Cuda 1970 questions

[ibt]

Have a 1970 Barracuda grand coupe with 340 engine 727 transmision. (Was born with 318 engine)
What was the app. price for this car when is was new in 1970?

I am looking for a spare motor, have a 360 on hand. Are there any particularly type of this engine size that are prefered.?
I have learned that the 340 cylinder heads can go on the 360 block. Is that correct.?
What other modifications are recommended to get the best performance compaired with the cost.?
I have already headers and a 650cfm Holley

My differential ratio is 3.23 Will a 3.55 ratio give lower engine rpm at the same speed. Or opposite.?
Will a change in ratio make trouble for the automatic transmision.?
Thanks for any advice
Ibt:

[superdart]

As far as gear ratio goes: The higher the number, the higher your RPM's will be in respect to a lower (numeric) ratio. At 70 MPH, your engine will turn more RPM's with 3.55 gears than with 3.23 gears. However, the higher the number, the better 0-60 and 1/4 mile times you will get. 3.55's are good all around gears...not too high an engine speed on the highway, but still good acceleration. 3.91 are the next step, and I've had them on a 340...way to steep for the open road.
Also - when someone says "low" gears they mean "high" numbers, and vice versa... a 4.10 gear is considered lower than a 3.55, which is lower than a 3.23 etc. Conversly, a 2.45 gear is higher than a 3.23...way to confuse someone huh?

As far as the 360 block, I know the earlier it was cast the better.. I'm not for sure, but I think anything made in the '70s is good, with the very early ones being the best. I understand the ones from the '80s have thinner walls and aren't good for high HP applications.

The 340 heads should fit the 360. I am not well versed in this area, I know 340 heads came in versions up to 10.25:1 compression and there is a great debate over which is better: the 340 or the 360. I prefer more cubes...the 360 is capable of everything the 340 could do and more. The 360 was just never really tapped as a HP engine...it came too late into the musclecar era. But, it is really cool say you have a 340, it's like the wedge, you can get a 440 to make lots of power, but a HEMI is just so COOL....

[dirty dan]

Originally posted by ibt
Have a 1970 Barracuda grand coupe with 340 engine 727 transmision.
Will a change in ratio make trouble for the automatic transmision.?
Thanks for any advice
Ibt:

Hey Ibt
Super dart is right on the gear ratio.
Small blocks are not my domain so I can`t help with that.
As for your 727 ,don`t worry about that.
The trans will perform as always .
Regaurdless of what gear ratio you use.

[340MAN]

My preferance is the 340 engine - there is a reason it was called the tiny Hemi. That is due to the h.p. it was capable of.
The 360 stroked & with w2 heads can be a power house, but as a rule the 340 in little warmed over factory form is better than 360 in the same fashion. Thats my opinion.
I ran 340 in '70 'Cuda with 3.55, 3.91 & 4.56 ratios. Te rpm's were as follows with 727 trans @ 65 mph
3.55 - 3180
3.91 - 3370
4.56 - 3790
If you are driving on street alot & like cruising, then I would sugest the 3.55 gears. If long distant rides are not in the picture, but cruising & track time are wanted, use the 3.91's.
That 340 will handle anything, since you have it make it a a engine to recon with.
Just my thoughts & hope it helps.

[rustycowl]

I would have to guess about $4000. Does your GC have the little quarter scoops in frt of the rear wheel openings? Increasing the ratio numerically will lower the speeds at which the trans changes gear. It will also raise the engine rpm for any given mph. Going from 3.23 to 3.55 won't be a huge increase in either of those conditions, but you'll probably feel the car to be a little peppier.

[6 packin]

Due to the cost of 340 enginea and parts, my choice would be a 360! The best 340 is 69/70 model year makes about the same power as the newer Dodge Trucks with the 360 magnum. Around 200-215 Horsepower and 260-280 ft/lbs of torque at the rear tires. Either engine can and will make way bigger numbers with little mods. The 360 and 340 heads have the same intake port design. The 360 heads have small 1.91 intake valves and 1.6 exhaust valves. Your "X" 340 heads had 2.02 intake and the same exhaust 1.6 valves. Drop the 2.02 into any 70's 360 head open up the bowl to the seat. Now you have a excellent head, for the same price as a used set of X's by they way which do not have harden exhaust seats for unleaded fuel. Some of the J heads had both valve sizes.

[340MAN]

Excuse me!
The 69/70 340 was advertised @ 275hp & 290 for six pack models. My original '70 340 with 118k miles pulled a 291 hp on dyno before rebuilt with one holley 750 dp.
I lightened the rotating asm & used forged pistons & increased the comp ratio to 12.5.1 & still ran pump gas @ 36 dgrs total making 470 hp @ flywhl with 90% of original parts just reworked.
I normally dont say much in argumentative fashion, but for what Ma Mopar gives you without putting a bunch of a/m parts in engine, the 340 is a power house. As far as I have spent money on all types of Mopar small blocks & the parts are the same price unless you are converting a 360 to a forged crank. Thats an expense I didnt care for.
It doesnt make any differance anyway. The fellow with the checkbook should do alot of research on both before dropping a dime.
My two cents for what it's worth.