Been awhile since i posted here. Been building an engine for my truck, lots of time consuming hurdles. Everything kinda came together all at once and i ended up with everything i need to finish the truck engine, but......

I acquired a 1972 Pontiac Catalina 4dr sedan in almost great condition. In a barn since 1989 from the original owner with 73k miles, all original and intact except the seats and carpet.

Should i just get a junkyard 5.3 to put back in the truck and do the hard work of making this car suitable for a torquey 5.7 and 4L80e, or do the boomer purist thing and refresh the lazy Pontiac 400?

 

Pontiac has the basic 400 2bbl, my 2005 Chevy Malibu technically has more HP and torque i believe. Everything to really boost the Pontiacs power puts me at the same cost as swap parts when you consider machine shop time on the block and heads. Im not a purist, I only care about keeping the interior old car feel.

So, i have a fully built iron LS6 essentially but not a high revving one. The SUM-8718R1 cam, slight valve job, 5.7 flat pistons, should be good for lots of low end torque. I would need a new oil pan, figure out the accessories, HVAC is a must in Houston, I'd like to semi-daily this beast switching with the truck. New driveshaft, fully rebuild and regear the differential, motor mounts and fuel supply.

To do the Pontiac right, heads need alot of work to be good with ethanol. Threaded rocker studs, hardened exhaust valves, decking, the whole nine yards. Would be well into $5k just on the engine work and parts, thats me doing all the labor except machining. Then i need to refresh the transmission, which wouldnt be much being a TH400. It has goid compression on 7 cylinders, #2 is finicky. Itll sputter with fuel but most likely leak and smoke like a geriatric sailor. So i couldnt daily it without doing rings and timing gears, engine is fully disassembled essentially for that. Any modernizing takes a lot of work to have carburetor issues still just by design.

So, help me out here. My wife and daughters love the old car feel inside and out, they dont care for the poncho soul. I dont really either, i just think it looks cool and a great candidate for reviving. Got it super cheap. Could probably sell the complete engine and transmission for close to what i got the car for not including renting a truck and trailer.

 

Been talked out of it. Keeping the old Pontiac iron.

 

Sell that 400 and drop a 5.3 with a turbo into that thing. Keep those rims on it too. A 1972 Catalina isn't a muscle car, and it's not suddenly a really valuable vehicle because it's got a 400 in it. Better yet, sell it to me and I'll make it run 9's, lol

 

This.

 

I never liked turbos on American V8s, if i had the Pontiac straight 6, maybe for ***** and giggles. But ive decided to keep it original, the LS build is going back in the truck like originally intended. New California odometer taxes, gubmint requiring kill switch access, all sorts of stuff just makes me want to keep the points ignition and no electronics at all.

 

Paint it black, throw some magnum 500s on it and call it a day.

 

Speaking from an economical point and a FUN/HP per dollar spent.... Why would anyone keep the old pontiac motor? Makes no sense to me. It will cost 5x what the LS 5.3 will by the time you get the dated motor machined with updated parts to be anywhere near the LS. Not that it can’t be done, but why would you want to? What difference does it make where the power is coming from once the hood is closed? What kind of power goal do you have?

Those 400’s were really anemic. 8.2:1 compression and had 175hp 2bbl base version and a 200hp 4bbl version. Even with basic upgrades I don’t think it’d hang with a cheap LS.

A $300 4.8 with a cam will walk circles around it. 5.3 even more so.

If drivable, I’d cruise it as is with the driveline FS. Might get lucky. Then put something fun in it. There’s enough room under that hood for 6 turbos. I saw a guy put 2 V8’s inline under that hood!

When It comes down to HP per $. The turbo is simply the correct answer. $300 motor with a $200 turbo running 6-8psi (no intercooler necessary ) will make every bit of 500hp+ with any small bore LS and a cheap cam. There is no cheaper way to make that kind of power I’m aware of. And you’ll want it with a 5000lb beast of a car.

Just my .02 anyway. Super cool car BTW, love the old boats!

 

My .02?
I think I would build the 400 and that comes from a big time LS swap guy.
Won't be cheap and finding an engine builder that's has lots of knowledge building these "old" engines maybe will take a bit of work.
The up side of the 400 is that you can it out and put it back with no mods that a LS swap would require. Gives you time to detail the engine compartment. LOL.
Been years but IIRC you can a buy stroker kits to change the 400 to a 455 that aren't crazy expensive. Edelbrock heads and a small cam it will be a torque monster.

 

"Speaking from an economical point and a FUN/HP per dollar spent.... Why would anyone keep the old pontiac motor?" - I have it already. Its there, complete and in decent condition.

"Makes no sense to me. It will cost 5x what the LS 5.3 will by the time you get the dated motor machined with updated parts to be anywhere near the LS. Not that it can’t be done, but why would you want to?" - im not chasing big power, im not drag racing, i just want a cruiser. Just getting a 5.3 and 4l60e costs more than a 4bbl intake with a rebuilt carb and exhaust shop work for true duals, which would put me at stick 5.3 power levels but with more low end torque. If i did the 5.3 and 4l60 i would also need a new driveshaft.

"What difference does it make where the power is coming from once the hood is closed? What kind of power goal do you have?" - the only real difference in powerplants is how they sound. Im not chasing big power, just a 4bbl and dual exhaust frees up alot on this Pontiac. Dont even need headers.

I have the iron LS6 still hanging. I would need to get a 4l80e preferably, would need to regear the diff, wiring harness, get an ECU tuned, theres quite a bit involved with the LS swap. Talking purely fun per dollar spent, would be more fun getting it going without changing anything. Just reviving it and driving it would be the most fun.

