SWCDuke

In response to some of the cooling issue posts I looked at my '63 Corvette Shop Manual to see how often Chevrolet recommended coolant changes. To my surprise I could not find any recommended change interval - only a recommendation for "periodic cleaning, reverse flushing, and reconditioning service". Me thinks that whoever wrote this just lifted it out of the passenger car manual for brass radiators written in the fifties.

Current OEM recommendations for conventional (green) antifreeze changes are typically two years, REGARDLESS OF MILEAGE. The recommendation for my Cosworth Vega with it's all aluminum engine is EVERY YEAR.

GM recommends a five year interval for Dexcool and this can be reasonable if you have completely overhauled the engine/cooling system and all deposits have been removed. If conventional antifreeze has ever been used, the recommendation is two years. This is because the salt deposts will slowly dissolve and reduce the effectiveness of Dexcool's inorganic corrosion inhibitor package. I always recommend Dexcool because it will not build up deposits over time and will extend the life of new aluminum radiators, but if you have an old aluminum radiator that has deposit buildup, there's not much you can do. Eventually is will either cause hot running or begin to seep, and at that point, it's toast and time to call DeWitts.

Reading the maintenance schdule is rather quaint. For example, oil changes are recommended EVERY 60 DAYS or 6000 miles, and a U-joint repack every 30K miles.

I've developed maintenance schedules for my cars based on the FAA model of an "annual inspection", using the best available modern fluids. Since our cars typically are only driven a few hunded to a few thousand miles per year, an annual maintenance should keep your car running for a long time. Here are some of the basics.

Every year:

1. Oil and filter change with 10W-40 CI-4 oil. If you store your car in the winter, this should be done just prior to storage.
2. Lubricate balljoints and steering linkage.
3. Check for leaks and oil level in the trans and diff
4. Check point resisitance, dwell angle, and initial timing
5.. Annually or every two to three years a thorough underbody inspection should be performed - U-joints, suspension bushings, brake pads/shoes material thickness, all vacuum, fuel, and coolant hoses.

Every Two years

1. Change antifreeze
2. Change brake fluid.

Every 12-15K miles

1. Check valve clearance (mechanical lifters)
2. Change points and change or clean spark plugs, inspect cap and rotor, centrifugal and vacuum advance system.
3. Idle speed and mixture check/adjustment.

I haven't formalized Corvette maintenance, but about ten years ago I developed a comprehensive maintenance and inspection schedule and checklist for the Cosworth Vega that I would go through prior to a track events. The "annually or every 2500 mile" checklist items number 74 and addiing the 2 year items, 6 year/15K items, and 12 year/30K items the total comes to 94 items.

Duke

achapman

Hey Duke,

If I bring my car over what do you charge for all of this.... :D

Daren Schneider

Duke:

Thanks for the checklist. I have been looking for something like this for a while. If you are ever in the NYC, Long Island area, I owe you a beer.
If I pull out a timing light during that night, dont be alarmed. I value good vette advice.

We all apreciate your input to this forum.

Regards,
:cheers:

SWCDuke

I charge the same hourly rate as Johnny Cochran and work REAL SLOW! ;)

Duke

Cliff63

:lolg: :lolg:

Good checklist, thanks. Looks like my Be Cool was installed by the previous owner in Sept of '00. No overheating problems but it looks like I am ready for a fluid change. BTW, Be Cool paperwork has a statement; "Early 327 CID engine block castings had particulary thin cylinder walls which results in running hot when they have been bored. If you experience this problem, an electric fan will be helpful in overcoming the problem." What is your opinion about adding a fan?

Thanks, Cliff

SWCDuke

Some say that bored SBs can have more of a tendency to run hot, but I don't have any personal experience with it. Anecdotal evidence and my own experience is that SBs should not run hot if they have an OEM type aluminum radiator and clutch fan in proper working order and the ignition map is suitable for the engine, which includes a vacuum advance suitable for the manifold vacuum characteristics of the engine.

Duke

62fuelie

Both of my vintaqge cars have "early 327's", both have been bored, and neither runs hot.

mrg

I remember I had a heck of a problem trying to keep the SB in my car from overheating after it was rebuilt. Any kind of slow city driving just about gauranteed that the temp gauge pointer would go to 3/4, easy .. ! . . The .030 overbore engine was still being broken in but is this enough in itself to cause such a large heat gain .. ? .. A new Harrison aluminum replacement radiator took care of the problem, though I really thought the original radiator was still "ok" to use, based on its prior performance before the rebuild. Guess that thing was really plugged up, after all .. ! ..

kcust62

Hey Duke,

After reading your post, I'm curious as to your oil viscosity preference or recommendation. I used to use 10W-40 in the 327/340 and the oil pressure gage always seemed to stay pegged @ 60 psi. I switched to 10W-30 and the pressure gage now registers 30 to 45 from idle to low engine rpm. At crusin' speed, it will register 50 to 60 psi depending upon engine rpm. This seems to me to be a more normal way for the gage to respond. Your thoughts!

Thanks in advance!
Karl

SWCDuke

The common multi-vis grade of CI-4 oil is 15W-40, which is suitable for all driving condition from about 10F to 100 plus.

