C2 Distributer Vacuum

[Mark H.]

does the distributer on an L-75 mid year have vacuum at idle, or only on acceleration? I cannot find a reference for this in any of my books. Thanks!

Mark

[John H.]

Re: C2 Distributer Vacuum

L-75's were set up to provide full manifold vacuum to the distributor; in '65, the L-75 advance can provided 16.5 degrees of advance at 8" Hg. vacuum, so it was fully-deployed at idle, which is essential for idle cooling, throttle response, idle stability, and fuel economy.

[Duke W.]

Re: C2 Distributer Vacuum

John - where did you get the vacuum advance spec for the '65 300 HP? The Corvette News that lists the '65 tunup specs has 0@6" and 24@13", but apparently the '65 shop manual supplement says otherwise.

It seems like GM kept diddling with the 300 HP vacuum specs almost every year.

Duke

[John H.]

Re: C2 Distributer Vacuum

Duke -

Got the specs from the back of the '65 Shop Manual Supplement.

[Duke W.]

Re: C2 Distributer Vacuum

Joe Ciaravino and I have been swapping e-mail on this subject. Here is my recent note to him. I think it can be resolved with the AMA specs. Do you have them? Joe doesn't, but he's going to call GM for his "care" package.

I suspect that the '65 Supplement is in error on the L-75 vacuum specs. I
note that
my Corvette News lists the 076 as the distributor, but the different vacuum
can
specs. If GM had implemented a running change on the distributor by
changing the
vacuum can, the distributor number would have changed.

About the only way to resolve this would be to find an unmolested 076
distributor, get
the vacuum can number and test it or cross reference it to published
specifications.

My parts catalog lists the 1115357 as the replacement vacuum can for the
'65 250/300
engines; '62-63 is the 1115163 (0 @ 8" 16 @ 15.5"). It changed again for '66,
and I
can't even find a list for non-AIR engines, but AIR was 1115355, and this
carried
through to '68. The 357 is listed again for base 350s, 69-70.

Corvette News specs for '66 list 0@6" 15@12 inches for 300 HP, but don't
list
different specs for AIR, so maybe they were the same.

I'm missing the Corvette News with the '67 specs.

Duke

[John H.]

Re: C2 Distributer Vacuum

Duke -

I have the AMA Specs for '67, but not for '65. I cross-checked the distributor number in the NCRS Spec Guide to verify the proper number, then found the specs for that distributor in the Shop Manual Supplement, which doesn't give the I.D. or part number for the advance can - just the specs.