i know the heading sounds crazy. Here we go. Doing a father son car. He's going to be a senior in college. His main focus is to finish college strong and try to find a job. My son bought a 72 cuda. Original 340 3 speed. Original motor long gone. So we are starting on the body first but trying to figure out a good motor to build with in a budget ,but a good strong dependable driver. Car came with a 340 cast crank motor that needs a rebuild. we could do a re-build but everyone says buy aluminum heads cause its to expensive to rebuild cast iron heads. Not cheap ! Another friend says use magnum heads on it. Another buddy says run a 5.7 hemi. now you have money in change over and mods. So I know its up to us but right now the body is getting done first. So as we look into motors what's your opinion for an good engine build for this car? throw us some info , costs any other info to help us make a good decision. thx

Really depends on what you want? and your budget.
Trying to make it look stock? use the 340 engine
want it to run like a modern car (EFI, Overdrive?) might want to swap in a Hemi or 5.9L Magnum engine?

If it's a fairly stock rebuild use the 340. Just doing the guides, clean-up, and a valve job won't be real bad unless the heads are really thrashed. The 340 block is also a good base for a stroker kit later.

As it stands now we were going to use the 340. Having gone to the machine shop, its needs bored, crank turned, basically a complete rebuild. Told that if we put 318 or 360 magnum heads on that 340 it would really wake it up. The heads we have were 1.88 not the good 2.02. plus they would need hardened seats installed. So am I better off to find a 318 or 360 magnum head? But I hear its fairly common that magnum heads are cracked. true? Spoke to another friend last night, told about the 360 Hot Rod article "junk yard jewel" . Im going into over load on the best way to go. Thought maybe find a running 360 magnum and install it? Do they have the same motor mount locations?

Magnum heads do have a tendency to crack between the valves. But honestly, the cracks are usually found during an overhaul, not because of misfires or overheating. I don't think a Scat replacement crank would be much more expensive than turning your old one down. And since you need new pistons for the overbore, you might want to check into a budget stroker kit. Aluminum heads would be a real good idea, best bang for the buck, in my opinion. I'm sure you can hunt around for everything used. Just have someone with you that can check out everything. I bought my Indy top end setup and 500 stroker rotating setup off of RJ for much less than half price of new. Everything checked out great and is just about ready to fire up.

First thing is to sit down and figure out your
budget on this project.. you know what you want
in the end(a rebuilt engine).. then start using
some of the discount parts places on line to see
if you are even close to that budget.. yeah we
all want the best parts but that isnt gonna happen
when you say budget.. then start wedding out what
you dont have to have.. it could be that a boneward
engine will fit the bill... in a lot of cases you
need to pull the engine down to see what you have
to get then work from that

I would be tempted to find a good running 360 Magnum out of a pickup truck. You would need to change the oil pan and change the intake system though. It would be a lot cheaper than rebuilding the 340. You would gain better heads, roller camshaft, usable compression ratio etc.
As a matter of fact I bet you could buy a good running 360 Magnum for the money you would get selling the 340 block.

This ^^^^^^ & below



Your going to need to crunch numbers before you do anything. The word budget is to wide and varied as well as open to point of view or wallet one is sitting on. In an example, you could purchase a rotating assembley and drop it into a good fresh block, rebuild the heads and be basically done. Re-sell the used parts for your "rebate" monies.

A lot of budget can be consumed in the parts other than stock. Do you need the RPM-AG and Holley up top? Will inexpensive Summit headers due or are the TTI's a must? Do you need the top of the line ignition or with the Chrome box and reworked distributor do?

Make a plan and stick to it! This is where a lot of expense come in when the planis not made or followed. IMO, to do it cheaply, it would be best just to get it up and running and driving. Then as time allows, make the purchase of the other parts.

Purchase the aluminum heads and intake later. Re-sell the OE parts when you get the aluminum parts.

OH, fwiw, the Magnum blocks do not have head oiling. Just food for thought.

In my opinion, it's a no brainer. Get a 360.

For a street motor I would not bother with the 2.02 valves.

Second thing to do is take an honest inventory of your and your sons combined mechanical skills. With a copy of "how to rebuild small block mopars" most anyone who can hold a wrench should be able to so a stock freshen up the 340 pretty cheaply and do most of the work yourself except for things like boring, valve job, etc that require machinist skills.

