Prior to acquiring my new '75 Coupe, read hundreds of pages of this Forum to learn about owners' concerns and preferences. Notwithstanding same, still looking to avoid making mistakes and take care of my new toy as best I can, money not being much of a factor at this point.

Prelim's: '75 "J" model 4 speed 78,000 original miles.
Never raced, never hit, all stock and mostly original. Engine in terrific shape despite her age. Body will need a repaint. Trying to stay as close to original as I can. Runs terrific, starts right up, smooth running ...

Picked her up this week and ready to get her "serviced". Oil looks very clean, but I don't have any maintenance records or history. Therefore, would like to do as much as I can to get her and keep her happy. Big believer in preventative maintenance.

My thoughts:

Oil: (Long Island) Mobil 1 15W-50 or Amsoil 10W40 (AMO) or Royal Purple 10W40 (concerned about flat tappet, zinc, etc.)?

Oil Filter: AC PF25 or Mobil 1 M1-111 or K&N HP2002?

Spark Plugs: ACR44TX @ .060" or AC plats 41-830?

Air Filter: AC 348C or K&N E1500

Will be replacing other parts as necessary once I examine the existing components (i.e. distributor cap, rotor, antifreeze, thermostat, belts, ignition wires, battery, etc.)

Tires have lots of meat (Goodrich TA's). Concerned over "correct" air pressure. Door jam label says originals were FR70-15. Car came with 225-70R15's which Tirerack claims is the correct replacement size.
Question: Why do forum members claim 30-32 psi is correct air pressure, when jam reads a remarkably low 20 psi?

Any other suggestions? Thanks .. and sorry for being so wordy!

 

Tire pressure will end up being a matter of personal choice. Drive the car at different pressures and see what you like.

 

I have a 1979 with 35000 miles. I have done a lot to up date.

You will find that after 30+ years most nuts and bolts become one, and will be very difficult to take off. Will need a good penetrating oil.

Most of your hoses will need to be replaced.

You will want to replace your brake calipers with stainless O ring. You may also need to replace the brake lines, if so go stainless.

I have added a Comp flat tapped cam , I use Red Line 10w 30. It is full synthetic with all of the Z ink etc. to protect your flat tapped cam.

I use a K&N, HP 3002. Oil filter it is a 1 Qt. The HP 2002 is a ½ qt.

I use a K&N dropped base air cleaner. This gives me hood clearance for intakes.

Have fun working on you Corvette, I found it is half of the fun.

 

I just hope that wasn't a LI car, because rust is a HUGE issue on that island.....

presumably you checked for all the rust issues, having mentioned you read up a bit so to cover your *** good....

enjoy....sharks get the LOOKS that's for sure....

get it painted, show up at a car scene, park with the vettes, and stand aside....the sharks get all the looks, the rest not so much....

 

The tire pressure numbers on the door jamb are for original type tires, which were probably bias ply. 32 is good for the tires you have now. The is a thread running here about the effects of aging on tires. You might want to check the date code on the tires (a series of numbers stamped near the tire bead). Your tires could easily be 10 years old - not good.

 

Hi BB,
It sounds like you've really done your homework and found a car you're pleased with.
There's been a lot of discussion lately about tires that look great, have lots of tread left, but are old. T/As have been around for many, many years, so you might want to determine how old your tires are and how safe they may be to drive on.
Have Fun!!!
Regards,
Alan

BK: You beat me to it! I'm a very slow typist!!!

 

Alan - I probably started before you.
You're right about T/As being around for a long time. 20 - 25 years I would guess.

 

T/A's were used on the Chargers in the 1979 TV series Dukes of Hazzard, so stretch it to AT LEAST 31 yrs!!

 

Longer than that. Here is someting I just looked up.

The BFGoodrich Radial T/A tire was the first radial to win in SCCA competition when the Tire Birds (based on Chevrolet Camaros and Pontiac Firebirds) won at Watkins Glen in 1971.
The BFGoodrich Radial T/A tire was the first street-legal radial to race at the 24 Hours of Le Mans when John Greenwood raced his 1972 Corvette.

Looks like they are close to 40 years old.

 

Thanks gentlemen ...for the quick and sage advice.

Tire pressure now at 30lbs I find that it is a nice compromise. I on't intend on much high speed driving.

The car has been garaged on Long Island for at least 25 years, and rust, surprisingly, is not a problem. Car has been very well maintained; interior is an 8/10. Brakes, calipers, lines, hoses look as if they were changed not too long ago. Only master cyclinder cover a bit oxidized, but that's a low cost replacement item.

