Hey guys. I just purchased a 66 coupe last weekend and am in the process of deciding on what to do to it first. Well last night during a quick spin I noticed that the 4 barrel carb is not opening the two back butterflies. Can someone point me in the right direction on how to fix this? The linkage and everything looks good, and I can open them manualy, but it will not do it while running (on it's own).

Thanks!

 

What type of carb is it? Does it have mechanical or vacuum secondaries?

 

as tx65coupe suggests, if they are vacuum secondaries then you don't want them to open when you rev the engine out of gear. only if there's actual engine load.
if unsure tape a little string to the secondary linkage, floor it down the road. you will see then if they opened at some stage

 

I think it's the stock carb. I have not found any type of markings on it to tell what brand it is. It does have vacuum secondaries.
Thanks for the tip. I will take it for a spin this afternoon and try the string trick!

 

ya. vacuum secondary need actual engine load to open. if you can open it by just reving in park, _then_ there's somethign wrong. make sure you're not blocking anything. just attach something ever so slight that will fall off when opening.
somethign that can't block your carb or linkage

 

Post a pic, these guys will know right away what carb you have.

 

If there are any markings saying "4200" on it, I'll trade you...

 

I'll try to get a pic of it and post it on here.
Is the 4200 the stock carb that came on the 289 Hi Po?

 

i never heard of a 4200 ?! looking for an autolite 4100 maybe? The A-Codes came with a 480cfm (1.08) autolite 4100 and the K-code with a 600-ish cfm (1.12) autolite 4100 I believe