I inherited a 68 firebird convertible in fair shape. Very little rust, dash is in good shape. Seats, top and all the foam molding needs to be replaced. Here is my dilemma and options I am considering so any advice is welcome. It does not have the original 400. It has the original automatic transmission with a 350 in it. It probably hasn't been driven in 25-30 years. Option 1: the engine isn't frozen. I can turn it by hand. Can I assume all seals and hoses will need to be replaced? Will I need to have the engine rebuilt? Or just seals and gaskets replaced and give it a tume up? I assume some parts fuel pump, sending unit, alternator, ac charging will need to be dealt with. Can anyone give me an idea of price for option 1?
Option 2: find a 400 that is in good shape so it is what it was supposed to be. This might be a silly question but if I find a working 400 it would include alternator, fuel pump, water pump? Correct? Or would it just be the block, and use those existing parts off of what I have now? What would option 2 cost? Option 3: restomod the engine and transmission to something more modern? Not looking to race it but have to have a v8 able to leave nice ling black marks. Don't really like it just having a 3 speed automatic. Ok for Sunday drives but not something you want to hope on the turnpike in and set the cruise at 85-90 fir four hours. Had an old 4spd manual83 mustang gt 5.0 302. Fun around the city but hoping on the highway engine just needed more gears. My current car is a 300s only a 6 cylinder but at 85-90 I'm only at 1500 rpm with the 8 speed transmission. So what would the cost of option 3, modern v8 and modern transmission run. Thanks for all the info
Since you’re asking for opinions, don’t restomod it. Appreciate it for what it is. A piece of automotive history. Get a newer mustang or challenger if you want to go fast.
I've got a honda rc51 for when I want to go fast. Kinda of leaning towards finding a 400 for it. Mostly curious as to what the different price points would be. And thanjs, all opinions welcome
We are in the same boat. I have been saving a '68 convertible for 40 years and I finally have time to get at it. First off, without the factory 400 engine originality is down the drain. You may find a good 400 but it won't be original. But all the parts interchange easily so not a problem there. So prime the oiling system, see what kind of oil pressure you get. Then do a compression test on that 350. If good, you are golden. Then do a basic tune-up and see if it runs. Even 350s are getting scarce. 400s are great but 350s are just as good and will take all the same improvements. The average person will NOT be able to tell if it is a 350 or 400. Is it a 4 barrel or 2? 'Most' 350s are 2 barrel. Someone may have swapped over the 400 top end/intake, etc. A 400 car usually had a Turbo 400 auto trans. If that is what you have you are now double golden! Bulletproof is the word usually used to describe that tranny. I agree, a manual trans is better and all the stuff needed to swap over is made re-pop. It is just expensive as all get out for a good manual these days, and the flywheel, bell housing, shifter, it is endlessly expensive. I would get it running solid, then fix all the suspension and drive-train issues it probably has. If you find a 400- great- they are out there and will swap right in. An old school Pontiac V-8 is a marvelous engine. Then you make it pretty. That is what I am doing. Mine was an OHC 6 two-speed automatic. Long gone. Now I have a Pontiac 455, a Super T-10 manual, and a posi 4-wheel disc brake rear out of a '79 TA. Originality is not an issue with me.
Thanks for all the input OS&U. Good luck on your restoration also. I did prime it with oil and turned it by hand just to make sure it wasn't locked up. I probably need to replace some gaskets before I try to fire it up. I can see one of the valve cover gaskets is broken. It is a 2bbrl and has the Turbo 400 auto trans so bullet proof is always good. I don't mind it being an auto. First 5 or 6 cars I owned were all manuals and I can't say I miss it. I am a little concerned about the gas tank. Smells like shellac. Got any pics of your bird? Thanks again for all the good info.