Tires are only 4 years old; I found the bill of sale and they all have only 4,000 miles on them.

I appreciate the advice on the K&N oil filter. Will use the larger one, if all the other specs are the same, except for capacity.

Any suggestions on plugs? Since it will not be driven much, my reasoning is to use AC R44TX and just change them annually.

And you guys are right, mainting it myself is half the fun. Now if it would only stop snowing ..... !

 

I don't know if the '75 has HEI or points, but even with points the plugs should be good for 10-15K miles. With HEI they will last a lot longer. You might want to clean and gap them annually, but changing them seems like overkill. I would spend my money elsewhere.

 

plug gap should be 40 thou for stock engine / low compression and 35 thou if you move on to higher compression. Otherwise the spark will jump in the capn not at the plug under hard acceleration.

 

... guys, for the advice. Going to pick up parts today after I get the baby registered.

 

Plug gap is .035" for points type system...but the '75 is HEI and plugs are gapped at .060". If you set the plugs with less gap and you lose the advantage of the HEI system. If the car is running well, just pull one of the plugs and look at it. If the electrodes are not burnt or eroded and the color is good (light tan to brown), leave them alone until you decide that they need it. If the tires only have 4K miles on them, chances are the plugs only have 4K miles on them, too. Probably done at the same time when owner decided to use or sell the car. If the radiator hoses and belts look to be in good shape (no cracking on the belts), they may have been changed then, too. Oil change and grease job (steering and ball joints plus U-joints, if they have fittings) should done just to be cautious and I would recommend the Mobil 1 swap; synthetic oil is better and lasts longer (time wise) than regular oil. If you don't drive much, once a year on the oil change is all you need with synthetic oil. Put the AC filter on when you have the car judged; otherwise, install a good quality filter. Have fun!

 

I'm clearly biased, but my thoughts on AMSOIL's AMO vs. Mobil 1's 15w50 - I'd go with the AMSOIL 10w40 for the following reasons:
- Higher ZDDP (AMSOIL phosphorus ~1265 ppm, zinc ~1378 ppm, Mobil 1 phosphorus 1200, zinc 1300)
- Similar High Temp High Shear (HTHS) rating (AMSOIL 4.3 cSt, Mobil 1 4.5 cSt - Note for comparison, AMSOIL's Premium Protection 20w50 is 5.0 cSt)
- Lower Viscosity (40 grade vs. 50 grade, actual numbers are AMSOIL: 14.6 cSt (212F), 90.5 (100F), Mobil 1: 18.1 (212F), 131.2 (100F) )

The short story is that I feel the AMO provides similar high temp protection to the higher viscosity Mobil 1 15w50 while providing the benefits of a significantly lower cold viscosity which I feel is important in a street car. If I was going to go with a 50 grade oil, which I personally feel is too high for a street car, I'd go with the AMSOIL 20w50 which provides better high temp protection than the Mobil 1 and despite it's 20w cold rating, actually has a lower 100F viscosity than does the Mobil 1 (123.8 vs. 130.2).

I can't comment on the RP as they don't publish their ZDDP, HTHS or viscosity ratings.

If you do decide to go with the AMO, please drop me a PM so I can set you up to get dealer wholesale pricing (about 25% off retail) via the AMSOIL Preferred Customer Program.

 

Check the DOT# on the tire, not the date on the invoice! If they are 4 years old, the last 4 numbers should be something like 2306 if made in the 23rd week of 2006. Post pics of your new ride!

 

If you haven't already, buy an AIM! It is your best friend when you are working on your vette!

http://shop.corvettecentral.com/Acce...-p6017371.html

 

Congrats on the new ride. Great choice with the 75.

 

This is good advice, just having the torque numbers for everything makes the AIM worth twice the price. I purchased the shop manual as well, but the Forum is better IMHO!

 

I had a '75 a few years back. It was my DD for about 4 years and I loved every minute I was in it. Anyway....., since you asked for "any other suggestions" I thought I throw one in. You may want to install a stock exhaust system from a '74 which were true duals with no CAT vice the '75 which had a Y pipe to a CAT to a single pipe split in the back to appear like duals. The no CAT and true duals will get you some extra horsepower....... Not sure what the laws in NY are..... just my 2cents The car isn't blue in color by any chance is it ?? My cousin owned one in NJ back in the early '80s (garage kept) and sold it in '86. Enjoy your new ride.........