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Engine SwapEverything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.
The 700R4. Already have the adapter plate. My concern is the distance between the engine mounts so that I don't have to remove and relocate them. If I had that measurement I could make block mounts to fit so I don't have to mess with the frame. I did measure the mount-to-bellhousing on a spare Chevy block and the Pontiac. The Pontiac mounts are positioned a little bit farther back on the block, so the trans will actually be pulled forward a little bit.
If the Pont. block mount is farther back, then that'll be beneficial with your bellhousing adapter. The adapter will push your motor farther forward, if you leave the tranny as is.
Just have to keep an eye on all your clearances on the frt of your motor, such as waterpump snout to radiator. I'm sure that 350 is a longer eng. than the chevy SBC. Imagine you'll probably go with a radiator with elect. fans?
The adapter is only 1/8" thick, so it won't make much difference. I think they are similar length, but the Poncho is definitely wider. The car came with electric fans, so yeah I'll be sticking with them. I am upgrading the radiator as well. I plan to figure a way to adapt the serpentine system also.
I also plan on doing this swap soon. Bought a standard bore Pontiac 400 and have taken it apart to be machined. Plan is to stroke it to 461 and put a T56 behind it. Should be a killer combo when it's done. My main concern is the mounts, it seems like some things work and some don't but if I have to I'll just make my own.
Just got another 3rd gen bird. Its already got a cowl inducted hood so i dont have to worry about clearance. Plan to swap in my 73 455 sometime in the next couple summers
I was gonna do the conversion in my 89 trans am but had a hard time trying to keep it under the factory hood and i didnt want to alter the factory appearance of a trans am. This one i can mock up with the second gen motor mounts and drill the right holes into the subframe.
HI all corect me if i am wrong in 82 when the 3rd gen wos about to be relesed .gm pulled the plug on the pontiac v8.and went corporate engine .the engine the car wos desined with wos the 301 turbo from the 81 gen 2 hence the cowl hood .so the pontiac engine should fit with little mods .
You must've seen the You Tube video titled "GM Quashed the 82 Turbo Trans Am", because most, if not all you mentioned is true. I've heard conflicting opinions about whether or not corporate intentionally used the hood bulge for "cosmetics", or if they in fact planned to put the 301T motor in it. None the less, it would be a unique automobile, and there is an extremely few people out there that have accomplished it. Not a lot of recognition for them.
TAJOE i have a book with the turbo lump car in it all the original press relese wos of this car when thay went on sale .so the book says ! if the 301 t wos in the car then with bit of reserch the parts used probably lurking in a gm parts book sumwhear .im looking to put a 400 in my 88 formula .
This thread has been around for sometime, and from the very beginning, there are very few members who have accomplished this swap, and even fewer that have posted pics, and given any real details. Page 10 has a few posters that show their stuff, and even the top of this page. I've yet to see a completed conversion tho, with details (pics) of mounts, exhausts, torque tube mods, and the final product in all it's glory. I'm guilty of the same scenario, because of lifes priorities, finances, and justifying time spent. It's extremely difficult to build a car, while raising a family with a conservative income. If you notice the dates of the posts in this thread, you'll see it goes way back, so be careful when looking for parts that are listed. Some of these companies are long gone.
I'm gunna go out on a limb here Bear, and state something that was told to me many years ago, and can't prove it on my end. It seems logical to me tho, and will be easy enuff to prove. The stock rubber clamshell mounts on the frame of the 3rd gen, will directly bolt to the stock 301, 301T motor mount brackets.. it's just that the stock 3rd gen mounts have to be relocated up and/or over on the frames crossmember. And there's a possibility that the frame already has the holes pre-drilled from the factory. But maybe this only applies to the 82 car(?). Some day I'll get under my 84, and measure the length of the rubber mount where the bolt passes thru it, and compare that distance to the steel brackets on my 81 301T motor. And I know you were asking about bolting the 400 to it, but I believe the later 2nd gen F-body motor mounts are the same as the 301 motors. Or should I say, the 301 block mounting holes, are positioned the same as the traditional 70s V-8 cars.