A 2 barrel 350 means the 400 was removed and replaced by an entire engine. I would have swapped the 4 barrel intake and heads just because the 4 barrel valves are bigger and the Quadrajet is a much better carb than the 2GC. That said, the 2GC carb is what they used on basic cars when the rear end has low highway gears. It is good for what it does and is relatively trouble free. Some of my best cars used it. A 1968 400 was a pretty high compression engine. It may have not survived the switch to unleaded gas and/or been replaced with a low-octane-gas-friendly low compression 350. Any 400 you consider should be low compression too. My gas tank is nasty too. In the old days I would just take it to a radiator shop and have it boiled out. I don't even know if such shops are still around. There are two options: get a new one, or clean it. You drop it down and remove the gas gauge assembly, empty anything still inside, and pour solvent into it. #2 heating oil [diesel] is good because it won't explode. Then let it sit for days, slosh it around, pour it out, keep doing that until the tank is clean inside. If you try and just pour fresh gas in as it is, expect it to be filthy inside. As gasoline evaporates it leaves gummy deposits that will cause mischief later on. In that case I would remove the gas line hose where it makes the jump from the frame to the fuel pump. Install a big in-line fuel filter in that line to catch all the crud. After a few tanks of gas have been used you can remove the filter and toss it. It is always a good idea to keep an in-line filter at that spot. This way it catches any debris that otherwise would clog the filter in the carb. No pics. My car is stripped and has a busted windshield, so, ugly is the word. I am replacing rusted floorboards and doing improvements so lots of work in progress. One last thing: don't be too quick to tear into that engine. I made that expensive mistake on my first 350. If the oil pressure is good, compression is good, no expensive noises, no obvious leaks, then all you need to do is get it running and then evaluate it. It may be fine and just need some new gaskets and fresh paint to look great. Find out what year it is and check the engine code on the front of the block just under the pass side head. That will tell you what it is and how it was used.
My engine code is YU and if I did my homework right it is a 2bbl 350 out of a 1970 tempest. I watch a video where a guy took his tank out, put a log chain and solvent inside and shook it around. Looked like a lit of crap came out. Byt who know how much was still in there. Didn't seem like the best idea. Hey on your floorboard, are you doing a full replacement or just patching it up? My drivers side floorboard has a good size hole in it I need to do something about. If I could weld worth a crap I would probably just patch it. I did see many years ago at a Starbucks rod and custom shoe instead of carpeting the interior, he rhino lined the bottom. Actually looked really good. Had to be early 90's or so. I'll probably have more questions for you as I move forward. If you don't mind anyway
That car is in pretty great shape! The YU was used in several years. All were a 2 barrel low compression 350 so good to go on today's crummy gas. Did you find a date code? Usually it is cast into the top of the block right next to the distributor hole.codes The chain-in-the-tank is a valid procedure. I have a 1983 Yamaha scooter that was allowed to sit for 30 years with gas in it. The carb was a solid lump of junk and needed a new one. But the gas tank I filled with fish tank gravel, solvent, and sloshed it around every day for several weeks. It came out nice and shiny inside. After I installed a new petcock and filter, it is running great. My floors are rusted in the usual spots, the front and rear footwells where water collects. I had an entire front driver side floor pan but I cut it down to replace just the driver floor between the seat mount,rocker, trans tunnel, and firewall. The leftover I used to make a patch for the passenger side. It was a triangle shaped section near the kick panel. The rear footwells I bought re-pops and trimmed those down to replace the rusty area. My welding skills are about the same as Dr. Frankenstein so luckily the floors will never be seen. My old hardtop had no carpets and the noise/heat level was unbearable. Now I usually coat the floors with POR-15 or Rustlok to waterproof them. Then I use the tar underlayments for heat and noise suppression and they quiet it down tremendously. New carpets are not expensive anymore so that goes on top and makes for a nice interior. It is tempting to use bedliner, Lizardskin [lizardskin], and/or Dynamat as a noise/heat suppressor but I would still use carpet to finish it of. Just fix the water leaks so it stays nice. Ask all you need. I have had lots of Firebirds over 50 years and it looks like the folks on this great site have also.
