70 LT-1 choke spring

[Wayne B.]

The carb on my LT-1 was wrong so I was able to get a date correct one but in the change out I noticed the choke spring, housing and rod were missing. Repro's of the rod and housing are pretty easy to find but all of the parts suppliers I've looked at have two choices for a choke spring; a BB or a SB for a 300/350 HP cars with no mention of the 370 HP LT-1. Is one of the two I find the same for an LT-1?

(picture from Ecklers catalog)

[Terry M.]

Re: 70 LT-1 choke spring

For C3s I thought there were two different choke springs -- one for Rochester and one for Holley. The springs are wound in opposite directions.

Wait and see what others have to say.

[Joe L.]

Re: 70 LT-1 choke spring

For C3s I thought there were two different choke springs -- one for Rochester and one for Holley. The springs are wound in opposite directions.

Wait and see what others have to say.

Terry and Wayne-----


That's exactly how it is. I guess some folks think that all big blocks use Holley carbs and all small blocks use Q-Jets. That's, of course, not how it is, though.

In any event, for a Q-Jet equipped engine THROUGH 1970, one needs to use the equivalent of GM #3927190 for the choke thermostat.

For a Holley-equipped engine of 1966 THROUGH 1970, one needs to use the equivalent of GM #3887148.

After 1970, things changed because the choke stove was integral with the thermostat. Still, the direction of rotation of the thermostat coil was the same as the above depending upon Holley or Q-Jet application.

[Wayne B.]

Re: 70 LT-1 choke spring

Thanks guys, saved again!

[Terry M.]

Re: 70 LT-1 choke spring

After 1970, things changed because the choke stove was integral with the thermostat.

Thanks Joe for the confirmation of what I thought. Sometimes when I think I know something, it turns out not to be true.

I am not sure I understand the above statement. Can you explain a little more?

[Joe L.]

Re: 70 LT-1 choke spring

Thanks Joe for the confirmation of what I thought. Sometimes when I think I know something, it turns out not to be true.

I am not sure I understand the above statement. Can you explain a little more?

Terry-----

All 1966-70 Corvette (and other Chevrolet) with divorced-stye chokes used a choke stove that was part of the manifold casting. The thermostat coil attached via a screw to the manifold and worked in conjunction with the manifold's integral stove.

For 1971-74 , the choke stove was removed from the manifold and replaced by a simple flat surface to which the choke stove and thermostat assembly attached with a screw. Attached is a photo of the 1971-74 style choke thermostat with integral stove. This, particular, piece is a GM #3989061 which was used for Holley carb applications (i.e. 71-72 LT-1 and 71 LS-6). The 71-74 Q-Jet version is similar except with "reverse" coil.

[Terry M.]

Re: 70 LT-1 choke spring

I got it now.

Up to and including 1970 sits in a depression. 1971 and up sits on top. With the cover on they don't look all that different, but merit a closer examination.

Thanks.

[Joe L.]

Re: 70 LT-1 choke spring

I got it now.

Up to and including 1970 sits in a depression. 1971 and up sits on top. With the cover on they don't look all that different, but merit a closer examination.

Thanks.

Terry-----


Yes, the covers conceal most of the stove and thermostat coil. However, there is actually a difference in the covers, too. The 66-70 use a "squarish" cover; the 71+ use a cover with a "rounded" top.

By the way, one slight correction to my previous information. I think that 1970 LS-5 also uses the 71-74 style choke thermostat with integral choke stove. 1970 small block, base, L-46 and LT-1, uses the 66-69 style.

[Terry M.]

Re: 70 LT-1 choke spring

I learn more and more form you all the time. Thanks.

[Wayne B.]

Re: 70 LT-1 choke spring

So I've been to a couple local Vette supply houses and about every part web site catalog as well as call and they list the thermostat choke spring for every vehicle EXCEPT the 70 LT-1. Should I just ignore that and get the spring for the Holley GM # 3887148 (or equivalent)? One supplier says he didn't think the 70 LT-1 had a choke spring but every pic I have scoured has one so that can't be right. Seems the part would be more linked with the carb type than the car model.

[Terry M.]

Re: 70 LT-1 choke spring

I can absolutely assure you 1970 LT1 HAS a choke spring. I don't have access to part numbers here at work -- beyond the Internet that you have already found confusing and obviously inaccurate.

Joe Lucia will answer your part number question with authority.

[Wayne B.]

Re: 70 LT-1 choke spring

Joe gave that part number so I'm just going to go with it, thanks!

[Joe L.]

Re: 70 LT-1 choke spring

Joe gave that part number so I'm just going to go with it, thanks!

Wayne------



The GM #3887148 is long-since discontinued. However, aftermarket equivalents and "reproduction" pieces are available. These will be essentially the same as the original piece and will be 100% functional. In fact, the only significant difference I have noted is that the frame (bracket section) of the original thermostats was plain steel; the replacements/reproductions are zinc plated steel. Otherwise, they're pretty much the same. The plating can't even be seen when the cover is installed.

[Paul O.]

Re: 70 LT-1 choke spring

Wayne look at Corvette Centrals item 352114 5th down on the page is for 327/350 cube inch holley equipped. That should be correct.
http://www.parts123.com/parts123/yb.dll?parta~partsort
Look like the link does not work so go to Corvette Central home page then C3 discription type in choke then go. Item should be 9th down includes clip, cover, rod and choke