My 412 is lurching

Longbeach412 · Post by **Longbeach412** » Wed Jan 26, 2005 4:37 pm

Hey all, like its not bad enough dealing with a 412, I am also new to the auto tranny deal

So the deal is the car feels like a stalion on the start line, can barely keep it under breaking. It also drags pretty bad from the start and the trany makes pounding noise before it finally coughs into 2nd. Motor runs pretty good with a hint of a miss. So, am thinking check the vaccuum line from the motor to tranny for starters, if there is one on a 74, where is it folks?

raygreenwood · Post by **raygreenwood** » Wed Jan 26, 2005 4:51 pm

It makes a pounding noise? and it "drags"....what do you mean by drag? Is it sluggish off the line? If its straining at the "leash"...what is your idle speed when sitting at a light with your foot on the brake? If the idle is too high, this can happen. Also, check the position of the throttle limiter. It is that gold vacuum pancake right by the TB. It should be out of contact with the throttle arm when just idleing either with in gear or not. That is a deceleration device.
The cauum line T's in right next to where that vacuum chamber is on the manifold...and goes to the right hand side of the transmission to a modulator valve on the edge of the pan parting line.
Also, if you get surging or pounding, you may need a band adjustemnt. they may be slipping. Also...check that the torque converter bolts are tight...and put some thin paint on the heads of the bolts so you can tell if they have been striking the bell housing. Ray

Longbeach412 · Post by **Longbeach412** » Wed Jan 26, 2005 5:05 pm

By Drag I mean, ummm.....it seems to be cycling in & out of 2nd before it finally sticks, and while cycling there some muffled pounding thuds going on. I'd say my free idel is around 1200 and engaged idle 800ish. Thanks ray, will check your recommendations when the rain stops. Till then I'll pester the forum with some more questions

Longbeach412 · Post by **Longbeach412** » Tue Feb 01, 2005 8:44 pm

I got to spend sometime on it today and I noticed that the motor (L-Jet) has a miss at idle, so I started feeling around for any leaky vacuum but couldn't find any obvious ones. And the decel device is ok. There is however a certain hiss coming from the motor, feels like left of the air distributor, but I've been told that L-Jet has a natural hiss to it! so, what are the probable causes of a miss in your collective minds?.....And the tranny still makes a couple of whacks at take off, Now as to adjusting the tranny belts, if need be, how does one do that? Although I like to get the motor miss ironed out first before messing with the tranny. Tomorrow I'll be changing the points since I felt a bump on the contact surface and will see.........Oh, and one more thing, Ray, when you say check the torque conv. bolts, where are they? I only saw a bunch of 8mm nuts on the case, but nothing on the TC itself!

raygreenwood · Post by **raygreenwood** » Wed Feb 02, 2005 12:34 pm

There is a hole in the left side bell housing up top. Ut should have a black plug in it. When you pull that out...there is access to the bolts (3 of them) as you turn the engine around by hand. You will need a lon extension a 13mm socket and a ratchet. The extension will pass under the left side runners. Ray

Longbeach412 · Post by **Longbeach412** » Wed Feb 02, 2005 12:39 pm

I thank you!