1965 L-76 327/365 tune-up advice

[Philip A.]

Ok, update if you have been following my vac can post question. I now have removed the electronic pointless module that failed, checked all circuitry, installed the correct vac can (236 from LIC), new points & condenser, and installed coil correctly. Engine fired right up on first try!

Questions
what is correct idle speed setting?
what is correct dwell setting?
what is correct timing setting?

i recall all above is to be set when engine is at operating temperature, the vac can hose disconnected and pluged. Is this correct?

i have a dial in advance timing gun if that helps.

Thanks and apologies for the basic questions, but sometimes you guys know better ways or tricks.

[Don H.]

Re: 1965 L-76 327/365 tune-up advice

Ok, update if you have been following my vac can post question. I now have removed the electronic pointless module that failed, checked all circuitry, installed the correct vac can (236 from LIC), new points & condenser, and installed coil correctly. Engine fired right up on first try!

Questions
what is correct idle speed setting? 750-850
what is correct dwell setting? 28-32
what is correct timing setting? 12 nom, 10-14 range

i recall all above is to be set when engine is at operating temperature, the vac can hose disconnected and plugged. Is this correct?

i have a dial in advance timing gun if that helps.

Thanks and apologies for the basic questions, but sometimes you guys know better ways or tricks.

all specs from section 6 "Engine Tune up Chart" of 1965 Corvette Shop Manual Supplement.

[Stuart F.]

Re: 1965 L-76 327/365 tune-up advice

Phil;

Did you check the VAC with a Mity Vac? I bought several cans in the past that did not meet spec and returned them. A lot of vendors buy from the same source, and that source was doing the right number stamping of 236 so they would pass judging, but didn't come close to meeting performance specs. None of the vendors ever tested them, just re-boxed them, marked up the price and shipped them.

Get yourself a Mity Vac, if you don't have one, and test that can: it should provide 0 degrees @ 4" Hg (in other words; it should start the plunger moving when the gauge on the Mity Vac reads 3 to 5" Hg) and should provide 16 degrees @ 8" Hg (plunger pulled in to stop when Mity Vac reads 5.75 to 8" Hg).

Like Don said, "follow the specs in the book for timing, idle speed and dwell" (your on your own on that one cause I don't mess with dwell anymore, Ha!

Stu Fox

[Philip A.]

Re: 1965 L-76 327/365 tune-up advice

Thanks Don.

Stu
when I purchased the vac can I was concerned if it was only cosmetically correct and not performance correct. I do not have a Mity Vac but will be purchasing one. Combined with the dial advance timing gun I will test it. Question for you: with the engine at idle and timing at 12 degrees, when I pull 8" Hg, will the timing read 16 total or will it add 16 for a total of 38?
Thanks for all your helpful replies.
Phil

[John H.]

Re: 1965 L-76 327/365 tune-up advice

Thanks Don.

Stu
when I purchased the vac can I was concerned if it was only cosmetically correct and not performance correct. I do not have a Mity Vac but will be purchasing one. Combined with the dial advance timing gun I will test it. Question for you: with the engine at idle and timing at 12 degrees, when I pull 8" Hg, will the timing read 16 total or will it add 16 for a total of 38?
Thanks for all your helpful replies.
Phil

Phil -

It should show 12 (initial) plus 16 (vacuum) for total idle timing of 28* (not 38*).

[Stuart F.]

Re: 1965 L-76 327/365 tune-up advice

Thanks John for helping Phil. I don't recall, but I'd like to ask him if his 65 L-76 is a straight up 365 hp and not a de-tuned version (cam and compression).

Stu Fox

[Michael J.]

Re: 1965 L-76 327/365 tune-up advice

You should also make sure your cold, fast idle is set properly, it should be 1600-2000 rpm, as per the NCRS Ops Check, PV manual.

[Stuart F.]

Re: 1965 L-76 327/365 tune-up advice

Michael;

My car spent it's first year at White Sands when I was in the service. Had a blast on the desert roads both on and off the range. We used aircraft landing lights in the high beam positions in order to see down those long straight stretches on the lookout for those big jack rabbits.

On Phil's car; is he planning to have it judged? Reason I ask is that for me the high idle is a low priority as long as I get it in the ballpark. I like to have a little more during the cool season to get me out of our village and on the road. I aim for 1750 rpm, in fact, I just did a little tweaking on it while it is sitting in the garage as it is too difficult to do while running with an AFB.

Stu Fox

[Michael J.]

[Duke W.]

Re: 1965 L-76 327/365 tune-up advice

You should also check the centrifugal and verify that it conforms to shop manual specs. It is difficult to get an acceptable idle at much less than 900 with the 30-30 cam, and since the centrifugal should start at 700 you need to get the speed down below this to set initial, but the engine may stall.

So the way to set timing is to set what is called "total WOT advance", which is simulated by disconnecting and plugging the VAC. Then rev the engine to a few hundred revs above the point where the centifugal stops advancing that you verfied as above, set the dial at 38, and rotate the dist. to bring the balancer notch to zero on the tab. If it doesn't detonate you are good to go, and you can even try 39-40.

Reconnect the VAC and check "total idle advance" at 900. It should be about 32-34 (14 initial, 16 vacuum and 2-4 centrifugal) and manifold vacuum should be about 10" Hg. Then rev the engine to above where the centrifugal stops and check "total cruise advance". It should be about 54 degrees (14 + 24 + 16)

The following article will tell you what contact set to install. Note that all the NAPA/Echlin contact sets are manufacturered by Standard Motor Products and are available in other brand boxes including Delco. Any parts store should be able to cross the NAPA/Echlin number to whatever "brand" they carry... Delco, Standard, Niehoff, BWD, etc.

Duke

[Dan H.]

Re: 1965 L-76 327/365 tune-up advice

Be careful with an reproduction VAC. Had a '236' repro can, went belly up in under a year, 2K of driving. I'd opt for a real one, they're out there.
Dan

[Stuart F.]

Re: 1965 L-76 327/365 tune-up advice

I think John H. And I got the last NOS a few years back, but there has been some repos that work good. As I mentioned in my previous post, I had bought several from different Vette product venders that were marked as #236's, but didn't test properly, and I too had one fail in a week.

Stu Fox

[Michael J.]

Re: 1965 L-76 327/365 tune-up advice

The ones I have are Airtex 4V1053, I have had no problems at all.

[Philip A.]

Re: 1965 L-76 327/365 tune-up advice

John
thanks for the math correction!

Duke
thanks for the instruction. Points are Standard Blue Streak DR2270P

Stu
engine is original and rebuilt to OE L-76 specs by previous mechanic owner. I have all previous receipts and photos to confirm. It was not de-tuned. Engine hates idling below 1,000 rpm and absolutely comes alive at high rpm. I intend to Flight judge, and want everything to perform per spec anyway. When I have the time I will tune and test everything.

Thanks everyone
Phil

[Jim T.]

Re: 1965 L-76 327/365 tune-up advice

Dwell setting I use is 30. My 63-64 service manuals if my memory is recalling correctly shows 28-32.