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Author Topic: big block to small block  (Read 9454 times)

Offline 74chev4x4

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big block to small block
« on: February 24, 2010, 10:23:12 am »
I have a 454 in my 74 chevy truck and it has some issues, the truck originally came with a small block from the factory and that is what I am wanting to put back into it.  What things from the big block will swap to the small block?  Trying to get an idea of what I will need to buy to do the swap, will probably get a new long block sbc or rebuilt one.  Any suggestions would be great, thanks!
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Offline Captkaos

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Re: big block to small block
« Reply #1 on: February 24, 2010, 01:17:12 pm »
Power steering and brackets, the alternator and depending on which one the AC compressor.
As for the other brackets, none, and your exhaust won't line up.
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Offline 74chev4x4

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Re: big block to small block
« Reply #2 on: February 25, 2010, 11:13:05 am »
so can I use the flex plate off the big block on the small block and the starter as well?
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Offline VileZambonie

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Re: big block to small block
« Reply #3 on: February 25, 2010, 11:52:38 am »
Why not fix the 454? The flexplate may be different. Do you know if it's internal or external balance? What year sb are you planning on installing?
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Offline 74chev4x4

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Re: big block to small block
« Reply #4 on: February 25, 2010, 12:42:55 pm »
Yea I was just thinking about fixing the big block, might just be easier.  I just hate that I cant get headers to fit in the darn thing.  Its the rear main seal that is leaking really bad in the 454 and its a goodwrench motor from 94 which means it has the one piece rear main seal correct?  Heard its a pain to change, its leaking all over the exhaust so I don't want to drive it, might catch fire.  I was thinking about just pulling the entire motor out fixing the seal and painting it up nice?  what is the deal with not getting headers on a 454 in a 4x4 truck?  Anyway around this.  Thanks everyone!
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Offline VileZambonie

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Re: big block to small block
« Reply #5 on: February 25, 2010, 12:47:24 pm »
I've never had a problem getting headers to fit. Are you sure the headers you have are for a truck? Rear main seal can be fixed in a few hours. You either have to pull the trans back or motor out.
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Offline 74chev4x4

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Re: big block to small block
« Reply #6 on: February 25, 2010, 01:00:34 pm »
would that be the one piece seal than?  Need a special tool to put it back in right?
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Offline choptop

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Re: big block to small block
« Reply #7 on: February 25, 2010, 01:15:37 pm »
Id rather change a 1 peice rear main than a two peice re main anyday. I didnt know the bigblocks had one peice rears on any of them tho. Either way, still easier than swapping engines. Headers are not problem if you get the right ones.
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Offline 74chev4x4

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Re: big block to small block
« Reply #8 on: February 25, 2010, 01:31:03 pm »
your probably right its a 2 piece,I tried to get the casting number but it is to tight in there to see. looks like the oil pan is leaking to so I will just pull it and do some clean up.  Not sure who I heard about the one piece seal from though?  So just get on summit racing.com and look for headers for my 74 with a big block and it will fit?  Cause they only have the big block headers in 2wd trucks on summit, thats my prob, but if you say they will fit I trust ya, thanks.
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Offline VileZambonie

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Re: big block to small block
« Reply #9 on: February 25, 2010, 04:05:15 pm »
Two of my big blocks have a one piece rear main. So you don't know if it's a Gen IV or Gen V? You should be able to quickly ID it. Does it have provisions for a mechanical fuel pump?
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Offline choptop

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Re: big block to small block
« Reply #10 on: February 25, 2010, 08:09:48 pm »
This is where I need one of the 4x4 bigblock guys to chime in. I got the ones for the 2wd. I tried 4x4 headers and they would not work, but I know they make them.
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Offline VileZambonie

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Re: big block to small block
« Reply #11 on: February 25, 2010, 11:07:53 pm »
The only issues I ever had was with clearance on the front spring shackle which is easily remedied but that was years ago with cheapo headers. Never had a problem since.
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Offline 74chev4x4

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Re: big block to small block
« Reply #12 on: February 25, 2010, 11:41:37 pm »
yea it has the mechanical fuel pump on it.  Getting ready to buy the headers on summit.com should I go with the 2wd or 4wd ones.  It does say in the application for the headers no motor swap and this is not the original motor?  Not sure, but it can't be that complicated because lots of people are running big blocks in 4wd's with headers.
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Offline 74chev4x4

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Re: big block to small block
« Reply #13 on: February 25, 2010, 11:43:27 pm »
VileZambonie, so which headers do you buy for your 4x4 truck with a big block?
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Offline VileZambonie

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Re: big block to small block
« Reply #14 on: February 26, 2010, 02:50:08 pm »
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