Engine performance upgrade

77NyKR

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Hi all, I love my 77 NYB I take it everywhere all over New England. Has about 80,000 miles. I have dual 2.5 inch exhaust on it. Looking for more of a punch from the 440. Obviously reliability is a must for me on long road trips but she just seems to fall flat on her face. Looking for some performance upgrades. The lean burn is gone. What should I be looking at to install? Thanks in advance!

53804FBB-78DA-4AF4-BE8A-568A917FE10E.jpeg
 

Slap Stick

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Before you so anything ensure the fuel and ignition systems are working properly.
Beyond that, I would look into different gearing, assuming it has highway gearing, say, 2.71:1. A big, heavy car like that needs some help getting moving and lower gears help. It could even improve gas mileage. If your exhaust is 2.5" all the way back that could be hurting the bottom end as you don't have enough flow to warrant the pipe size. Does the exhaust have a crossover pipe back near the tranny?
 

77NyKR

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1662225819415.png

Negative. Do believe it has the highway gears. I do a lot of long distance trips, would the 3.23 hurt me on the highway?
 

413

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Does it still have the lean burn carburetor? If so get that off of there.

3.23 gears will help a bunch.
 

CBODY67

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Automobiles are engineering compromises. Seeking to "hit that sweet spot", but not always getting there. Desired "styling" is not always the most aerodynamic way to do things, too! "Road hugging weight" can be good on the open road, but not good in city traffic. Adding 50 horsepower (at 5000rpm) is not going to make a big lot of difference in performance at 30mph, even at WOT.

The question is where does it "fall flat"?? The stock 2.7 rear axle is great for open road cruising at 60mph+, plus contributing to good fuel economy at those speeds, too. That "good fuel economy" CAN depend upon the items used to replace the ELB system, by observation. Basically, which carb and which distributor????

Probably the best upgrade would be to install higher compression ratio pistons, to get the CR back up into the middle 9s, BUT that can compromise the ability of the engine to run on (comparatively) inexpensive 87 Pump Octane fuels. The extra money to buy 91 Pump Octane fuel might not seem too bad by itself, but filling a 20+ gallon fuel tank can make it add up quickly. Then compound that on any kind of road trip and you suddently get into $$$$$ territory. Now, somebody with a car can have different sensitivities to those higher fuel costs than, possibly, somebody who regularly fills up a pickup truck or SUV, but "more" always costs "more" in the end.

Does your car have a lock-up torque converter? Is it still operational, if it had one from the factory?

When the "air" sees your car coming, or one like it, it might seek to get out of the way before it is pushed out of the way. LOL

At 55mph, the engine should be running right at 2000rpm. Not too much rpm, but also low enough that a wilder cam can make it weaker in that speed range compared to the factory cam, which means a bit less throttle response or available torque to move things along. Going to a 3.21 would be 2000rpm at 50mph. Not a whole lot of difference, but possibly enough that throttle response might be increased a bit due to the higher engine speed. But also expect about a 5% fuel economy decrease, too, from Chrysler's own figures, IIRC . Better throtte response can mean less throttle input to increase speed a bit, which can also mean the carb stays out of the "power mixture circuit", too.

The camshaft from the factory is just a bit more than the old 256/260 cam of 1966, but the heads can be slightly better with a few port tweaks and 1.74 exhaust valves. Chrysler did a few engineering tweaks to make the engines "better air pumps", by observation. Plus electronic ignitions and lean-limit carbs for better fuel economy and emissions. AND those tweaks did work, when the cars were new and they WOULD beat similar GM and Ford cars in on-road fuel economy. But with a bit more "touchy" driveability sometimes, as @saforwardlook has mentioned a few times before.

At this point in time, getting more power and possible economy out of a car like yours might take a Holley (or similar) EFI unit that can also control the engine timing. With any EFI, driving style can make more difference in on-road fuel economy because with a carb, as the throttle opens, intake manifold flow must PULL fuel out of the float bowl for the engine, whereas with EFI, the millisecond the throttle moves, more fuel is added to the air flow, which means better throttle response, but can also decrease fuel economy without a steady foot on the accel pedal, by observation.

The EFI will provide a more vapor-like fuel mixture to the intake manifold, which can increase fuel economy on the road. BUT . . . using that as a reason to go to EFI is not a financially-viable reason to do so, by its self. Not sure if you might desire to spend approx $4K to get the EFI kit and related equipment/hardware (and installation labor) to make it work as it should.

And EFI and higher compression pistons can make the expenditures more than the car is worth, I suspect, so little return on investment, other than how things feel when the throttle is moved. Similar, too, if 3.21 gears are put into the mix.

To me, I enjoy the "long legs" of a 2.71 (and tall tires) on Texas roads, where normal Interstate cruising speeds are in the 80mph range (actual rather than posted). At those speeds, the engines are just barely getting close to 2800 rpm (in the meat of the torque curve) and everything works well. And this can happen for HOURS on end, so the quieter engine and better fuel economy of that 2.71 equipment works well down here. Or into NM and AZ, or even in KS. "Trips" in your region might be different, which I understand.

