63_Misc engine questions

[Steve D.]

I have a 63 convertible. The VIN plate code indicates original engine was 327/300. The present engine is a 327, but very non-original: 65 block, 67 heads, aftermarket aluminum intake (Weiand), and Holley carburetor w/electric choke. I have never had the engine apart, so I don’t know what is inside. I was looking through the AIM and noticed some other differences.

Distributor – no points and no vacuum advance. It is a tach drive distributor. I assume this is a centrifugal advance distributor that someone added an electronic kit to ? Was there a factory application (Corvette) for centrifugal advance distributors ?

Resistor on firewall – shown in AIM diagram (pg 140), but I couldn’t find it in the wiring diagram. Ballast resistor I assume. Two terminals on the resistor. The top one is connected to the coil. The bottom is connected to the electric choke. Since the choke is not original, what was the bottom terminal originally connected to (if anything)?

Intake manifold has a ½” blank brass plug behind the carburetor. For use with automatic transmission, if installed ?

The AIM (pg 133) shows a hose (item 16) coming from the back of the carburetor and connecting to a tube (item 12) which runs down to the bottom of the exhaust manifold (passenger side), right above where it connects to the exhaust pipe. The description for item 12 is “Pipe assembly_ Air Intake”. The hose and tube are not present on my set up, nor can I find a connection at the bottom of the exhaust manifold. What is this ?

Above the voltage regulator, on the radiator mount, is another electrical device. I could not locate this in either the drawings or electrical diagram. This would be the …???

Steve

[Duke W.]

Re: 63_Misc engine questions

There is no engine code in the VIN on '63s. The only way to determine the original engine HP rating is to look for other circumstantial evidence. The 350/300 HP engines have tachs with a redline of 5300; 6500 on SHP/FI engines. The transmission can also be a clue if it is original - 250/300 had a wide ratio and SHP/FI had a close ratio. Also, 250/300 only were available with 3.08 or 3.36 axle ratios. SHP/FI were available with these and four others from 3.55 to 4.11.

All '63 engines had a single point distributor with centrifugal and vacuum advance. The input to the ballast resistor comes from the ignition switch. The ballast resistor is at the extreme right hand side of the shop manual wiring diagram, Fig 41a.

The tube you refer to is part of the choke clean air system. A hose from the carb. air horn routed to a tube, which runs through the exhaust manifold, with a another tube to the choke housing. A vaccum port in the carb body draws clean air from the air horn, through the manifold and into the housing that contains the thermostatic spring that operates the choke valve.

The device above the regulator would be the horn relay. Since your inlet manifold is aftermarket I have no comment on the brass plug it contains.

Duke

[Duke W.]

Re: 63_Misc engine questions

There is no engine code in the VIN on '63s. The only way to determine the original engine HP rating is to look for other circumstantial evidence. The 350/300 HP engines have tachs with a redline of 5300; 6500 on SHP/FI engines. The transmission can also be a clue if it is original - 250/300 had a wide ratio and SHP/FI had a close ratio. Also, 250/300 only were available with 3.08 or 3.36 axle ratios. SHP/FI were available with these and four others from 3.55 to 4.11.

All '63 engines had a single point distributor with centrifugal and vacuum advance. The input to the ballast resistor comes from the ignition switch. The ballast resistor is at the extreme right hand side of the shop manual wiring diagram, Fig 41a.

The tube you refer to is part of the choke clean air system. A hose from the carb. air horn routed to a tube, which runs through the exhaust manifold, with a another tube to the choke housing. A vaccum port in the carb body draws clean air from the air horn, through the manifold and into the housing that contains the thermostatic spring that operates the choke valve.

The device above the regulator would be the horn relay. Since your inlet manifold is aftermarket I have no comment on the brass plug it contains.

Duke

[Tom B.]

Re: 63_Misc engine questions

Steve,

You have to go back to the 283 2-4bbl engines for a centrifugal advance distributor but they weren't tach drive. Sounds like a conversion to electonic or possibly an aftermarket distributor. Some people remove the vacuum advance for racing only engines or to help avoid detination when running high compression and big advance. The ballast resistor isn't used with electronic ignition so it was probably pitched.

Tom

[Tom B.]

Re: 63_Misc engine questions

Steve,

You have to go back to the 283 2-4bbl engines for a centrifugal advance distributor but they weren't tach drive. Sounds like a conversion to electonic or possibly an aftermarket distributor. Some people remove the vacuum advance for racing only engines or to help avoid detination when running high compression and big advance. The ballast resistor isn't used with electronic ignition so it was probably pitched.

Tom

[Steve D.]

Re: 63_Misc engine questions

Duke, Tom

Thanks for the comments. I'm going to look more closely at the distributor and resistor to see if I can find a brand or part # that might shed some light on this.

Steve

[Steve D.]

Re: 63_Misc engine questions

Duke, Tom

Thanks for the comments. I'm going to look more closely at the distributor and resistor to see if I can find a brand or part # that might shed some light on this.

Steve