needing to change speeds a bit, I just leave it set to the max setting so it doesn't cycle on/off or otherwise become a pita with the downshifting. Frankly, I don't like to force a downshift with it locked as it tends to be too violent and scares me. The few times it happened I found myself looking in the rear view mirror for tranny parts bouncing down the road!:eek:

Adding a speed switch to the vaccum switch grounded on a normally open 4th gear pressure switch would be the best deal out there, UMHO.

Doing so would NOT allow the TCC to apply until 4th gear, and above a set MPH.

I would unlock when coasting, unlock when you came out of OD, and unlock at heavy/full throttle, just like the factory set-ups do.

I would also route the voltage thru a toggle switch, in case any of the other stuff started giving troubles, then you could still drive it home without any big issues to make repairs.....Cliff

Well, the vacuum switch has an adjustment range of 1-6 inches, and can be wired to open or close when it reaches the threshold. So, if it were to go open when it reaches 6 inches, such as under heavy throttle, that would be desired, though in a coasting situation, wouldn't it be a high vacuum reading? Meaning I wouldn't have both, only one or the other, which is why I was thinking a throttle position or switch for coasting. Or am I overlooking something?

I played around with the TPS idea a while back, but there was some problem using that. Can't remember if it was the TPS relaying the open signal through the computer or adding a relay or something. Probably solved without alot of difficulty but I didn't want to spend any more time on it at the time.

I do notice how our Buick GN's unlock when the throttle is closed. However, I believe even those are also speed referenced, meaning they don't open once a certain speed is reached causing the TCC to remain locked even when one lifts off the throttle. But not 100% on that. FWIW.

If the vacuum switch is connected to ported vaccum on the carb, not manifold vacuum, the vacuum will be drop to zero when the throttle plates close on coasting and unlock the converter.

A well located ported source is required. Using manifold vacuum, the TCC will stay locked up when coasting, locked up at part throttle, and unlock at heavy/full throttle.

Using a ported source, it will only lock-up at part throttle. Any heavy/full throttle will unlock the TCC, it will also unlock when coasting.....Cliff

Got it. Yeah, figured I was missing something there! I was stuck on using manifold/full-time since a number of the controller/wiring docs state if you have cycling to use the delay and go full-time. Ported makes sense, and will do so.

Yep, the ported sources works perfectly. Some folks don't understand how ported vacuum works. Basically, it only applies at light throttle/light load. The only real difference between full manifold vacuum, and ported, is that manifold vacuum will have a signal at idle or anytime the throttle plates are closed. Since the source location for a ported source is just above the leading edge of the primary throttle plates at idle, it is uncovered, or activated with the slightest movement of the throttle, and from there on up represents the same reading as any manifold source which is also below the throttle plates.....confused yet?......Cliff

Nope, totally understand how ported works, but thank you for the refresher course! My problem was brain-lock! No two ways around that! Heh-heh! Hey, but I'm NOT old!!! I was thinking down the road of full-time because I was planning on using the GM vacuum delay.