[oldman66gto]

Hi, New Member.

I just bought a '66 GTO and have a couple of questions. Only had it a couple of days, so still learning what I can about it. All documentation was supposedly lost when the original builder passed away, & wife inadvertantly threw them out. (What I was told) Am trying to figure out what's best for it, at this time.

1) Do you use engine oil with a "zinc"? Such as Valvoline "VR-1", or Shell Rotella "T-4" or "T-6", or Pennzoil "high mileage conventional", or maybe Amsoil "Z-Rod"?

2) I ask, because this car is about a 10 year old restoration, but has a 428 in it, & I'm not sure of the engine internals, i.e., a flat tappet, or roller tappet cam. Older flat tappet cams are seemingly recommended to be used with the "zinc" content oils to prevent premature wear on cam lobes, & lifter bottoms.

3) It has a bit of a rumpity-rump cam, but not sure what! Runs smooth, starts right up, no "pinging" (has HEI ignition), & performs fine, so far.

4) Is there a better "93 Octane" premium gas to run in it? Seems Shell "V-Power" is about highest rated, then BP "Ultimate".

5) Your opinion of premium "ethanol" gas, vs a "non-etahanol" gas?

I look forward to the Pontiac "Forums"

Thanks,
Allan

[ZeGermanHam]

Congrats on your acquisition of one of the coolest cars ever built!

Use an oil with zinc in it, such as Valvoline VR1, Lucas Hot Rod, or Amsoil Z-rod.

For gas, I prefer to use fuel with NO ethanol because these cars can struggle with fuel boiling in the carb bowls and any amount of ethanol in the gas will significantly reduce the boiling point. I run non-ethanol 92 octane in my GTO. If you don't have easy access to non-ethanol gas, just use a top-tier premium octane. Shell, BP, Chevron, etc., are fine.

[mgarblik]

You will probably get dozens of opinions on gas and oil to use in your car. I can only relate what has been working fine for me in dozens of cars/engines over the past 20 years or so without wasting allot of money on "designer fluids". Valvoline VR1 is readily available everywhere, moderate cost and has enough zinc for flat tappet or roller cams. Fuel wise, I much prefer any fuel WITHOUT alcohol in it for any engine with a carburetor. The only slight problem is at least in Ohio, 91 octane is about the highest rating you can get alcohol free at the pump, Marketed here as "recreational fuel" If your engine will run on 91 octane without a hint of detonation, I would use that. If that is a concern, then your locked into 93-94 octane fuel with alcohol. You will probably need to replace all your rubber fuel hoses and rebuild the carburetor with alcohol compatible rubber parts to avoid trouble at some point in the near future, unless already done.

Should have started my post by saying congratulations on your 66 GTO purchase. One of my favorite models. Checks off ALL the boxes for a classic muscle car.

[Green Elephant]

You could run a compression check to see what your compression is and that might shed some light on your fuel requirements. It would also give you an idea of the cylinder to cylinder health of the engine.
Congrats on your purchase, I think the 428 is one of the best engines Pontiac made.

[steve25]

Do a compression test now just so you have it documented and can reference back to those numbers if need be.

What is the two letter block code on the passenger front of the block.
This code will tell you if it’s a 2 bolt main block or a really nice to have 4 bolt main block.

1967 codes could be WG, YY, WH,W2, XD, WJ, XK, WK,W3,
Codes WJ thru W3 would have had high performance exh manifolds.

1968 428 block codes.
WG, YH, WJ, Yk.. the last two codes would have had high performance exh manifolds and all 67 and 68 blocks where 4 bolt main.

1969 block codes.
YL, YH, WG, XK, XE, XJ, WJ, WJ, YK, WF, XF, WL, XG..

All but the YL and YH blocks had 4 bolt mains.

The WJ. YK, WL, XG blocks since they where the 390 HP models all had the high performance exh manifolds, but in 1969 the 370 HP models might have had them also.
I would have to dig out my notes on that .

The two main blocks would have had the Casting number 46 heads with small valves and pressed in rocker studs.

[oldman66gto]

Here in Florida, We can get 93 octane nost anywhere. However "non-etanol" is not as readily available.
Since the car was deleivered on "E" (and not everlasting), I went to the closest station, a Racetrac, and put 93 octane in it.
Previous owner said he ran that in it with no pinging, or ignition issues.
Am going to look for a "non-etanol" station, somewhere close by.
Thanks!

[oldman66gto]

Originally Posted by Green Elephant

You could run a compression check to see what your compression is and that might shed some light on your fuel requirements. It would also give you an idea of the cylinder to cylinder health of the engine.
Congrats on your purchase, I think the 428 is one of the best engines Pontiac made.

A "compression" test is in its future, as you said, may shed some light on the fuel situation, and hopefully will give a good indicator of "engine health"

Car seems to be about an 8 year old restoration. Odometer shows 11,272 miles, & am thinking/guessing, original builder reset it to "0".
The car looks almost like new! I think I was very fortunate to get such a quality rebuilt car.

Thanks,
Allan

[oldman66gto]

Originally Posted by steve25

Do a compression test now just so you have it documented and can reference back to those numbers if need be.

What is the two letter block code on the passenger front of the block.
This code will tell you if it’s a 2 bolt main block or a really nice to have 4 bolt main block.

1967 codes could be WG, YY, WH,W2, XD, WJ, XK, WK,W3,
Codes WJ thru W3 would have had high performance exh manifolds.

