Looking for 1969 Pontiac help

[=diego=]

I'm trying to find out more about the L83 engine that seems to have been a 370-horsepower 428 that was available for police duty. 

 

I have AMA specs for B-body Pontiacs but nothing in there features this engine. 

 

This engine appears to be a hybrid of sorts between the L79 428/360 and the L75 428/390, but I could be wrong. One source shows it to be 360 horsepower, while Pontiac's "special equipment" page (which also included trailering) shows it to be 370; the latter also shows it to have 10.75 compression.

 

Anyone have any info that shows some technical stats? Thank you!

[Aaron65]

These guys are pretty knowledgeable; maybe they can help...

 

http://forums.maxperformanceinc.com/forums/index.php

[=diego=]

One step ahead of ya already....

 

http://forums.maxperformanceinc.com/forums/showthread.php?t=806799

 

And no dice so far. 

Edited August 25, 2017 by =diego= (see edit history)

[padgett]

L83 is further down the page, lines 8 & 14: code XK with M40 automagic, 370 hp 3.08 axle or 3.23 (NA w/air). You will find more under "XK" than L83. HP changed daily according to the marketeers in that era.

 

Seems to be more of a street engine than something "more", note that it uses a stock distributer (not the hardened gear or 60 psi oil pump). Does this help:

 

Edited August 26, 2017 by padgett (see edit history)

[=diego=]

1 hour ago, padgett said:

L83 is further down the page, lines 8 & 14: code XK with M40 automagic, 370 hp 3.08 axle or 3.23 (NA w/air). You will find more under "XK" than L83. HP changed daily according to the marketeers in that era.

 

I already saw that, but what I'm not finding is the distinction between the L83 and the 428s available to the general public.

I do appreciate the image you posted and it does help somewhat, but what's your take on the L83? It's like a super-duper L79 428 but not quite an L75 428 HO?

[padgett]

As I said, a decent street engine but does not have the hardened gear distributer with 60 psi oil pump relief (stock is 40) and has the 067 cam, not the 944 or 041 (which would need the HD valve springs). I'd say a decent mid-range for  all day high speed cruising with an automatic and AC but not anything that would go past 5,000 rpm or surprise people at the drag strip.

 

As to the hp, in 69-70 they had the exact same engine in three different cars all rated differently. They also had two quite different engines rated exactly the same in the same car line. You really need a scorecard to keep track. 

[8E45E]

Diego,

 

Are you now writing a book on high-performance engine-equipped police cars?

 

If so, don't forget to include Canadian Pontiacs from those years!!

 

Craig

[lump]

Can't speak with authority on Pontiacs of that era, but for Chevrolet engines it was common to list different horsepower ratings where there was actually little or no difference. For example, Corvettes used different exhaust manifolds than Camaros, which supposedly breathed better. But I sat in Chevrolet corporate offices talking with some of the top PR people who had been there "back in the day," when I was researching books and magazines that I wrote about Chevy engines and Chevrolet muscle cars. They pointed out that they weren't going to rate the top Camaro engine with exactly the same horsepower as their flagship performance car, the Corvette, regardless if the engines were identical. 

 

Sometimes there was a slightly different cam, sometimes different exhaust manifolds, sometimes nothing more than a decision being made for marketing purposes. 

[padgett]

That was in the period when Chev also was quite creative particularly with engines that had to be available to the public but they really only wanted racers to buy. Perhaps the most famous was the L88  (430 hp advertised) while the top L-71 tripower was 435hp. Or the Camaro SS-350 L-48 was 295 hp while the Z-28 was rated at 290 hp. The key I used back then for spotting an interesting engine was N/A C60 (not available with air conditioning) though the option price (ZL1 was a $3k option on a $2995 car) or lack of a warranty was another.

 

Was also the period when there was yet another set of engines that had aluminum blocks and "no relationship with the 427 exists", the 430-465-495 cid. Of course you had to be on Vince Piggins list to get the green sheets.

[=diego=]

On 8/28/2017 at 6:09 AM, 8E45E said:

Are you now writing a book on high-performance engine-equipped police cars?

 

 

Sorry for the late reply – was on vacation and will be playing catch-up with the other posts as well. (I was in Victoria, BC yesterday and saw a '66 Parisienne ragtop among several Beaumonts and Acadians too!)

 

Anyway, working on an article for Don Keefe's Poncho Perfection magazine on 428s based on production info I scored from the GM Heritage Center.

[8E45E]

Diego,

 

I hope you enjoyed Victoria!  I plan to retire there in the not too distant future.

 

Will you be at MCACN again this November?

 

Craig

[=diego=]

Yeah, I'll be in MCACN unless my wife spends all my money. 

 

Need more time to respond to the others....

[=diego=]

On 8/28/2017 at 8:07 AM, lump said:

Can't speak with authority on Pontiacs of that era, but for Chevrolet engines it was common to list different horsepower ratings where there was actually little or no difference.

 

Trying to catch up now.....thanks for your input.

 

But I'm curious what engines you are thinking of where Chevrolet had different horsepower ratings?

[lump]

For example, the 1970 Z28 Camaro came with a high performance 350 cubic inch small block engine. It was rated at 360 horsepower. The 1970 Corvette also had a high performance 350 engine that year, which carried the designation of "LT-1" (SIDE NOTE: The name "LT-1" is commonly applied to 1970 Z28 engines, but GM only applied that term to Corvette engines, as far as I know). The Corvette LT-1 was essentially the same engine, but rated at 370 horsepower. The only real difference between those two engines I am aware of is different exhaust manifolds.

 

Yet years ago when I was writing books and articles about Camaros and other high performance cars quite often, I was blessed with access to many GM execs, and allowed to search through the Chevrolet archive files all day long, on several occasions. I enjoyed finding old memos back and forth from GM execs, discussing their opinions of various brand new models, "back in the day." During this time, more than one GM exec smiled and pointed out quietly to me that GM wanted to rate the horsepower higher in Corvettes, for obvious reasons. 

 

 

 

[1912Staver]

Victoria is a very nice place. I am there for any where from a week to a month many winters while the Ferry I work on has it's maintenance drydocking.  Quite a bit more liveable than Vancouver.  I hope you bought a place 5 or 6 years ago , assuming you aren't planning on renting.  The real estate bubble is in full swing.  How high can it go ? Makes almost any collector car seem a bargain . 

 

Greg in Canada

[=diego=]

Lump:

 

I completely forgot about the LT1......I must've stopped at 1969 as I was thinking the L79 had different hp ratings in 1967-68 but I think the ones installed in Chevelles and Chevy IIs featured downgrades compared to 1966 (although strangely not available in the Chevelle that year, prob due to the introduction of the 396). But don't you think the exhaust manifolds could make a 10-hp difference?

 

Otherwise, I am unsure if there was a Corvette with a higher hp rating for a +/- identical engine.

 

Regarding LT1 terminology, I believe it was the ordering code (much like L79), and that engine was an option for the Corvette; in comparison, the engine was not an option for the Camaro but rather part of the Z28 package (also an ordering code).

[padgett]

There were a lot of games played by GM in that period. Chev usually derated engines they did not want the general public to buy. Meanwhile Pontiac would rate the same engine three different ways depending on the car line or the trans (well the QJ on the Firebird 400 had a bendable tab to limit the throttle opening) or put a higher performance cam in a stick car but rate it the same as a lower performance cam with an automagic. And then there was the round port RAIV that was rated 4 hp higher than the D-port RA (was no RAIII).

 

Back then a better indicator of an interesting engine was "not available with A/C" (C60).