To 512 or not

[70ChargerRT]

I’d get another 440 block and build the 512 out of it but for the life of me why do some guys build Stroker motors and put these shitty top ends on them? At the last cruise in I had a guy from the neighboring town toying with me in his 505 69 GTX 4-speed stealth head motor after the cruise in was over with. I decided to let my 440 240 TF T-56 Magnum eat. He got me a tad from the start but I started to pull away from him in 3rd and then I steadily kept walking away from him. He accused me of having a stroker motor also but I told him that’s just not the case and your heads and cam is killing your power. I’ll probably do a stroker build the next time around though.

 

[Xp29h]

I own a 33,000 mile numbers matching Medium Green A12 RR coupe. I purchased and restored it in 1999-2000, and in the 23 years since then, I have driven it approximately 5,000 miles. It had 28,000 when I bought it 1999. Other than the Mr. Sixpack cam, it is a completely stock A12. Largely due to months of sitting in the garage and infrequent driving, I recently developed an issue with the cam lobes and lifters. Since I will already be into the engine, I am considering pulling it and building a 512 Stroker; and wanted opinions from the Mopar community about whether: 1) this would be "committing Chrysler Sacrilege", or 2) adversely affect the value, or 3) just increase "the smiles per mile". I appreciate ya'll's feedback, direction, and opinions.

Went thru almost same dilemma. But my car is not original so I wasn’t concerned about that at all. A good friend of mine build race car engines. Been Chevy guy mostly but wanted to do Mopar! As I was looking at stroker kits, they were the same price so my initial thinking was not the 512. But as I got talking to my friend he said as long as we get what he called the “squish” to provide the power, and keep the compression ratio on the lower side why wouldn’t I go with the 512?

So I did just that. 440 source 512 kit with dome pistons and trying for that 10 cr area. It cam in at 9.8 and rounds like a champ. Cruising around is no issues whatsoever. If I stomp on it, hang on. Probably the only thing I should have done differently is not use the single plane intake. But it goes so well I haven’t felt the need to change it out.

Bottom line, for the same money, I wouldn’t change a thing. 512!

Good luck!

 

[70 sublime]

Hmmm is bigger going to be better ?
Seems you put about only 250 miles a year on your car
If your car is a very nice original type car does it not make you happy when you drive it now ?

If you go bigger engine for more gooooo are you going to do anything for the brakes on the car so you will have more stop also ??
One thing leads to the next ........

Think I would just be happy to keep it running and enjoy it as an original type of car

 

[j-c-c-62]

Hmmm is bigger going to be better ?
Seems you put about only 250 miles a year on your car
If your car is a very nice original type car does it not make you happy when you drive it now ?

If you go bigger engine for more gooooo are you going to do anything for the brakes on the car so you will have more stop also ??
One thing leads to the next ........

Often yes, but accelerating faster does not necessarily mean going faster.

 

[6PKRTSE]

OT. hard to make out, is the mounting on the Hemi a plate or motor mounts, I don't see how there is much play in that upper Rad hose. and nice car BTW.

It is mounted with a front and mid plates.

 

[gkent]

70 sublime said:

If you go bigger engine for more gooooo are you going to do anything for the brakes on the car so you will have more stop also ??
One thing leads to the next ........

Since the '40's cars have been built with three times the necessary braking as a safety precaution. What he has should be adequate.

Do you go to car shows and lecture every car owner that has "skinnies" on the front ?!?! Since the front brakes do 70% of the stopping, decreasing front tire footprint is much more serious than adding a few cubic inches and horsepower !!!

 

[MarPar]

 

[1967coronet]

If your cam and lifters are going bad like you said that engine will need a complete tear down and cleaning anyway.
You can do the stroker kit and still maintain the stock look.
Anybody questions the performance just tell them you have a good curve on the distributor.

 

[#41]

I would not stroke it if it is a numbers matching car with that low of mileage. My reasoning is to preserve the car's originality and value, and you are not racing or really driving it anyway so .......why?! If you just gotta do it, then set the number's matching stuff aside and go to town on another engine core.