1968 428 block codes.
WG, YH, WJ, Yk.. the last two codes would have had high performance exh manifolds and all 67 and 68 blocks where 4 bolt main.

1969 block codes.
YL, YH, WG, XK, XE, XJ, WJ, WJ, YK, WF, XF, WL, XG..

All but the YL and YH blocks had 4 bolt mains.

The WJ. YK, WL, XG blocks since they where the 390 HP models all had the high performance exh manifolds, but in 1969 the 370 HP models might have had them also.
I would have to dig out my notes on that .

The two main blocks would have had the Casting number 46 heads with small valves and pressed in rocker studs.

Hi,

Did some research and it is "WG", numbers 9786135, stamping by distributor is "K066", and has 670 heads, along with an Edelbrock intake & 4 bbl, and an "HEI" ignition system.
It coded out to be a "B"body, '67, 48, 360HP,4 spd, 4 bbl, & a 4bolt main block.
Also has "670" heads, & according to the previous owner has the "HO" exhaust manifolds. Not sure how to determine that.

Do you think you could double check, & make sure I'm correct.
Seems like Valvoline "VR1" would be a good oil for it. Your opinion?

Thanks for the help.
Allan

[grivera]

Congrats on a very cool car purchase!!

Where are the photos - we need to see it!

Post pics of the exhaust manifolds too.

[steve25]

Here’s what the HO exh manifolds would look like.

Part numbers for 1967.
9779493
9779495

[The Champ]

I live in MN where ethanol is very prevalent. When available, I will run pure gas, but it is not always available while driving around in MN/WI/IA (corn country).

I've been using E10 in my GTO for 30 years without any problems. Down in FL, you probably would never have to park your GTO for more than a month, so storage issues with E10 should not be a problem. When I park my toy cars (see list under my signature) for the season, usually some time in November, I add a can of Seafoam to prevent issues until I fire them back up in April.

Oil wise, I've chosen to go with the most readily available synthetic oil - Mobil1. Mobil specifically recommends their 15W50 or their 0W40 FS (foreign spec) oil for flat tappet cams. What i like about M1 is that I can easily get it almost everywhere around here. For lower prices, I sometimes go online.

Have fun with your new ride!

And we need PICTURES!!!

[oldman66gto]

Originally Posted by steve25

Here’s what the HO exh manifolds would look like.

Part numbers for 1967.
9779493
9779495

Appears the manifold # 9777848 (possibly a 6)
Can't get a decent picture, but at first thought they were shaped like the picture.
Oh Well, Thanks for the info.

Allan

[Tandyman]

Possibly 977646 and 977641 ?
https://www.thepartsplaceinc.com/pro...42-rh-pr/17641

Glenn

[grandam1979]

In Ohio Walmart has VR1 in 10w30 or 20w50 for $27.00 for a 5 quart jug.

[oldman66gto]

Originally Posted by Tandyman

Possibly 977646 and 977641 ?
https://www.thepartsplaceinc.com/pro...42-rh-pr/17641

Glenn

Must be 9777646, which would be the left side manifold.
As best I could tell, it looks like the picture.
If so, I think I'm fortunate to have them.
Thanks for your help! You guys are a "plethora" of information!
I wish I knew what the "Internals" all are, but danged if I'm gonna pull it apart to find out. runs too good, & looks to good to me to take it apart! And maybe, I'm just getting old & lazy

Again, Thanks, and appreciate the help!

Allan

[HWYSTR455]

Originally Posted by mgarblik

You will probably get dozens of opinions on gas and oil to use in your car. I can only relate what has been working fine for me in dozens of cars/engines over the past 20 years or so without wasting allot of money on "designer fluids". Valvoline VR1 is readily available everywhere, moderate cost and has enough zinc for flat tappet or roller cams. Fuel wise, I much prefer any fuel WITHOUT alcohol in it for any engine with a carburetor. The only slight problem is at least in Ohio, 91 octane is about the highest rating you can get alcohol free at the pump, Marketed here as "recreational fuel" If your engine will run on 91 octane without a hint of detonation, I would use that. If that is a concern, then your locked into 93-94 octane fuel with alcohol. You will probably need to replace all your rubber fuel hoses and rebuild the carburetor with alcohol compatible rubber parts to avoid trouble at some point in the near future, unless already done.

Should have started my post by saying congratulations on your 66 GTO purchase. One of my favorite models. Checks off ALL the boxes for a classic muscle car.

I religiously used Valvoline VR1 for many years, and then at one point switched to Rotella T5. Looking at the properties of a 'diesel' fuel, it's come to my attention that it would be better to use a regular gas engine automotive oil, and will be switching back.

There are other oils that would work fine too, there's a Pennzoil one that is supposed to be very good. But just to say, many say the newer additive packages have replaced zinc and are more effective, even in older HFT engines.

Agree too, purchase fuel from the top name-brand oil companies, they have standards for transportation, storage, and do regular contamination testing of station' tanks.

The standard is 'Top Tier' licensing, and you can research and search for Top Tier stations:

https://www.toptiergas.com/

.

[HWYSTR455]

Here's a sample of a search from TOP TIER for St. Augustine FL:

.

[Green Elephant]

If you had access to a bore scope you could drain the oil and take a peak inside the drain hole to see if you can spot a connecting rod. A windage tray might block a lot of your view if it’s a full length tray but I would attempt it just out of curiosity.