Rebuild or Replace 360 Engine in my 74 Cuda?

[1 Wild R/T]

I'd take it apart and spend the extra money on performance machining operations- align hone the main saddles, do the final cylinder hone with a torque plate, check and equalize the deck height. Any competent machine shop can perform these steps. In my mind this is the difference between an engine that merely runs good and one that really rocks. Essentially you're "blueprinting" the engine, in fact back in the old days the magazine test cars that were "ringers" usually had this stuff done. You could easily free up 30-40 hp by just doing this..

Your better at spending other peoples money than I am....

lol, and I've done pretty badly spending some of my own..

Don't feel alone...  It's easy to chase extra power but machine shop time doesn't come cheap so if it were me I'd grab the extra two points of compression & call it a day....

[HP_Cuda]

 

There definitely is a trade off and a point of diminishing returns of $$$ spent at the machine shop.

You can be anal and recheck the balance on your internals like me but luckily that cost me very little.

[bennydodge]

I'd take it apart and spend the extra money on performance machining operations- align hone the main saddles, do the final cylinder hone with a torque plate, check and equalize the deck height. Any competent machine shop can perform these steps. In my mind this is the difference between an engine that merely runs good and one that really rocks. Essentially you're "blueprinting" the engine, in fact back in the old days the magazine test cars that were "ringers" usually had this stuff done. You could easily free up 30-40 hp by just doing this..

Your better at spending other peoples money than I am....

lol, and I've done pretty badly spending some of my own..

Don't feel alone...  It's easy to chase extra power but machine shop time doesn't come cheap so if it were me I'd grab the extra two points of compression & call it a day....

No doubt compression builds power and I went overboard on mine(11.25 to 1) but if it were me I'd want everything right. Unless  everything is measured and checked you're just guessing...

[bennydodge]

There definitely is a trade off and a point of diminishing returns of $$$ spent at the machine shop.

You can be anal and recheck the balance on your internals like me but luckily that cost me very little.

Balance is one thing(not as important as ring seal), but if the cylinder bores are totally straight and round the rings will seal better. Having the main saddles straight allows faster throttle response from the engine. This stuff is easy to do and is relatively cheap for any decent machine shop. I know the OP's engine is already assembled but it's not in the car yet. 

[1 Wild R/T]

I'd take it apart and spend the extra money on performance machining operations- align hone the main saddles, do the final cylinder hone with a torque plate, check and equalize the deck height. Any competent machine shop can perform these steps. In my mind this is the difference between an engine that merely runs good and one that really rocks. Essentially you're "blueprinting" the engine, in fact back in the old days the magazine test cars that were "ringers" usually had this stuff done. You could easily free up 30-40 hp by just doing this..

Your better at spending other peoples money than I am....

lol, and I've done pretty badly spending some of my own..

Don't feel alone...  It's easy to chase extra power but machine shop time doesn't come cheap so if it were me I'd grab the extra two points of compression & call it a day....

No doubt compression builds power and I went overboard on mine(11.25 to 1) but if it were me I'd want everything right. Unless  everything is measured and checked you're just guessing...

I'll touch on a few of these...

Line Hone.... If you drop the crank on lightly oiled bearings & it turns easily chances are the alignment isn't bad enough to cause an issue..... 

Equalize Deck Heights....  In the most extreme cases you might see a 5cc change in volume from best to worse, It won't hurt anything... 

Final Hone with Deck Plates.... Not every shop has deck plates for a small block Mopar.. Ford or Chevy probably.. Mopar probably not... And hundreds of thousands if not millions of engines have been built without it....  With it make more power? Possibly... But if your gonna hone with torque plates you should consider getting the block up to operating temperature while doing that final hone....  Serious racers do it why wouldn't you?  Well simply put, cost As I mentioned before machine shop time is money & the diminished returns comment is spot on.....

Put those KB107's in & don't look back....

The 68 340 cam will love the extra cylinder pressure.....  As will the driver..

[HP_Cuda]

Was just providing an example of extraneous work that isn't absolutely necessary, just like filing rings down.

[bennydodge]

I'd take it apart and spend the extra money on performance machining operations- align hone the main saddles, do the final cylinder hone with a torque plate, check and equalize the deck height. Any competent machine shop can perform these steps. In my mind this is the difference between an engine that merely runs good and one that really rocks. Essentially you're "blueprinting" the engine, in fact back in the old days the magazine test cars that were "ringers" usually had this stuff done. You could easily free up 30-40 hp by just doing this..

Your better at spending other peoples money than I am....

lol, and I've done pretty badly spending some of my own..

Don't feel alone...  It's easy to chase extra power but machine shop time doesn't come cheap so if it were me I'd grab the extra two points of compression & call it a day....

No doubt compression builds power and I went overboard on mine(11.25 to 1) but if it were me I'd want everything right. Unless  everything is measured and checked you're just guessing...

I'll touch on a few of these...

Line Hone.... If you drop the crank on lightly oiled bearings & it turns easily chances are the alignment isn't bad enough to cause an issue..... 

Equalize Deck Heights....  In the most extreme cases you might see a 5cc change in volume from best to worse, It won't hurt anything... 

Final Hone with Deck Plates.... Not every shop has deck plates for a small block Mopar.. Ford or Chevy probably.. Mopar probably not... And hundreds of thousands if not millions of engines have been built without it....  With it make more power? Possibly... But if your gonna hone with torque plates you should consider getting the block up to operating temperature while doing that final hone....  Serious racers do it why wouldn't you?  Well simply put, cost As I mentioned before machine shop time is money & the diminished returns comment is spot on.....

Put those KB107's in & don't look back....

The 68 340 cam will love the extra cylinder pressure.....  As will the driver..

I can't disagree. Even if the balance, mains, cylinder bores and decks are way out he still MIGHT not notice the seat-of-the-pants benefit of the machine work. The biggest SINGLE improvement to the OP's engine would be getting the compression up. The reason I mentioned the other stuff was due to the questionable condition of the engine block. As far as the 1968 340 4 spd cam, that's a great piece. In fact the car that got me into Mopars was a 68 Dart 340 4 spd car-all stock. It did really well in the stoplight derby..

[bennydodge]

Was just providing an example of extraneous work that isn't absolutely necessary, just like filing rings down.

?? You don't mean filing the end gap do you? I guess if the rings are pre-gapped it's fine.

[YellowThumper]

To add in a different perspective following up what Wild has stated.
Replacement (rebuild) pistons generally remain the same deck height as factory original. You now have overbored cylinders. This overbore increases the volume. The resulting compression is then reduced.
Motor performance expectation then whould be less then factory original.
I also have suffered this fate in the past.
It is noticeable and frustrating after all has been spent.

Good luck with your decision.
Mike.

[RUNCHARGER]

I've went really, really fast with no line hone, no deck plate hone but high compression pistons and medium size cams. I don't build Super Stockers. I do check stuff but a lot of them time it's runable.

[steelcuda]

I really appreciate all of the perspectives and ideas. I'll share them all. When I have the full build sheet together I'll share it here.


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[HP_Cuda]

What else would you do with the rings? put it on your finger?

Was just providing an example of extraneous work that isn't absolutely necessary, just like filing rings down.

?? You don't mean filing the end gap do you? I guess if the rings are pre-gapped it's fine.

[bennydodge]

All the engines I've done required filing to achieve the proper gap. I guess that makes it a "necessary" operation.

[steelcuda]

Fuel Pump eccentric came in today.  I should have mentioned the engine was back from the machine shop but not yet in the car.

[jimynick]

Don't forget to put a dab of good moly lube on the rim of that eccentric when you bolt it on.