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Discussion Starter #1 (Edited)
68-69 400 block boat anchor UPDATE

OK I took out the crank and wow thing looked NEW, it was cast though. I just had to share the pic of the piston! I'm not an expert but can I say very little run time! Honestly I cleaned the top and top 2 areas above oil ring THAT's IT...notice though, on the rod there looks to be something hit it.

So I was able to free it up and tapped out the pistons. Damn, cylinders below area where there is surface rust is so nice too.

Any recommendations? Rods will be replaced but should I find another 400 block and use these pistons or go another (try) +.030 so total is +.060. I'm leaning to find a short block and use these pistons.




The guy I bought my 68 from has a Pontiac 400 that's the light blue color looks like OE iron heads the OE 4 barrel intake (air gapish). Its a long block that IS SEIZED, engine is together with chrome valve covers. The guy asked me for 300...Isn't that a bit much for a seized engine? I thought value is more like 150 tops 200.

Before I turn it down on a period correct engine, thought I'd ask experts and before I regret turning it down later.

My plan is to use a LSx but don't want to ignore a period correct engine. I could always use the EFI carb on it.

Thoughts?? What's the cast number I'd look for?
 

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I just junked a '67 400 and a '69 428 in the past two years that were not seized but would have needed sleeves. A seized block, unless it's a rare code for your numbers matching car, is scrap iron value the rest of the time. $300 will buy you a decent rebuildable 4oo core that turns, maybe even runs. There's a good running later 400 with the TH400 trans for sale on the other forum for $500. I wouldn't pay $10 for a seized engine....I don't need the scrap money that bad for the labor involved taking it to the recyclers.
 

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Even if the block is seized the heads and the intake should be good, and worth $300. The crank might even be useable. Then if the block is salvageable it's a win-win. If it still had the original Quadrajet even better, but you mentioned it has an EFI carb? Which is also great. Everything will need rebuild, mind you, but if you got on ebay and tried to find a set of 68 GTO heads you would probably spend more than $300, and an intake would be $85-$125. If the block turns out to be junk you can find another bare block and use as many parts from the original engine as possible. LS swaps are nice but the reason so many Pontiac people keep the Pontiac engines is that they're just so damn good!! It's one of the few engines that can put out significantly more torque than horsepower, the cranks are absolutely bulletproof, the heads and intake are some of the best flowing, and quadrajets once tuned properly are nearly comparable to fuel injection. That being said, there are plenty of other great options, and an LS swap is one of them.
 

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Discussion Starter #4
I think 300 is a bit much. Too many factors. So it does seem like these blocks are not so rare? No EFI carb on it, just a plan. I would rather lean into this than a LS1 swap just because its cheaper right now. I'll offer the guy less and see, will try 150. Thanks
 

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Is it the right block for your car? Or another year/car model? These Pontiac engines bolt right in to your '68 GTO, and if you do the math, have more torque and power than an LS1. If the engine is seized because of rust in the cylinders, it's probably junk. BTDT many times.
 

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Discussion Starter #6
Thanks, please correct me I thought these older iron blocks can be bored a good amount. I agree, I just don't know. So my question then becomes whats the max bore I can go?

I was told it was rebuilt once, so yeah there can be a good chance block is junk.

On the LS1 fact, I average 400+ on my H/C builds and my Pace Car 408LS3 is 520/500 RHP/TQ so I thought about putting this in the goat with a better drivable cam. Really though, I would lean more towards the 400 Pont. Cost point is much better with the 400 without the wiring needed.
 

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You can easily get 500hp and 530+ torque out of a 400 Pontiac engine if you wanna build a 461 Stroker motor. Bear would be the man to talk to regarding such a build as far as cost, builders, parts, etc.

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Discussion Starter #9
We dealed down to 200 for the 400, so now I have a 68 and a 400. The cast on the block is 9799914, so its a 70 400. Don't know what the heads are yet since I looked at it once. I pray it isn't too bad inside. I want to keep it original looking with some mods. I'd like to get 500hp out of it.

I've done some research and don't understand why 9.5cr seems to be the edge for pump gas. I have 11.2 on my 408LS3 and did 10.4 on my Ford 347. I'd at least shoot for 10.5 with the stock heads. Honestly, I've never messed with Iron heads and from what I read there is tons of CC volume to mill depending on code.

I have much to learn but I do have enough knowledge to understand what and why.

Thanks guys
 

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If it's a numbers matching 70 the heads will either be #12's or #13's, unless you stumbled upon a Ram Air IV engine, which is unlikely. If it was you would also have an aluminum intake.

If you want 500hp out of a 400 the best approach is a stroker kit. Like I mentioned earlier, Bear has a 400 built into a 461 stroker with Edelbrock heads and is running over 500hp and under a 12 second 1/4 mile. Talk to him if you think you'll go that route.

Static compression does not determine whether you can run on pump gas or not, dynamic compression does. If your car is running at 10.5:1 static comression ratio, the dynamic compression will likely be below 9.5:1, which will run on pump gas. Read this PY forum thread. It might help with understanding a little:
static vs. dynamic compression ratio - PY Online Forums
 

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Did some more research. This article explains Static vs Dynamic Compression Ratio, and how cubic inches, cam choice, stroke, etc all affect what your SCR and DCR will be, and the difference between the two. It refers to Chevy engines but the principle is still the same. I'm still learning all of this stuff myself.
Static Vs Dynamic Compression Ratio | Piston Ratio
 

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Discussion Starter #12
Thank you so much for the info. I will read into this.

