sprice
Active Member
Am considering the taller pistons. Found a set locally however .30 over. Wont know until summer if that's what I need but could just plan to bore the block if i can get a descent deal. Thanks..
Will a head upgrade bring compression up on 73’ Imperial?
- Thread starter sprice
- Start date
Here is a good post about results of a 72 440 stock on dyno.
Doing a little dyno testing on a low compression 440.
Doing a little dyno testing on a low compression 440.
dodgecharger.com
doesnt seem like it was a stock 72 440......
The first 2 Engine set ups are a pretty good representation of a stock rebuilt.
sprice
Active Member
Seems to point to breathing more than anything. Good link. Thanks.
twostick
Senior Member
What kind of shape is the engine in now?
If it's not a worn out oil burner with decent compression, there are some super tune tricks that cost not much more than some time and the price of some gaskets. CBODY67 touched on a few of them.
I would add that it probably needs a timing chain and gears anyway so some free bottom end torque is available by using a multi keyway timing set and advancing the cam 4 degrees. Ideally this should be done with a degree wheel so you know EXACTLY where your cam is installed at but if you line up the dots before you pull it apart and the new set will install dot to dot in the same position, you could then advance it to the 4 degree keyway and know you had at least advanced it from wherever it was.
As far as heads go, the pre 1967 516 castings are closed chamber as well but don't flow quite as well as the 915, 906 or 452 but they will give you a bump in compression. The chambers usually measure in the low to mid 80s cc wise, about 10 less than an open chamber. Best part is they are considered almost worthless so cheap $$. Shop around and you may find a freshened up set for a lot less than you could do a set yourself.
Kevin
If it's not a worn out oil burner with decent compression, there are some super tune tricks that cost not much more than some time and the price of some gaskets. CBODY67 touched on a few of them.
I would add that it probably needs a timing chain and gears anyway so some free bottom end torque is available by using a multi keyway timing set and advancing the cam 4 degrees. Ideally this should be done with a degree wheel so you know EXACTLY where your cam is installed at but if you line up the dots before you pull it apart and the new set will install dot to dot in the same position, you could then advance it to the 4 degree keyway and know you had at least advanced it from wherever it was.
As far as heads go, the pre 1967 516 castings are closed chamber as well but don't flow quite as well as the 915, 906 or 452 but they will give you a bump in compression. The chambers usually measure in the low to mid 80s cc wise, about 10 less than an open chamber. Best part is they are considered almost worthless so cheap $$. Shop around and you may find a freshened up set for a lot less than you could do a set yourself.
Kevin
sprice
Active Member
Engine ran, but not well. 85,000 miles, very rough at idle, trans is leaking bad aftervtest run. Lots not known about the car. Interior I would say 9/10, exterior 7/10. Sat for probably 20 years or more. I did try a newer Edelbrock AVS and it did improve the idle but so many other things to clean up. I want this to be a distance runner so like to know what's inside. Would like to do a refresh as many have suggested. Not go crazy with new or changed parts but little things that will improve performance. Will be a complete front to rear rebuild with fresh suspension. I have four sets of heads however only remember the 516's that were on the 67' Imperial. Unfortunately the 915's were swapped out. That link from Boydsdodge was interesting using 516's. Hopefully can get away with, new bearings, timing chain, upgrade the cam, new carb, do some port and polish the 516's or better heads if I have or find some at a reasonable price, hone the cylinders and since I already have, the HP manifolds (I know, next to 0 added power, but need a use for them on something), and we should be good....... I hope.
Remember, you want lots of torque down low. Imperial is a heavy cruiser.
Plymouth man
Member
Hughes whiplash cams are advertised to bring compression up
SuperDave
Member
If you're on a budget, choose the heads that have the smallest chambers, send them out for a 3 angle valve job and hardened seats and invest in a Dremil. Not one of those cheap Harbor Freight knockoffs either, they'll fall apart within the 1st ten hours of use. (Ask me how I know). Then watch a few videos of how to port & polish. Especially one dealing with Mopar big blocks.
It is possible to get factory iron castings to flow comparable to high performance aluminum heads with a little time, effort and love. However, in the end they're still iron castings, and as such prone to heat soaking & detonation. Aluminum heads are more forgiving on that point, but on the other end of the spectrum, aluminum heads are prone to warping if pushed beyond their tolerances. Tune up & dial in is crucial, either way.
9.5 to 1 compression is good for a street car on pump gas, probably the best you can get giving today's fuels without resorting to expensive additives or race gas. You can build a rock-'n'-roll big block to motivate a land barge that'll surprise a turbo tuner honda with the coffee can exhausts and the sticker wrap decals. However, if you want to keep up with the turbo LS's lurking out there, there's no replacement for displacement: stroke it! 440Source has a 543" kit I've had my eye on for a while. Even with a mild tune, it's a torque pig that will easily render asphalt to gravel under a heavy right foot.
Just my two cents.
It is possible to get factory iron castings to flow comparable to high performance aluminum heads with a little time, effort and love. However, in the end they're still iron castings, and as such prone to heat soaking & detonation. Aluminum heads are more forgiving on that point, but on the other end of the spectrum, aluminum heads are prone to warping if pushed beyond their tolerances. Tune up & dial in is crucial, either way.
9.5 to 1 compression is good for a street car on pump gas, probably the best you can get giving today's fuels without resorting to expensive additives or race gas. You can build a rock-'n'-roll big block to motivate a land barge that'll surprise a turbo tuner honda with the coffee can exhausts and the sticker wrap decals. However, if you want to keep up with the turbo LS's lurking out there, there's no replacement for displacement: stroke it! 440Source has a 543" kit I've had my eye on for a while. Even with a mild tune, it's a torque pig that will easily render asphalt to gravel under a heavy right foot.
Just my two cents.
I like the 440 source heads, less weight, better flow, smaller combustion chamber, hardened seats, bronze guides and look like a stock head when painted. Remember to have the gasket thickness machined from head.
stubs300
Senior Member
Where does it say that?
The "cam connection" in effective compression ratio is where the cam actions increase the cylinder pressure above what it normally would be via better "cylinder filling". The original Comp Cams HE-series cams were reputed to do this. Not sure about any others, fwiw.
CBODY67
CBODY67
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