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Author Topic: What's the difference between a 350 & a 400 Big Block?  (Read 1467 times)

lvlyfun

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What's the difference between a 350 & a 400 Big Block?
« on: April 23, 2012, 02:57:28 PM »
I found out today that my motorhome doesn't have the 350 in it, it actually has the 400 big block. What is the difference with this considering I am going to pulling something with my RV?

donn

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Re: What's the difference between a 350 & a 400 Big Block?
« Reply #1 on: April 23, 2012, 03:20:39 PM »
If you are asking about the GM motors, they are both small blocks,  The 350 is/was probably one of the best motors ever produced for passenger car/light truck use.  The 400 was a stroked version of the 350.  Not as reliable in the long run.

zukIzzy

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Re: What's the difference between a 350 & a 400 Big Block?
« Reply #2 on: April 23, 2012, 05:51:47 PM »
If you are asking about the GM motors, they are both small blocks,  The 350 is/was probably one of the best motors ever produced for passenger car/light truck use.  The 400 was a stroked version of the 350.  Not as reliable in the long run.

There was a big block Turbo Jet 400 as well, in reality it is a 396/402 but was labled 396 in the cars and Turbo Jet 400 in trucks. Base on the W series.  The 400 Small block was based on the 350 but it only shared design dimensions, the block was a different casting and it was prone to over heating an other things the 350 were not know for. Connected cylinders and stuff like that made for a throw away block.

Gary RV Roamer

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Re: What's the difference between a 350 & a 400 Big Block?
« Reply #3 on: April 23, 2012, 05:56:31 PM »
With respect to towing, more cubic inches gives a bit better low end performance because you get more torque in low RPM range. It has no effect on the amount of weight you can tow.
Gary
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Gary Brinck
2004 American Tradition
2007 GMC Acadia
Homebase: Ocala National Forest, FL

catblaster

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Re: What's the difference between a 350 & a 400 Big Block?
« Reply #4 on: April 23, 2012, 06:16:45 PM »
400 big block has a longer stroke giving it more torque but less rpm. lower torque curve. I did not realize it was considered a "throw away block" so will someone please throw one my way :D
Will and Jane
95 Winnebago Luxor

ironrat

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Re: What's the difference between a 350 & a 400 Big Block?
« Reply #5 on: April 23, 2012, 09:33:46 PM »
If it is the small block 400 you really have no problems with it if in good condition, the so called heating problems was in cars, the cooling system you would have in your RV would cause NP's. To check to see what you have you can look at the valve covers, if you have two bolts along the bottom and two on the intake side of the cover it is the small block. The big blocks had 4 bolts on the bottom and 3 on the top, also in truck use the small block was a two barrel carb and the big block used a 4 barrel carb.
Manuel & Denise
2001 Safari Trek 2830
8.1 WorkHorse
Loma Rica, Calif