This is a link the entrepreneur that actually has accomplished this swap. Not sure if it's already been posted, but lets just call it a "refresher".
I have a 83 firebird F body . I am trying to put a GM 350 with a T5 transmition. The transmition and rearend is out of a 1992 Iroc. Engine is in having problems with bellhousing and starter. Any ideas. This car had a mechanical clutch. The bellhousing I have is from the Iroc. Hydraulic clutch. I got the petals for a hydraulic clutch out of a 84 bird. All bolts up but the starter won’t fit.
I also need the Torsan bar that will work with the T5
You're in the wrong thread. This is for swapping traditional Pontiac V8s into 3rd gens.
(I was under the impression that 83s were hyd. clutches. Only 82s had mechanical clutches.)
At this time no I do not. I know I took a lot of pics along the way but I started this project about 5 or 6 years ago so I’d have to dig on my hard drive to find them and start one!
Bought the car in 1996 when I was 19. Did bolt ons and other mods initially before building a decent 355 in 1998 and drove it for a couple more years before developing some problems that I couldn’t sort out so I went crazy and said hell with EFI and was gonna switch to carb. Long story short, parked car in 2000 and it continued to sit in my backyard with no drivetrain until 2013. Had gotten married with two kids, and decided it was time to do something with it. One of my best friends who is also a member here had initially intended to do this swap in his 88 (which is also same color) before deciding to go the LS route. Having been a lifelong Pontiac nut but owning Pontiacs with SBC’s and not Pontiac power left me with a void. This is how we arrived here. ��
As far as mounts go, when I had the small block in it I had also installed moroso solid engine and frame mounts that were bolted in the factory spot and then welded. When it came time to start the install, I took a bare 400 Pontiac block that I had and attached my original 700r4 with an adapter plate, and set the transmission mount in the crossmember in stock location. Bolted a long piece of heavy angle across the front of the block to each frame rail, then shimmed each side until I was happy with center, level, and layback. From there I just fabricated engine mounts to the moroso mounts by bolting 1” square to the block, then cut cereal box board into shapes I needed to connect and used that to trace and cut the plate steel. All in all, it was not to difficult.
Getting headers to fit was by far the biggest challenge and if I had to do it again I might go with RA reproduction manifold, or go right for a tubular k member. The headers I used were a set of Headman ceramic coated shorty headers, and I had to pull the stock k member out and some some fair amount of work to it to get them to fit. Again, not difficult but more time consuming as I tend to over analyze things. As I was taught long ago, measure twice, cut once! LOL!!
Now onto the fun part. When I started the swap the plan was to run a carburetor and keep things simple. Pulled tank to remove electric pump and add hose to pickup from bottom of tank. It was a std. bore 400, ported 4X heads, Lunati bracket master cam, performer intake, and a Q-Jet. The engine would start up, run and idle fine. However, bringing engine off idle and holding say 2500 rpm or so it would pop and miss out the exhaust, and if provoked enough occasionally back through the carb. Tried different distributor and carburetors to no avail. Not happy with the way thing were headed, I decided to make some changes. A lot.
Now onto fun part, part 2. Deciding I wanted to make more power then what I had currently, I decided the only think that was going to stay the same was the short block. Changed heads to a set of 12 “RA III” to raise compression some, as well as a factory style RA III cam, FITech EFI, RPM style intake, 1.6 full roller rockers, Pro Comp distributor and coils, Taylor plug wires, and pulled the tank, again, to reinstall a new high flow pump. Having thought I had surely eliminated whatever could have potentially eliminated whatever could have been my issue before, surely would be right now. Boy was I wrong. This car starts up, sounds amazing and runs beautiful. As long as it doesn’t move lol. Off idle it still has the same exact misfire and popping out the exhaust. Trying to drive it around the block resulted in sluggish performance stumbling on its face. Easy throttle it doesn’t react much. ����*♂️
This is where I’m at currently with it. Aside from needing to install power steering and do some brake work. Seeing that the whole top end, induction, ignition, fuel system is completely different, and the same exact problem persists in the same manner, I’m more than baffled. If anyone has any suggestions on things to check, or potential causes of this, I’m all ears!!
