# Need engine advice - seized motor



## 32sbct (Jul 28, 2016)

Hello, I just picked up a 1966 GTO original Tripower convertible (auto trans). Its a solid car but it's been sitting in a garage slowly deteriorating since 1989. The car currently has a non running 1967 400 motor in it (XV code) that is seized. The original YR block was removed from the car in 1989. Per the last owner, it was rebuilt in 1988 and rebored to 30 over. After 1,500 miles it started knocking and was removed from the car. The heads, intake, etc. were removed and put on the 400. The 389 engine was left uncovered in a garage with the spark plugs out and now it is in really rough condition. It is also seized. There is very heavy corrosion in all the cylinder bores.

I'd love to have the original block back in the car. But my question is this. Do you think it's salvageable without spending a significant amount of money? I'm guessing the cylinders could be sleeved but that looks like it runs around $200 per cylinder. And that would just be the beginning. The car will be driver not a show car. 

I have access to a bare 1968 Pontiac 350 block that could be used as the basis for a new build. It's been cleaned and magna fluxed and still has the std bore. As I mentioned, the car needs everything. Its definitely worth saving but and I don't want to break the bank either. Your thoughts are appreciated.


----------



## Pinion head (Jan 3, 2015)

have torn down literally hundreds of Pontiac V8 core engines, from gimmee's to very very expensive original round port engines. On a longblock that won't turn over, I typically, use a large ratcheting 1/2" drive breakover and carefully remove the cylinder head bolts. Once the heads are off, the short block gets lifted and bolted to one of my HD engine stands. On a shortblock with considerable rust in the cylinders, I'll look at the tops of the pistons first....can spot oem cast pistons fairly easily. Original freeze plugs and original pistons area welcome sight. Next, on a rusty cyl bore shortblock, I'll grab an orange snap knife and carefully go around in a circle on any standing rust in the cyl bores. Next, comes penetrating oil. On a relatively rusty block, I'll make a mixture of Acetone (KleenStrip from HomeDepot or ACE) & auto trans fluid. Make the mixture a 1-1 mix, and place it in an old squeezable container, i use empty gearlube bottles. The acetone/ATF mixture is the BEST working penetrating oil you will ever use. You'll have to take turns lsoaking down the tops of the piston ring lands. I have a 455 shortblock right now, that is upside down on an engine stand. It was stuck due to some cyl wall rust. I've managed to take turns soaking it and have 3 piston/rod combo's out. With a little more soaking & use of a cheap ballhone in the cyl bores, the remaining piston/rods will be ale to be driven out. If the block needs a sleeve or two, I'm looking at around $140 a hole. Two holes are the most I've ever had to sleeve. Have gone through the disassembly/rusty bore process so many times on cores, it's like old hat. Have a Starett inside micrometer set that I use to mike all the cyl walls. Typically, even really clean original bore 455's have enough taper in the cyl bores that they will need to be bored .030. I prefer not to go .060 on 455 Pontiac blocks, but most likely would not have an issue with it on a 389.

One thing i read above, and is of major importance, the GTO convert invoices out as an original tripower car. Would seriously put some thought to rebuilding the original engine, possibly lowering C/R, and considering how rare and valuable real tripower converts are, would strongly recommend a well thought out restoration/an exercise that slants to well thought minimal driving. In so many areas of the country, it is just near impossible to keep such a vehicle in really nice shape while fighting the absolute war that is parking lot dings & total idiots on the streets. In the last 2 days I've had inquiry's for sheetmetal, bumpers, and stainless from 3 locals, all to replace collision damaged parts on their "drivers". Only one of these guys am I able to help, the other two... to be honest need to be crashing and bashing something else on the street, both are contraption builders. The fenders, doors, and bumpers the latter two need are not reproduced. If they were, most likely they would be ill fitting junk,thats just typical. Though I have these parts,, it's 110 in the warehouse, and I could jump through every hoop for both of these two, and Id still get he short end of the stick... been there.


----------



## 32sbct (Jul 28, 2016)

Pinion head, thanks for your detailed advice. You've given me hope that the block can be salvaged. I picked up the car last week but the flatbed didn't have room for the original motor so I'll be picking it up tomorrow. I'll get it up on the engine stand and start the process you outlined to see if I can get it apart. The only original part I'm missing in the drivetrain is the transmission. The previous owner swapped out the ST300 for a TH400. Although he seemed to have kept everything, he discarded the transmission.

I've sent to PHS for the documentation but I was lucky enough to find most of the build sheet in the trunk buried under trash, mouse nests and parts. So far the car it looks like the car is a GTO tri-power convertible, two speed auto trans, 3:55 posi rear, console, power top and antenna, tinted glass, and remote control outside mirror. Thanks.

