[77GP]

My 74 I bought a while back has a 91 octane sticker on the radiator cover panel. Its hard to get 91 around here. Seems like most have 87-89-93 but I did find it at one place. Why does it require 91? I have ran all different octanes and can't seem to tell a difference. Does anyone use a lead additive, if so Why? Just curious on this. It has a 400. Thanks

[rexs73gto]

Your car was designed to use 87 oct. gas. Your only wasting you money by using 91. You also don't need a lead additive as the heads on the 71 & newer engine all have hardened seat on the valve seat. All Pontiac's after 1971 were designed to run on low lead or no lead gas. I would say someone put that sticker on from a different year car. The last year that any Pontiac had a sticker on it saying it needed 91 or better octane would have been I think 69 & that would have been for the RA IV & 428 HO engines. All other used reg. gas.

[77GP]

Thanks Rex.

[77 Canamman]

Back in 1974, the pumps reflected a Research Octane number. Today, the number at the pumps is an Anti-Knock Index, which is an average of Research Octane and Motor octane. Today's 91 might be a bit overkill, but it will run fine on it. Properly tuned, the car should work ok with 87.

[north]

71 to 74 Pontiacs could run on regular unleaded (87) back in the day and today if they have clean combustion chamber but often older engines are carboned up and ping even with the gas they were built for. The problem is that you can't hear detonation (pinging) until its really bad.

[rexs73gto]

If you think you may have carbon on the valves or in the combustion chamber there an easy way to clean it up. You can take a spray bottle with just water or with a mix of water & rubbing alcohol & while the engine is running you spray right into the top of the carb. It will slow the engine a bit but it will sound like your throwing rock into the engine but what it's doing is breaking up the carbon. You can also buy some stuff that you add through your brake booster hose but thats a little expensive to use to. The water trick is what we used a long time ago when they got carboned up.

[Sirrotica]

Originally Posted by rexs73gto

Your car was designed to use 87 oct. gas. Your only wasting you money by using 91. You also don't need a lead additive as the heads on the 71 & newer engine all have hardened seat on the valve seat. All Pontiac's after 1971 were designed to run on low lead or no lead gas. I would say someone put that sticker on from a different year car. The last year that any Pontiac had a sticker on it saying it needed 91 or better octane would have been I think 69 & that would have been for the RA IV & 428 HO engines. All other used reg. gas.

Not true, my LS2 05 GTO has a sticker on the gas door that says "Premium unleaded recommended". Any of the supercharged 3800s Bonnevilles and GPs also required premium fuel and the lowest recommended octane is 91 octane.

The LT1/LS1 Firebirds used premium fuel as did the 6.2 G8s. Like it or not, these are also Pontiacs with corporate engines that are high compression and require premium fuel.

Yeah I've heard the tired old spiel about Pontiac not making cars after 1981, I however don't agree. My 05 GTO daily driver is a hell of a lot more fun to drive than the hondas, toyota, mopar/fiat, ford and whatever else doesn't have an arrowhead emblem on it that some of the other so called Pontiac people drive daily.

OP, it's true unless someone has done something to your 74 400 to modify it so it has other than factory parts and up the compression it will run just fine on 87 octane fuel. In 1971 and later there were a few individuals that thought they needed a higher compression ratio to be fast and transplanted earlier heads on the post 70 engines. If yours still has the factory issue heads/pistons, it will run fine on 87 octane.

[77GP]

Thanks guys, its factory with only 54K miles. Runs great now. Was just wondering about the whole 91 thing.

[rexs73gto]

Your right about one thing I did forget to say, The last time a REAL Pontiac had the 91 sticker would have been 1981, because after that they had chebby engine or buick engines in them so they don't qualify as real Pontiac's. But your correct those cars are not real Pontiac's they only pretend to be by PMD having to put Pontiac emblems on all those wanna bee's.