Here’s a little better shot of being able to see the headers. Quite similar to the shape of manifolds but some clearance needed around a couple tubes and the collectors. As I said, tubular K member and probably wouldn’t have had to do a thing.
Looks like you're making good progress CK. As for your popping issues, if you're confident it's not fuel or ign. related, how bout valve train? Could one or more of the rockers be a little off adjustment?
And once again, I keep asking this question to Pontiac eng. swaps into 3rd gens, but no-one seems to confirm it. I could've sworn a member who did this quite a few years ago, said he used his frame mounts from the original 305, (but moved them up on the K-frame to another already pre-drilled holes from the factory), and used the original Pontiac 301 eng. mount brackets from his 2nd gen bird. Says it dropped right in. His car was an 82, and not sure if that would matter.
Anyway, good luck with your power steering. That might be challenging?
Thank you guys! As always it’s a labor of love for all of us. This problem I’m experiencing has been more than enough to keep me putting it aside. That and a job that sucked the life out of me for years, raising kids, etc. I’m sure many can relate. Lol
And as far as valve train goes? I speculated this at one point but I’ve set many lifters over the years be it hydraulic, solid, roller, and never had an issue. Also, this miss (or whatever you want to call it) was present with the old top end/parts that was assembled by an engine shop. So short of us both being off, I kinda ruled that out.
If anyone has any experience with the following, I’d love some input. My brother, the smart one in the family ��, has suggested I try running 12v directly from the battery to the coil and see if that changes anything. Also, he questioned that I check my grounds, etc.
Only other thing I can think of is this is a grounding, or electrical problem when put under a decent load. The positive battery cable is original to the car, and I suspect it could be one of the common links? Fairly certain my 12v source for ignition is full 12v for power, it was a purple wire from fuse block if I recall.
Anyone has any experience with problems resulting from a pop/misfire due to a bad ground/electrical/voltage supply issue?
And Tajoe as far as the engine mounts go I wish I could be more helpful there. The way I did mine by fabricating the mounts to existing sbc mounts I figured if anyone ever swapped back to one it would be an easy job. Although this is never happening in my lifetime! Lol
TTOP350, I’ve drooled over your garage many many times. I spent some time reading your thread on the JY Firehawk clone, outstanding my friend. This is perhaps my pipe dream to do with my 91 Formula. Alas, I’ll probably end up somewhere in between. I see you’re in central IL, would love to come see that thing in person sometime!
TTOP350, I’ve drooled over your garage many many times. I spent some time reading your thread on the JY Firehawk clone, outstanding my friend. This is perhaps my pipe dream to do with my 91 Formula. Alas, I’ll probably end up somewhere in between. I see you’re in central IL, would love to come see that thing in person sometime!
Well thanks, and anytime, just shoot me a message when you'll be swinging through and we'll try and make it work!
lt1 guy,
As far as compression on the 455 engines in the 70's were around 8.5:1. To get it up to 9 to 9.5 on a 455, look for the heads on a 70's 400. You want to get the 6x heads, the casting # are on the center port. These are some of the best flowing stock heads made by Pontiac. If you want to run headers, you will have to drill the rear exhaust bolt in the head.
Well, you're on the right thread. Want more power? Remove the 305, and install a Pontiac, like some of the above members have done. it's not easy, but rewarding.
Just a brief up-date, from past postings.
My goal years ago was to put a 301T motor, in an 84 T/A. Have both the items, and through this site have acquired some components to add/modify the car, to make it more simple,(?) and reliable, by ridding it of some of the unnecessary creature comforts. Such as dumping these nasty electric window actuators, and converting to mechanical. And because I'm in the north, banish all traces of A/C which does nothing more than clog up the engine compartment. (I know the southerners will have a hard time with this). it's a tight enuff squeeze under the hood as it is. Wish there was a manual steering box, to get the pump off the engine, but maybe in a T/A road car, should probably figure a way to adapt the early Pontiac pump and hoses, to the 84 steering box.
