1968 427 quadrajet choke linkage

[John B.]

I bought a 7028209 quadrajet for my 68 several years ago only to find out that it had the small block choke linkage on it. Recently I came across what I believe is the correct linkage and am trying to figure out how it connects to the manifold coil. I purchased the link rod, coil, and cover years ago from one of the suppliers that was supposedly correct for the 68 big block. As you can see from the pictures the coil and linkage to the choke arm on the carb connect well and if I apply heat to the coil, the choke works as it is supposed to. The problem is that the cover has the cutout for the link rod to exit on the inboard side. When I try to position the link rod on the inside so that it would exit through the cover, it fits poorly and binds. I am thinking that perhaps there was a different cover for the big blocks or that the coil and link that I bought are wrong, even though it seems like they will work. Does anyone with a 68 427 have some good pictures of choke linkage that might help me figure out how this is to go together?

Regards,

John

DSCN7662.jpgDSCN7663.jpg

[Edward B.]

Re: 1968 427 quadrajet choke linkage

John, I don't think you have the correct choke assembly on the carb. 68 and 69 are basically the same, and as you can see from this picture of mine (1969 L36 4 speed), your's is completely different. HERE'S ONE on ebay too, and it's nothing like yours.

Ed

[Dale C.]

Re: 1968 427 quadrajet choke linkage

IMG_0871.jpgJohn, Here is a picture of my 68 390hp. Different side from Edwards. Dale

[Edward B.]

Re: 1968 427 quadrajet choke linkage

Yes, Dale's choke rod is on the outside and mine's on the inside, but the attaching hole in the chole assembly on both is "rear" of the pivot, unlike yours which is "forward" of the pivot. That's why I don't think you have the correct assembly on the carb.

[John B.]

Re: 1968 427 quadrajet choke linkage

Thanks for the pictures and help. When I bought the carb it had a choke linkage on it just like in Dales picture and also like the picture of the 7028209 that is on EBay. I included a picture of my carb before I changed the choke linkage. I am certainly no quadrajet expert, but several quadrajet carb restorers have told me that the choke linkage that was on my carb was for a small block. They also told me that the choke linkage for a 68 big block quadrajet was one year, corvette only, and difficult to find. From talking with several restorers, apparently many of the 7028209 carbs have a small block linkage because when they were turned in as cores for rebuilding many years ago, the rebuilders just put the small block linkage on them since it was used in more applications. The service manual shows a different linkage for the small block and big block and shows the big block forward although they are really fuzzy scans. The coil for the small block pulls down when heated and the big block pushes up (or maybe it is the other way around). I have both coils and have verified that they work differently. There is a tech bulletin in the 68 AIM that discusses a change to design of the choke rod and has some drawings that show the rod exiting from the choke coil to the outside and forward. If I had a cover like Dales with the opening to the outside, my problem with getting it to work would be solved. However I've not been able to find one like that anywhere. Which choke linkage configuration is correct remains unclear to me. There are some posts in the archives about the unique 68 corvette quadrajet choke linkage, but could not find any good pictures of it.

John





DSCN1368.jpgDSCN1370.jpgDSCN1388.jpg

[Edward B.]

Re: 1968 427 quadrajet choke linkage

Well, I've not heard that, but I'm by no means a Q-Jet expert. You might want to contact Lars about this. He really IS a Q-Jet expert!

Ed

[Dale C.]

Re: 1968 427 quadrajet choke linkage

Looked at the service manual and it looks like the 427 390 is coiled opposite. Also my service manual shows position just opposite of your drawing. I wonder if C60 makes a difference. It does not say though. They also depict the coil linking to rod aft not foreword like on our corvettes, and your drawing. The 390 links to the coils that comes up whereas the generic links with coils coming down, opposite operation. Dale

[Dale C.]

Re: 1968 427 quadrajet choke linkage

IMG_7431.jpgBoy, I've got a lot to learn. Why are the rods in the back here? Looks like I need the 390 linkage and you need the cover.Dale

[Terry M.]