[Sirrotica]

Originally Posted by rexs73gto

Your right about one thing I did forget to say, The last time a REAL Pontiac had the 91 sticker would have been 1981, because after that they had chebby engine or buick engines in them so they don't qualify as real Pontiac's. But your correct those cars are not real Pontiac's they only pretend to be by PMD having to put Pontiac emblems on all those wanna bee's.

Rex, those are just regurgitated words, not the facts.

And your daily driver is what?

If you quit buying Pontiacs as of 1981, you surely missed some of the best cars the division made. I know full well your not driving a 73 GTO everyday as a daily driver because there would be nothing left of it.

I currently own a 73 T/A, have previously owned two 73 Grand Ams, as well as a 455 73 GTO, and 73 Luxury LeMans so I know how the bad metal in these cars rusted when driven everyday in a rust belt environment. Due to the poor quality sheet metal GM used in 73-74, these cars rust even when stored inside a dry building.

Plenty of room in my garage, as well as my mind, for new as well as old Pontiac muscle. I own both, and happy I do.

FYI, the LS engines are NOT chevy engines, they are true corporate engines made and designed by GM Powetrain division. Chevy as well as most of the other divisions have not had their own engine family for 20+ years now. Pontiac has used the SBC design until 1998 model year whereupon they started installing the LS V8 in their cars. The 3800 Buick design was the last holdover from GM division designed engines, and was dropped in 2008.

There are NO division architecture engines left being manufactured and installed in GM cars. GM Powertrain has manufactured their own engine designs exclusively for 9 years now. There hasn't been a chevy designed V8 installed in a GM car since 1997.

If your going to deride the post 81 model Pontiacs, at least get your facts correct on what engines reside under the hood, as well as what part of GM makes, and engineered them.

All the cars in my stable have red arrowheads on them so I actually drive a Pontiac everyday, not just during the summer. The only vehicles in my stable that aren't Pontiacs are my S1600 IH wrecker 7.3 IH diesel engine, and my 93 K3500 stake body, powered by a 6.5 turbo diesel designed by Detroit Diesel. If Pontiac made trucks I'd drive one of them.

I hope you never get behind the wheel of a late model GTO, G8 or a T/A, you might actually like the way they perform, if you ever drove one. There are plenty of people on PY that own old GTOs/T/As as well as late model GTOs/G8s/TAs, and love them both.

C Cass (PY founder) http://gtog8ta.com/, as well as the Butlers have started embracing all of the performance Pontiacs, new and old because they can no longer sustain their businesses just pandering to the pre 81 Pontiac cars and owners. Butlers have recently started building and selling LS parts and engines http://butler-ls.com.

Jim Wagners is an acquaintance of mine, Jim has signed under the hoods of many late model GTOs re-affirming these are "Real GTOs/Pontiacs" even if the owners of the older cars don't acknowledge it.

[rexs73gto]

For me your just spitting in the wind. If your lucky enough to have a lot of older Pontiac 's thats great. But yes for the last 43 1/2 years I have driven my 73 for most of the year , up until the time the weather gets to bad to drive it. When it starts to rain & such it goes away for the winter. I have driven all the cars your talking about & yes they do drive great. I am a retired GM service mgr. & your almost correct on the LS engine. Chevy does claim that engine as there own & i have a lot of old paperwork for when I did work that say just that. Yes GM power train builds the engine but Chevy claims it & every GM dealership will tell you you the same. Chevy is very proud of the LS engine as they should but Chevy engineers designed & built the 1st LS engines & then they built the GM power train plant to build them in that building. The newer cars are good but I am a real Pontiac guy & drive Pontiac with Pontiac engines, built by Pontiac. If others want to have those engine in their car then it's fine, but it's not for me. Plus if Chevy wouldn't have cried to GM corp. about the 301 , the TRUE designed 301 it would have been around a long time. Mac Mceller's true designed 301 engine was actually built as the Twin Turbo with the forged crank & rods with the HP ratings it would have had it would have been built today. But Chevy complained that if Pontiac was to build it any car with that engine would have been faster then their flagship corvette. The true 301 was going to have an est. output of 400+ hp. which scared Chevy, & still get 25 mpg's . But enough of that , New cars are fast & good drivers & they last in the winter too now. But your again just spitting in the wind when you talk to a real Pontiac guy or gal, & I worked in GM dealerships for 33 years.

