Looking to buy/build 500-600 fwhp 360

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justinp61 said:
Why do you think that?
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The oil pump inlet is small, so this limits flow, cast pistons for a stock 340. Distributor/ oil pump drive isn't a heavy duty, the tip going into the oil pump can / has rounded off. Why spin a 340 to 7k to begin with? The stock 340 cam is only good for about 5,500 rpm's.
 
justinp61 said:
Why do you think that?
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A unbalanced engine with a stock oiling system isn't going to stay together very long with those kind of rpm's. Even with quality machine work and forged parts with that kind of rpm's the engine isn't going to last long.
 
512Stroker said:
**** ,I regularly take my 340 past 6 grand with a balanced factory forged crank and stock rods.
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This is what you quoted, so where did the unbalanced part come from? Back in the day I knew a bunch of guys that regularly turned their stock 340's 6k with no ill effects. Yes eventually you can break anything, but if your engine is healthy it'll be fine at 6K.

Dan the man said:
A unbalanced engine with a stock oiling system isn't going to stay together very long with those kind of rpm's. Even with quality machine work and forged parts with that kind of rpm's the engine isn't going to last long.
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Did you read that somewhere or have you broke a bunch of 340's? My 340 was balanced, Ross flat tops, Eagle SIR (cheap) rods and ported Edelbrock heads. It got turned 6700 with the stock oiling system. It did have a HV pump and a Milodon pan. After five years of street/strip use the bearings looked fine.
 
justinp61 said:
This is what you quoted, so where did the unbalanced part come from? Back in the day I knew a bunch of guys that regularly turned their stock 340's 6k with no ill effects. Yes eventually you can break anything, but if your engine is healthy it'll be fine at 6K.



Did you read that somewhere or have you broke a bunch of 340's? My 340 was balanced, Ross flat tops, Eagle SIR (cheap) rods and ported Edelbrock heads. It got turned 6700 with the stock oiling system. It did have a HV pump and a Milodon pan. After five years of street/strip use the bearings looked fine.
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Have friends who have built small block mopars and the oil pump inlet is small and the pickup tampers down going into the pump causing further restrictions. I'm not saying that your bearings didn't look fine, but I do find it hard to believe with a steady diet of high rpm's.
 
justinp61 said:
This is what you quoted, so where did the unbalanced part come from? Back in the day I knew a bunch of guys that regularly turned their stock 340's 6k with no ill effects. Yes eventually you can break anything, but if your engine is healthy it'll be fine at 6K.
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I had the rotating assembly rebalanced as I used a lighter weight pistons than the factory bucket's. I was amazed how far off the factory rods were, and these were the original set of connecting rods not a mixed set from different engines.
 
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my 340 had a stock bottom end bsalanced never had a problem except for noisey lifters if i revved over 7500 rpm
 
Nat said:
my 340 had a stock bottom end bsalanced never had a problem except for noisey lifters if i revved over 7500 rpm
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What's the purpose of spinning it so tight? Unless you have a carb,intake manifold, cam to support those rpm's,it's pretty much useless as most cams power band starts to drop off around 6,500 rpm's.
 
Dan the man said:
What's the purpose of spinning it so tight? Unless you have a carb,intake manifold, cam to support those rpm's,it's pretty much useless as most cams power band starts to drop off around 6,500 rpm's.
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What cam, intake and carb do you think it takes to make power above the 5200 RPM factory number?
 
Dan the man said:
What's the purpose of spinning it so tight? Unless you have a carb,intake manifold, cam to support those rpm's,it's pretty much useless as most cams power band starts to drop off around 6,500 rpm's.
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I think it's safe to assume the bottom end was stock but the top end wasn't. There are more modified 340s around here than stock ones, pretty much everyone has an upgraded cam/carb/intake unless it's for a numbers-matching show car.

I'd suggest taking a peek over in the Racer's Forum and see how those guys are building their 340s and what oiling mods are needed for what RPMs. I think there's a sticky thread in this forum as well about oiling mods for SBMs and it was posted by a credible member who races his Mopar.
 
My 340 runs quicker if i shift about 500 above max hp. It just recovers better on the shift. I run a low gear set in my 904 so a big split on the 1 2 shift.
 
Dan the man said:
What's the purpose of spinning it so tight? Unless you have a carb,intake manifold, cam to support those rpm's,it's pretty much useless as most cams power band starts to drop off around 6,500 rpm's.
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sometimes I forget to shift
 
I have a question about going from my current externally balanced 360 to an internally balanced 408. Will I have to do anything special to the existing flywheel (it's a 4 speed) when I swap in the new motor?

The car is having the differential narrowed. I am told it has truck axles. It looks like 295's will fit under the rear. Differential and glass are going in shortly.
 
512Stroker said:
I rather be lucky than good. LOL
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Good guys finish last, they don't get "lucky."

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512Stroker said:
I dont believe so.
I know some NHRA Stock Eliminator racers that spin their 340's past 7000 rpm every time they hit the track and that after the launch the cars hard at 5000+ rpm
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The reason why I don't like to spin a 340 like a chain saw is because 340 cars are very rare in the area of Missouri where I live. I'm thinking that maybe I've seen like seven 340 cars and I think that 3 maybe 4 of those were at a classic car dealership. The last time I saw a 340 car at a car show was about 3 years ago. I'm looking for a clean rust free A body with a 318,ps ac and haven't had any luck and it's been 2 years. I don't have the funds to travel the country looking at cars, I can travel about a hundred miles from my house.
 
I run a 360 with KB107 pistons. Did not rebalance! Has been this way for the last 11 years. Have run it hard and has kept together just fine. Every person that has rode in it thinks it's been balanced since it runs smooth. Runs the 292 mopar purple cam which likes rpm's. 3.91's out back too.
 
Lurch59 said:
I have a question about going from my current externally balanced 360 to an internally balanced 408. Will I have to do anything special to the existing flywheel (it's a 4 speed) when I swap in the new motor?

The car is having the differential narrowed. I am told it has truck axles. It looks like 295's will fit under the rear. Differential and glass are going in shortly.
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what dif you have 8 3/4 or a Dana ? 83/4 with 500 hp and torque with sticky tires , looking for trouble , I broke 2 83/4 with an automatic am looking for A dana , 83/4 are good to a point
 
Nat said:
what dif you have 8 3/4 or a Dana ? 83/4 with 500 hp and torque with sticky tires , looking for trouble , I broke 2 83/4 with an automatic am looking for A dana , 83/4 are good to a point
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I’m going to argue to a point. My son has run 100’s of passes in the 6.50-6.60 range and about 100 in the 10.10-10.20 range. No backbrace, no special caps, just Dr Differential axles and a spool. Slicks and for the last five years of racing (it’s been sitting for 3 years so we are not counting those. Low 1.40 sixty foot times with and without a transbrake. He has never broken a set of gears or axles. He does try and I said try to change out the gears every three years. His last set were bought by a friend even though Matt didn’t want to sell them to him and are running in 9’s in a 1974 big block duster.
 
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