As I've read through this thread, I notice lots of concerns about mounting the Pontiac engine in the 3rd gen, and continually bring up the fact, a member here put his 301 in and on the original 3rd gen Chevy rubber frame mounts, and his 2nd gen Pontiac eng brackets. Because we had such a gorgeous day here last Fri, I decided to uncover my T/A, and compare and measure distances, relative to the (complete) 301T in my eng. stand. The 1980 301 steel brackets on the side of the motor, are the same shape and "basically" the same size as the 305 mount. The centerline of the horizontal mounts bolts are also "relatively close", as is the distance from the back of the block, to the rear of the mounts. And I see an extra set of holes drilled on the frame member which holds the rubber mounts. Also the basic width and length of the motor are similar. And the exhaust for the Turbo down pipe should eliminate the need for custom hedders. (And now the wife is pestering me for supper...gutta go).
If anyone is interested, I will be glad to continue.
Last edited by tajoe; 04-12-2021 at 03:49 PM.
Reason: mis-spelling
I have been working on my swap. Pretty much all done except exhaust. Keep the 700r4 in place used a adapter plate to mate up the 440 ( 4” stroke .060 bore). I spent a lot of time on this and money I wanted it to look factory like Pontiac intended it to. It was a original 50,000 mile car with the lg4 and yes I could have put a more powerful sbc in, but went the more difficult route. I could write a book on this swap. Was so many little items to make it work.
Super clean looking install. Does it run? Have you been driving it? Performance reports?
You mentioned the bellhousing adapter for the 700R4. That would move the tranny rearward, further from the hub on the converter. Does it still engage the frt pump? Curious how thick the adapter is, and does the kit consist of an extension for that, or is it not needed? Anyway, hope to hear more about the install. Is there a build thread for your car?
Runs great, too much motor really for the light car, especially with the torque. A 'vetter killer for sure, at least the ZO6, not sure on the newer models . The adapter plate is from summit, standard adapter 3/16 thick, and it includes bolt spacers for the torque converter to make sure it engages the pump tangs. I left the 700r4 is the stock location and mounted a mock up of the block and heads, intake to get it level and make sure the hood closes. The driver head is close to the brake lines so you need to turn that fitting around 180 degrees to get clearance. I removed the a/c and found an original NOS steel heater core housing to have it look like a a/c delete car. I have attached a few more pictures. Fully welded GTO frame mounts took some time to get level and in the centerline of the car. Driver side head, need to relocate this brake line, just move the clip 180 degrees Fits under the formula hood, barely
Well done "Souperman".
I see the welded on solid eng. mount bracket., which I assume is something like a Summit item? Get any noise from that solid mount, or does the exhaust system cover it up?
And speaking of exhaust, are you using custom hedders, or factory exhaust manifolds? I now see you mentioned not having an exhaust yet. Have you been driving it with open exhaust ports?
I like your removal of the bulky evaporator case. I have a std heater box replacement too. Was curious about any need for welding open holes, and does the duct work on the interior suitcase need attention too? And lastly, I'm amazed you're able to shut the hood. My 301T motor has a shorter deck height, (than yours), and barely fits under the 84 hood. What year was yours? Not sure if you mentioned. Thanks for your replies.
These are not solid mounts, the block mounts are rubber, but instead of bolted these frame mounts I welded them. The early year Pontiac had it this way, the later years late 70’s had rubber mounts on the frame. This triangular mount allows the engine to sit lower, it is barely off the center link bar. I had a exhaust but switched to this dual 3” speed engineering exhaust package I got for $350, see the other thread with pics in the exhaust section.
I wanted the evap and a/c removal to be clean, like the factory intended, I hate seeing the evap case just hanging there, there looks really bad. . I think the repop fiberglass a/c delete case is similar but this is the factory steel a/c delete. I believe all the holes will be covered no need to weld anything on the firewall.
I had a built 301, but was built to a 383 (exotic with a forged crank etc.) by Joe Sherman engines in LA, that I was going to put in, that 301 dynoed at 475hp, but I sold it last year.
Last edited by soupman; 04-12-2021 at 04:50 PM.
Reason: Spelling
You had Tom's 383? Would you mind sharing who has it now? I want that engine, or to replicate it at least... it sold for way less than I thought it would.
Estimate on how much lower the engine sits using the mount the way you are doing it vs the later rubber and clamshell? That's what I am going to use with my tubular K-member.
