[t walgamuth]

I am buying the 65 with the tri power 338 hp engine with 10.75 CR. What are folks using for gasoline in one of these beasts?

[ponyakr]

The best we got around here is Shell 93 octane. With a true 10.75 CR I wouldn't feel safe with this gas unless I mixed in some race gas. I think the most common around here is 108 octane.

I ran a 455 bracket engine, with #215 heads, which had to be over 11:1 CR. I mixed about 1/3 108 race with 2/3 93 Shell. Ran good--no problems.

Probably wouldn't need that much for your engine. Maybe 25% race, or even 20%. You probably wouldn't want to use any more race gas than necessary, since it costs more than $10 a gal, in most places.

I don't know exactly how to figure what octane certain mixes will produce. I assume that info is available online. Anybody have the links to any sites with good info on this subject ?

[mgarblik]

Unfortunately, if the engine is mostly stock and untouched, it will not run well on any pump gas under heavy load/high rpm's. You can drive it on pump premium without damage but percolation/vapor lock/ lean surges are all part of the game with this crap. Leaving the engine stock, the best alternative will be to mix some leaded race gasoline with the pump gas. Since I have some readily available, it's no big deal for me. I mix about 10% 118 octane race gas which we use in the race car with pump premium and it runs like a completely different engine. All the driveability issue go away almost instantly. With typical race gas, 104-108 octane, you will probably need 15% or so for the engine to really run right. Adding a small, low pressure electric pusher pump from the tank to the mechanical fuel pump will help with the vapor lock/percolation issue you will probably have. Finding and using pump gas with the least alcohol possible will also help. Finally, having the distrubuter advance curve modified and limited for total advance to 32-33 degrees will tone down the full throttle detonation on just pump gas.
If you are just putting around town, it will run on pump premium. But if you want it to run right under power you will need to do this stuff. If you want it to run properly on just pump gas and no race fuel, you will need to get into the engine and reduce the compression to 9-9.5:1 and change the camshaft to get the power back from the compression loss. I would also install hard valve seats at that time if you are going to keep the stock heads. There are many things that can be done on a rebuild to make it run better than new on just pump gas, but they all involve an overhaul and different internal parts. If the engine is in good condition, a shot of race gas is the easiest and least expensive band-aid for this crap gasoline . ENJOY your new car. Race gas is no big deal.

I might add that running too much race gas WILL NOT hurt your engine. It just hurts your wallet. So start with say 10% and add a little till the engine runs properly. The high octane race fuel calms the potential detonation and and smooths and lengthens the burn time of the fuel. It is LESS volatile than lower octane fuel. If the ratio gets very high, too much race gas, say 50%, the engine may be slightly harder to start cold and may run poorly cold because of this. But it will not hurt anything or damage any parts.

[t walgamuth]

Thanks guys! The engine is low miles so I won't be doing anything to it except replace seals as necessary due to age. I can get race gas I think fairly easily so that is probably the way to go. I figured I'd need an electric pusher to avoid vapor lock based on past experience too.

[Stuart]

I run unleaded premium in my car without any issues, but I don't drive it hard either.

[bob d]

I use a gallon of race gas when I put in fuel. 1965 gto rebuilt stock. stopped pinging and dieseling. runs great. if you ever rebuild your engine listen to what these guys say. bob.

[64gp4spd]

I have been running AV GAS 100LL in my Pontiacs for 20 years without an issue. For the amount of miles I drive these cars per year it is worth the extra money. I do mix in 93 Octane Pump Gas as well probably around a 50/50 mix.

[Engine-Ear]

While I too have used gasoline blended for aviation (so called "AvGas"), people smarter than me have made the case to not use it because the specific gravity of AvGas can differ enough from on-highway gasoline and carb rejetting may be needed.

I can't vouch for the complete accuracy of this article, but it gets to matter:
http://www.ktm950.info/how/Orange%20...c_gravity.html

[Engine-Ear]

...seriously!

https://en.wikipedia.org/wiki/Water_...n_%28engine%29

This can buy us some anti-detonation headroom for the '60s Pontiac engine with OEM compression levels.

[mgarblik]

I used a water injection set-up from Thompson Products around 1980. Thompson was the T in TRW. I used it on a 1966 Ventura with a high compression 389 2bbl. engine. It did help with "ping" or detonation way back then a little. I could run 3-4 degrees more timing with it than without. Race gas is easier and less hassle for me today. My fondest memory of that car was that pale yellow 4-door Ventura beating a guy that had just bought a new 1979 Corvette at the drag strip. I still have the picture of that huge 4-door with a little 2BBL 389, 6-8 lengths ahead of the Vette at the finish line. He barely fit in the same frame. The guy was so pissed he was screaming about how it was going back to the dealer first thing Monday. Man those mid-late 70's cars were slooooow.

