1987 ECU remove & keep 700r4

[xylorex]

I recently purchased a FAST multiport retro kit (30404-KIT) to go with an edelbrock pro-flo 3500 and would like to remove the factory ECU and all those extra wires from my 1987 V10 (gmc v1500).

could i use the existing VSS at the speedometer to control the lockup somehow instead of buying one of those aftermarket lockup controllers?

i'm open to any suggestions. thank you.

[kalbert]

No. You'll need something to monitor engine load, brakes applied, and current gear in addition to speed to control the lockup solenoid.

[xylorex]

thanks kalbert..... i figured it wasn't going to be that easy

[Jrgunn5150]

I had the B&M one on my 87, it worked really well, I could adjust lockup going down the road with the little knob.

[xylorex]

thanks jrgunn. researching the b&m led me to the Painless 60109 (http://www.painlessperformance.com/webcat/60109) amazon is selling it for $158!!

anyways, with the addition of the aftermarket lockup controller -- do you guys know of any other reason i'd have to keep the factory ecu in my truck?

thanks

['68 Newtricks]

Does the FAST system control spark?

I had a BTO lockup kit similar to the one you posted. Worked well. Easy fit. Locks instantly in 4th, so you kinda lose any slipping in 4th. It's ok though, by that time you're probably on the freeway already.

[kalbert]

That painless kit looks like about the simplest yet effective way to control the lockup. I like it. With that and the FAST ecm you won't need the factory one at all.

['68 Newtricks]

You can find them cheaper BTW. $200 is a lot. Check out MonsterTransmissions and TCI. Mine was from BowTieOverdrives but I think they are out of business now

EDIT: $110
http://www.bowtieoverdrives.com/cata...php?ITEMID=332

[kalbert]

That kit hasn't got the vacuum switch to prevent lockup/unlock when the engine is under more load. It will shift into 4th and lockup immediately, and not unlock until it downshifts 3rd or you apply brake. The painless kit includes the vacuum switch so when engine load increases slightly it will unlock for you.

['68 Newtricks]

Does that vacuum switch go straight to manifold?

Hmmm, I only have experience with the BTO kit. I'm not completely sold on the vacuum switch. These transess'es tend to be overhappy with down shifting already, unless you've got good HP/TQ for them. I'm happy with it staying locked, less drama and less heat build up. But then again, my 400sb helps.

[xylorex]

new tricks - the painless instructions say:

" A VACUUM HOSE FROM THE SWITCH TO A PORTED MANIFOLD VACUUM SOURCE THAT ONLY HAS VACCUM WHEN THE THROTTLE IS OPENED."

then there is a note at the bottom of the page:

"IF YOU ENCOUNTER A CONSTANT LOCK-UNLOCK SITUATION IN CITY TRAFFIC A VACUUM VALVE (STANDARD IGNITION #DSV31 ) MAY BE INSTALLED IN THE VACUUM SWITCH HOSE TO CORRECT THE PROBLEM"

http://www.painlessperformance.com/Manuals/60109.pdf

[kalbert]

That sounds about right. You really don't want it locked when you're acellerating or coasting, only when you're cruising steady when there is light engine load.

[xylorex]

forgive my ignorance, where would i find that vacuum source (only when throttle is opened)? i kinda thought that all the vacuum ports had vacuum constantly.

[kalbert]

Manifold vacuum sources have manifold pressure available all the time. A ported vacuum source has atmospheric pressure when the throttle valve is closed, but when it comes open off the idle position will have manifold pressure available. There is a tiny hole just above the throttle blades, when they move slightly open that hole becomes behind the blades instead of ahead of them. Manifold pressure is very low (vacuum) at idle and low engine loads and becomes higher (closer to atmospheric pressure) the more load is put on the engine.

You don't really want the converter locked when coasting (with the throttle blades closed) or when accelerating (high load). Using a ported source will allow the contacts in the switch to open when throttle blades are closed and there is no vacuum on the ported tap or when there is high load and not enough vacuum on the ported tap, de-energizing the converter clutch solenoid.

Most carburetors have a ported vacuum source, make sure whatever throttle body you're using for the EFI also has one and you'll be all set.

[Jrgunn5150]

Man they've gone way up in price, I think I paid half that back in the day,

I wouldn't buy anything in the world from Monster Transmissions. There's no further need to keep the factory ECU with any kit you go with.

[xylorex]

kalbert -- again, thank you very much for the info.

[kalbert]

My pleasure... I hope it helps get your project done and working the best it can!

[GRADYS Performance]

The TCI Part number 376600 Is the best priced kit with a vacuum switch. It works very well. Contact me if you have any questions.

[gmachinz]

I've used the TCI setup before too and it works well also. The TCI kit Unused had a hall effect adapter that threaded onto the speedo gear @ the trans. It was calibrated to not allow lockup unless you were @ 45 mph or higher-combined with their vacuum switch manifold vacuum had to reach a minimum of 15 psi and hold it for at least 20 seconds before OD would occur. So basically those two situations have to occur to allow 4th gear to lock up. Pretty simple to install kit too I must say.

[xylorex]

So.... I finally got my engine put together. I am just now realizing that the throttle body does't have a "ported vacuum" source.

do you guys know if it would be acceptable to install a barbed fitting into the base of the air cleaner to achieve this? Or should I go another direction?

Thanks.

['68 Newtricks]

I'd give you my opinion but it's been overruled lol. I'll just take my well beat on, 3k offroad miles plus 4k highway mile BTO kit equipped 700r4 and roll home on my 38s hahaha

You could try the barb, might work since it's above the butterflies. But I doubt it will see 15 psi. Kinda has to be in the venturi or under the butterflies.