Low Compression 440 Build Questions

[hilly101111111]

Good evening everyone hope all is going well. I have a low compression 440 from my 1973 chrysler New Yorker

im looking to build horse power and torque into. Any blue print or formula I can follow. I already have a carb and intake for it and plan to acquire hp exhaust manifolds. I don't mind spending some money however I want to sort of maximize my dollar per horsepower and torque for lack of better words. Any ideas or suggestions.

Id defiantly be happy with a crazy amount of torque over anything else. My rear end is a 3.23 gear with a sure grip brand new ready to go and Im also curious about what torque converter I should go with.

 

[Xcudame]

How deep into the engine do you want to go? Obviously higher compression pistons will go a long way for making torque and horsepower! Please provide more details on how far you willing to go. I can provide information for a full rebuild or simple camshaft and valve spring swap depending on how you want to go. It should have can with a Thermoquad from the factory and those were great carburators in my opinion.
Try to find a 383 4bbl HP torque converter or one from a 225 slant six with a 727 transmission. Sadly, the 440 was saddled with the lousiest torque converter for some reason! If you can't find the above factory torque converter, buy a well known brand in the "2500" rpm stall range. Although I hate how they sell converters this way because it's stupid, but I degress!

 

[CBODY67]

I ran across a "POWENATION" segment on YouTube where they took a stock, well-used 440 our of a motorhome (or similar) and ran it to get a baseline of what it would do before they built it. Amazingly, it made LOTS of torque below 3000rpm, as is. After 3000rpm, apparently, the low compression ratio hurt ultimate power.

The interesting thing Chrysler did with their "smog" engines was to not really touch the heads or cams. The cams in those motors were a little bit larger in duration, overlap, and lift than the prior 256/260 cams of old. The intakes for the TQ can have the mounting plate cut-out to allow a normal carb to be used on them. As the mounting stud patter is the same for spreadbore and post-1967 Carter and Holley 4bbl carbs. The main orientation was to make the engine a better air pump, with the slightly longer cam timing.

SO, just the compression ratio was the main change, plus some fuel and spark calibrations. IF Mahle has some "MM" ring pistons with a 10.0CR rating with the existing heads, that would be where I headed as the thin rings unlock power through decreased friction. More than might be suspected. Might even be lighter than OEM, too?

Otherwise, a "quench dome" piston, like Hughes used to sell, might be a more-normal option. The dome increases quench/turbulence/compression ratio to approximate a closed-chamber head on the engine, without using the older closed-chamber heads with flat-top pistons.

I COMPLETELY concur with the torque converter statements above. When the '68 Road Runner 383 came out, we knew it had a bit looser converter in it for better off-line performance. Years later, in a listing for Chrysler Re-Man torque converters, the 10.75" '68 RR converter listing was the same as for the Slant 6. Made perfect sense as if the converter is "tight" enough for a Slant 6, with more power in front of it, the stall speed will be higher as a result. Slick move! Chevy did something similar with the '77+ Z/28s, using a V-6 torque converter behind their normal 350 V-8 of the time. Of like many racers using "Vega" converters to get more stall speed with their 350s. And some Opel 8" converters before that. FWIW

Of course, dual exhausts. Many options there.

Summit used to sell a Lunati cam (in a Summit Racing box) that was a modernized version of the Chrysler HP B/RB cam for a very good price. Lunati does not seem to sell that cam anymore (after their absorption into the Edelbrock Group), though. Might still be in the Summit catalog, though.

IF the budget can support it, a set of more modern design aluminum cyl heads can certainly increase air flow into and out of the motor. TrickFlow or AirFlowReasarch, as some others are based on the Chry 906 castings, but built in aluminum.

To me, a "torque motor" that "rpms" to 5500rpm or higher can be the best engine for general street use. Getting that "balance" can be tricky, sometimes. Probably need to watch some of the Nick's Garage YouTube videos to see what is possible!

Enjoy!
CBODY67

 

[HOT FURY]

Good evening everyone hope all is going well. I have a low compression 440 from my 1973 chrysler New Yorker

im looking to build horse power and torque into. Any blue print or formula I can follow. I already have a carb and intake for it and plan to acquire hp exhaust manifolds. I don't mind spending some money however I want to sort of maximize my dollar per horsepower and torque for lack of better words. Any ideas or suggestions.

