69 Grand Prix Info Please

[Guest Bob Call]

I know that the 69 GP's came in three option/trim packages. The base was the Model J with 400 CI engine and 3 speed manual trans with option for 428 CI and TH400 auto. The model SJ came with 428 CI and 4 speed or TH 400. 428 was available in 370 and 390 HP. 455 CI was option. What was the difference between the Model SJ and Model LJ ?

[Guest]

I know that the 69 GP's came in three option/trim packages. The base was the Model J with 400 CI engine and 3 speed manual trans with option for 428 CI and TH400 auto. The model SJ came with 428 CI and 4 speed or TH 400. 428 was available in 370 and 390 HP. 455 CI was option. What was the difference between the Model SJ and Model LJ ?

the SJ was the big engine option and the LJ is a luxury option. In 1969 there is NO 455 engine. In 1970 the 428 is bored and stroked to a 455, and if you do the math the Pontiac 455 is really a 456 just like the Pontiac 350 is not a 350. It's a 354.74 or a 355 rounded up.

[PONTIAC1953]

i used to have a 1969 grand prix model j that was special ordered with the 370 horse 428 engine. charles coker, 1953 pontiac tech advisor.

[padgett]

The 428 was a fine engine though I prefer the 400, had a '70 GP 400/4speed, are a few four speeds and even fewer three speeds around. Most had the THM400. The '70 455 long stroke engine had a terrible reputation for a weak bottom end. It was much improved as the 455HO in 71 and the 455SD in 73 but few wanted on in 71 (were about 56 4 speed GPs in 71).

Delorean said he wanted a longer hood than the Mark III and got it.

Manual transmission cars used mostly A-body (Tempest/GTO) components, only two pieces were GP-specific, the console top plate and the ash tray.

[Guest]

You would think from the above thread that all 455 Pontiac engines with the exception of the H-O and the SD are a bad choice. The fact of the matter is that most 455 Pontiac's that are raced are of the garden variety, my 70 455 included. My car is especially set up for Grand Touring which means high speed for a prolonged time out on the track. If you set the engine up properly and drive the car or use the engine within it's design parameters the engine will live with no problems...Even the two bolt main engines.

Case in point. Many people give the old air cooled VW engines of 1100, 1200, 1300, 1500, and 1600 a bad mark for longevity. But the fact of the matter is most people never drive or maintain them properly. Those engines require a oil change every 1500 miles, a valve adjustment every 3,000 miles, must be warmed up sufficiently before being driven off (just like any air cooled airplane piston engine), and the engines must stay in the proper engine RPM band ( just like any airplane piston engine). That means no lugging below 2,000 and no revving beyond 3,800 and a few other little things I won't mention for space, but if you do those things they will last an enormous amount of time.

The Olds 400 engine from 1968 and beyond had a terrible reputation for blowing out bottom ends, why? Because the 1965-1967 400 engine was a tall deck short stroke Gen 2 engine. In 1968 Olds introduced the 455. Olds figured they could save money by using the 455 crank in the 400.... so the 68 400 uses the 455 crank and was now de-bored to give 400 inches. The problem was people revved the engine like the old short stroke 400 and blew them up. If you drove the new Olds 400 and used the engine within it's design parameters the engine will live with no problem. This holds true for the Pontiac 455 as well. It's a TORQUE engine and it's torque is made in the bottom and mid range rpm band. That's where it makes it's power and that is where you want it to be if you want it to live. If you treat it like a 400 Pontiac it will not only not make the power you want but it will break prematurly.

Edited July 11, 2013 by helfen (see edit history)

[padgett]

Sorry, thought I was specific that the problem was with the '70s and fixed for '71 but it took a while for confidence to be restored. Personally I have a problem with strokes over 4" but that is me. Chevvy had the same problem with '67 350s.

[mdh157]

Does anyone have the production breakdown by engine and trans? I want to specifically know the breakdown of 428 HO cars by trans and trim level. I know of a guy who has a '69 400 for sale. Any ideas on what a fair price might be? will prob need both lwr qtrs and 2 small patches in the floors, not sure if the trunk needs patching or not.

Edited May 12, 2014 by mdh157 (see edit history)

[Guest]

Does anyone have the production breakdown by engine and trans? I want to specifically know the breakdown of 428 HO cars by trans and trim level. I also know of a guy who has a 69 400/3 speed hurst for sale, runs and drives but needs a resto. Any ideas on what a fair price might be? will prob need both lwr qtrs and 2 small patches in the floors, not sure if the trunk needs patching or not.

The only information I have is that 1,014 69 GP's were built with stick shift and approx. 676 were four speeds.