1973 Corvette, L-48, need EGR TVS switch

[Robert C.]

Anyone run across a suitable AM part number ?

Seems the vendors sell them for 1974-1981 - '73 must be different.

I tried my local part stores too - so far, no luck.

Thanks in advance for any help,

Bob

[Joe L.]

Re: 1973 Corvette, L-48, need EGR TVS switch

Anyone run across a suitable AM part number ?

Seems the vendors sell them for 1974-1981 - '73 must be different.

I tried my local part stores too - so far, no luck.

Thanks in advance for any help,

Bob

Bob--------


I'm not 100% sure but I don't think that 1973 used the EGR switch. If it did, it was not mounted in the thermostat housing as was 74+.

[Robert C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

Hmmmm.......this one is a barn find and appears un-touched. This has the EGR TVS on the thermostat housing.

Water housing has 2 ports, one is plugged.

This is an original California Emision (CE) car - has the Cali emission sticker, engine is code CLH. Casting number for the block, intake match, as does the number/VIN.

So - I'm thinking this is unique to CE cars.


Bob

[Ralph S.]

Re: 1973 Corvette, L-48, need EGR TVS switch

I am the original owner of a 1973 L-48 and the hose from the EGR goes to the carb. not the thermostat housing. I looked in the 1973 shop manual and it says nothing about CA engines being different.

[Joe L.]

Re: 1973 Corvette, L-48, need EGR TVS switch

Hmmmm.......this one is a barn find and appears un-touched. This has the EGR TVS on the thermostat housing.

Water housing has 2 ports, one is plugged.

This is an original California Emision (CE) car - has the Cali emission sticker, engine is code CLH. Casting number for the block, intake match, as does the number/VIN.

So - I'm thinking this is unique to CE cars.


Bob

Bob------



I have no information that 1973 California Emissions cars used an EGR switch.

Also, that 2 fitting thermostat housing didn't even exist in 1973 so it could not be original to the car. What is the part number embossed on the thermostat housing?

[Robert C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

Ralph - realized we have an L82. VIN T, motor code is CLH.

Car has "L48" emblems on the hood that someone added in a weird spot.

Interesting about the shop manual and CA emissions. I don't have the '73 AIM.....which may help.

Thanks for your input.

[Robert C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

I'll check and update everyone Monday night.

[Rich C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

I have the '73 edition of parts and illustration catalog (as well as '74 edition). No listing for ANY '73 application. No thermostat housing depictions in A.I.M. showing the temp/vacuum switch in EGR circuit as the '74's have either. Maybe an addition by a former owner to improve cold engine running?

1973 LS-4 454 coupe owned 24 years
1996 LT-4 CE coupe
Victory Hop Devil Ale- currently on tap!

[Edward J.]

Re: 1973 Corvette, L-48, need EGR TVS switch

Rich, I think you have the right idea, The EGR appears around 73, and they likely ran into driveabllity problems while the engine was cold with this valve working, GM had many driveabilty issues over the 70's and 80's with this valve. Working at a Chevrolet dealership in those years GM had a lot of calibration issues with carburation and emission components.

Bob it may require a little research on you engine( date on block, late? correct intake?), thermostat housing (part no.). Ralphs 73 is a untouched car, basicly I have seen it a few times. L82/L48?? I am thinking the same configuration, maybe a different calibration for the EGR valve.

[Robert C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

I'm agreeing with you guys - this was probably modified.

I don't have a current DocRebuild catalog handy - but an older one doesn't show a break out for L82's for '73's.

I'll get the housing off and see what it says. It's too hard to see if we have a p/n on this.

And - maybe Chevy had a TSB that suggested this as a fix at some point, or a mechanic somewhere decided to try this
configuration.

Thanks everyone for your help !!

Bob

Rich, I think you have the right idea, The EGR appears around 73, and they likely ran into driveabllity problems while the engine was cold with this valve working, GM had many driveabilty issues over the 70's and 80's with this valve. Working at a Chevrolet dealership in those years GM had a lot of calibration issues with carburation and emission components.

Bob it may require a little research on you engine( date on block, late? correct intake?), thermostat housing (part no.). Ralphs 73 is a untouched car, basicly I have seen it a few times. L82/L48?? I am thinking the same configuration, maybe a different calibration for the EGR valve.

[Robert C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

I'll get the housing off tonight - all I see is a "60" under the rust near the hose.

[Rich C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

The part # I believe is stamped along the mounting flange.


1973 LS-4 454 coupe owned 24 years
1996 LT-4 CE coupe
Victory Hop Devil Ale- currently on tap!

[Robert C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

Thanks Rich - yeah, I was able to see something, just couldn't get a camera in there to take a shot.

I'm interested in seeing what we have........

Bob

The part # I believe is stamped along the mounting flange.


1973 LS-4 454 coupe owned 24 years
1996 LT-4 CE coupe
Victory Hop Devil Ale- currently on tap!

[Robert C.]

Re: 1973 Corvette, L-48, need EGR TVS switch

part number shows 6132 - between the 2 ports.

[Joe L.]

Re: 1973 Corvette, L-48, need EGR TVS switch

part number shows 6132 - between the 2 ports.

Robert------


That's not a GM part number or a derivative of any GM part number for a thermostat housing that I'm aware of. GM outlets usually have a full 6, 7, or 8 digit part number embossed on them. Outlets with "short numbers" are often aftermarket.