To stroke or not to stroke?

We found two bores that won't clean up enough to run standard bore pistons on the Imperial's 440. It's time to bore it.

I made the mistake of buying pistons based on the opinions of the last shop that had the block. They're hanging on the rods already.

Now, I get to buy pistons again.

Knowing that I want as much torque as possible but want to keep some sort of mpg, I'm fighting the question of going with a long arm on the 440.

Again, 5300 lb car built for road trips. 3.23 gears, 28.5" tall tires, and a 727. I do have a 518 and Ultrabell for an ID swap.

So, what do you folks think?

1/2" stroker, 505. Road Runner type cam might keep some semblance of mileage. The 518 might be worth a MPG on the highway?

Fewer cubic inches requires less fuel regardless of how efficient the rest of the build is. If you can keep the cid down while increasing the efficiency of the burn, that is the best answer.

440 in my one ton crew cab did just fine with torque in reserve and mileage that was most often seen in much lighter cars. 4:11 gears with 33" tires and a 727. I'd guess its weight to have been around the 5k range, give or take a couple hundred.

would sleeving to standard bore be cheaper than new pistons?

Exactly what I was wondering, too. It's about $125 a hole to sleeve here.

Do you know for sure what size the bores would clean up at?
Has the block been sonic checked (which may be paranoia, but I always do it just to know) ?
More stroke will of course build more low-mid torque, all else being equal.
I would think a 505 would use more fuel than a 440, all else being equal, but I have no personal data on that.
That said, 440CI moves even an Imperial along pretty well on the highway.
So you might not want/need to reinvent the wheel, so to speak, let your wallet decide the sleeve/piston issue.
If that trans is a 30% reduction in RPM, that amount of OD on my 5500-5800 lb Dually (depending on what's in the bed) is worth 2-3 MPG.

Stroke it. That bigger cube will work less to move that car. Not hard to put together a big displacement/mild build these days. Idle at 800 rpm and pull like a freight train......can look stock as well! My buddy has a 540" Hemi in his Coronet....has a bit of a lumpy idle but looks stock as hell. Runs like a mother when he leans on it!!

One word. Boost!!!

Orrr... 9:1 4.25 stroke 505.

500 hp and 600 ft/lbs all in by 5000 rpm on 87 regular.

Orrr... 505 cubes AND boost!!!

Kevin

I understand the desire and appeal to keep the 440, but the Imperial is a big ol' CRUISER not a drag car. Drop a modern Hemi in it and be done.

While I'm all about torque, you do still have to have the traction to use it. It's great bragging rights to have 600 ftlbs but if you can only use 400 what's the point?

So, with the stock 440, if you could blow off the tires, why stroke it?

Maybe just sleeve the block and find some 276 gears for the freeway?

Had this years ago,3.23 rear,8x20 15 tires,changed the cam,did a few other mods,saw hardly any difference in mileage and performance,5500 lbs and low compression killed it,waste of time and money. It would do 15/16 mpg hauling my 24" travel trailer as it was,that should have told me something before I started fooling with it..

I have a 518 behind my 540 Hemi with 3.91s. I love it and am glad I went to all the effort to put it in my Cuda. And that experience causes me to ask some questions about putting a 518 behind a 440 to do that particular job.

First, someone check my math here, but isn't the final drive ratio of 3.23s with the .69 OD of the 518 something like 2.23? And I get that a 440/518/3.23 would RPM about 1,900 @ 70mph. If that's ballpark, I think there are some additional things to consider.

Is the 5,300 lb loaded or empty weight? Are you going to use a lock-up 518? If not, are you concerned that the RPM at hiway speed may allow a lot of converter slip with that much weight and pushing a lot of air? Would there be a concern that the 440's RPM would be low enough at hiway speed that it wouldn't have enough torque to pull the weight and push the air without eating a bunch of gas?

I am not saying that this combo won't work. I am only asking if it would be as efficient as the OP wants.

My 9:1 493 with an MP509 way wrong cam choice for bottom end torque, made 500 ft/lbs by 1500 rpm. It wasn't happy doing it but that's where no replacement for displacement pays dividends. A better choice in cam specs is all mine would need to make it tractor rpm friendly.

500 cubes will never be short on torque. Short on traction perhaps but never torque.