[red1975pacer]

Ive never had any problems running 87 octane in any of the cars ive owned, Grand Nationals, Mustang GTs, 70-72 Monte Carlos {Big blocks} Trans ams, 77, 78 79 , GT0's, ect ect ect. Even my 2000 Trans Am Ram Air would probably be ok with it

[Held for Ransom]

Here's the doc.

[Sirrotica]

Originally Posted by rexs73gto

For me your just spitting in the wind. If your lucky enough to have a lot of older Pontiac 's thats great. But yes for the last 43 1/2 years I have driven my 73 for most of the year , up until the time the weather gets to bad to drive it. When it starts to rain & such it goes away for the winter. I have driven all the cars your talking about & yes they do drive great. I am a retired GM service mgr. & your almost correct on the LS engine. Chevy does claim that engine as there own & i have a lot of old paperwork for when I did work that say just that. Yes GM power train builds the engine but Chevy claims it & every GM dealership will tell you you the same. Chevy is very proud of the LS engine as they should but Chevy engineers designed & built the 1st LS engines & then they built the GM power train plant to build them in that building. The newer cars are good but I am a real Pontiac guy & drive Pontiac with Pontiac engines, built by Pontiac. If others want to have those engine in their car then it's fine, but it's not for me. Plus if Chevy wouldn't have cried to GM corp. about the 301 , the TRUE designed 301 it would have been around a long time. Mac Mceller's true designed 301 engine was actually built as the Twin Turbo with the forged crank & rods with the HP ratings it would have had it would have been built today. But Chevy complained that if Pontiac was to build it any car with that engine would have been faster then their flagship corvette. The true 301 was going to have an est. output of 400+ hp. which scared Chevy, & still get 25 mpg's . But enough of that , New cars are fast & good drivers & they last in the winter too now. But your again just spitting in the wind when you talk to a real Pontiac guy or gal, & I worked in GM dealerships for 33 years.

You're a youngster if you only worked 33 years in the automotive field, I have 12 years on you.

chevy never engineered, designed or built anything on an LS engine, it was built from a clean sheet of paper using all the best division engine concepts from all the former V8s. GM Powertrain did all the work from engineering concept to execution of building it.

It shares the small block bore spacing and not any other parts or features with a chevy engine. Not sure where you get your information about LS engines, but most everything I said is in print for anyone to research on the internet.

chevy fans would like to take credit for the world class pushrod LS V8. Fact is chevy buys LS engines from GM Powetrain, same as buick or cadillac does. chevy does not have enough talent in their whole division over the last 60+ years to design and build anything close to the LS engine. Anyone that gives chevy engineers that much credit for designing that engine needs to read up on who actually deserves credit for the LS engines, it surely IS NOT chevy.

Real Pontiac guy LOL, that has to be the funniest quote on PY. Often heard, but rarely proven. They own an old car that happens to be a Pontiac driven 1000-2000 miles a year, and drive anything but an Pontiac vehicle 365 days a year, honda toyota, ford anything but a Pontiac.

Your daily driver is? never answered that question "REAL" Pontiac guy.

301-265 now there's a real powerhouse that rarely ever lasted 75,000 miles with immaculate care. Owned one in a 78 GP, and have worked on dozens of them. The turbo birds 80-81 couldn't even beat a NA 400 in the same car. Sorry, I don't share any excitement when 301-265 Pontiac V8s and performance are mentioned in the same sentence.

Just a FYI I've owned and driven Pontiacs since 1969, last count was roughly 65 different Pontiacs. I'm still driving them today and currently own 4 of them. Oldest one owned was a 56 chieftan, newest one is a 2008 Vibe, 2 Fieros thrown in there too.

