The Stovebolt Site Forums The Parking Lot Big Bolts Engine swap and Bearings for a 66 gmc 4000

Hello gentlemen, I am new to the site and I have a few questions. I need to know if it is possible to swap out the old knocking 305 v6 for a 400 sbc with semi ease and what are the part numbers or specs on the front wheel bearings. It is a 1966 GMC 4000 and it is 2x4. 4 speed 2 speed rear with a 305 v6 that knocks like a hammer.

I would imagine a '66's front wheel bearing info could be located at a parts store even though they won't have it in stock(?). RockAuto stops at the GMC 3500...parts link
Check out the GM Heritage Center , and Kieth Hardy's OCMP.
Welcome to Stovebolt.
Brad

(Also- you will probably get some specific answers to your questions... you can read in the manuals until that)

Swapping a V8 for a V6 won't be cheap or easy- - - -the bellhousing bolt pattern on the V6 block does not match any V8 I'm aware of, so you'll end up fabricating mounts both front and rear, and swapping the bellhousing, adapting or fabricating clutch linkage, etc. On the bigger rigs like yours, you're probably going to find the transmission has the full round SAE-style bellhousing flange. Those housings are available for all sorts of engines, gas and Diesel, but they're scarce and expensive.

I'd suggest dropping the oil pan and confirming the source of the knock. The GMC V6 engines are pretty pricey to rebuild, and they're gas hogs, but once one is rebuilt properly it's a long lasting, high torque engine, and it's tougher than a two dollar steak!
Jerry

Thank you, its knocking hard and tbh 165 hp and 260 tq is alot lower than the tq monster 400 i have sitting in my shop. Seeing i cant find any parts that are not cheap in any aspect for a 305 it might be beneficial for me to go to a 5.9 cummins at that point. Thanks man. I am all for keeping something original but for the money to rebuild a v6 i could have a 5.9 with 200 more hp and 400 more tq for the same price lol.

I think i have narrowed down some bearings so i will try tomorrow and make sure i can swap them out. Thanks for the insight guys. You have made this easier.

Where are these manuals located? And nope local napas which have the rearest parts near me dont even list a 66 gmc 4000 lol im flying solo on this one!

What ever you do, don't send the 305 v6 to the junkyard. They are hard to find in any condition. I'm sure you could find a good home for it somewhere. JP

Oh I wont bud, I cant get rid of any old parts lol some call those people hoarders I call them prepared for the future!

My 61 GMC American LaFrance pumper has the 305's big brother in it, the 401. It's got a Clark 5 speed trans with direct drive in 5th. gear, but once I remove the driveshaft mounted pump and install a 3 speed Brownie with under, direct, and over ratios I'll have 15 forwards and 3 reverse gears. Plans are to retire the rotted-out fire bed and replace it with a commercial 5th. wheel and a gooseneck trailer hitch, and tow just about anything I choose to!

http://www.hunt101.com/data/500/61_GMC_001.jpg

Jerry