As far as hot oil pressure is concerned, oil viscosity, within reason should not make much difference. There was a change in the relief spring in very late '63 on SHP/FI engines to increase oil pressure from a nominal 40-45 psi to 55-60 psi. This internal engine change was accompanied by a change in the inst. cluster to a 80 psi gage, but I'm not sure how the plant kept track of the correct combination.

It's common for guys to install aftermarket "high volume" oil pumps with 60 psi springs, but this can cause the 60 psi gage to be pegged most of the time. Such oil pumps are a complete waste of money as "high volume" and higher delivery pressure is not necessary for a street engine. They just use more horsepower churning and heating the oil, most of which is bypassed back to the sump. My recommendation is to just with the OEM pump and a 40-45 psi spring if you have a 60 psi gage. A higher pressure spring that keeps the 60 psi gage pegged is not a reliablilty issue. The gage in my '88 Merc tops out at 3 bar and at engine speeds over 2000 it is always pegged, and typical idle pressure is 1.5 bar. The Corvette gage is a mechanical bourdon tube gage and a 60 psi spring will not damage it.

Duke


[Modified by SWCDuke, 10:49 AM 7/15/2003]

JoesC5

Duke, I'm not sure on the 63's but all 64's had 80PSIG oil gages, and I believe all the 63's had the 80PSIG gages.

SWCDuke

My mid production '63 has a 60 psi gage and a 45 psi relief spring. According to the NCRS JG late '63s (16000-up) had both 60 and 80 psi gages with no seeming correlation to engine. Years ago, one Corvette "expert" once told me that I could not have an original SHP engine because I did not have an 80 psi gage. If you look at the applicable AIM sheet change records, you can see changes that correlate to these events.

The change in relief spring pressure applied only to SHP/FI engines and this should have been accompanied by an 80 psi gage. Could be that the 80 psi gages were only installed in SHP/FI clusters, and 60 psi were used in base/HP clusters until the supply was exhausted, then 80 psi gages were installed in all clusters, but the anecdotal evidence indicates that they didn't do too good a job matching the proper gage to the engine's pressure relief spring value.

You are correct that all '64s have an 80 psi gage, and this is stated in the JG, but only the SHP/FI engines should run 55-60 psi hot oil pressure. Base/HP engines should run 40-45.

Duke

Matt Gruber

Duke
you finally convinced me to change the antifreeze. i've got 3 gallons, 1 for each car, and i promise to change them by this december.
That's 13 years on the galaxie and about 5 years on the vettes. Hopefully all 3 will be ruined so i will have an excuse to buy a new vette.LOL
Now the question.
HOW LONG TO CHANGE THE GAS?
My galaxie sat for 1 year and i was lazy and rode it around 'til E, then added 7 gallons.
When i was young i changed the oil every 3 months, now i'm lucky if the gas gets changed that often. ;) :p: :seeya

simard

I never change antifreeze on a regular basis. However, it does get changed annually due to various engine, radiator, or heater problems.

SWCDuke

Gasoline has a nominal shelf life about a year. Actual shelf life is dependent on temperature. The lower the temperature, the lower the rate of oxidation that causes gum and varnish formation. I regularly store cars for six months to a year. I always fill the fuel tank with fresh fuel prior to storage, and have never had any fuel system problems.

If you have a car that has old gasoline, I'd suggest siphoning it out, placing it in your daily driver, and filling the collector car fuel tank with fresh fuel.

Keeping the fuel tank full during strorage is important as this minimizes the vapor dome that "breathes" according to changes in atmospheric pressure. The larger the vapor dome, the more moisture will build up in the tank with time, and it will eventually form a pool at the bottom of the tank and start corroding the metal.

Duke

Matt Gruber

i think that's good advice Duke, don't get me wrong. But it sounds like you got it out of an old text book. I can't imagine doing that in the real world! filling it with gas and then draining it out! LOL
My life experience is quite different, as i moved to my dream location, from NJ to FL, 800 feet from the beach. I eliminated daily driving. i do ride my bicycle and scooters much more often than cars.
in 1983 i tried filling the tank in my 61 while it was in storage for 10 years. when it was trucked down here, there was less than 2 gallons(the only gas i ever drained out), no water or rust in the tank. My vapor bubbles appear to be gas fumes, not water vapor.
I have removed the sock/strainer in all 3 cars. This allows any water to be sucked into the carb as i bent the line to draw from the bottom of the tanks. Over the last 14 years i have never put more than 10 gal, usually 4-6 gallons. this way i have a constant supply of fresh gas every 3 months or so. the galaxie was an exception this year, and i found out it ran fine on 1+ year old gas. i intend to run them all at least once a month. i put dri-gas in twice in 14 years also.
just an alternative lifestyle, with no messy gas changes :lol:





[Modified by Matt Gruber, 1:09 PM 7/16/2003]

68shark

Thanks Duke for another informative post!!

ragtop65

Outstanding post! Thanks Duke. BTW, my DeWitts radiatior is beautiful and is going in tomorrow with DexCool.

Any opinion on pre-coolant change use of prestone radiator flush?

Phil

SWCDuke

Just do a very thorough flush of the system with water to purge all traces of the green stuff. If you want to drain/flush and then use a chemical flushing agent with a second drain and flush before installing the new radiator, that's okay, but I'm not sure if it will have any real benefit.

Maintain as close to the two-year Dexcool change interval as possible and the new DeWitts radiator should outlive most of us.

Duke