Ouch really stroke to 460! That's big ci. More than I'm used to, to make 500rwhp.

Hmm I figured I need to go with aftermarket heads...I'm not sure about the intake, I'm sure its 4 barrel with a air gapish intake. I hope it is alum and not cast. Not sure on the head cast yet. I should see it on Thurs.
 

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You will find that the old Pontiac motors make their power a lot lower in the rev range than SBC's and their power curve is more symmetric. A well built Pontiac will redline safely at around 6000 RPM and be all in. The key is to build the motor to put the power where you plan on using it the most. Cam, transmission and rear end all play into this. Because our cars make heavy torque early they tend to be a little traction deficient so its a balancing act to get the power to the pavement and not up in a cloud of tire smoke. If you are not running an OD or 5 speed trans stay away from rear end gears over 3:55. You don't want that much gear unless you plan on just driving at the track and light to light. I always get a kick out of those cars with the hi stall converters winding up to 5000 RPM's just to get into their power range, motor sounds bad ass but they are only doing 30MPH. I'm pushing a salt flats 2:56 gear and although its not head snapping on launch it will break the tires from the dig up to a 20 roll with just a stomp of your foot. Get her out on the freeway at 70 and my motors just starting to breath and the 70-100 jump will snap your head back. All that and 16+ mpg with a 461 cu in engine amounts to a whole lotta fun.



Putting this on it soon...



This is an interesting video...In the early days Pontiacs were the king of the strip

 

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Thank you so much for the info. I will read into this.

Ouch really stroke to 460! That's big ci. More than I'm used to, to make 500rwhp.

Hmm I figured I need to go with aftermarket heads...I'm not sure about the intake, I'm sure its 4 barrel with a air gapish intake. I hope it is alum and not cast. Not sure on the head cast yet. I should see it on Thurs.
Most all Pontiac intakes are "air gapish" lol. They use a valley pan and the coolant crossover can actually be divorced from the intake allowing you to remove the intake manifold without draining the coolant. Very few Pontiac intakes were aluminum from the factory, mostly RA and SD intakes are aluminum, all others were cast iron. Some of the aluminum intakes even had cast iron exhaust cross overs. That said even the cast iron intakes flow very well and are highly sought after for performance rebuilds. Should be adequate up to 400-425 hp.

Have you considered forced induction?:cool A mild 400 cu in build with a turbo or centri blower would certainly fill your HP quest. Plenty of room under the hood and you can run a relatively mild cam profile. :D
 

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Discussion Starter #15
Thanks guys, for some reason I don't see the sig I created. My Pace Car is far from stock with the 408 LS3 520/500 rwhp with 6spd Viper internals. Stock rear!!lol with 373 gears haha 80 to 150 is a massive ride. I've always been a HWY guy anyone can spin the tires.

I agree, for a 4 speed like a 700r4 a great all around gear is 3.42s. I really wish on timing to be right and put in the TCI six. With the nice built 400 should give the fun factor. I'm looking to do the right twist on this build. With the 400 now, I'd aim for a stockish looking appearance under the hood. With the modern brakes, susp and trans.

For the stall, I aim for a 2200-2600 stall. More than this isn't for me.

As far as FI (forced induction) I really want a TVS for my Pace Car. Only thing is my CR is a bit high for it but eng will take the boost with all forged, studs and all arp. For this, I can't see FI unless it was a big bug catcher out of the hood. Turbo would be ok with all the room but still can't see it in this car. YET

I'll be picking up the 400 tomorrow and hope it isn't too bad.

I like the dual quads!
 

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Discussion Starter #16
Well the 400 is home and under a cover in my garage! So the wife no looky lol. So good news is its a numbers matching engine. Its all 1970 head casting #13 so it looks to be the 2.11/1.77 with 72 cc chamber. Didn't check the intake yet but will tomorrow but the 4 holes look big.

It is locked up so hope it can be saved. Good news sort of, is he has another 400.

Pulling heads off tomorrow too.
 

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Good deal. Like I said, the heads and the intake alone make the deal plenty worth it. The #12/13 heads are probably the best D-port heads you could get on a GTO. Should make a good starting point for your build. If this block is useable what is your build plan?

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Discussion Starter #18
Plans are to free it up and hope it can be saved. Been reading on what to use on a block to free it up. For now, it will be a rebuild best I know how. Will go with some rollers rockers, mid perf cam with decent lope but decent drivability, as much head work as I can, I'd like to use the stock intake but ported, I know I'll need new pistons, machine work, ARP everything...

I plan to just free up the motor, just to take it apart, so least damage on walls and hope for the best. I'll post up some pics of it.

Thanks for confirming I have a good stock head. Just have to figure what went wrong. From what I see intake is a bit rusty inside.

Excited to have my first old muscle.
 

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Soak the bores for several days (a week is better ;)) in trans fluid or PB blaster. Kroil oil is good too if you can find it. It is some slick stuff and I've use it everywhere but the bedroom......:lol:
 

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Discussion Starter #20
I mixed a cocktail that has PB blaster but there is one bore that I'm almost positive makes this TOASTED! Its such a heard break to see such a nice internal block with clean heads, cam lifters. I was so sad but not surprised. My garage really stinks!

The cylinders on the other side I feel the block could've been saved. One cylinder is flawless with cross hatching easily seen.

So what's the max I can go? Is it 4.060? I've seen pistons for the 400 like 4.120...I'm reading up on it now.
 

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