My 75 has a broken stud on the pass side and a crack on the driver side and want to replace both before I put on my new exhaust.

Are these manifolds the same as any other small block Chevy manifolds used on other GM cars?

Where is the best place to buy a new pair?

Any tricks to getting the rusted bolts out of the head? I have them soaking in PB Blaster now.

Does the choke take a long time to open if you take out the block off valve on the bottom of the pass side?

Thanks in advance

Mark

 

on most cars the block off does nothing for the choke it just pushes warm air up to the carburetor air cleaner assembly which helps in cold weather upon initial starting.....the choke spring is heated from other sources either from the lifter valley or electrically. many people just take out the internal butterfly and spring...cars with headers dont have these at all.

many of the exhaust manifolds are the same but some are different for exhaust emissions tubing etc.

do you have enough of the stud left to put a stud extraction tool on it? its basically a big rotating cam that locks down on the stud and as you turn the tool it locks down tighter on the stud unitl something gives.....

 

No,you would have to go way back to the mid sixties to find a similiar manifold to the ram's horn.There is usually a set or two on this forum for sale,you should look there first.I have a good set off a 74 available if you can't find any closer to you.

 

You will want o get manifolds for a Corvette due to the location of the area where your pipes connect can be different. Using manifolds with 2-1/2" exhaust will allow your car to breathe better....and often times...the exhaust pipes being made offer an option for 2-1/2".

Check out Eckler's, Paragon Reproductions, Long Island Corvette Supply, Corvette Central. If going with teh 2-1/2" design...some grinding may be required due to changes in the outside appearance...but they will bolt up to your cylinder heads...because I have used them before.


Yes. I use heat and wax. I heat up the cast iron and apply the wax to it. I do not get it cherry red..just hot. Then I try to get the stud to move a "frog hair". If the stud moves the slightest amount...then the mechanical bond is now broken and the stud will come out with a little patience, heat and wax. The wax will get into the threads and make it so the stud will come out a bit easier. Just make sure that you do not heat the stud...you are trying to get the cast iron AROUND the stud to expand and not the stud with it. You may need to allow it to cool and repeat the process. It is this expanding and contracting that will aid in breaking the mechanical bond. There is no way the STUD welded itself to the cast iron. These are two totally different types of ferrous metals and they may get stuck...but can not become one. I have never had one that I could not get out. Just takes time and patience.

If your carburetor has an electric choke...than the heat riser does not effect it....the choke pull off issue. But if your choke is controlled by the provision mounted on the intake manifold...than it can AID the choke working better.

There is a passage made into your intake manifold...that runs from side to side in the center..where this provision is located. Exhaust from each side of the engine feeds this area ...thus causing the area under your choke provision on the intake to get HOT. It will get hot regardless....just may take longer than "normal"....unless it is plugged up by carbon deposits...like I have seen many times...and not allowed to get hot. But the heat riser...which will open when it gets hot enough...blocks off/restricts the exhaust ...thus allowing the exhaust to linger in this area long enough to allow the engine to warm up and allow the choke to pull off. GM also used a "ported vacuum switch" that controlled the heat riser via through a vacuum actuator. When the coolant temperatue got hot enough....the switch would allow the actuator to open the heat riser valve. Then GM did completely away with them all together.

"DUB"

"DUB"

 

If you don't want to do headers, you might want to check these folks out.. Brzezinski Racing Products, Inc.
http://www.castheads.com/corvette_systems.php#manifolds



Photo comparing 2 ports. On top is the modified port opening. Bottom photo shows the stock port opening.

They have some awesome cast iron manifolds that are perfect for the Corvette. They are not cheap, but they are some of the best manifolds for these engines and they are NEW... so no issues with cracked flanges or studs that don't come out.

Good luck... GUSTO