Re: 1968 427 quadrajet choke linkage

Looked at the service manual and it looks like the 427 390 is coiled opposite. Also my service manual shows position just opposite of your drawing. I wonder if C60 makes a difference. It does not say though. They also depict the coil linking to rod aft not foreword like on our corvettes, and your drawing. The 390 links to the coils that comes up whereas the generic links with coils coming down, opposite operation. Dale

It does not say because C60 makes no difference. If it did there would be a different carburetor number for w/ C60, and there is not.

[John B.]

Re: 1968 427 quadrajet choke linkage

Dale, the picture you posted from the service manual was the one I was looking for when I posted, but could not find it at the time. Anyway, from looking at the service manual it appears as though the new coils are not correct either since the rod should be connecting at the rear rather than forward as it does on coils that I have. However, in the new TMJG, in the service bulletin section, the bulletin on the new choke link design shows the coil connection facing forward I believe although the drawing is not completely clear on orientation. Also, the link rod that I have seems to match the picture of the "late" rod shown in Figure 1 of the service bulletin. The coil, link rod, and cover that was shown on my original picture was purchased from Paragon shortly after I bought the carb about 7 years ago. The coil was listed for 1968 and 1969 w/427, the link rod was listed for 1968 427 -390hp and the cover was listed for 1968 - 1970 except for 3x2. The 427 coil and link would not work with the small block choke assembly that was on the carb originally. That is one reason why I did not get the carb restored and put it in service. The carb that was on the car and ran very well was a rebuilt generic quadrajet with unknown internals, but it had the small block choke linkage. When I used a small block coil and link rod, the choke worked OK. Finding the linkage was a long and expensive process and even then the one I found has an extra hole drilled in it so it is not pristine. I suspect finding a cover will be equally difficult. I did contact Lars probably 6 or 7 years ago when I was originally thinking about having the carb redone. I probably discussed the choke linkage issue with him, but don't remember the conversation details. I plan on contacting him again to see if he can shed any light on this.

Wondering if any of these components of the choke system would be listed in the parts manuals? If they were, perhaps it could shed some light on the discussion.

Thanks,

John

[John B.]

Re: 1968 427 quadrajet choke linkage

I emailed Lars with some pictures and he replied that the linkage that I have on my carb is correct for the 68 big block. It takes a different cover than the small block. So, the hunt is on for a cover.

John

[Edward B.]

Re: 1968 427 quadrajet choke linkage

Do you have a picture of what it looks like? I'll dig through my parts and see what I have.

Ed

[John B.]

Re: 1968 427 quadrajet choke linkage

Ed, Thanks for offering to take a look through your stash. I do not have a picture better than the one that Dale posted earlier in this thread. I imagine it looks like the one on your car, except the rectangular hole in the top of the cover would be on the valve cover side of the top of the cover rather than on the carb side.

Regards,
John

[Edward B.]

Re: 1968 427 quadrajet choke linkage

If I'm reading that drawing correctly (see attached), the rod is situated on the inside of the thermostat (and inside of the lever). This would mean that the cutout in the cover would need to be at the inside of the cover (carb side) toward the rear of the engine (see cover-1.jpg).

If the rod is situated on the OUTSIDE of the thermostat (and the outside of the lever), then the hole would have to be on the outside of the cover (valve cover side) toward the rear of the engine (see cover-2.jpg).

By the way, I checked and I don't have one that looks like either. Sorry.

Ed

[Joe L.]

Re: 1968 427 quadrajet choke linkage

If I'm reading that drawing correctly (see attached), the rod is situated on the inside of the thermostat (and inside of the lever). This would mean that the cutout in the cover would need to be at the inside of the cover (carb side) toward the rear of the engine (see cover-1.jpg).

If the rod is situated on the OUTSIDE of the thermostat (and the outside of the lever), then the hole would have to be on the outside of the cover (valve cover side) toward the rear of the engine (see cover-2.jpg).

By the way, I checked and I don't have one that looks like either. Sorry.

Ed

Edward-----


The auto choke coil cover you seek was GM #3921900. It was unique to 1968 Corvettes with big block. It was discontinued in February, 1972 and replaced by GM #3946095 which was the 1969 Corvette big block part. The latter was discontinued without supercession in August, 1980.