454 in a 63' GMC SWB

[Grumpy63]

Hello everyone.

I have a project build thread started but haven't done much on it as it is winter here and we have plenty of snow. During the interim I've been reading and studying on this site and others to prepare myself to take Grumpy apart in the spring and put him back together.

Recently I was given the opportunity to get a 1977 Chevy 454/TH400 (may be a 475) out of a motor home. The engine and tranny only have 10,333 miles on them and the price was really good.

I'm sure there are a few of you out there that have put a BBC in your 60's model trucks. What advice would you have for a fella who is about to do it for the first time himself?

Also, the same friend who traded me for my 63' GMC and sold me the 454 and tranny owns a big junk yard (as you can probably imagine). I can pretty much pick whatever I want out of the yard to upgrade Grumpy. I'd welcome your thoughts there as well.

And then there is the 99' Suburban sitting in my front yard that has a little over 250k miles on that I got for next to nothing. I bought it to take a few parts off of for my 94' Burb. Any parts on it that you think I should scavenge for the project?

Thanks for your time folks. I know how valuable it is for all of us. I'm looking forward to moving along with Grumpy when the thaw hits.

[PGSigns]

I had a 64 with a 402 in it and liked the power but not the nose heavy truck. For me it killed the handling. I had the truck for years with a small block. If the burb has a Vortec head small block in it I would freshen it. I have one in my 66 and like it. My Burb is getting an LS. Just hard to beat the power, fuel milage and the weight off the nose. If you go with the BB you will need set of mounts, a 4 core radiator, trans mount, maybe a high hump to clear the turbo 400, a trans yoke for the 400, a drive shaft to match the length of the 400, a trip to the junk yard to get a cross member from a 73 to 87 with 1 1/4" rotors, the power steering and the power brakes. The list goes on but that will get you started.
Jimmy

[shortstep60]

You will need motor mounts from a 1968-1971 big block. If you want new motor mounts Jegs sales them good look

[oldusafmsgt]

I've got a 60 and a 66 with big blocks. It is no more involved than swapping from a 6 cylinder to a small block. There is only a 100 pound difference in weight between an iron headed BBC and a small block V8, and an original 63 GMC V6 is only 40 pounds lighter than a BBC. There is no need to swap the front suspension cross member, (especially on a 63-66) and a TH400/475 will clear a low trans tunnel floor. 68-72 BBC motor mounts, or aftermarket mounts (CPP) is all you really need, along with the driveshaft shortened slightly. It's an easy, common swap that people have been doing since these trucks were new.

[Chevy Fleetside]

I have an 89 BB in my truck with a 700R4 tranny. I used aftermarket mounts. I have a thread on all this and is in my signature.

[gizmoduck81]

I have a mark IV 454 with a TH400 in my low hump 63 (it's out right now being built as a 496). It was a prior owner install. The one thing I don't like is there isn't much space between the water pump and radiator so he had the electric fan mounted as a pusher instead of a puller. No overheating problems as a 454, but I'm upgrading the radiator for the 496 (plus aluminum heads) and am hoping it'll sit 0.5" - 1" or so further back with my new mounts to allow space for a puller. The TH400 fits just fine with the low hump.

[Grumpy63]

Thank you for all the great advice guys, and for pointing me towards some great threads on the matter. I'll look forward to reading anything you all put forth in order to prepare me for this project as well as can be expected.

[Robert Haas]

We went with the standard position so we had some valve cover clearance issues. Many just move the engine forward a small amount but I am kind of stubborn and chose not to do that.

We will be building a smooth (custom) firewall so having to massage it for a little valve cover clearance was not that big of a problem.

[Captainfab]

For engine mounts either '68-'72 BB brackets and mounts or the brackets from a '73-'87 C20/30 and corresponding clamshell mounts. If you switch to the short water pump, you will not have any issues with fan to radiator clearance. All trucks from '55-'72 used short water pumps on both small and big block engines. The '68+ truck frames have a narrower top flange on the frame in the engine bay for exhaust manifold/header clearance.

[urmyboyblue]

I have a couple of BBC's in my 65 and 66. Someone mentioned poor handling- if you don't like the handling after install, put some new springs on the front end. Made all the difference in the world for mine- I guess 40 years does a number on them. As for the TH400 you have out of a motor home- check to see if it has a companion flange or if it has a slip yoke. The one I got out of a motor home had a companion flange that required a slip yoke on the drive shaft. Not normally done with a single piece drive shaft, so you will either have to use a 2 piece drive shaft or have the trans reworked to add a tail housing and output shaft for a slip yoke.

I like my BBC's. They work well and are simpler. The LS has the advantage of being newer tech and more efficient, but when it breaks it is a little more complicated to fix.

[Robert Haas]

Besides, what looks cooler then a Big Block in one of our trucks?

[Chevy Fleetside]

Yes BB's do fill it up nice.

[Grumpy63]

All these pictures, you guys making me wish for warm dry weather so I can go to the yard and yank my motor and trany out of the RV! The good thing is, I'll get all the wiring, mounts, radiator, AC, PS, and pretty much any other parts I want from the pull out because, well, it's a package deal.

[Grumpy63]

You guys with the BBC's, are you running Ford 9" rear ends or are you rolling with Chevy 12 or 14 bolts?

[Captainfab]

The truck 12 bolt will withstand a lot of abuse. Just how much is relative to the tires that are bolted to each end of it and exactly how much torque is applied to the pinion. For what you are planning, the truck 12 bolt will be just fine.

Originally Posted by Grumpy63

You guys with the BBC's, are you running Ford 9" rear ends or are you rolling with Chevy 12 or 14 bolts?

[karlbenz]

Are Y'all talking bout the motor mounts or the frame mounts? or both?. my son is putting a rv 454 in his 63

[Captainfab]

The frame mounts as well as the engine mount and clamshell on the block for the '73+

Originally Posted by karlbenz

Are Y'all talking bout the motor mounts or the frame mounts? or both?. my son is putting a rv 454 in his 63