I had a built 301, but was built to a 383 (exotic with a forged crank etc.) by Joe Sherman engines in LA, that I was going to put in, that 301 dynoed at 475hp, but I sold it last year.
475 on a 2 bolt main, 301 thin wall block casting ?!!! Did they fill the water jackets with anything, to stiffen it up? I'm sure there wasn't much 301 components left on it, to make that much power. Traditional style heads, and crank, I'll bet. Internally balanced , And some type of fabricated intake. Can't even fathom the cost. Wonder what it ended up in?
I sold it to a guy in Maryland. Would have to look this guy up. Yeah Tom spent some coin on that motor. I bought it for $5000, I think he had well over $10k into that 301. I was so close to putting that motor in this car but decided to use a 1969 400 block with a 4” forged stroker crank. I love the way the 4” stroke revs, especially in a lighter car. The 301 would have sit lower, its deck height is 1” lower. Actually the 301T block is pretty beefy, people don’t realize that the main webs are the same thickness as a traditional poncho motor. The ‘557 400 block is weaker than the 301T block. The regular 301 is pretty weak. That motor had a 1963 forged 303 crank in it.
andrew-not sure how much lower but it is as low as it can go since it’s about 1/8” above the centerlink bar to oil pan clearance.
Last edited by soupman; 04-12-2021 at 07:16 PM.
Reason: Spelling.
I didn't know the Turbo block was beefier than the NA motor. Learn something new every day.
I know what you mean about a 4" stroker. Had a 439 (+.060 428) in my 69 bird years ago. With some modified 62 heads.
Thanks again for your responses. I'll have-ta dig deeper into your car photos and story.
Nice picture! That 301 (383) had 15 heads and a torker manifold, had a short fill too. Heads and manifold ported by Dave @ SD. Made 478hp @ 6000 and was still climbing after shut down the dyno at 6000. Easy 500 hp if we ran it past 6000. Probably be a awesome motor in a thirdgen firebird. Just need to finalize thus new exhaust to get my car back on the road.
I have a 301T, some mildly ported 16s and a T2 (not modified yet) sitting in the garage. Just need to get me a pontiac crankshaft. Of course that's after I get it on the road with a 301 to start with...
...and yes I could have put a more powerful sbc in, but went the more difficult route.
No, you definitely went the right route, that is a very clean install and looks fantastic. Would love to see that thing boogie down the track. Are you considering fuel injection in the future, maybe a Holley Sniper.... ?
thanks for the comment.
The carb is a Ruggalized quadrajet. It is dial in perfect, a/f ratio are right on the edge of lean. I may do fuel injection, but this carb runs so good.....
Originally this car had the lg4 and qjet, so I was about to take the measurements from the brackets that mount the tv cable, throttle and cruise control to the Pontiac intake. I was able to retain all those features without bastardizing these brackets.
The key to this swap is the exhaust, if is extremely hard to get headers on these cars. I went with ram air manifolds and mandrel bent downpipes. I got the CNC manifolds that where opened up to a true 2.5" and hand blended so hopefully will full almost as good as headers. They fit really well and exit the car with good ground clearance. I am now doing the 3" dual swap, and taking some time. Here is a picture under the car.
Your work continues to impress me Souperman. Good choice on the RA manifolds. Always liked them on the street. So many benefits over hedders. (But I do like open hedders at the drags, but those days seem to be long gone.). By the way, do you really think there's a need for 3" pipes, over 2 1/2s? Not sure how much there is for a performance gain, with the manifolds. Just curious, cause I know how tight it is squeezing anything under these cars.
Testing has shown that on a 450HP motor, the RA manifolds are down about 20HP but less than 10ft-lbs over long tubes, and are right in there with shorty headers. https://www.hotrod.com/articles/hppp...-vs-manifolds/
What they didn't show in there is the loss with factory manifolds on the big engine, but I'm guessing that they'd be down another 10-15HP.
On a less powerful engine, the loss is lower. Since my starting point is definitely on the lower end, I'm going to try the shorty headers for my NA 301.
01-16-2018, 05:44 PM
