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swapping 400 to a 454 motor 1979 g30 motorhome
#724880 June 18th 2017 3:24 pm
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Kinger9 Offline OP
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Hey guys, I am new to the forum so i hope i found the right place. I have a few questions/concerns about my 1979 g30 chevy motorhome. It has a 400 small block in it and a 400 turbo transmission. basically at 67000 miles driving it out to a wedding yesterday the motor decided to let go. punched about 3 holes in the oil pan and there was coolant on the ground as well so im assuming the block has been damaged as well. havent had time to look all that thouroughly. My question is due to my lack of knowledge in this area, will i be able to pick that 400 out and drop a used 454 in it. will i need a different transmission and will the engine need to be altered for different rpm and torque. Another question. Is the 454 a good or bad swap choice. what other options are ther to drop in. i know there is not much room in that doghouse! Thanks in advance for any feedback.

Last edited by Kinger9; June 18th 2017 3:25 pm.
Re: swapping 400 to a 454 motor 1979 g30 motorhome
Kinger9 #724883 June 18th 2017 3:43 pm
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Welcome to the site .... I know a 454 fits. Wither a 400 fits IDK....again welcome


SUNSHINE VANS-VAN DIEGO
ADRENALIN BY THE GALLON & CHASIN RACIN
ONE FOR THE DIRT & ONE FOR THE STREETS
'93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB
'92 CHEVY G30 454 BEAUVILLE EXT 146" WB
Re: swapping 400 to a 454 motor 1979 g30 motorhome
Kinger9 #724886 June 18th 2017 7:06 pm
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I love my big block, so go ahead and enjoy BBC power, the TH400 fits, from what I understand the mounts are the same, don't go crazy looking for mounts use later models for reference on parts. Your early van so engine cover's smaller but it fits. GM opened it up a bit in '83 and waited until '89 to install the first big block. I have a TBI motor and even thou it's a big block, I'm getting some of best MPG of my life. Consider a FItech system if you got the coin.

Re: swapping 400 to a 454 motor 1979 g30 motorhome
jcd74 #724933 June 20th 2017 2:18 am
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Kinger9 Offline OP
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thanks for all the feedback I was expecting an email when feedback happened but i did not recieve anything. logged on to check and i got a few responses. I have another question. if i pull a 454 out of a pickup truck lets say will it need to be tuned for a motorhome. To get the torque needed ive heard guys changing cams and lifters. If i bolt up this thing I want one go at it and have it run I do not want to be pulling it back out because my power is way out or something wont line up. Ive seen guys mention changing ring gears but i dont see what they will gain by that. Basically I want to know if i can go ahead and bolt up the first running 454 i have that probably will not be out of a motorhome, and have it run the best it can. I am looking to do this one time only and get it done right the first time. Thanks again for the feedback

Re: swapping 400 to a 454 motor 1979 g30 motorhome
Kinger9 #724936 June 20th 2017 11:18 am
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Your 454 will rip the chrome off a bumper ball. The gears you have in motor home rearend for the 400 will be ok for the 454. Tune it up, bolt it up, tear it up.


SUNSHINE VANS-VAN DIEGO
ADRENALIN BY THE GALLON & CHASIN RACIN
ONE FOR THE DIRT & ONE FOR THE STREETS
'93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB
'92 CHEVY G30 454 BEAUVILLE EXT 146" WB
Re: swapping 400 to a 454 motor 1979 g30 motorhome
frscke1 #724999 June 22nd 2017 12:18 pm
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will i need any adapter plates from engine to transmission? and can i drop in the 454 with the old transmission or will i need to swap flywheels for weight purposes. If needed to be swapped will the flywheel off my 400 sbcswitch over to the 454 bbc. I do not have the transmission for the 454 but the turbo 400 that is in the motorhome i hope will bolt up with no questions

Re: swapping 400 to a 454 motor 1979 g30 motorhome
Kinger9 #725052 June 24th 2017 5:26 pm
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Will need to use the 454 flexplate/flywheel for balance on the engine. No need for engine to trans
adapter, it will bolt to the transmission. The accessory drives {Alt, PS, AC,etc} from the 400 sbc will not fit the 454. Have been told that headers for a 72 Camaro will work for this swap.

Hope it helps.


'89 GMC 1 ton Ralley STX

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