O like the idea of gravel better than the chain. When you say date code you talking about th 1 letter 3 digit code on the driver's side? If so that is j139. There is another number on the passenger side but I don't think it's a date code. It is 9799916 or 09799916. I threw in pics of those, also a pic if the carburetor. I'm wondering if it came with the new engine. I've also thrown in a couple of mystery pictures. One is inside the trunk. I'm guessing possibly an add on air ride system and the other is a set of wires attached to the drivers side wheel well with only the black wire grounded to the throttle cable bracket. Don't know where the others are supposed to go but the other side of that box says MAGNA PULSE.
Man, lots of info to crunch here. The block number 9799916 says 1970, 350cu. The date code on the head J139 says it was cast December 13, 1969. Correct for a 1970 engine. The YU says 255hp 8.8 compression 2 barrel 350. But that 17054905 carburetor number is from the twilight zone. 1705 means after 1975. 4 means 1984. 9 is not a normal division, maybe a truck? 0 is Chevrolet, and 5 is manual transmission. Is the fuel line on the passenger side? Chevrolet. Electric choke? 1980 and later. [ I upgrade all my Q-jets to that]. All Q-jets 1981 and later were CCC computer controlled except for trucks up to about 1985. WOW my head hurts. The schraeder valve in the trunk was probably for air shocks. There should be plastic air lines going to each rear shock area. Still there? Not leaking? Amazing. The HAYES Stinger Magna Pulse was a points eliminator electronic ignition system. Back in the day, GM HEI was hard to come by. Lots of companies produced points eliminator systems. If it works, great. If not, a GM HEI is EZPZ to pop right in there. You just need to replace the 6 volt coil resistance wire with a fat 12 volt wire [pink wire]. Here is the Stinger wiring diagram. Can you take a pic of the top and front of the carburetor?
I am more confused than before now. That is an early Q-jet air horn but the number is totally wrong. It may be a custom built carb or re-stamped original 1968 400 carb. The part number search came up with these listings but again, that number is totally wrong for 1968. It should start as 702. 17054905 carb17054905 carb Show a pic of the choke side. If it has a divorced choke then it is a '65 to '72 carb. I just don't get that part number.
Check this out: Probably a service replacement carb. That would explain a lot. And it did not come cheap if it is. Fleabay carb And finally this is what makes more sense. It is a service replacement carb that was used on a few different engines. OEM carbs were model specific and never crossed over between applications. Oddball carb numbers Even manual vs automatic trans used a different number.
Yup, that is an era correct Q-jet. Notice the divorced choke with the rod that goes down into the little metal box. Inside is a bi-metal coil that sits in a well on the exhaust crossover. As it gets hot it opens the choke. Since an electric choke won't fit that model the divorced choke is the best of that time. What I always liked about it is that residual engine heat keeps the choke where it should be so restarting is easy. Now you have to figure out if that factory replacement cab was ordered for the original 400 or the 350. Technically the carbs for each are not jetted that much differently, but any replacement carb that is specified for a 350,400, and 428 has to be a compromise. Q-jets are very tune-able. The specs and parts are available and you can re-jet and metering rod that carb to the exact specs that your engine was originally supplied with.
Hey buddy, how you doing? I ran across something the other day that has me confu6. I mentioned in one of the texts above that I thought I had figured out the the engine was a 350 from a 1970 tempest. But the I ran across an article from Hagerty that said engines built in 1970 and after have either the 350 or 400 stamped on the lower right front of the engine. But mine doesn't have that. So now I'm not as sure as I thought it was about what it is. Any thoughts? Thanks
I like Hagerty, I have them for insurance, and the magazine is incredible. That said, they are not all that Pontiac knowledgeable just like HOT ROD and others are not. Go to a Pontiac specific site and you will find all your information from people that love Pontiacs. I myself always look for the casting numbers that are right next to the distributor hole for my date. I have more than once trashed an unscrupulous seller's claim that he had a 455 when the displacement casting clearly said 350. Check this out. Engine ID. Or this; Engine ID And this: Engine codes Remember that all Pontiac heads will bolt onto all Pontiac blocks so that any combination is possible. Back when they took the lead out of gas and it was worse than cat pee I took 455 heads and put them on a 350. That gave me super low compression that allowed me to use whatever sludge gas was available while also allowing me to use 52° total timing and very rich carb jetting. It as 1950's hot rodding all over again. Count the engine mount holes on the side of the block. Check your head and intake manifold numbers too and let us know what you figure out.
