C-3 70 ls-5 distributor questions Vacuum Can

[Mark Z.]

I had to pull my distributor to replace a broken valve guide and before I reinstall would like to clean it up. Is it a natural finish or painted? Also, the old vacuum is not working and will need to be replaced. The number on it is 217 16. What is a aftermarket replacement number? Thanks

[Duke W.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Without knowing the specs (if you have a CSM, how about listing them), I would recommend the same one as is best suited to non-ported vacuum advance big blocks, which is the NAPA VC1765 or equivalent, 0@6", 16@12", and a assuming your LS5 has ported vacuum advance, convert it to full time, and bypass the TCS if so equipped.

The '70 LS5 is basically a stroked L-36 - same camshaft - so basic idle vacuum characteristics, which determine the best suited VAC are essentially the same.

Duke

[Duke W.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Without knowing the specs (if you have a CSM, how about listing them), I would recommend the same one as is best suited to non-ported vacuum advance big blocks, which is the NAPA VC1765 or equivalent, 0@6", 16@12", and a assuming your LS5 has ported vacuum advance, convert it to full time, and bypass the TCS if so equipped.

The '70 LS5 is basically a stroked L-36 - same camshaft - so basic idle vacuum characteristics, which determine the best suited VAC are essentially the same.

Duke

[Mark Z.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Duke,
I'm taking a shot in the dark that you are asking for cam specs. (CSM) The GM part # on the tube is 3904359 that the cam came in years ago. I have been using the TCS system and haven't had any overheat problems unless I was hotlapping in final rounds at track in summer. When I was trouble shooting the valve guide problem I had 14.5" to 15" at the manifold @ 625 RPM.
Is the dist housing outside the intake painted black?

[Mark Z.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Duke,
I'm taking a shot in the dark that you are asking for cam specs. (CSM) The GM part # on the tube is 3904359 that the cam came in years ago. I have been using the TCS system and haven't had any overheat problems unless I was hotlapping in final rounds at track in summer. When I was trouble shooting the valve guide problem I had 14.5" to 15" at the manifold @ 625 RPM.
Is the dist housing outside the intake painted black?

[Duke W.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

No I was interested in the VAC (vacuum advance control) specs, which should be in the specs section of the CSM, Section 6Y.

The ...359 camshaft was used in L-36/68, LS5 from '67 to '73, and it does not have a groove in the rear journal.

Your idle vacuum is about right for that cam, and a 12" VAC will comply with the "2-inch rule" with full time advance.

Ported vacuum advance/TCS will not have any effect on hot-lapping since the engine spends most of its time at high throttle/low vacuum, but it will cost in fuel economy during normal road operation, especially in town.

If your car doesn't have to be emission tested, I would convert to full time vacuum advance and bypass the TCS. There are probably creative ways of doing this without actually removing the system, so you maintain OE appearance.

Duke

[Duke W.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

No I was interested in the VAC (vacuum advance control) specs, which should be in the specs section of the CSM, Section 6Y.

The ...359 camshaft was used in L-36/68, LS5 from '67 to '73, and it does not have a groove in the rear journal.

Your idle vacuum is about right for that cam, and a 12" VAC will comply with the "2-inch rule" with full time advance.

Ported vacuum advance/TCS will not have any effect on hot-lapping since the engine spends most of its time at high throttle/low vacuum, but it will cost in fuel economy during normal road operation, especially in town.

If your car doesn't have to be emission tested, I would convert to full time vacuum advance and bypass the TCS. There are probably creative ways of doing this without actually removing the system, so you maintain OE appearance.

Duke

[Mark Z.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Duke,
Sorry about that. Specs are 0 @ 8" and 15 @ 15.5"

[Mark Z.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Duke,
Sorry about that. Specs are 0 @ 8" and 15 @ 15.5"

[Terry M.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Mark,
The distributor (the outside of the metal part above the intake) is painted a semi-gloss black. There is a color blotch on the housing that is unique for that distributor part number. The color is listed in the NCRS Technical Information Manual & Judging Guide (TIM&JG).

[Terry M.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Mark,
The distributor (the outside of the metal part above the intake) is painted a semi-gloss black. There is a color blotch on the housing that is unique for that distributor part number. The color is listed in the NCRS Technical Information Manual & Judging Guide (TIM&JG).

[Mark Z.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Thanks I knew about the grey dot from the JG but didn't know if the black was flat or semi.

[Mark Z.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Thanks I knew about the grey dot from the JG but didn't know if the black was flat or semi.

[William C.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Semi, leaning to the glossy side.

[William C.]

Re: C-3 70 ls-5 distributor questions Vacuum Can

Semi, leaning to the glossy side.