Kevin

He'll need some carb and converter work at the very least to cruise at that low an RPM. Unless he under carbs it, he will be trying to cruise on the idle circuit. And that causes some serious compromises to be made. And the converter will not even be close to fully engaged at that RPM pushing all that. Been there, done that. The OP desires economy which calls for a different set of priorities than are usually discussed here. Especially when it comes to strokers and tall gears.

I'm not saying it can't be done. Just sayin' that there will be additional things to consider with that kind of combo. Having torque to spare just moves the issues around, it doesn't necessarily cure 'em.

That was an early consideration. However, the Gen III suffers from the same issue as the earlier variants. There's nobody home down low. You have to get the revs up to find any torque. It would be a fun motor but similar to driving around a pickup.




As for my OD swap, I do have the lockup trans and converter.


Turbos have been calling me, especially since I still have them but that would be an even bigger distraction than what I've already got in front of me with the Imp and the roadster to follow.

If budget is tight then sleeve the 2 bad cylinders. If budget is not "Uncle Tony" tight then indulge in the hobby and stroke it. (If you didnt know Tony Defeo builds engines on an EXTREME budget.)

You mean the ones that eat themselves on the dyno like the one they tried to dyno at Nicks Garage?

Tony was a great writer for the rags and has some good ideas but his execution is lacking.

As for a mild stroker for the street, that's exactly what I built. Our 505" RB uses an 11" converter and 3.54 gear. It is a great street toy and pulls down 11 mpg on the highway with an old school carb.

We used it yesterday to beat up on full on race cars at the track and win the 11.50 index. A shot of spray has propelled it to 10.33 @ 130.

Gotta love adding insult to injury.

Kevin

I think a very mild, big cubic inch engine would be a great fit for the car.

I have an Old's 455 in a '79 Trans Am that is like that. Extremely mild build, purrs like a kitten, but lays down some serious torque to get the car moving. I have highway gears in the car, and it is still a blast to drive.

Sounds like you're between a rock and a hard spot. You've got a land yacht you want to accelerate like a mid-size sedan and still knock back decent MPG.


Either big block stroke it and get the down low torque, but with crap mileage, or G3 Hemi it and get the mileage, but no torque.

Have you thought about a G3 swap with a trans that has more forward gears than a 518 (my knowledge of what is available is nil)? Could make up for the lack of torque if you can slide an eight speed in. Bonus, stick as close to OEM as possible and get OEM reliability since you plan on using it as a daily driver.

A Gearvendors on the back of the 727 would give you a 6 speed with an OD that would be a good fit with a 3.55 or 3.73 gear.

Final drive in OD would be 2.76 and 2.90 respectively.

505 cubes with 600+ ft/lbs and that combination would hurl that Imperial across an intersection with authority and still be capable of Warp Speed across West Texas.

Kevin

Interesting suggestion.

Gear vendors has an OD ratio of .78 while the 518 that the OP already has is .69 and has lock-up converter. Hard to see the GV's advantage there. As to the split shifts, most don't feel that 'feature' is really practical in daily driving.

I’d call Dwayne Porter and pick his brain if I wanted a stroker. Fuel injection would work great on this application, big cubes, od transmission, high gears and low cruise rpm’s.

I’d stroke it!

The gear splitting that GV touts always came across as a gimmick to me. Not enough spread in the ratios to make that really worth anything.

8HP70: 4.7143 3.1429 2.1064 1.6667 1.2847 1.0000 0.8392 0.6667
727: 2.54 1.45 1.0

GV can only split between those ratios on the 727. I haven't read of any way to control an 8HP70 through aftermarket though.

If it was my car I'd go with a modest compression 505. Probably keep it down in the 9.50 range for compression with a small hyd roller cam and then put a Holley Sniper on it. We just finished an engine like that up the other day and it was smooth as silk. Had about 20 inches of vacuum and made close to 600 torque. It made around 500 on hp but it was all over by 5000 rpm due to the small cam. Keep the cam small and it will drive nice and smooth with decent mileage. The Holley Sniper with a Hyperspark ignition system gives you complete computer control over the AFR and the timing curve so you can dial in the tune at cruise. Costs some money to build an engine like that but it would be a fun car. Might even surprise a few BMWs with it.