1970 Carburetor question

[Patrick H.]

Re: 1970 Carburetor question

Gentlemen,
If you would please, tell me the reason for a service replacement?
Did Rochester have a problem with that particular model of carburetor
and or in general and the "service replacement" was used to either fix and
or replace the problem?

If Yes, were measures taken to improve this particular model - 07040507?

Patrick, you stated 07040507, I didn't remember seeing the first zero stamped
on the carburetor. Are you adding the zero because there is a Julian date
beneath the serial number, designating it as a service part?

Thank you.

Joe

Service replacement = part bought over-the-counter from GM with a number or configuration different than original. There are other Q-jets of other model numbers with a "0" prefix showing they were OTC units. It's not just this model.

Patrick

[Jeffrey S.]

Re: 1970 Carburetor question

Jeff:
From the picture you posted, it appears that the hose from the AIR diverter valve and the hose to the vacuum advance have been switched. The hose to the vacuum advance is ported (only supplies vacuum off idle) where the diverter valve opening is not-it supplies vacuum at idle or off idle.
Jeff

[Joe L.]

Re: 1970 Carburetor question

I answered and posted these pics on another forum. Should have asked this a long time ago.Maybe someone can set the record straight.

I researched the advance tube on the 207 for a couple of years to duplicate, and in the process noticed some differences in the 207 and 507. Someone here was kind enough to send me that photo during my research, and did not get the number. Only that it was from a very correct L-46.
In the pics I believe the first photo is of a 507 and the second a 207. You'll notice the capped off tube extending out the side on the top photo. Not there on the lower photo.(my original 207)

My question is did the 507 being a L-46 california version, have a smog system? It appears from what I'm told that the 69 207 did, and that capped off tube should have a hose to the smog pump.

Dennis-----

If by "smog system" you are referring to the air injection reactor system, then NO 1970 Corvette with Rochester Q-Jet carb was ever equipped with that system. So, cars originally equipped with the California-only 7040507 carb definitely were NOT also equipped with AIR.

The only 1970 Corvettes equipped with AIR were LT-1 engine cars, whether for California or not.

[Joe W.]

Re: 1970 Carburetor question

Greetings!

I went to the barn but forgot my camera.
I verified that Patrick's carburetor does in fact have the zero
at the beginning of the number - 07040507, with a date code of 0706.

Looking at the front of the carburetor,
there was (1) large hose and (1) small hose routed.
The larger one, went to the left valve cover and the one small hose,
at the far left (looking straight at carb from front of car), going to the vacuum
advance on the distributor. Another smaller nipple on the far right of carb did not have a hose,
rather a black rubber cap. Would this be a smog control?

I also saw a black container inside my front lower left fender,
with a yellow striped rubber hose coming off of and going to what
I believe to be a vacuum check valve mounted to the right firewall.

There are (3) hoses going to this valve, in a street light configuration -
Red stripe at the top, yellow in the center and green at the bottom. What is
the black container and does it have a function?

Thanks.

Joe

[Dennis D.]

Re: 1970 Carburetor question

Dennis-----

If by "smog system" you are referring to the air injection reactor system, then NO 1970 Corvette with Rochester Q-Jet carb was ever equipped with that system. So, cars originally equipped with the California-only 7040507 carb definitely were NOT also equipped with AIR.

The only 1970 Corvettes equipped with AIR were LT-1 engine cars, whether for California or not.

So....... Would you say the carb in the upper pic I posted is NOT a 507 carb? Or, is that tube provided for another vacuum source on the 507?

[Joe W.]

Re: 1970 Carburetor question

The plot thickens.
When I bought the car, it didn't run and was all wrong under the hood.
I removed the Holley carburetor, aluminum intake manifold and headers.

At Carlisle, I found the correct intake manifold and distributor.
Shortly thereafter, I found the correct exhaust manifolds. At the present
time,the car does not have the spark control solenoid and I didn't look to see
if the skinny nipple coming off the top/rear of carburetor had a hose on it or
not. I think it may have a rubber cap on it as well.

[Joe L.]

Re: 1970 Carburetor question

So....... Would you say the carb in the upper pic I posted is NOT a 507 carb? Or, is that tube provided for another vacuum source on the 507?