So, unfortunately, no simple or easy answers, but a consideration of priorities and what each of them might ultimately cost. "Change" cost and "resulting daily" costs.

If we know which carb and distributor were used to de-ELB the motor, we might know better what might be done. Plus where the "falls flat" comes into play.

Take care,
CBODY67
 

Davea Lux

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The '77 440 is a low compression engine that was set up for emission control, not performance. Chrysler big blocks in '77'-78 did not run locking convertors. They used a low by pass convertor to improve mileage. The down side of these convertors was that they tended to overheat the transmission oil leading to more frequent servicing. Putting large diameter tubing on a low compression engine tends to cause the engine to lean out as the back pressure is reduced. You can try to go up a size on the carb jets to see if that helps. Depending on which carb you are running a larger diameter nozzle for the accelerator pump might also help. If you are still running the stock Thermoquad, that needs to go away as it runs too lean for any performance potential. The factory rated 8.2 compression ratio does not lend itself readily to performance enhancements. A lot of these engines were below that spec, ratios in the 7.8 range were not uncommon. To get much in the way of performance out of this engine, higher comp pistons are a must. If the factory manifold still has an EGR valve attached, you should purchase a block off plate as the EGR system was famous for carbon build up which caused the intake manifold vacum to drop as the valve became stuck open. A dead spot on acceleration can be one indication of this especially if the engine farts back thru the carb as the throttle is mashed.

Dave
 

1970FuryConv

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Before you so anything ensure the fuel and ignition systems are working properly.
Beyond that, I would look into different gearing, assuming it has highway gearing, say, 2.71:1. A big, heavy car like that needs some help getting moving and lower gears help. It could even improve gas mileage. If your exhaust is 2.5" all the way back that could be hurting the bottom end as you don't have enough flow to warrant the pipe size. Does the exhaust have a crossover pipe back near the tranny?
How does she fall flat on her face? what happens exactly?

2.5" exhaust would handle 9.0:1 compression which would be a big performance enhancement, but would require rebuilding the engine.

If you press the accelerator pedal hard and the engine almost dies, I agree with carb problems,. especially accelerator pump. Ditch the thermoquad and buy an Edelbrock AVS2 with annularized booster. If you are willing to wait 3 months, Dale Woodruff could rebuild your thermoquad better than new. Good Luck!
 

Mr onetwo

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Try a Holley Street Demon and put an O2 sensor on it so you can do some tuning.
 

USSMOPAR

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No h pipe on the exhaust, the 2.5 size is fine, quit over analyzing as the real details get run over as always, just look at a brake thread where so-in-so is so smart and rest of us are just ^%&*(!

Needs mopar oem type hemi mufflers or better yet the c body version

I see nothing done to improve rolling resistance which right now i bet is significant.
In fact is don't recall anyone on here discussing rolling resistance. Maybe that concept is too complex for you-all.

These cars respond very well to a converter with some stall 2000-2500 and 2.94 gears which gives the car get up and go along with good mpg and some long legs for the interstate.

block the crossover on the intake manifold

tune up with custom dist curve
real plug wires that work - Firecore - not that junk that gets fawned over
 

marty koirtyohann

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Hi all, I love my 77 NYB I take it everywhere all over New England. Has about 80,000 miles. I have dual 2.5 inch exhaust on it. Looking for more of a punch from the 440. Obviously reliability is a must for me on long road trips but she just seems to fall flat on her face. Looking for some performance upgrades. The lean burn is gone. What should I be looking at to install? Thanks in advance!

View attachment 555956
mill the heads at least 25 thousands put in a mopar pwrformance resteation cam / lifters & valve springs a 440 magnum/ six pack cam
 

david hill

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To make this doable first replace the cyl heads w/ a closed chambered pair. this will increase the compression ratio up to approx. 9:00 to 1 compression ratio. A change in camshafts will restore HP and torque that is missing. Duration of about 244/266 w/ valve lift of 440/458 will complement the cyl. change. Block off the EGR and add a Carter AVS4966. Recurve the dist w/ 34 degrees total advance. This combo will makegood horsepower and fair mpg.
 

i_taz

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Mine had 3.23 gears put in and power is not an issue. Sometimes I yearn for an OD gear
on a trip but once I set the cruise I seem to forget about it and still get 14 mpg with a TQ.
 

marty koirtyohann

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Mine had 3.23 gears put in and power is not an issue. Sometimes I yearn for an OD gear
on a trip but once I set the cruise I seem to forget about it and still get 14 mpg with a TQ.
WELL THEN PUT IN A OD TRANY . BIUT U WILL HAVE TO MODIFY THE TRANY TUNNEL CAUSE THE OD TRANY IS BIGGER . NOW I DONT KNOW THIS FOR A FACT but a guy i know (he runs a resteration yard . said yes to modifying the trany tunnel . now u could put in a 5 speed stick?
 

