Hi, this is my first post so here’s a quick introduction of me and my car. I’m a 38 year old Norwegian guy that bought an 86 Trans Am last summer. First attached pic iswhen I picked up the car, it has a 305 with carb and 700R4 and is in overall pretty good stock shape. I am a mechanical engineer and have had a few American cars, I owned a 68 Charger RT from 2000 to 2007. Being a kid in the eighties I used to think the third gen Firebirds and Camaros were so modern and sporty – and out of my league I just had to have one one day. Now I have one and it’s still modern enough to drive the kids to school before driving to work.

Ok, back to topic. I know this topic has been discussed a million times but there are a few things I haven’t figured out about the Edelbrock geometry corrector bracket, especially regarding the tv cable housing mount position in relation to the throttle arm.

Most of you have probably seen the drawing of the geometry needed. On idle the line between the tv connection point and throttle centre point is 23 degrees to the rear of the vertical line from the throttle centrepoint. On about quarter throttle the connection point is 0 degrees directly below the throttle centre, and wot should be 78 degrees total.

The previous owner had changed to a 1406 Edelbrock and used the hole that has slightly to large radius from the throttle centrepoint to mount the tv, so I bought the corrector bracket and a kit for relocating the wire housings since the tv cable mountpoint on the bracket is on the outside and not the inside of the throttle arm.

I always assumed that the above mentioned drawing was oriented parallel or horisontal to the carb seen from the left side, or put another way, that on quarter throttle the connection point for tv cable should be vertically below the throttle centre point, also meaning the wires housing must be horizontal and at the same height to get 90 degrees compared to the line between tv connection point and throttle centre at quarter throttle. This assumption was strengthened by the fact that the housing relocation brackets being horizontal or parallel to the carb.

When I started mounting this I noticed that it didn’t seem to look like the geometry was correct. The connection point seemed too far to the rear compared to the drawing and the wire was pulled downward from the horizontally mounted wirehousing.

From my second attached picture it seems that the connection point is at 40 degrees to the rear. In my mind I then have to raise the tv housing mount and angle it so that the wire has a 17 degree angle to get the 90 degree thing right at quarter throttle? Or put another way the whole drawing is rotated 17 degrees counterclockwise if you hold it beside the carb when you take into consideration that using a correction bracket the idle position for the tv connection point is at around 40 degrees to the rear.Am I thinking right? If anyone has pics of this and not just the correction bracket I am thankfull. One issue of raising the housing mount is it conflicts with the throttle cable mount that is now on the same side. To sum it up I don’t know exactly the correct location and angle of the tv cable housing. I do not trust that the kit I have is correct, (it is also to weak and flexes). As far as I can tell any stock location of the tv cable housing could not work because all the correction brackets I have seen move the connection points farther rearward than stock carbs brackets.

Another issue is the total rotation of the throttle. As the last pic shows I can only rotate the throttle 65-70 degrees and not the required 78, and this would also effect how far the cable is pulled out at idle and low revs. Does anybody know if wot on the 1406 is 78 degrees from idle, in that case I’m doing something wrong.

Well this was a long first thread but reading all the warnings about the importance of this adjustment I just want to be sure I get it right


Thanks


Claus

 

Attached is the drawing I mention in the previous post. I have tryed to look at all the carb pictures I can find and many of the cables are horisontal even with the correction bracket mounted. That means that if the correction brackets have the connection point around 40 degrees behind the throttle centerline you have about half throttle when the cable is 90 degrees to the line between the connection point and throttle centerpoint. According to the drawing it should be at quarter throttle so I'm confused. I dont know where this drawing comes from, does anybody here know?

 

Welcome to TGO!

Go to

www.tvmadeez.com

Click on

Edelbrock1406 / Carter AFB

See if there is something missing & compare the pics to what your set up is.

 

Also might want to check the Edelbrock site

 

Thanks, yes I've checked out that site and it seems they have done some serious engineering into the design of their products. They also seem to have raised the position of the cable housing mount and put it at an angle to get the geometry correct. Still It's hard to see exactly the geometry from the pictures.

I think I'll make my own housing brackets since I have already bought the correction bracket, and already have the stud type tv connection. I would buy the tvmadeez package if I had know about it from the start, but then I would need a ball type tv cable as well. tvmedeez also has radius adjustment on their brackets that would require connecting a pressure guage to test if everything is adjusted correctly I think.

I'm still concerned about not bein able to rotate the throttle a full 78 degrees though as this would effect the pulling of the cable.