Dennis-----


I don't really know. I don't think that original 507 carbs had an unused vacuum fitting that was capped off with a rubber plug. I don't recall seeing it and it's very "un-factory-like". However, I don't rule it out. As far as emissions goes, things were very "unstable" in the 70's. It may be that the '507' carb was designed with the possibility that AIR would be used in conjunction with it. I really doubt that since the '507' was otherwise designed as a CCS emissions systems carb and the "twain does not meet".

I do not see the side vacuum outlet as having any other function than AIR, at least on these early 70's carbs.

[Dennis D.]

Re: 1970 Carburetor question

I've been told that the 69 L-46 carb (7029207) HAS the smog,(AIR), and that is the tube that connects to the AIR pump. Still puzzled about my 507 photo. Going to inquire more about that carb.

Just to add to the confusion, check out this 70 '507 description and date???

http://cgi.ebay.com/ebaymotors/1970-Chevrolet-Corvette-Carburetor-350-350-HP_W0QQcmdZViewItemQQ_trkparmsZ66Q3a2Q7c65Q3a10Q7c39Q3a1Q7c240Q3a1318QQ_trksidZp3286Q2ec0Q2em14QQhashZitem200324537849QQitemZ200324537849QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

[Patrick H.]

Re: 1970 Carburetor question

The plot thickens.
When I bought the car, it didn't run and was all wrong under the hood.
I removed the Holley carburetor, aluminum intake manifold and headers.

At Carlisle, I found the correct intake manifold and distributor.
Shortly thereafter, I found the correct exhaust manifolds. At the present
time,the car does not have the spark control solenoid and I didn't look to see
if the skinny nipple coming off the top/rear of carburetor had a hose on it or
not. I think it may have a rubber cap on it as well.

No guarantee that I've left the carb as I found it, nor that when it went on the car in 1993 (?) before I bought it that it hadn't been altered. I've been in it a couple of times for variouis reasons.

[Terry M.]

Re: 1970 Carburetor question

Back when a certain judging organization had a gathering of 25-year old Corvettes There were a whole bunch of 1970s gathered. I think there was between 100 and 200 there in 1995. There were many Rochester carburetors on those 1970s with that extra pipe plugged with the same rubber cap. I am convinced that is how the 1970 Richesters came.

I'm sure there is a story behind it, but I don't know what it is. Maybe we will again get a chance to see that many 1970 Corvettes in one place when they are 50 years old.

[Dennis D.]

Re: 1970 Carburetor question

Maybe we will again get a chance to see that many 1970 Corvettes in one place when they are 50 years old.

Along with their same owners

[Terry M.]

Re: 1970 Carburetor question

I'll se you there Dennis, if they do it. It might be a little premature to make room reservaations just yet, though.

It ought to be time to start judging the 2008 by then too.

[Joe L.]

Re: 1970 Carburetor question

I've been told that the 69 L-46 carb (7029207) HAS the smog,(AIR), and that is the tube that connects to the AIR pump. Still puzzled about my 507 photo. Going to inquire more about that carb.

Just to add to the confusion, check out this 70 '507 description and date???
http://cgi.ebay.com/ebaymotors/1970-...Q5fAccessories

Dennis-----

1969 L-46 WAS equipped with AIR; 1970 L-46 WAS NOT.

[Joe W.]

Re: 1970 Carburetor question

Hello,
Did anyone see my second to last post? If at all possible,
I still would like to get some of those questions answered.

Here they are again.

I saw a black container inside my front lower left fender,
with a yellow striped rubber hose coming off of and going to what
I believe to be a vacuum check valve mounted to the right firewall.

There are (3) hoses going to this valve, in a street light configuration -
Red stripe at the top, yellow in the center and green at the bottom.
What is the black container and does it have a function?

[Joe L.]

Re: 1970 Carburetor question

Hello,
Did anyone see my second to last post? If at all possible,
I still would like to get some of those questions answered.

Here they are again.

I saw a black container inside my front lower left fender,
with a yellow striped rubber hose coming off of and going to what
I believe to be a vacuum check valve mounted to the right firewall.

There are (3) hoses going to this valve, in a street light configuration -
Red stripe at the top, yellow in the center and green at the bottom.
What is the black container and does it have a function?

Joe-----


If you're referring to the "container" which is more-or-less under the fender area next to the master cylinder, that is the vacuum tank which serves to store vacuum to operate headlamps and wiper doors after engine shutdown.