 

[ksurfer2]

I didn't do a 512, but I did do a 493 is my Road Runner, not an A12, but a well done clone. I kept the HP manifolds, and painted the aluminum heads. Externally, the motor looked stock, but it made 600hp!!! This a waaaaay more power than it needed on the street!

 

[6PKRTSE]

I didn't do a 512, but I did do a 493 is my Road Runner, not an A12, but a well done close. I kept the HP manifolds, and painted the aluminum heads. Externally, the motor looked stock, but it made 600hp!!! This a waaaaay more power than it needed on the street!
View attachment 1614559View attachment 1614560View attachment 1614564

Never waaaay too much. I drive all of this on the street. However, I have much more tire and chassis to help it hook up.

 

[TorRed]

if mine were already a 440 I'd keep it mostly stock internally to save the block. At one point I was going the 440 stroker route in mine than started to appreciate the fact that the car had survived pretty much intact for OVER 50 YEARS and it would be a shame to change out motor, trans & rear like I was planning. So now I'm planning a small stroker (432 c.i. 3.75 crank) making around 500 HP and calling it a day. The car was already modified when I bought it in 74 so for me, reasonable hop ups are basically keeping it 'stock' since it hasn't known any different since it was new. Your car, your call but I wouldn't stroke it or remove the motor to put another in. Just my .02

Later,
Jim

 

[gkent]

I didn't do a 512, but I did do a 493 is my Road Runner, not an A12, but a well done clone. I kept the HP manifolds, and painted the aluminum heads. Externally, the motor looked stock, but it made 600hp!!! This a waaaaay more power than it needed on the street!

This brings up a good point ... exhaust. Assuming you want to maintain the stock look, the exhaust and intake are going to be the most restrictive things on the motor and will certainly impact the performance and benefits of the extra 72 cubes! While I fully support big cubes, I wonder if you wouldn't be just as well off with just a freshening of the bottom end and a bit of a cam upgrade. Maybe throw in some "mild" port work and leave it at that. You'd be leaving a lot of power on the table if you go with a 512 kit and don't slap on headers and a better intake.

 

[4speed68rt]

Remember that you are only the keeper of the car now, the car will live on after you are gone. I say keep it original, they are only original once.
You dont really drive the car much anyways. You aren't a drag racer, trying to win a championship, you probably arent a teen ager out street racing, so you really dont have anything to gain, only value and money and time to lose with all that. If you do it get you a different block and keep the original for the next person.

 

[gkent]

If you go through life worrying about the "next person" you'll accomplish nothing for yourself !!

 

[Llamaback]

In my opinion the stock drivetrain pushed these cars too far, especially A12 cars. The cars that got driven hard got twisted a little and have the crack on the top front edge of the quarter panel. If you have a nicely restored car that does not have any reinforcing done to it than why would you want to put more power in it? What is the point of having a 512 if you aren't going to romp on it and use all that torque? I vote keep it stock.

 

[Fran Blacker]

I'm with get another 440 or 400 bare block or whole engine crowd.

 

[gkent]

In my opinion the stock drivetrain pushed these cars too far, especially A12 cars. The cars that got driven hard got twisted a little and have the crack on the top front edge of the quarter panel. If you have a nicely restored car that does not have any reinforcing done to it than why would you want to put more power in it? What is the point of having a 512 if you aren't going to romp on it and use all that torque? I vote keep it stock.

Hmmm... take a look at those cars running the F.A.S.T. series and tell me again about the limits !!

 

[Llamaback]

Hmmm... take a look at those cars running the F.A.S.T. series and tell me again about the limits !!

You make a good point. I wish I lived closer to the F.A.S.T events. I would love to check those cars out and watch them run! I bet nearly every one of them has had the edge of the quarter panel welded up at some point. It is a known issue with these cars, I just wouldn't be willing to put more power into a stock A12 if it was really precious to me.

 

[F4R/T]

Build another car let someone else enjoy it. Find a 318 car and go crazy.