rebuild badly damaged 340 vs build with 360 short block

[Rebecca Harvey]

Hi,
We have a 1970 Cuda with 340 stroker (previous build) that is in bad shape (cracked block, crank not usable etc etc). The block can probably be repaired but it would need expensive custom pistons for .035 over bore.
Should we consider buying 360 short block (ATK?). Do a lot of people have 360 stroker replacements? If yes, what oil pan did you use. I have looked at the info on www.magnumswap.com but it did not specify an actual oil pan that I can look for (just a general description).

thanks,
Rebecca

 

[rogue]

I have a 360 stroker and used a Milodon 30941... it's a 7 quart pan and explicitly states that it is "stroker clearanced".

as for repairing the 340... i suppose if it's the original block for the car it would be better for the overall value to repair it... or at least hold on to it and go with the 360 for now depending on cost and what you want from the car.

 

[Rebecca Harvey]

it is not a numbers matching engine (was from a Duster).
would a Milodon 30941 fit in a stock height stock suspension 1970 Cuda with something like 408 Stroker 360 (built as much as possible to look like a 340 stroker)?
Rebecca

 

[Rebecca Harvey]

we have hooker headers and custom exhaust and would rather not change those things I understand that some grinding would be needed to get the LA headers to fix. Some other accessories may need to change as well. Is it a lot of headache to solve these things or is the list short?
Rebecca

 

[rogue]

My 360 (stroked to 408) went into an original stock 71 challenger 318 with no mods to suspension. I don't thing there's any real external size difference in the 340 v. 360 block so should just fit. That's pretty much my experience in going from a 318 to a 360 stroker in a 71 challenger... don't see it being any different for a 70 cuda.

as for accessories like alternator and ac etc, that all just bolted up. The engine mounts, if i recall coorectly, were different from 318 to 360. There was some difference in mating headers to exhaust.

mostly it was not a bad swap just a few headaches along the way

 

[rogue]

re: the milodon oil pan... if you do go that route make sure you get the appropriate pick up to match the pan

 

[Chryco Psycho]

340 & 360 engine mounts are the same so you are good there
Overall a simple swap 360 blocks are common & cheap to buy where 340 are not but the 360 does use a unique oil pan .
You can make the 360 into a stroker also , I would recommend it really the cost is similar to rebuilding stock parts & the result is far better if the crank is damaged all you can use is the rods from the 340 , the pistons will not work unless the 340 was not bored when it was stroked which may be the case so the 360 could be bored to fit the existing pistons .

 

[moparlee]

Welcome to the site from Michigan. When you get a chance show us some pics of your Cuda.

 

[gtxncuda]

Rick Ehrenberg at Mopar Action is currently building the 360 408 stoker motor using an eBay short block to show case the new Trick Flow 190 aluminum heads. (They are on the second article now) I'm planning this build myself this fall for my 71 Cuda to supplant the original, but tired numbers matching motor in there now. The 360 block is stronger and more plentiful than the 340, and you can use the stock roller cam and lifter set up the 360's used if you choose to go that route. Easy to make it look like your stocker too! Good luck!

 

[Rebecca Harvey]

we may have a new plan. Now we are considering Hughes LA block. Here is the most recent photo of my husbands Cuda (which I am helping to rescue). Not great photo. Might have a better one somewhere.
Rebecca

 

[Rebecca Harvey]

Welcome to the site from Michigan. When you get a chance show us some pics of your Cuda.

 

[Rebecca Harvey]

340 & 360 engine mounts are the same so you are good there
Overall a simple swap 360 blocks are common & cheap to buy where 340 are not but the 360 does use a unique oil pan .
You can make the 360 into a stroker also , I would recommend it really the cost is similar to rebuilding stock parts & the result is far better if the crank is damaged all you can use is the rods from the 340 , the pistons will not work unless the 340 was not bored when it was stroked which may be the case so the 360 could be bored to fit the existing pistons .

the Rods in our 340 cannot be used either. Previous builder from previous owner a joke. That engine turned out to have Chevy connecting rods. ha ha.
Rebecca

 

[Chryco Psycho]

no wonder it failed , chev rods in a Mopar !!
The 87 - 92 360 blocks had roller cams ,you can reuse the lifters & slide in a better cam while building a stroker , this would be the preferable route

 

[chargerdon]

My 76 vintage 360 LA blew this past spring.

So

I found a 72 360 La for $100. There were no later model roller blocks avail in my area. Had it bored to .030 and a SCAT 408 stroker kit put into it. (all new pistons -15 dish, rods, and crank). Re-used the J heads with 2.02 intake valves, Lunati 703 cam, Edlebrock rpm air-gap intake, Patriot full headers. Also, reused the double roller timing chain, sprocket and cover. I used the STOCK oil pan from the 72 block. No clearance problems using a new stock oil pump and a new stock miloden oil pick up. The rotating assembly comes close to the oil pump but didn't need any clearancing . Since i needed new push rods and hydraulic lifters anyways, i bought a used set of "273" adjustable rocker arms and shafts, new pushrods.

After paying for the Scat 408 stroker kit and about $1,000 for machine shop (decked the block and heads, balancing of the rotating assembly, and assembly of the short block including new cam bearings, new frost plugs, new distributor shaft brass bearing, etc.. So now an internally balanced engine, so new neutral damper, and flexplate. I did the assembly of the heads intake manifold, carb etc.. My total cost was about $4,800. It feels so strong !!

Oh, the calculated static compression is right around 9.8. Do not know what the rear wheel HP is but my guess is somewhere around 400. Took it to the local track on test and tune night and ran 1/8 at 8.95 (equates to 13.96 qtr and thats with street tires (no prep) on an 85 degree evening with 65% humidity... that track is at 400 ft above sea level. More than enough to satisfy me.