What's the best way to get 400+ horsepower with a GS400 motor.

**Dr. Frankenbuick** · 10-12-2012, 04:28 AM

The 67 GS has a ST 400 trans with a variable pitch converter. It is a nice trans (similar to the TH 400) and can be made to work nicely for performance applications. But, it was only available for a few years in the BOP bolt pattern and is rare like the 400 engine. I would pick up the other trans if you can. Then you have no worries about breaking a numbers matching part, and can hot rod it to your hearts content.

1 - $500 is a good price for the working cores.
2 - The 455 fits exactly where a 400 would and uses all accessory drives/wiring/plumbing of a 400. There is boundless information on 455 recipes: pick one and follow it to your desired HP.
3 - You can make well over 650 HP with ported iron stage one heads in a 455. You could look around for a used set (many have gone to aluminum for even more power) or send them to a respected Buick porter (like Greg Gessler).
4 - See above
5 - $300-$400
6 - You can go to 500 HP with no more then improvements to oiling, heads, pistons. These will need to be complemented with headers, exhaust, cam, and carburetor changes. You will need to look at block girdles, aftermarket studs, and high stall converters when approaching 600 hp, and it most likely will not run on pump gas.

**raycow** · 10-12-2012, 11:48 AM

I just now looked at the specs for the GS400 and the Doctor is absolutely right about the ST400 transmission. Of course it would have been a lot less embarrassing if I had checked before I posted.

Ray

**bob k. mando** · 10-12-2012, 12:23 PM

where's the comedy value in that?

also i think the small block GS actually did have the ST-300 trans, which would make you right, kinda.

http://en.wikipedia.org/wiki/Buick_G..._GS_California

**raycow** · 10-12-2012, 02:30 PM

I really should have known better, because I was around back then. A friend of mine bought a GS in 66 with the 2-speed automatic and he hated it. He asked me to help him swap to a 3-speed and it took a long time to find one. For 67, GM corrected their mistake and gave all of their big-engined A-bodies the 3-speed.

Ray

**Dr. Frankenbuick** · 10-12-2012, 03:36 PM

Who could bear the pressure of being right all the time? I know I couldn't. We just need to help one another the best we can. I learn here all the time.

**joshhirst13** · 10-12-2012, 04:49 PM

Damn you guys are good & you sure do know your Buick motors. So I'm going to try & pick up this motor & trans if it is what he says it is. One last question for now. At what point do you start going from pump gas to performance fuel. I'd like to get to that upper limit if pump fuel performance & leave it at that. I still want to be able to drive it around town.
Thanks again. You guys are all Legends in my mind.
Thanks,
Josh

**joshhirst13** · 10-12-2012, 06:34 PM

Hey Guys. One more thing. This is the post for the motor I'm planning on buying. "have a Buick 455 mated to a turbo 400 out of a 1970 Buick Electra was a running motor but the water pump froze on it and the water pump bolts broke off so the timing cover will need to be removed and the bolts will need to be easyouted I have the new water pump already and I no longer have the car so I don't need the motor 500 bucks its a complete motor"
Being that this is the case with the water pump should I still buy the motor. Is it hard to easy out the broken bolts? Also could the water pump sneezing cause major damage to the motor or is this really no big deal since I'm planning on tearing it all the way down anyways. Sorry if these are dumb questions but I'm still learning & I'm sure I always will be. Besides my dad always told me that there's no such thing as a stupid question. Ha ha. Thanks again guys for all of your help.
Josh

**pmuller9** · 10-12-2012, 08:14 PM

Originally Posted by joshhirst13

Hey Guys. One more thing. This is the post for the motor I'm planning on buying. "have a Buick 455 mated to a turbo 400 out of a 1970 Buick Electra was a running motor but the water pump froze on it and the water pump bolts broke off so the timing cover will need to be removed and the bolts will need to be easyouted I have the new water pump already and I no longer have the car so I don't need the motor 500 bucks its a complete motor"
Being that this is the case with the water pump should I still buy the motor. Is it hard to easy out the broken bolts? Also could the water pump sneezing cause major damage to the motor or is this really no big deal since I'm planning on tearing it all the way down anyways. Sorry if these are dumb questions but I'm still learning & I'm sure I always will be. Besides my dad always told me that there's no such thing as a stupid question. Ha ha. Thanks again guys for all of your help.
Josh

Josh

If the water pump was damaged by frozen water, then you would have to be concerned that any water in the block might have also frozen and cracked the block.
You would have to take the bare block in and have it Magnafluxed.

At what point do you start going from pump gas to performance fuel. I'd like to get to that upper limit if pump fuel performance & leave it at that. I still want to be able to drive it around town.

You can easily have up to a 600 hp motor that runs on pump gas. It all depends on the combination of camshaft and the static compression ratio.
The static compression combined with when the intake valve closes after bottom dead center determines the Dynamic compression ratio.
In general a Dynamic compression ratio of 8:1 or less will allow the use of pump gas without detonation.

Paul

**bob k. mando** · 10-12-2012, 08:37 PM

remember, the timing cover/water pump are aluminum. because the block is cast iron, this means the water pump is prone to electrolysis damage.

once, i pulled a water pump off of a 455 which had been setting for years and it was completely full of alum corrosion. this would certainly "freeze" the water pump.

Also could the water pump sneezing cause major damage to the motor

only if they tried to run it more than ~10 minutes at a time not pumping water. if he just started it up and moved it around the yard it's unlikely to have gotten any serious damage from the heat.

some all out drag guys make passes with the water out of the block or the belt routed around the pump pulley to save parasitic loss.

otoh, if he wasn't paying attention and REALLY smoked it good it's possible to melt the cam bearings out of the block. i've seen that too. you should be able to smell the stink on a motor that's been overheated that bad.

or is this really no big deal since I'm planning on tearing it all the way down anyways.

i'd say, no big deal so long as he hasn't windowed the block or something. it sounds like he was aware of it though.

there are also oil mods to be done to the timing cover ( Buick timing covers also contain the oil pump and filter ). if you want something to try your hand at grinding on, the timing cover would be the thing to do it on. alternatively, you can get a new timing cover from TA. pricey, but they're nice.

something else for you to know, the 'SF' code 455 out of the big cars was actually factory rated for higher hp than the 'SS' code stage 1 engines. don't believe everything the factory tells you, though.

the 1970 engine should have a 750cfm Quadrajet on it. i think every 455 after 73 has an 800cfm Quad on it ( except for the very rare 1974 2v engine ), so that would be a pretty straight forward performance upgrade.

**joshhirst13** · 10-12-2012, 08:56 PM

OK, so I just got off the phone with the guy selling the motor. I called him to clarify the frozen water pump issue. He said it wasn't frozen from freezing water, what he meant to say or was trying to say was that the bearings went bad in the water pump and it seized. I'm going to assume that this is a better situation than if there was frozen water inside the pump and block. Please correct me if I'm wrong. He says that it is a running motor with no issues and the only thing wrong is that it needs a new water pump, which I'm getting with the motor. So with all of the information you guys have all given me it sounds like i'm getting a great motor for a fair price.
Thanks Again,
Josh