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77NyKR,
3.23 gears, but since your car doesn't have a 8 3/4" drop out center, and setting up Spicer gears properly can be costly, it would probably be cheaper to buy a complete rear end with the 3.23s. Add a non-emission 4 brl carb, re-curve dist, valve job or at least new stem seals, and likely a new smaller performance cam for the low compression era motors like a Lunati Voodoo. Your 80k motor cam is low perf and probably worn out, as most of the ones I pulled out of similar era motors that I used for rebuild cores with as little as 50k miles were shot.
 

marty koirtyohann

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mill the heads at least 25 thousands put in a Mopar performance resteration cam / lifters & valve springs a 440 magnum/ six pack cam
well all i told u i did on my 72 smog 440 i rebuilt it to 71 specs . i had a set of heads that was all ready milled 25 thousands i cc'ed the heads that was 90cc's (i was told with the block i had the heads would make it 9-1 compression motor i also added a windage tray &a double row timing chain the oem chains r only good for 90-110k miles then i added a Mopar performance resteration cam the had already had the battleship double springs good for .500" lift . i trashed the Holley & put on a 750 cmf carter carb from a 71 440 new yorker . it has 2.76 gears in a 8 3/4 "banjo" rear end . now if i had put in a 3.23 gear the mpg's would had droped to 10 on the highway. its no jack rabbit @ the traffic light but it runs out ok i wish the mpg's would be better
 

Mr C

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The '77 440 is a low compression engine that was set up for emission control, not performance. Chrysler big blocks in '77'-78 did not run locking convertors. They used a low by pass convertor to improve mileage. The down side of these convertors was that they tended to overheat the transmission oil leading to more frequent servicing. Putting large diameter tubing on a low compression engine tends to cause the engine to lean out as the back pressure is reduced. You can try to go up a size on the carb jets to see if that helps. Depending on which carb you are running a larger diameter nozzle for the accelerator pump might also help. If you are still running the stock Thermoquad, that needs to go away as it runs too lean for any performance potential. The factory rated 8.2 compression ratio does not lend itself readily to performance enhancements. A lot of these engines were below that spec, ratios in the 7.8 range were not uncommon. To get much in the way of performance out of this engine, higher comp pistons are a must. If the factory manifold still has an EGR valve attached, you should purchase a block off plate as the EGR system was famous for carbon build up which caused the intake manifold vacum to drop as the valve became stuck open. A dead spot on acceleration can be one indication of this especially if the engine farts back thru the carb as the throttle is mashed.

Dave
I must correct you on one thing in particular. In 1978 the 400 could be had with a lock up torque converter. Some did...some didn't, but I have seen them. It's mentioned in the 78 brochure under availability...
78-Chrysler-engineering_0019.jpg
 

marty koirtyohann

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I must correct you on one thing in particular. In 1978 the 400 could be had with a lock up torque converter. Some did...some didn't, but I have seen them. It's mentioned in the 78 brochure under availability...
View attachment 558674
yes a lock up convertor will help some but just about all the ones u get now r junk (my trany guy tells me they disable all their lock up ones when they rebuild the trany's)
 

70bigblockdodge

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I hate to go down this path.
Here goes.
Milling the heads is useless without milling the deck and a piston change. Now you are into a complete build. Any pistons you are getting off the shelf that don't cost $800-$1000 a set are going to put you right back in crap compression ratio. Someone mentioned milling the heads to 90cc hear is what that gets you if you also deck the block to 0.0 and use stock cast type pistons.


Screenshot_20220917-150539.png

Here is what you really get from the average mid70s 440 or 400
Screenshot_20220917-150634.png

Now you could mill the heads and replace the pistons with some KB step head pistons and you might get to 9+:1 compression, but that's a good chunk of change, a lot of work and probably net you 25-30 horsepower and a mile or maybe 2 pet gallon fuel mileage.
Gear changes in the 9.25 rear in your car are a PITA, and with modern traffic all rolling at 70-80 mph, 2.9 gears is as low as I would go without a overdrive transmission. Sucks being in a cool old car and getting passed by a old lady in a Toyota, also sucks humming along at 3000+ rpm at 75mph with those flowdrones you have on there.
My suggestion is just stick with basic hot rodding tips.
Put a good aluminum intake on there, block your heat crossovers. Fix or change your carburetor. The TQ is a great carburetor, but yours is a lean burn. Not lean when you bury the pedal in the carpet but normal driving it is lean, you opening the exhaust and ditching the cat has made this worse. Woodruff's carburetor (sponsor here) can set your TQ up to run spot on, or you can switch to another aftermarket carb and go down that road, still will require tuning because you do not have a 350 Chevy.
Distributor could use tweaking (they all need it even dead stock). There is a crap pile of info on YouTube and Google on what and how to do this. Basically you need the advance curve to come in early (like early in low 2k rpm) to light that lazy compression ratio and make some pressure early in power stroke. I forgot to mention you need to set the timing for total timing @3500 rpm. Needs to be 36° BTDC, although 38-40 is not out of the question for one of these 7.5:1 low compression slugs. Your torque converter is most likely a low stall unit and they don't help anything, also a PITA to change without a lift. If your trans starts going away it may be something to consider.
Hope this helps.
 
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