to bore a 340 motor

Zach8200 · 05-05-2008, 05:38 PM

Well I have a 72 road runner with a 340 auto in it and I have been doing allot of thinking on how to build the motor my question I dont really have the money to buy a 440 right now to rebuild but I want to squeeze 600 hp some way out of the car I just dont know if boring a 340 is such a good idea is it? it seems to me that there would be some serious stress on the motor what should I do is there a safe way to get 600 out of a 340 I know thats pushing the buttons but is it worth the trouble I dont know what I should put on for performance whats good whats not

440roadrunner · 05-05-2008, 09:09 PM

Just my opinion but:

1 I don't think bore size is going to have all that much impact on horsepower, given the same heads, cam, ETC

2 I doubt that yo can build a 600hp 340 as cheaply as you can build a 600hp BB

3 The other thing to consider is the originality of the car. If this is a "number matching" engine, it makes the car MUCH more valuable, and so building the original engine, given the greater chances of "grenading" it later, makes your car instantly worth much less

4 If you don't have the money, you don't.

6 Getting that kind of power out of a SB is no small deal. You'll need some comrpression, a good solid bottom end, good heads and cam. That means that if the present engine runs pretty good, you'll be "discarding" much of what you have. You might want to consider building a 360--but that is STILL going to take money. Why a 360? It'll cost you as much as the 340, but unlike the BB, you'll not have to do as much changing for "the swap." The new "stroker" will fit right in. If you now have headers, you'll even be able to re-use them.

78D200 · 05-06-2008, 11:20 AM

money seems to be the problem everywhere. if you don't have the moeny to buy and build a big block, then you won't have the kind of money it takes to get that kind of HP out of a small block.

i vote leave the motor the way it is and save your money and spend it wisely. no point in wasting your money on a small block if your just going to buy a big block to build up.

Zach8200 · 05-06-2008, 02:40 PM

I think Ill leave the original motor alone get the car running on a 440 when I can get one but 600 hp is my goal and I will just have to save some money I want the car to be a rare occasional car that doesent see the road much maybe a traveling museum or car show the car will have allot into after its all said and done I have added some receipts and im up to 30,000 and climbing I havent even touched the motor or trans yet thanks for the advice

05-05-2008, 05:38 PM	#1 (permalink)
Zach8200 Member Join Date: Jan 2008 Posts: 75	to bore a 340 motor Well I have a 72 road runner with a 340 auto in it and I have been doing allot of thinking on how to build the motor my question I dont really have the money to buy a 440 right now to rebuild but I want to squeeze 600 hp some way out of the car I just dont know if boring a 340 is such a good idea is it? it seems to me that there would be some serious stress on the motor what should I do is there a safe way to get 600 out of a 340 I know thats pushing the buttons but is it worth the trouble I dont know what I should put on for performance whats good whats not

05-06-2008, 11:20 AM	#3 (permalink)
78D200 Ph.D in wheelinology Join Date: Apr 2008 Location: Manchester, NH Posts: 461	money seems to be the problem everywhere. if you don't have the moeny to buy and build a big block, then you won't have the kind of money it takes to get that kind of HP out of a small block. i vote leave the motor the way it is and save your money and spend it wisely. no point in wasting your money on a small block if your just going to buy a big block to build up. __________________ Tim and Heather 1974 J10 - getting built up some more. built 360, built TH400, D300, D60(detroit)/14B(spool), SOA, inboard rear 64" springs, 38.5 thornbirds jeep pics - http://s149.photobucket.com/albums/s63/jeeping1974/J10/

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05-05-2008, 09:09 PM	#2 (permalink)
440roadrunner Senior Member Join Date: Nov 2007 Posts: 272	Just my opinion but: 1 I don't think bore size is going to have all that much impact on horsepower, given the same heads, cam, ETC 2 I doubt that yo can build a 600hp 340 as cheaply as you can build a 600hp BB 3 The other thing to consider is the originality of the car. If this is a "number matching" engine, it makes the car MUCH more valuable, and so building the original engine, given the greater chances of "grenading" it later, makes your car instantly worth much less 4 If you don't have the money, you don't. 6 Getting that kind of power out of a SB is no small deal. You'll need some comrpression, a good solid bottom end, good heads and cam. That means that if the present engine runs pretty good, you'll be "discarding" much of what you have. You might want to consider building a 360--but that is STILL going to take money. Why a 360? It'll cost you as much as the 340, but unlike the BB, you'll not have to do as much changing for "the swap." The new "stroker" will fit right in. If you now have headers, you'll even be able to re-use them.

05-06-2008, 02:40 PM	#4 (permalink)
Zach8200 Member Join Date: Jan 2008 Posts: 75	I think Ill leave the original motor alone get the car running on a 440 when I can get one but 600 hp is my goal and I will just have to save some money I want the car to be a rare occasional car that doesent see the road much maybe a traveling museum or car show the car will have allot into after its all said and done I have added some receipts and im up to 30,000 and climbing I havent even touched the motor or trans yet thanks for the advice