alright guys i recently swapped in my 305 carb engine. car was a TBI. drove maybe 300 total miles already on the engine. i never hooked up the torque converter lock up switch. tranny has always shifted fine (although it slips a little from 1st to 2nd).

heres whats goin on

out of nowhere one day im on my way home, about 5 miles from home im doing around 60 mph and the car just falls on its face. bogs like hell, i stomp the gas and NOTHING. it doesnt go anywhere. acts like it just died or something. it falls to about 50 mph and i keep pumping the gas pedal and it starts speeding up then falls on its face again. no matter what i do i cant get it to stay going. itll bog and then speed up 5 mph and then bog again and again and agian until i get to the stop sign and it eventually just died. it started right back up with no issues. i get on the gas a little and go through 1st just fine then 2nd just fine then 3rd just fine then the second it shifts to 4th it does it again.. it just acts like its not getting fuel at all.

so i took it for a couple test drives up the street to see if i can figure out whats wrong. i begin to think its a carb issue. so i take the holley 600 off my dads desoto (same carb) and throw it on mine. start goin down the road again and it still does it. at this point im thinkin maybe im suckin air somewhere. but if that were the case it would run like **** all the time. so i chaned the fuel pump on the side of the engine since it was leaking anyway, and it continued to do it. ive rueled out fuel problem. so im thinkin maybe spark? well no all the plugs are fine the wires are fine everything is good. i start thinkin, my uncles old pickup had a torque converter problem. it would start and go down the road a bit and die. maybe this is my problem to? maybe my torque converter is going bad?? i never installed the lock up switch, would this be a result of that??

took it for a couple more runs today. i found out that if i get up to speed quickly (not WOT but more of like 50% throttle) then it will do it as soon as it hits 4th gear, and it will continue to do it until i finally stop and it dies.but if i get up to speed granny style (20% throttle or so) then it NEVER once does it. once i get up to 60 mph i start slowing down and it does just fine. but when i granny style it up to 60 mph then i WOT it falls on its face again!! idk wtf is wrong lol. help guys!!

 

Sounds like it's starving for gas-fuel pump might be
sucking air,check for leaks-also is the electric fuel
pump still in place?,sometimes mechanical fuel pumps
have trouble pulling fuel through an electric pump that
is not running,though TBI usually has a turbine type
electric pump that fuel can be pulled through easy.

 

The 700r4 design has a flaw, where the converter has to lockup in 4th gear, or it will only be able to pump about 50% line pressure. Most 700r4/4e60 failures occur when using 4th gear under load, with the converter unlocked.

Sound like you trashed your 4th gear frictions by not hooking up your lockup.

If it's not a sticky in the 700r4 FAQ, it should be...

 

8t2 z-chev its not a fuel issue, the mechanical pump is unplugged and not working at all, the mechanical pump is brand new. like less than 2 miles are on it. its gettin fuel just fine. ill admit that it FEELS like a fuel issue, but infortunately its not that simple.

85MIKE TPI - I was going to hook up the torque converter lock up switch, it was on my to do list, but if i had known that a torque converter could take a crap after only maybe 150 to 200 miles then i would have done it before it left the garage.. so can a torque converter really trash my tranny that quickly??? tranny is pretty old but still.. 700R4's arnt cheap, is there anyway i can try to rule out a tranny problem? if it is a tranny problem ill pop in a 350turbo and buy a new driveshaft. i actually got one laying around..

but yeah any tests i can do? and how long do you think my tranny will survive like this cause its my only transportation for now. havent been driving it the past couple days caus of this problem, been using girlfriends car, but i def need this thing running.

 

forgot something! if it was a problem with my 4th gear or something, every time i smashed the gas while it was boging, it would have revved the hell out of it wouldnt it? i thought for a minute maybe it was jumping in and out of gear but if it was in between gears the rpms would go crazy or am i wrong?

 

It's not the converter that fails, its the clutches/bands inside the transmission burn up because the fluid pressure isn't there in 4th gear, without the converter locked up.

You hear about it all the time in the 4e60 trucks that tow trailers. If they are in OD and the converter unlocks due to RPM drop, they burn up the transmissions quick.. The 4e65s have a tow/haul button on them that keeps the converter locked up.

When I road-raced with my 700r4, I programmed the ECM to force a lockup at 90mph, and I knew to stay in 3rd until over 90, then it was safe to shift to 4th. I burned up two 700r4s before I talked with the trans rebuilder about what I was doing.

 

If it was burned out the rpm's would rev, it sounds more like the foward sprag is locked tight and won't overrun in fourth.

 

Quick question here.


How exactly do you 'lock up' a 700r4? I run one in my 85' K10 Pickup, and I have gone through a few 700r4s because I smoked the 3/4 clutches. I run oversized tires and I thought that along with my driving habits were the cause. Maybe its cuz my converter isnt locked in 4th gear?

Sorry for thread jacking. Its not really thirdgen related since the tranny is in a pickup so I didnt want to make a separate thread.