Marty


----------



## 32sbct (Jul 28, 2016)

*Update*

I picked the original engine up yesterday. In daylight it looked a lot better than before. When I got it up on the engine stand I squirted some wD40 in the cylinders and let it sit for a few hours. Much to my surprise it turned with no issue. I pulled the oil pan today and everything looked pretty clean on the bottom end. I'll proceed with the strip down and get it to the machine shop for cleaning and magna flux. Hopefully everything will check out ok.


----------



## geeteeohguy (Feb 2, 2008)

Congrats, Marty.....you'll be bringing back a very, very rare GTO....in one of the best years ever. What Pinionhead said...you can rebuild your original engine and it will run fine on pump gas, you just need to use dished pistons. Helped a friend a few years ago do this exact build on his 389, and using Ross pistons, we were able to use the stock heads and a decent camshaft, and ended up with a reliable, super strong engine that runs on 89 octane. Cruise around on this site, as there is a TON of engine build information here, check out Jim Hand's Pontiac engine book, and check out engine options on the AMES Performance Years forum. There is no need to rush into anything with the original engine...be advised that having the original engine in your car adds significantly to its value.....about 15K when the car is done. Where are you located?


----------



## 32sbct (Jul 28, 2016)

Geeteeohguy, I'm located in southeast Pa. I'm really excited about bringing this car back. I just got my documentation on the car back from PHS. It verify's that the car is an original tri-power convertible with the two speed auto trans. Options include: Push-button radio with power antenna, door edge guards, outside remote control mirror, luggage lamp, glove box lamp, ash tray lamp, under hood lamp, seat belts custom front and rear, rally gauge cluster & tach, rally wheels, custom sports steering wheel, console, exhaust splitters, power steering, power brakes, soft ray glass - all windows, floor mats front and rear, white wall tires, 3:55 safe T-track rear, power top.

I have been going through the casting dates on all the parts and so far I have the original: engine block, heads, intake and carbs, water neck, distributor, timing chain cover, water pump, & alternator. I haven't pulled them out yet, but I think the car still has the original starter and power steering pump. 

The one item I'm missing is the ST-300 transmission. It currently has a 1970 Buick TH-400 in the car. The previous owner also gave me a 1970 Pontiac TH-400. He also gave me a 1967 GTO Hurst His and Hers shifter in excellent condition along with a complete 1967 GTO console, four extra Rally I wheels, two 1973 Rally II wheels, and two plain steel wheels.

All of the interior items are in tact but worn. I have some moderate rust issues in the rear quarters behind the rear tires and along the bottom of one door. There are a few other spots that need attention. The floors and trunk are very solid, just some light surface rust in a few areas. The frame has surface rust but zero rot. The suspension is totally shot as are all of the brake, fuel lines, etc. I'm planning on a full restoration.

Marty


----------



## bigD (Jul 21, 2016)

*St-300*

"...The one item I'm missing is the ST-300 transmission..."


Lots of guys throw these away. So, you can probably find one cheap. There are probably lots of guys who would be glad to swap their ST-300 for your '70 TH400. :smile3:

Just for kicks, I checked Ebay. There are some listed.

http://www.ebay.com/itm/1960s-Buick...ash=item33bcbf140e:g:Z7sAAOSwZVlXpA8R&vxp=mtr

http://www.ebay.com/itm/1960s-Ponti...5ccf41b&pid=100005&rk=1&rkt=1&sd=222209971214

http://www.ebay.com/itm/68-Buick-Ol...ash=item3ac9a45b6f:g:t~UAAOSwFGNWTcSA&vxp=mtr

If you can't find one, the best place to ask might be over on the PY forum, or one of the other Pontiac forums.

http://forums.maxperformanceinc.com/forums/forumdisplay.php?f=446

http://psp.aquacomp.net/forum.asp?FORUM_ID=6

http://firstgenfirebird.org/forums/ubbthreads.php?ubb=postlist&Board=3&page=1

https://www.facebook.com/groups/pontiacsonline/

But, Pinion head might have some or know where to find one.


----------



## tonyskala (Feb 7, 2015)

bigD said:


> *St-300*
> 
> "...The one item I'm missing is the ST-300 transmission..."
> 
> ...


i just went through the saga of that st300


----------



## tonyskala (Feb 7, 2015)

I just went through the saga of that st300. There are 2 varienents of it. One with varible pitch stators and 1 with fixed. The varivle pitch stator torque convertor is really hard to find . But that st300 is not really that hard to find . Just buy it complete with the torque converter and dipstick. Otherwise parts individually will cost you a bit


----------

