# Rebuild original engine or replace? Need your 2 cents



## docmark1 (Feb 27, 2009)

After shopping for rebuild prices for the existing 350 in my 70 lemans sport convertible the bottom line is going to be about $5500. Will have about $12000 into the car, not including the $2000 I paid for it 15 years ago, and it will be fully restored. I can replace the engine with a new 400ci for about the same price. The kicker is the current engine is the original matching numbers engine. I'm not worried about having a street rod or a performance engine. The car is going to be weekend driver. The place where I'm going to have it done says after rebuild, boring 30 over I should get about 290 to 300HP. Should I keep it matching numbers car or will make that much of a differnce in value of the car replacing it with the new bigger engine. The pros to the new engine would be warranty and more horses, the cons, numbers won't match. Appreciate eveyones thoughts


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## auburnconsulting (Nov 3, 2008)

put the new motor in and save the old one. then later rebuild the old and reinstall if selling otherwise engine more horse without fear of destroying old block.


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## 68greengoat (Sep 15, 2005)

IMO, there is no question but to rebuild the numbers matching motor. Why sink money into 2 different motors. If you have to get rid of the numbers matching to purchase the new one, you would take a huge hit on the value of your Lemans. Numbers matching is everything in this hobby as far as getting the most bang for your buck. Alot of guys wish they could have a numbers matching car. If all it will be is a weekend driver or even a daily driver, I wont worry about destroying anything. Keep the original!


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## MasterFab (Mar 30, 2009)

Having been in the restoration business for quite a few years, numbers matching cars just aren't as sought after as one would think. Of course if its an all original car thats never been touched with a spray gun except for some touch ups you're not going to want to mess with it, and not saying a le mans isn't a valuable car, but only the most sought after cars in the muscle car world should be concerned about their original stampings on the engine. For example we just finished a 75 T/A a guy purchased when he was 16 and it was all original. He had to have his motor rebuilt with the 455 upgrade from the 400. It was even sent to Bulter Performance per his request. It came back with more problems then it was sent off with and Butler is the primo pontiac engine building company. Of course after 8 months of knocking down Butlers door the issues were resolved, but had the engine been rebuilt by a reputable local machine shop or been a crate, the customer would have recieved his car much sooner and with fewer problems. Unless you have a machine shop that you know fairly well and trust, crate is really the only way to go as far as turn key goes. And truly, if you were going to resell the vehicle does the engine NEED rebuilt? Let that be the responsibility of the buyer if thats the case. Anyways, thats just my input, be sure to absorb all input from everyone you do end up asking, and remember that its your car, consider all the factors and ultimately you decide.


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## Jstreet (Mar 9, 2009)

MasterFab said:


> Having been in the restoration business for quite a few years, numbers matching cars just aren't as sought after as one would think. Of course if its an all original car thats never been touched with a spray gun except for some touch ups you're not going to want to mess with it, and not saying a le mans isn't a valuable car, but only the most sought after cars in the muscle car world should be concerned about their original stampings on the engine. For example we just finished a 75 T/A a guy purchased when he was 16 and it was all original. He had to have his motor rebuilt with the 455 upgrade from the 400. It was even sent to Bulter Performance per his request. It came back with more problems then it was sent off with and Butler is the primo pontiac engine building company. Of course after 8 months of knocking down Butlers door the issues were resolved, but had the engine been rebuilt by a reputable local machine shop or been a crate, the customer would have recieved his car much sooner and with fewer problems. Unless you have a machine shop that you know fairly well and trust, crate is really the only way to go as far as turn key goes. And truly, if you were going to resell the vehicle does the engine NEED rebuilt? Let that be the responsibility of the buyer if thats the case. Anyways, thats just my input, be sure to absorb all input from everyone you do end up asking, and remember that its your car, consider all the factors and ultimately you decide.



Normally, I'd say all original. But, Masterfab has brought up some interesting points. A crate motor will get you going faster and carb/ancillaries will probably be bolt-on performance with light tuning. You can keep/store the original for the next owner if you like with the added value of having 2 engine options on the sale. Without a doubt, I think the crate option will be more expensive unless you really get into building and blueprinting with High Perf options and workings on the original block.....which takes away from the originality anyway. Of course, if you're in no rush and like to build powerplants, you'll probably get more satisfaction from doing it yourself. Things to think about.....there's no wrong answer.


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## cybernco (Apr 9, 2006)

If you have the guts to change over to a Chevy engine, I'd go with the extended cruising version of the Scott Shafiroff 598 cid; 725 HP @ 5500 RPM and 770 TQ @ 4600 RPM. Okay, that's just me...
UltraStreet High Performance Crate Engines By Scott Shafiroff Race Engines


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## Rukee (Feb 8, 2007)

cybernco said:


> If you have the guts to change over to a Chevy engine, I'd go with the extended cruising version of the Scott Shafiroff 598 cid; 725 HP @ 5500 RPM and 770 TQ @ 4600 RPM. Okay, that's just me...
> UltraStreet High Performance Crate Engines By Scott Shafiroff Race Engines


Changing to a Chevy engine would entail a diffrent tranny, exhaust manifolds, motor mounts, gas lines and starter`s on the other side, way too much stuff is different to just swap it out.


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## gn300 (Mar 31, 2009)

If you are selling put the #'s engine in, if you are keeping to have fun with .... keep the #'s engine on a stand and enjoy knowing if you break it you won't ruin it forever!

Same with other parts like a gto hood etc.


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