The more you want to start swapping things around or making them faster than the factory did, the more you need skills, experience, and cash.

And beware of asking really open or vague questions here (god bless this place's little heart), there is a vast difference in peoples incomes and budgets, and therefor their idea of a budget build. If the cost of aluminum heads seems pricey to you, then things like strokers and late model hemi swaps should probably be respectfully ignored.

If I were you (and we probably have a similar concept of budget) get the old 340 purring again unless there is a block problem. Bore it as little as possible to fit new stock weight pistons on the factory rods after a machinist checks them or rebuilds them. One thing I would do is set aside the factory heads. If you can find a set of 308 heads (later model LA 360) in a junk yard they will flow well and have hardened seats. I've had a few done, and they usually just need a valve job and exhaust guides, and will look stock. Use a well reviewed cam like the comp XE268 and comp 901 springs. And it should work well with just about any other parts you have.

Are you open to a big block? Mounts and linkage are pretty cheap to gain 100 cubes.

72 340 Cuda with an iron crank 340? Id be sure to prove to my own eyes that it wasnt the original block. It just might be.

Those 1.88 valve heads already have the hardened seats if they are 72 and up. Pretty sure it was 71 and earlier they were soft.

Check the bores yourself. A budget street car doesnt need super clean bores to get by. Trust *your* bore gauge, and take no one else's word for it. Borrow one if you have to, but verify yourself.

For a truly budget build follow the HotRod Magnum build. They used a stock weight piston to save balancing costs, and if you spend the time and a few extra $$ to get a great 5.9 Magnum core you won't need an overbore. The EQ Replacement Magnum heads can be had for about $585 a pair if you shop around. Figure on replacing guides but you can get by with stock valves. Buy the EQs that are 318B, and you get a set that can use 340 or 360 intake manifolds. See if you can find a stock Thermoquad and manifold combo. What you wind up with is a 360 inch, roller cam motor with durable stock 1.6 ratio rockers as about as cheap as you can build.

I would get a junkyard 318/360 magnum and stick it in. You can have the whole thing done for basically what a set of 340 pistons will cost you. It will run, drive, light the tires and when he's in a position to do so he can build up the 340 slowly while still being able to drive his car.

I did not have time yesterday, but what I was trying to get to is if you want an engine with EFI, serpentine belt drive, modern accessories like high output alternator, and A/C, then might be less expensive to start with an engine that originally came with those items (junkyard takeout), than it is to add aftermarket versions to the older 340 engine.
If your don't want or need the more modern stuff, the 340 with carb and V-belts will look much more original.

You also need to plan which transmission you will be using?
The 904 or small block 727 would be the easiest, and most likely least expensive option. If you want manual transmission, or overdrive transmission you have many options, but they will likely require some transmission tunnel modifications to get them to fit.

It really depends on what the end goal is for the car? Are you looking for more of a restored original, 1970s-1980s hot rod, Drag race car, track car, pro-touring, or whatever?
I would at least start planning what you want from the car and how much you plan to budget. You may also want to evaluate what you can do and what you will have to farm out.
You said father/son project, but I have no idea of what tools and skills you have or what your time schedule is? Also, if you have to do body/interior work, you will need extra space to store the removed parts while doing body work and such.

In planning a budget, consider the cost of the engine, ignition system, fuel system, cooling system, accessories, transmission (with clutch or converter and shifter), axle/differential (limited slip, gearing, bearings), brakes, suspension, rims/tires, paint/body, interior, instrumentation, stereo/speakers, etc.

Much of the budget will depend on what can be re-used on the car you have.

This is what I would do. Sell the 340 to the restoration crowd and use the money to buy a 360 Magnum motor. Check it out, regasket it, top it off with an aluminum airgap manifold, a 600 Holley and a set of cheap headers. Easy 300HP.

thanks so much for all the information guys. body getting done first. Over the winter ill keep looking for a motor that's running. Bottom line at this point is we have a 318 and the original 3 speed trans that can go in. Talked to my buddies and we are going to tackle the body over the next few months. Will keep you all posted. but if you got parts for him let us know at par12730@sbcglobal.net. funny 2 cars of my own to restore but willing to set mine again to the side to help him get into this hobby.

This.Or use the existing 318 until you can rebuild the 340.A 340 'cuda should have just that,a 340,at some point anyway!

By the time it gets out of body shop purgatory, you will have had plenty of time to build a motor.