Claus

 

Hi again,

Been doing more research and measuring.

OK, it’s clear that the geometry is critical and one MUST, if using an Edelbrock 1406 use the geometry corrector, so I have bought one. ( At first I actually thought all I needed to buy was the corrector and I could use the original cable housing mounts, since it’s called a corrector I assumed it moved the connection stud to the original position , this is not the case)

But nowhere when you buy the corrector does it say what cable housing brackets must be used with it to ensure correct geometry.

As can be seen from the first attached pic the actual original setup corresponds with the drawing I posted earlier, idle is about 23 degrees behind the vertical throttle centerline and the cable parallel with the carb and so on.

The second pic shows the approximate position of the connecting stud on the correction bracket (white circle), compared to original (see my above post about the corrector stud being 40 degrees behind centerline). The thin short black line would be the corrector bracket stud position on quarter throttle and the long black line 90 degrees on this would be the wire leading to the thick black line which is the approximate required new position of the cable housing mount.

I have already bought one housing bracket that was rubbish, and the reason I started investigating this is that ordering parts to Norway is expensive and time consuming so it has to be right.

Doing a lot of searching, also on this site I see there are a few housing brackets to choose from, many that are adjustable. Since they are adjustable I decided to make my own bracket since the adjustments will have to be done by the guy mounting it anyway, me.

The rubbish bracket I bought was mounted on the rear left nut on the carb at almost exactly the same height as indicated with the thick black line on my second attached pic, so maybe that part was not so rubbish, but it is still too weak and flexed. I also see that tvmadeez position the wire housing in that position, at the same height as the bottom face of the carb, so I’m pretty sure I have got this part right.

The third picis the bracket half finished, I will be trimming the sharp edges when I have positioned the cruise control cable. On the pic I am holding the throttle at quarter throttle to see if I have 90 degrees between the cable and line from stud to throttle centre

I still have one thing I don’t understand though. I am not able to rotate the Edelbrock throttle the full 78 degrees like the original carb from idle to wot. It also seems as if the corrector bracket tv connection stud is positioned closer tothe throttle centrepoint than recommended (hard to measure exactly).This means the cable will never be pulled in the same way as on the original carb! Does anyone have any thoughts on this?

Now I am just willing to accept the fact that I have bought the recommended corrector and if it works for others it should work for me, right?

Claus

 

the adjustment is critical but not that sensitive, i made my own adjustable corrector and been working great for almost 3 years no problems, as long as you can pull the cable 100% at full throttle and its at least 1/4" past rest point at idle you should have no problems

 

Clause
Sorry this event is not going easy for you!
We had to use an aftermarket throttle cable mount and TV cable mount because we had no intake, carburetor, linkages or anything!
We are currently using a Summit stage2 intake with a Holley carb.

If you would like some pics PM me your email.
Our TV cable is at an angle but have no issues as yet.

camarito
Can you post a pic?
Photobucket isn't working for me

 

here you go, not much to it just a little offset

 

camarito--
Interesting idea!!

Clausoe--
Do you have access to equipment to test trans pressure?
My thought is--
Follow the procedure in the tvmadeez site or some other trusted site that has 700R4 info.
Or even PM Dana at Probuilt Automatics, maybe he can be of most assistance.
That way, you would be assured one way or the other if there are any issues or not.

 

I did test it when i made it, I have a 300psi gauge on a long high pressure hose and if I remember right I had 80 psi at idle and at wot it maxed out the gauge

 

camarito
Thanks for the pic & info!

 

Goog idea, thanks for the picture. Have you tried adusting it, I suppose any adjustment mainly affects what happens at the lower throttle range? (Since it always should be set to be completely pulled at full throttle)
Is the pressure guage job a complicated one? I havent done any research on that yet. Connection type? Hydraulic gauge? Will fluid come out while connecting?

T-top havoc: I'll send you my email for pictures

 

That link I gave you tells where to use the pressure gauge.
I believe its towards the end of the write up.

Im ready to send pics when you PM me your email address.

 

there is a port right above the shift linckage if you connect with the engine off it doesnt spill any oil.
My transmission was built to handle high HP so line pressure is higher, i don't know what was done to it but it has neck snapping shifts even at light throttle

 

I have attached pics of what I finally ended up doing to get the geometry issues correct - a custom made cable housing bracket. Took a little time but this thing doesnt flex at least

 

That is some nice machining! Looks very clean

 

Thanks I see now that those were not the latest pics, I have also machined the bracket holding the tv cable as well because I needed to get it further back.