Changing intake manifold

Sidlo

Sidlo

New member
Replacing the manifold and distributor on my 1956 292 vicky. With a stock 312 manifold,edelbrock 600 and a mallory elec. distributor & wires. to get rid of the stock tall carburetor
1. Using the mallory about what should the timing be ?
2. In changing the intake manifold. What should the Ft. Lb. torque Be ?
3. My fuel pump is a new orginal 292 type. Does it or should it be replaced
4. the fuel pump is the type that has a vacuum going to the distributor.
Can I stiil the fuel pump just block off the vacuum line going to
the distributor.
5. Hopefully the throttle and kick down linkage will not be that much
trouble to modify.
5. I might of missed something, if I did let me know.
Just to mention it, this is a automatic car, like 500 miles on rebuild.
THANKS !
 
i did this to my 55 wagon linkage won't line up {throttle} mine was a stick don't know about the kickdown unless you have vaccum wipers you won't need that fuel pump speedway has a replacement minus all the due dads you will need to change the coil if you are running 6 volt also ck to see if you need a resistor also add an inline fuel filter before the pump good luck
 
Are you using an "A" or a "B" manifold?? Make sure you use a distributor for a 57 and up (available at UAP etc) because the 55/56 aren't equiped with mechanical advance.
 
Initial timing should be the same as the stock dizzy. Use about 10 degrees as YBlocks usually like a little more than stock recommendation

Around 25 lbs but check a shop manual or Motors/Chilton book to be sure.

The original fuel pump will work with no problems.

Just block off the vacuum line.

You may have to modify the throttle and kickdown linkage although I don't think so. You will have to find a way to connect the linkage at the carb.

Sidlo said:
Replacing the manifold and distributor on my 1956 292 vicky. With a stock 312 manifold,edelbrock 600 and a mallory elec. distributor & wires. to get rid of the stock tall carburetor
1. Using the mallory about what should the timing be ?
2. In changing the intake manifold. What should the Ft. Lb. torque Be ?
3. My fuel pump is a new orginal 292 type. Does it or should it be replaced
4. the fuel pump is the type that has a vacuum going to the distributor.
Can I stiil the fuel pump just block off the vacuum line going to
the distributor.
5. Hopefully the throttle and kick down linkage will not be that much
trouble to modify.
5. I might of missed something, if I did let me know.
Just to mention it, this is a automatic car, like 500 miles on rebuild.
THANKS !
Click to expand...
 
When installing the intake, I have been using no sealant, only a very light coating of grease on both surfaces. No leaks. And when or if it is necessary to remove the intake in the future, it is easy with little cleanup, and there is good chance the gaskets can be reused.
 
If you are using the 57 style iron intake, it can be improved greatly with an hour of Dremel work. Outline a new gasket opening with a scribe, and open the intake holes all the way down to that diameter. Then remove the metal between the front and back holes, but not right to left. Reach down and blend the bottom of the holes. If yours has the little trench around the top opening, clean it out with carb cleaner and a wire brush, dry well, and fill with epoxy. 24 hours later, file flat. The mid range will amaze you. If you use an Edelbrock carb, use at least a 1/2 inch insulating spacer. For street use, 500 CFM is good.
 
This is the modification Don refers to....... Inlet bores are matched to a gasket that matches the carb throttle plate, then slotted together front to rear.

The isolation chambers have to be filled with epoxy as he suggests - or milled off completely as shown in this picture.....
Bmanifoldopenedup-1.jpg

Use of a temperature isolator / spacer is highly recommended. You might also look for a "truck" type manifold gasket set, where the passages to the center heat crossover are reduced with a steel insert.
 
GREENBIRD56 said:
This is the modification Don refers to....... Inlet bores are matched to a gasket that matches the carb throttle plate, then slotted together front to rear.

The isolation chambers have to be filled with epoxy as he suggests - or milled off completely as shown in this picture.....
Click to expand...

Guys... can anyone post a photo of these isolation chambers? I am not familiar with them.
 
If you look at a stock four barrel intake, then look at one modified like this, the difference is huge. Then when you look at a Blue Thunder or Mummert, that difference is huge again. John Mummert wrote about this change years ago in the Y Block Magazine. This was the biggest single improvement I made for my street 312, and its free! I now use a Blue Thunder.
 
This photo shows what happens when you just slot the factory manifold - without trying to fill in some of the carb base air gap.

Slottedopenings.jpg


There are some trick spacers around that act as both heat isolator and airflow guide - in some higher rpm set-ups they can be worth big power. For this sort of slot, they have a set of four holes under the throttle bores and they blend (open) together at the wall between the front and rear bores (but not side to side).

QFT-300-4150-1AL.jpg


The above is for illustration only. This one is for a completely open plenum - and it isn't recommended for use on a slot like the Y-block manifold - but it does show the blending betwen adjacent bores fore and aft. It is also plain billet aluminum and won't do too good a job of being a heat isolator.
 
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As a side benefit when you use the truck gasket or block off the heat crossover you help prevent burning the paint in that area.
 
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