#1  
Old 12-05-2017, 10:28 PM
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iowapub iowapub is offline
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Default Looking for engine sugeestions 400, 455 or 428?

I've recently found a local guy with several Pontiac engines.
I believe the 400 would offer a stronger block, but I'm not sure if this is really an issue for me.
He has so many parts, I could pick date codes, heads, intakes and carbs.

This will be for my 79 Grand AM 4 speed car.
Also, I'm not sure if I should even keep the Saginaw 4 speed or go 5 or 6 speed...
I'm starting with the frame, so I have some time, but would like to lock in on some of these parts.
Any suggestions would be appreciated.

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  #2  
Old 12-06-2017, 01:29 PM
ck67goat ck67goat is offline
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That really depends on a lot of factors, such as what are your goals with the car (daily driver, street/strip, full race)? What are your HP goals and what final drive train and accessories will you run on the car. The '79 G body is a relatively light car, so you could not really go wrong with any of the 3 engine sizes since all will make decent power as long as you match engine components and build to go your transmission and rear end appropriately.
Also make sure you get the date and block codes before you choose and diligently research each block to see what exactly they are since you cannot make a blanket statement that a 400 block is stronger. Lastly, what is the condition of each block and the history of each. Are the engines currently running or disassembled? Are they original, rebuilt and previously bored out and crank turned? All these factors need to be taken into consideration to determine how much remaining using life is left in the engine as well as what will best suit your needs.

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  #3  
Old 12-06-2017, 01:56 PM
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Yeah, as stated, there are LOTS of things to consider.

If you just want decent power to burn some rubber & not wipe out the Sag trans, then a low compression 400 is probably all you can stand.

I personally love to snatch on a Muncie 4-speed. So, for a decent pump gas car, I'd go with a Muncie & a low CR 400, such as a '78-'79 W72, or equivalent.

Would avoid any 400 block with a casting number ending in 557. Would also avoid a pre-'70 block, since they are not set up for the 3-bolt motor mounts. That eliminates all 428 blocks.

A 350 might give the Sag a better chance of survival. The '74 GTO engine is a good example. Had #46 heads. I like the 6x-4 heads. But most of the 350's which had those heads have the 500810 block, which is weak, just like the 557 blocks. Some say that's not a problem up to 400hp. Some disagree.

A 481988 block probably has the best resale value, of the common reasonably priced 400 blocks, since lots of guys use those for stroker builds. The XX 481988 blocks are the same, but do not have the holes drilled for the pre-70 2-bolt motor mounts

I'd avoid the '72 heads, and any others which do not have any end holes for the exhaust manifolds. I'd also go with heads which have screw-in rocker studs. Beginning sometime in May of 1973, all Pontiac heads have screw-in studs. These also have factory hardened valve seats, which are better for unleaded fuel. Some pre-'73 Hi-Perf heads have screw-in studs, but not hardened seats.

A good 455 will probably eat the Sag, and can break other stuff, if you get any traction. Probably not the best choice for a mild street car, with manual trans.

Just curious if your car has an 8.5 rear or the much weaker 7.5 ?


Last edited by ponyakr; 12-06-2017 at 02:31 PM.
  #4  
Old 12-07-2017, 01:39 AM
rock rock is offline
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I was prepping a 301 turbo for the grand am I had thirty years ago ( never completed it). I always thought it would have been a much more special car if Pontiac had installed the turbo in the 1980 grand am.

I have a 350 Pontiac in mine and it's ok, it seems a little nose heavy

Shifter hole location will be an issue if you change the transmission

The 7.5 will be fine unless your drag racing

  #5  
Old 12-07-2017, 11:54 PM
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iowapub iowapub is offline
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That is a lot of great information. Thanks..
I'm looking for a strong driver that I can still rip around in. The car currently has the original 7.5 posi rear.
The engines are all in good dry storage. Heads and intakes are off for inspection. The guy will build whatever I want.
I've only been through the place once. I need to get back for a better look and see the other half of his stash.
I'll get some #'s next time through
The 78-79 block would be the closest to what the factory should have/could have done

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Last edited by iowapub; 12-08-2017 at 12:03 AM.
  #6  
Old 12-08-2017, 12:40 AM
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"...The car currently has the original 7.5 posi rear..."

If you plan to keep that rear, I wouldn't go with any more motor than a low compression 400. I'd go with 6X, 5C, or '74 model #46 heads, with either a 481988 or XX 481988 block.