Hey OS&U, got a question that's probably easy for you. Not sure if I mentioned in previous texts or not, this car hasn't run in a good 20 years. My aunt always had it garaged. But just sitting there. The other day I un hooked the radiator hoses so I could flush the radiator. The antifreeze was pretty brown and nasty so I removed the hoses altogether. There was obviously a lit of corrosion inside the tube. My question I guess is. Is there a way to flush the old antifreeze and what ever else has built up inside the engine without actually having to start the engine? You the man man. Thanks
What? The drain plugs OPENED?!? Alert the media! Seriously, that is unheard of. Usually they are so rusted they break or your tool breaks. Yes, a good flush will clean out the junk. I also learned to add a shot of [Cascade] dishwasher soap to the water only system and let it run a while. But it cleans so well, that any pinholes will be opened.That usually means a new radiator or water pump. So I reserve this for extremely filthy systems that need new parts anyway. It is also a good idea to use only distilled water mixed 50/50 with a good brand of anti-freeze in the cooling system. That is mandatory for cars with aluminum engine/cooling parts. But it helps keep rust and corrosion at bay in our old systems too.
I'd strip the whole thing down, including the timing cover. Get a new set of gears and chain, new pump, new thermostat and throw in a fuel pump while you're there.
So I stripped it down and attached a couple of pics. Doesn't look great. Nit sure how much of this stuff can be in an engine Blick without destroying it. At what point do I just need to look for a different engine? Thus isn't the original engine to begin with so it's not like I would be losing "matching numbers" or anything. Don't have much money tied up in the engine yet. Mostly/all is just hours of me taking it apart. Any advice is welcome. Thanks
Looking for a new engine means that one has to come out. Might as well have a good engine builder or machine shop assess it's condition. Definitely needs a timing, and if any crap got down into the oil pan, don't put it back together and try to run it.
You may not believe this, but I have seen worse. It is possible to clean that mess without removing the engine. As I mentioned, the cooling system can be flushed with dishwashing soap. CLR is good too. Letting it sit for a good while will dissolve that rust but, again, will ruin the water pump and probably the radiator too. Sometimes I rig the radiator hoses in a circle, sidestepping the radiator altogether. Leave the thermostat out while doing this. But you need the engine running first. The oil system is easier. I remove the distributor, and insert an oil pump priming tool. They are available commercially but I make one by cutting apart an old distributor. You take a 1/2" drill. and spin the oil pump without starting the engine. I drain the oil, and fill the oil pan with solvent. #2 heating oil [diesel fuel] is a great solvent as it won't explode. Spin the pump several times a day, let it sit, and watch as all the crud gets loosened and flushed out. Rotate the engine now and then with a breaker bar so all the oil passages in the crank and lifters see solvent. The oil filter will probably need changing a few times too. After a week or so you can drain out the filthy solvent and do it again. You won't believe the crap that comes out. Once you are happy with the condition of the engine, drain and fill with the cheapest oil you can get. Use that to flush out the solvent. Then you can drain that and fill with your favorite oil and a fresh filter for a test run. Start the engine, time it, adjust the idle, and check your oil pressure, listen for expensive noises, and shut it down before it gets hot. Now you can start cleaning the coolant passages. Lots of work, but much less than yanking an engine.