 

Yeah it would take a bit of effort finding a decent shop setup for this big engine and heads. I do want to be budget minded with this, im not looking to drop $5 in parte and machining like i did on the LS6 build i have. I dont think it really needs anything besides the timing gears changed, pretty sure it has the original nylon coated *****. From what i can tell, only the water pump and ignition bits have been changed. Got a wiring issue i need to figure out, not getting power to the coil but it cranks no problem. I just haven't been able to work on it with daylight.

On the stroker, i dont think it can get to 455 without boring. I think its 440ish, but i can't remember. I haven't looked into that yet. Ive been focusing on finding the suspension bits and other hard parts. Its got good compression, just need to find the wiring issue or rig something up. Still need a gas tank and fuel lines though.

 

Unfortunately, the juice isn’t worth the squeeze on the Pontiac motor anyway you look at it. Aside from keeping it “as is”. You could easily sink over 5k into that and not make the power you could with slightly modded small bore LS. For less than half the $.

Boost is still the cheapest and best option, but if its not for you...I get that. Is E85 an option?

Recently put together a super cheap/mean NA 5.3. Picked it up for $550. Then sold the 799 heads everyone wants for $400. So I had a whole $150 in the motor. Grabbed the dirt cheap 706 heads no one wants and had them milled .100.($400) You end up with a about 13.3:1 (e85 fuel). Add $100 ebay headers with cam/springs. End up with a nasty sounding budget LS making pretty dang good power for very little spent. Was told I could have gone .120 on the heads to get another ½ point or so. Def would do that if I were to go this route again.

 

As much as I love LS's, build the 400. I can guide you or even build the 400 and make it run strong and reliable, I have built a lot of old iron and know the ins/outs of that particular motor. Making 1.5hp per cube isn't hard with aftermarket alum heads and a hyd roller cam. Big questions you need to ask are do want to stay carb or go injection and how much power do you realistically want it to make. LS would make sense if you wanted more than 600hp and/or go boosted, but if it's NA, the Pontiac is not a bad platform to build. The 400 block is the one to build, I would not even bother stroking it if the crank is in good shape. Will make plenty of power and lots of torque if you get the topend right.

 

Guess you didn't read the part where i said im not chasing power and want a cruiser....

 

I mean, if you don't mind single digit mileage when you're cruising, the 400 will work fine. Kind of ruins the point of cruising, however. Having decent mileage means you can drive it more. Why not buy a junkyard pullout 5.3 and 4L60E? You'd see an easy 20+ mpg, don't have to pump the throttle to start it, and driveability will be much better. As you said, a 400 with trans is going to be worth some money to someone, and would likely finance an engine and trans, with enough left over for ancillaries.

 

I mean, youre not wrong. Just the previous recipe for high compression and e85 doesn't fit my imagination of a cruiser.

This is why i started this thread. I have plenty of people with good arguments about keeping it original. The main arguments for it is, its only got 73k original miles, everything is there, just gotta fix the crap that rots from sitting. Get it running and driving with what it has now, then decide what to do.

I am very tempted to find a decent engine and just slap it in the truck, and start piecing together the swap essentials. After pricing everything out, it adds up quick.

The weather is finally getting better in Houston, the biggest challenge I have right now is not having enough energy to dick around with stuff after work and getting the daughters settled.

 

I did, And a old 400 is far from a cruisier. That thing gets horrible mileage! Both options I suggested would be MUCH better cruisers than that wheezy old pontiac motor would ever dream to be. They would also make much more power.

Higher compression is better for mileage. Even throwing in the 20ish% loss for E85, I still net over 20mpg with the 5.3. That assumes you have E85 pumps all over town though. Here, its no harder to fill on E85 than pump gas. But I know not everyone has that. Without E85, boost is still the best bang for your buck by far.

As mentioned even a bone stock 4.8 would cruise 10x better eff. wise and still out perform the 400.

 

I kinda like the wheezing sound.....

E85 has lost some popularity in Houston. But I think all HEBs have it. It is around enough. So, for the swap, if i went 4l60 or 4l80, i would absolutely need to regear the rear diff. I could get a Chevy th400 instead, but that kinda defeats the purpose of the swap if i dont also get OD.

This means a new driveshaft and yokes i think, atleast one. Relocating cross member, its super simple on this car, and shifter linkage. Then wiring, getting a tune, electric fuel pump, blah blah blah.

If i keep the Pontiac, an Edelbrock intake and dual exhaust would get me 250hp and probably 350tq. The tq is what matters most. No stock 4.8 or 5.3 will get me that much torque where i need it. The swap is really a complete power train swap, not just the engine. That's what makes this add up really fast. Especially when i want to actually drive it semi-daily. I can get a 5.3 with 4l60e and harness with ecu for around 1000$, fuel pump, regear of diff, driveshaft, getting headers that actually fit, mind you, none of the gauges will work without modernizing as well, were talking well over 3000$ just getting it working on the old body.

As opposed to 150$ for an intake, 350$ for a 4bbl, 500$ in true dual work, and i have basically 4.8 HP but significantly more torque off idle. And like probably 8-12mpg.

The engine I have hanging should be 400hp/tq at the wheels once its in my truck. And should be all midrange power. Its just a big endeavor is all. Not against it entirely, i still think i should atleast get the original setup running and driving, so maybe itll remind me how much carbs suck and fully motivate me for the swap..

 

Fellas, we're wasting out time explaining ways an LS swap is gonna' be to his advantage, it's obvious he has his mind made up to go with the antiquated Pont engine route. Like they say "You can lead a horse to water. but you can't make him drink"...

 

"Agree with me completely or **** off", is that just the standard attitude for LS guys? Seems to be the norm.