Id defiantly be happy with a crazy amount of torque over anything else. My rear end is a 3.23 gear with a sure grip brand new ready to go and Im also curious about what torque converter I should go with.

throw a howards rattler camshaft in it

 

[66 Monaco 500 365]

Back a few decades ago, I built a '67 GTX 440. I put 6bbl pistons in the motor with 915 heads (not recommend now, it would need race gas)
I used the stock magnum cam retarded 5° a 4 angle valve job, aluminum 6bbl intake and new stock carbs. I used the Roadrunner 383 / 340 torque converter. in an A12 clone '69 Roadrunner with 3.23s, 11.50 30" tall slicks and it ran 13.05 at 104. it had way too much compression, but ran amazingly well, it was a torque monster. it was amazing how much power compression makes. The motor had the normal stuff, balanced, shot peened rods, medium tension rings, aligned honed and deck equalized block etc. it would annihilate the L-60s (yea, that long ago) for as long as you kept the throttle open.
I bet 452 heads on this combo would run amazingly well, throw a cam that's not so big that you would need more gear or converter you could have 500+ torque and a solid 450 horsepower street engine.
My $.02

 

[CBODY67]

Not many people realize that with a 440, retarding the cam bleeds off a bit of low-end torque (for better and easier hookups) and then adds it back in on the top end power. Especially on street tires (as that's what he had to run for the nostalgic street car class.

In prior times, it was felt the open chamber 906s would be better than the small chamber heads which came before it. In a close exam of the 915s vs Stage IV heads, the port sizing looked to be the same, or very similar. My un-calibrated eyeballs did not detect any real differences in the ports, although there could have been. The tip-off that they were pretty much the same came when the Mopar Perf Porting Template kit would work on all B/RB heads, with the same ultimate results. Perhaps the "better breathing" aspect was hidden in the 1.74" exhaust valves? Same size valves that were in the GTX 440 of 1967, in that motor's closed chamber heads. It was very easy to not "read through" some of Chrysler's "marketing hype" back then! We were in too much awe of "newer, better, more powerful", by observation. BUT it was FUN1!

Open chamber were supposed to breathe better as the valves were not shrouded on the edges, nearly as much. Then by the earlier 1980s or so, David Vizard had determined the combustion dynamics of the closed chamber heads (with more "quench") would make more power with less detonation tendencies. After NASCAR engine builders had done enough research to know that "active air" in the combustion chamber was better than "lazy air". When early combustion chamber mapping could be done visually by noticing where carbon was accumulating on the cyl head from "lazy air flow" compared to where it was not accumulating due to "active air flow". As my late machine shop operative noted, if they put some roughness into the areas where the carbon was living, that roughness would be clean after the next race, as it changed the flow enough to keep things clean. Back then, I was lucky enough to be tied-into some friend networks with friends who worked at or were close to Reher-Morrison in Arlington, TX at the time. Even got an after-hours tour of their engine shop one night. Seeing some "experimental" GM and Ford cylinder heads for their drag racing customers. Some heads with no casting numbers or date codes on them, as they were "not ready for production". There was one set of Ford heads where you could "stick your fist" into the exhaust port, which was a straight path to the exh valve. NEAT STUFF!

CBODY67

 

[66 Monaco 500 365]

I believe the closed chamber heads and the flat top pistons with valve notches is the reason I could run pump gas back then, excellent quench. I had .024" between the piston and head.

 

[hilly101111111]

How deep into the engine do you want to go? Obviously higher compression pistons will go a long way for making torque and horsepower! Please provide more details on how far you willing to go. I can provide information for a full rebuild or simple camshaft and valve spring swap depending on how you want to go. It should have can with a Thermoquad from the factory and those were great carburators in my opinion.
Try to find a 383 4bbl HP torque converter or one from a 225 slant six with a 727 transmission. Sadly, the 440 was saddled with the lousiest torque converter for some reason! If you can't find the above factory torque converter, buy a well known brand in the "2500" rpm stall range. Although I hate how they sell converters this way because it's stupid, but I degress!

thank you for the reply im interested in rebuilding the entire engine and if I can ill gather some hp pistons rods and crank. I have a Holley 770 I'll be using. I appreciate the info !

 

[hilly101111111]

throw a howards rattler camshaft in it

what sort of gains would I get from that ? over factory low compression garbage

 

[hilly101111111]

thank you for the reply im interested in rebuilding the entire engine and if I can ill gather some hp pistons rods and crank. I have a Holley 770 I'll be using. I appreciate the info !

keep in mind I would like to be able to use pump gas and I just really wanna spend my money where its gonna count you know

 

[HOT FURY]

what sort of gains would I get from that ? over factory low compression garbage

lol sorry meant to say go with one of the hughes whiplash cams, not rattler. Had a brain fart and got the two mixed up. The whiplash cams are meant for factory low compression motor cam swaps and by design they increase cylinder pressure. check out their website if you want more details

 

[Big_John]

if I can ill gather some hp pistons rods and crank.

If you are going to replace the rods and crank along with the pistons, go look at a stroker kit.

No replacement for displacement.