Dude, once again you vast amount of knowledge is unbelievable and greatly appreciated. I went ahead and pulled the engine and transmission and put it on a stand, mostly because I'm getting old and it way easier to work on. Gonna start prepping to start it using your suggestions, and then compression checking it. Wife keeps slowing me down with honey do lists and such, lol
Wife keeps slowing me down with honey do lists and such, lol
Yeah that is my main obstacle too. I have two kids that think I am their private mechanic. On the stand is good. That is how I flushed my 1970 Pontiac 400. It was very grimey, and had poor oil pressure. I had the valley pan off and I could see many lifters were not getting oil. I think it had sat for a long time getting cruddy inside. I used Permatex Carb and Choke cleaner that used to be available in a gallon can. That stuff literally scoured the oil passages spotless. After I was done I had 60 lbs of oil pressure with a new Melling oil pump. All lifters were flowing oil. I can't find the Permatex gallon anymore which is probably a good thing. It stunk like a chemical factory and burned your skin. The #2 oil is slower but much safer. I use it to soak cylinder heads and they come out looking like they were hot-tanked. On the stand you can seal the cooling system with a couple of radiator hoses connected with a section of PVC pipe. Leave the thermostat cover off. Then fill it with water and a dose of CLR or some other rust buster type product. Spin the water pump by hand to agitate it. Let it sit, then flush with a hose. I used the Cascade dishwashing detergent on a very rusty Jeep engine and the insides of the block looked like virgin cast iron. You may find that your freeze plugs are crusty looking. Now would be a great time to replace with new ones. But first, since you are unsure about the condition, why not fill it with cheap oil, prime the oil system with a priming tool, hook up a mechanical oil pressure gauge, and see what kind of oil pressure you have. If good, then you can hook up a starter to crank it and test the compression. If you have good compression then go ahead and clean it up. If not, don't waste your time.
Well crap. Didn't have a priming tool or an extra distributor laying around so I was going to make a key with a cutoff Allen wrench and an old socket. Off course pulling the alien out after making sure it was the right size, dropped it. *%#$ had to take the oil pan off to get it out. *sigh*. Let's rebuild a firebird they said. It will be fun they said, lmao
Look on the bright side. You wanted to see what was in the pan, check the oil pump, inspect the rods, crank, and everything else. Does that engine have the windage tray? TIP: the full length windage tray, combined with a 301 baffled oil pan, makes for a great oil control system. When I have an engine on a stand I hate oily messes. I grab a big black plastic cement mixing tub from Home Dupa and place it on the stand legs, to catch any oil or other drippings. As for the priming tool, a big flat bladed screwdriver with the handle busted off will do. Just chuck the shaft in a drill but be careful because there is nothing to bold the blade in place. Go slow!
Not sure I'm real clear on the oil pan and windage tray but I attached pics. What really has me curious is the crannk matches up to a 400 engine. But the block is clearly marked with a 350 cast. Any thoughts?
That is the 3/4 windage tray which is good. There is a full length tray also. The 326,350, and 400 all used the same 3.75" stroke and 3" main bearing size. Only the bore changed. So the cranks interchange. The 421, 428, and 455 used the 3.25" main bearings so that is different. Did you clean that yet? Because if not, that is super nice condition! I see the 350 cast clearly on the side. Pretty nice of them to do that, eh?
Thanks again for the info. You da man. Ya, I've been cleaning as I go. Popped the expansion plugs and soaked one side of the coolant chambers the other night. Soaking the other side today. Been scrapping grease if the outside as well. Once I get the coolant chambers cleaned and plugs replaced I'll look back over your instructions for lubing the engine and checking compression.
If an engine passes the compression test, and was not burning oil, I used to do what I called a "$100 rebuild" [yes, I'm older than dirt]. That is when I would take off the heads, soak them in #2 oil, de-carbonize the combustion chambers, valve faces, and piston tops with a wire brush on an angle grinder, put in a new oil pump, timing chain, water pump, fresh gaskets, then a good ignition/carb tune up. After that I had a really great running engine. Of course today's prices knock that all to 'ell but you get what I mean. I would leave a tight block alone and just refurbish everything else. The compression test lets you know if the rings and valves are good. The oil pressure test lets you know if the bearings are good. If not I stop right there before wasting money. The spark plugs will tell you if the engine has been burning oil. If nice and clean then you have a good solid engine there to expand upon.
Sounds like a plan. Again, can't thank you enough. I'll post the readings if you wouldn't mind looking at them. Not sure how long that will take, spring is coming and the wife decided to buy a chicken coop of all things. Looks like I'm building the pen. *sigh*