[Hitman]

I drove a 65 Bonneville last weekend. A untouched car with 105k miles on it. The owner said it had 5 month old gas in it. We stopped and put some 93 in it and took it out on I-40 and ran the crap out of it up and down the interstate. Not one ping, knock or even hesitation. The car pulled off the line like it had fuel injection. I'm going to drive a 66 Bonneville tomorrow, hopefully it will be as good of a driver.

[Ben M.]

I drove a 10.5:1 '67 400-4bbl that was worn for a while and it did ok on California gas, a little bit of power loss going up the Sunol grade but no audible knocking on the streets or freeway (the lady I sold it to flogged the hell out of it on the test drive and it didn't flinch either). I would say if you're not going to beat on it you'll be ok, especially if the engine has been driven semi-regularly and doesn't show any signs of junk in the oil and filter.

[mgarblik]

I saw the OP was in Indiana before I made my first post. Lots of alcohol in Indiana and Ohio gas where I live. The alcohol causes more sags, hesitations and general damage to the fuel system than the lack of octane. The vapor pressure is much higher too. This causes vapor lock. Try straight 93 and see how it runs. If you head any audible ping, you need to deal with it ASAP. Enjoy your car.

[t walgamuth]

Yeah, I bought the car today. On the test drive it really did not run all that well but it seemed fuel related. It was in South Dakota so that is where the gas came from. I think I'll get a nice load of racing or av gas so that I can get the secondary carb bowls filled with something that won't gunk up.

I don't plan to run it hard all that much but never know, might want to go to the pure stock drags and see how it does.

Its a lovely 28,000 mile car that is in astonishing original (mostly) condition. Great carpets seat and dash. The radio sounds wonderful, though it appears just an AM. The clock does not work. It has an 8 lug spare but I did not see a jack. Where would it be?

I'll want to go through it and replace fuel lines and such so its reliable. I expect to have to install an electric pusher pump to combat vapor lock.

It has these wonderful looking narrow whitewall michelin tires (how old must they be?). It has a thumpy tire or two and pulls hard to the left on braking. The clear plastic steering wheel is in perfect condition. The original looking shocks are knackered. New exhausts.

Interesting specs....tri power, posi, 8 lugs, crank windows and power seat...no aC....oh yeah...SD has 80 mph speed limit on the interstate. Lots of straight flat roads out there.

It fit into my covered Haulmark trailer with a couple of inches to spare each side, but I had to climb out the windows...no inconsequential trick for this stout grandpa....glad its a four door hardtop!

Lovin it so far.

I'm near de moines now. I'll post pics when i get home....turquoise bottom white top.

I'll be dozing off with a smile on my face tonight having Bonneville dreams!

[Engine-Ear]

EXCELLENT update, T!

Yes, Pics!

[stevep]

The jack is supposed to be under the spare tire.

[Heybuck]

This car as you describe it sounds remarkably like a car I was soooo close to buying a year or so back. Owned by a really nice guy in Idaho ( I think). He had it on eBay, and I was negotiating with him to buy it, pay in full for it and he agreed to store it for 9 months.

Seller was a Funeral Home operator out in the sticks somewhere. He had a very nice collection of Pontiacs, which he was selling to raise some capital. A friend of ours bought his '67 Bonneville 4 door HT which is out here in Australia now.

I was buying the '65 Bonneville in partnership with a mate of mine and I was ready to hit the Buy it Now button when it just disappeared from the screen. A specialist dealer had just hit the button before me. Could not believe my bad luck. I just spent some time trying to find the pictures of the '65 Bonneville he was selling but can't find them.

I do recall the sellers eBay name is dembowski. Interested to know if its the same car?????

Ian

[Heybuck]

Originally Posted by stevep

The jack is supposed to be under the spare tire.

Isn't it on the ledge up over the differential and hidden by the spare wheel and the base of the jack is held down by the tire???

[t walgamuth]

This is all I have handy at the moment. I'll post more later.

[t walgamuth]

Originally Posted by Heybuck

This car as you describe it sounds remarkably like a car I was soooo close to buying a year or so back. Owned by a really nice guy in Idaho ( I think). He had it on eBay, and I was negotiating with him to buy it, pay in full for it and he agreed to store it for 9 months.

Seller was a Funeral Home operator out in the sticks somewhere. He had a very nice collection of Pontiacs, which he was selling to raise some capital. A friend of ours bought his '67 Bonneville 4 door HT which is out here in Australia now.

I was buying the '65 Bonneville in partnership with a mate of mine and I was ready to hit the Buy it Now button when it just disappeared from the screen. A specialist dealer had just hit the button before me. Could not believe my bad luck. I just spent some time trying to find the pictures of the '65 Bonneville he was selling but can't find them.

I do recall the sellers eBay name is dembowski. Interested to know if its the same car?????

Ian

Could be the one. How many tripower eight lug cars are out there anyhow? Surely not many.