A 262 Voodoo cam would perk it up a little. Or, to save a few bucks, you can go with an 066 clone cam, and stock valve springs.

https://www.ebay.com/itm/New-Sealed-...FZuHy6&vxp=mtr

https://www.amazon.com/Melling-SPC-4.../dp/B000C4KLKI

https://www.ebay.com/p/Engine-Camsha...SPC-5/77094380

https://www.ebay.com/itm/New-Hydraul...xZODlz&vxp=mtr

The 066 cam was last used in '76 400 4-barrel engines.

http://www.wallaceracing.com/enginesearch4.htm

The Summit 2800 has more lift & duration. And the Summit 2801 is a notch bigger, but will definitely need at least some new stock replacement springs.

https://www.ebay.com/itm/Pontiac-V8-...lU0mJ9&vxp=mtr


Last edited by ponyakr; 12-08-2017 at 01:25 AM.
  #7  
Old 12-08-2017, 04:53 PM
mrrat1 mrrat1 is offline
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I would go with a 428 if it was my choice!

  #8  
Old 12-08-2017, 06:13 PM
tom s tom s is offline
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I would keep a eye out for either a 428 or 455 good rebuildable core engine.You have time.You will need more gear box for either.The choice is just numbers in a check book.Muncie or ST-10 will be the cheapest and most easy to put in.The 5 and 6 not so much.Tom

  #9  
Old 12-08-2017, 06:48 PM
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Default Pump Gas 455

Don't have a clue what your budget is. But I have a pump gas 455, that I had built by a member here. Was gonna do some bracket racing with it. But, the track closed & I sold the roller.

It has forged rods & pistons, with 6x-8 heads, which have stainless valves, CC 1.52 roller tip rockers, 7/16 studs with poly-locks. Has a Torker 2 intake with a 750 vac Holley carb, and a Flowkooler alum water pump.

All it needs to make a good street engine is a smaller cam. It now has a CC 292 Magnum(I was told), with Rhoads lifters. I think the idle is a little to nasty for a street engine. With something like a Summit 2802, it should make a great street engine.

Will sell as is, picked up here, in North Louisiana, for $3000. Most guys can't even buy a forged shortblock that cheap. And the head cores + parts & labor will cost another $1000.

It will have about 400hp/500torque, or a bit more. It WILL require a good trans & rear end. Hey, it's just one option.

Email: speedbarn455@gmail.com if intersted.
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Last edited by ponyakr; 12-08-2017 at 07:00 PM.
  #10  
Old 12-09-2017, 09:24 PM
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iowapub iowapub is offline
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I'm pretty sure the 428 will bolt in to a G body frame with the factory 301 mounts.
A friend in high school had a 68 Bonneville with a 428. He'd smoke the tires forever lol
I'm not too concerned with the rear, as it needs rebuilt, so it will be removed sooner than later.
As for the Saginaw,it will probably be removed as well. It's not the original, though I do have that.
I just have access to different options on Pontiac engine parts.
The seller can/will build whatever I want. If he dosn't object, I'll get a couple pictures of what he has.
I don't know block/heads etc. Never been down this road.

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Old 12-09-2017, 10:00 PM
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"...the 428 will bolt in to a G body frame with the factory 301 mounts..."

Not without adapters. The 428's do not have motor mount holes in the correct locations.

https://butlerperformance.com/i-2445...tegory:1393557

"...don't know block/heads etc. Never been down this road..."

Don't buy a 500557 or 568557 casting number block. Don't buy heads with press-in rocker studs. By 1974 & later heads, such as #46, 5C, & 6X. They have screw-in studs & factory hardened valve seats, for unleaded gas. The 5C & 6X heads have larger 2.11 intake valves. The 6X heads are very popular on 455 engines, and are quite common. The '71-up D-port 455 heads have big combustion chambers & will not make enuff compression for a smaller engine. The '75-'76 6H 455 heads have 124cc chambers, and are especially low compression.


Last edited by ponyakr; 12-09-2017 at 10:25 PM.
  #12  
Old 12-09-2017, 11:09 PM
ck67goat ck67goat is offline
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"I'm not too concerned with the rear, as it needs rebuilt, so it will be removed sooner than later. "

I'd recommend sooner. I knew 3 guys with a 7.5 rear in a G body running small blocks and all 3 blew the rears in short order - one broke an axle on a turn, it came out the tube and took out his entire quarter panel. A torque motor with a manual transmission will eat the 7.5 pretty quickly.

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