I started racing them in 1970 at a local dirt track and raced them until 1982. I was quite successful as an owner builder and driver. I've sponsored numerous Pontiac dirt cars as well as drag cars. I raced 3 different T/As in autocross and won the SCCA Misery Bay region in C/Prepared in 1980. I designed and sold Pontiac t shirts (Indianhead Acres Pontiac Tees) from 2005-2012 very successfully.

Look at the picture in my signature, It's my 69 428 SJ Grand Prix dirt car, in the background you'll see the service station/garage I owned in the 70s and early 80s. Do you see any Pontiacs on that lot? My 1973 Jeep wrecker was powered by a 455 Pontiac and I've personally re-powered 4 jeeps with Pontiac V8s, 350, 389, 400, and 455s.

My father was the man that got me started on Pontiacs in the first place, he turned wrenches as did my grandfather at guess where? The local Pontiac dealership starting in the late 30s.

Please explain to me what a "REAL" Pontiac guy/gal is again, I guess I must miss the criteria ? I'll try harder though!!!!!!

[Sirrotica]

For the doubters that still believe an LS GM Powetrain corporate engine is a chevy, here's proof that GM Powertrain has trademarked the LS engine, NOT CHEVY.

[rexs73gto]

I don't have to measure up to you , but I to have had several, I've had 27 GTO's 5 birds 2 of which were T/A's & 6 different years of LeMans. But I'm not trying to compete with you. I only have 33 years in the dealer as I was in the Navy for 3 1/2 years & worked as a cop for almost 5 years to. I have a few other jobs in between but always found myself back in the dealerships. I grew up in them as my mother was the bookkeeper for a Chrysler , Plymouth, Imperial dealer for 20 years & then my sister married into the owners family. But thats then. Now being retired I still own just my 73 GTO right now & my daily driver is a Chevy Tracker because I live where it snows a lot. The most at one time I have had 7 Pontiac's in my yard or garage. Again I said the real designed 301 not the one that they were forced to let out the door. Evidently you only read what you wanted to as do most that want to make their opinion the only one. My info came from GM when it was happening & now all the info is GM power train did it all. Propaganda , That is was in response to the problem they had in 78-9 when Olds started putting chevy engine in the Olds 88 & 98's. But as you seem to know all you won't listen to any thing other then the stuff thats out there now. Also for your info so you know I have been driving Pontiac since 1971 with my very 1st Pontiac being a 69 Bird after having mostly Plymouth, again because of the family ties with them. Also if you read my previous post you will see I said that the chevy engineers designed the LS , & yes it says that GM power train got to claim it, but look into the original design & you will see who designed it. It's all one family . So it doesn't seem to matter who gets the credit other then who designed it & who claims it .

[Sirrotica]

It's a free country (for the time being), you can believe whatever you want to.

If you have the paperwork you claim you have, just post it up here for all to read. I deal in facts, not hearsay or opinions. Maybe the people that have documented the history of the origination of the LS engines have it all wrong.

Have a nice day.................

[mrrat1]

regular gas is good enough, happy cruising the 74'

[77GP]

Well I went back to the 87 octane for a while and it suffered a little run on or whatever you want to call it when I shut it off. Back to 91 and no issues. I will stick with the 89 or 91. Thanks for all the input.

[Sirrotica]

Nine times out of ten run on is caused by the idle being set too high, higher octane gas is just a band aid for the root problem.

This is why the factory used idle stop solenoids, when the ignition was shut off the carb butterflies closed tight to stop the engines fuel flow, effectively stopping the engine immediately.

The older cars have two curb idle adjustments, a higher RPM one when the idle stop solenoid is energized and set with the plunger on the solenoid. It also has a lower idle speed when it is when the ignition is shut off de-energizing the solenoid. The lower one is made using the idle stop screw on the carb linkage. to stop dieseling (run on) they must be set correctly.