Ticking
Le Mans Master
Joined: May 2007
Posts: 5,028
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From: North tonawanda NY
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
and you just remove the riser and put the spacer in its place?
If I decide to gut the flapper how is that done and will I need a gasket?
Race Director
Joined: Mar 2017
Posts: 11,949
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From: Virginia
A picture will confirm the presence, or absence, of a heat riser. It probably looks like this, and is heat-activated in 1973 (no vacuum, no TVS). Feel free to edit your first post when you add photos, so anyone who starts reading the thread can skip right to the end with the correct answer (which may well be a sticking lifter).
https://www.zip-corvette.com/57-74-2in-heat-riser.html
And as Jebby stated, the heat riser has no business being on your car at all.
Are we up to 1000 words of speculation yet?
https://www.zip-corvette.com/57-74-2in-heat-riser.html
And as Jebby stated, the heat riser has no business being on your car at all.
Are we up to 1000 words of speculation yet?
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Some cut them out then weld the pivot arm to the spacer so it looks factory....
A heat riser can tick and then when hot go away.....it was classic in the 70's and 80's....about one in four did it....
Jebby
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Yes, just swap the Heat Riser out for the spacer......call Corvette Central.....they will point you in the right direction.
Some cut them out then weld the pivot arm to the spacer so it looks factory....
A heat riser can tick and then when hot go away.....it was classic in the 70's and 80's....about one in four did it....
Jebby
Some cut them out then weld the pivot arm to the spacer so it looks factory....
A heat riser can tick and then when hot go away.....it was classic in the 70's and 80's....about one in four did it....
Jebby
Last edited by 7T3stinger; Mar 15, 2024 at 02:43 PM.
Le Mans Master
Joined: May 2007
Posts: 5,028
Likes: 1,120
From: North tonawanda NY
Thanks for your help. As before. I'm no mechanic. Know a little not a lot. So why are some asking for a photo of the intake with the air cleaner off? Is the riser somehow connected to that? If so I can pretty much guarantee there is nothing coming up from that riser to my aluminum intake. But I will post pic later for them.
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Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Thanks for your help. As before. I'm no mechanic. Know a little not a lot. So why are some asking for a photo of the intake with the air cleaner off? Is the riser somehow connected to that? If so I can pretty much guarantee there is nothing coming up from that riser to my aluminum intake. But I will post pic later for them.
Jebby
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Because there are Nixon era Vacuum switches on there and hoses that go to the intake......and just to see if anything else looks out of place, you would be amazed at the split second knowledge a lot of our contributors have on these engines and engine compartments......I can close my eyes and see a C3 engine compartment my head......working on C3's with my Pops are some of my earliest and best memories.......just experience
Jebby
Jebby
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Because there are Nixon era Vacuum switches on there and hoses that go to the intake......and just to see if anything else looks out of place, you would be amazed at the split second knowledge a lot of our contributors have on these engines and engine compartments......I can close my eyes and see a C3 engine compartment my head......working on C3's with my Pops are some of my earliest and best memories.......just experience
Jebby
Jebby
Drifting
Joined: Jun 2015
Posts: 1,345
Likes: 753
From: Doctors Inlet Florida
You definitely have an exhaust leak at the heat riser. You need to find a local exhaust shop to make you a new piece of tubing going to the manifold. Throw the heat riser in the trash.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
I was told in an earlier post to get a spacer to replace the riser. I don’t even know if it’s working. Thanks for your reply.
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
Thanks for posting photos!
So, no TVSs are present.
Do you happen to know the part number for that intake? Your carb has an electric choke, and it looks like the vacuum advance hose feeds under the intake (like an LS intake).
Is it this?
https://www.edelbrock.com/rpm-air-ga...fold-7561.html
With no crossover, the passenger side exhaust has nowhere to go if the heat riser valve is closed. Two pictures, and we found your problem. 
So, no TVSs are present.
Do you happen to know the part number for that intake? Your carb has an electric choke, and it looks like the vacuum advance hose feeds under the intake (like an LS intake).
Is it this?
https://www.edelbrock.com/rpm-air-ga...fold-7561.html
Originally Posted by Edelbrock RPM Air Gap
... No provision for exhaust heated chokes and no exhaust crossover.
Last edited by Bikespace; Mar 15, 2024 at 08:05 PM.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Thanks for posting photos!
So, no TVSs are present.
Do you happen to know the part number for that intake? Your carb has an electric choke, and it looks like the vacuum advance hose feeds under the intake (like an LS intake).
Is it this?
https://www.edelbrock.com/rpm-air-ga...fold-7561.html
Two pictures, and we found your problem.
So, no TVSs are present.
Do you happen to know the part number for that intake? Your carb has an electric choke, and it looks like the vacuum advance hose feeds under the intake (like an LS intake).
Is it this?
https://www.edelbrock.com/rpm-air-ga...fold-7561.html
Two pictures, and we found your problem.
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
Can you get a picture of the other side? There's a bi-metallic spring that heats up and opens the valve (and closes the valve when cool). Perhaps it is already pinned open.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
It never should have been installed at all with that intake. It blocks the exhaust from that side of the head, which then has nowhere to go but make a ticking noise as it blasts through your gaskets.
Can you get a picture of the other side? There's a bi-metallic spring that heats up and opens the valve (and closes the valve when cool). Perhaps it is already pinned open.
Can you get a picture of the other side? There's a bi-metallic spring that heats up and opens the valve (and closes the valve when cool). Perhaps it is already pinned open.
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
Thanks for the additional photos!
That's a spacer, not a heat riser.
Good to confirm with photos. The exhaust leak may still be present, but the heat riser valve is not the issue, since you don't have one.
That's a spacer, not a heat riser.
Good to confirm with photos. The exhaust leak may still be present, but the heat riser valve is not the issue, since you don't have one.