Engine Upgrade on my 71 !
 

OK so it's time to retire the 402. It has low power, leaks everywhere, and needs to be rebuilt and given a good home. The carb is a quadrajet and it has stock intake.
http://pic20.picturetrail.com/VOL122.../392358007.jpg
I have an 83 one ton GMC with a 454 that only has 10k miles on it after rebuild that I used to use as my camper. It is wrecked on the side you don't see here and it will be the donor truck.
http://pic20.picturetrail.com/VOL122.../367539005.jpg
Here's the donor engine being repainted.
http://pic20.picturetrail.com/VOL122.../392358008.jpg
http://pic20.picturetrail.com/VOL122.../392358009.jpg
All shiny with the headers on and on the engine stand.
http://pic20.picturetrail.com/VOL122.../392358012.jpg
http://pic20.picturetrail.com/VOL122.../392358038.jpg
About a year ago, I replaced the turbo 400 with a rebuilt one out of a chevelle. The speedo hasn't worked since then, so I pulled it with the engine to bench it and figure out why. The drive worm gear on the tail shaft was missing, so I replaced it with the old one I still had. Those little clips are wierd so I looked it up and saw that all you have to do is hold the spring clip down and slide out the gear.

With the tranny fixed, I bolted it up to the new motor.
http://pic20.picturetrail.com/VOL122.../392358042.jpg
Heres the truck sans motor.
http://pic20.picturetrail.com/VOL122.../392358010.jpg
and the installation...
http://pic20.picturetrail.com/VOL122.../392358052.jpg
Look at this mess!!!
http://pic20.picturetrail.com/VOL122.../392358057.jpg
I added an Edelbrock performer and an Edelbrock 750 CFM square bore carb, same as Carter AFB.
http://pic20.picturetrail.com/VOL122.../392358054.jpg


Well, that's the story so far, I need to install the headers and fab the exhaust a little to fit. Then finish up with the radiator and all hoses and fuel lines. I'll let you guys know how it runs!

See you soon!

Dan
:gmc2:

Re: Engine Upgrade on my 71 !
 

looking good!

Re: Engine Upgrade on my 71 !
 

Looks like it should be fun! I'm am considering dropping a 454 in mine, but right now I have too many other (non-truck) projects going on. Good luck and let us know how it runs.

Re: Engine Upgrade on my 71 !
 

whats up with the tired 402??

Re: Engine Upgrade on my 71 !
 

I'm not sure what you mean?

Re: Engine Upgrade on my 71 !
 

I am pretty sure he means, what are you gonna do with it ?

I am not intersted in it, just trying to help out.

Re: Engine Upgrade on my 71 !
 

Hilandr452,

That is awesome buddy, glad you got the swap done! Looks great, how does it run now?

:lol:

Re: Engine Upgrade on my 71 !
 

Looks great!

Re: Engine Upgrade on my 71 !
 

OK, my son and I put on the headers, installed the alternator and power steering pump, hooked up all the lines, added coolant and oil, but were only able to hook up one exhaust pipe to the headers, the drivers side header is canted up slightly, so theres a 1/2 inch gap. Looks like I'll be welding pipe tomorrow.

I fired it up for like 2 seconds just to see if she'd go and she did, but it was 11 pm so I quickly turned it off. That open header is LOUD!!!!!

I'm too tired to upload the photos, so I'll catch you tomorrow.

Dan

:gmc:

Re: Engine Upgrade on my 71 !
 

Here's a pic of my boy workin' on the truck.
http://pic20.picturetrail.com/VOL122.../392406844.jpg
Putting on the plug wires.
http://pic20.picturetrail.com/VOL122.../392406851.jpg
Passenger side header tube lines up, but driver's side is canted up.
http://pic20.picturetrail.com/VOL122.../392406853.jpg
Two sawzall batteries, some upside down welding, and a day later and it's all good!
http://pic20.picturetrail.com/VOL122.../392406860.jpg
Final product minus the aftermarket air cleaner I have to go buy.
http://pic20.picturetrail.com/VOL122.../392406855.jpg

Well, that's it folks, the truck runs like a bat outta hell now. Took the wife for a spin tonight and it really flies!! Turns out the old transmission modulator vacuum line was leaking bad and with the new line in place it shifts like a dream.

Now I just need those 16 x 10 inch steelies, a new tail gate, bed side, new bed wood, new seats, a bunch of body work and a paint job.....

At least I won't be bored!

:gmc2:

Dan

Re: Engine Upgrade on my 71 !
 

Thats awesome buddy, glad you got it all sorted out, now drive the wheels off of it!

Re: Engine Upgrade on my 71 !
 

Figured I'd post the problems I had after the swap. First off, the upper hose clamp wasn't tight enough and leaked coolant. I took off the radiator cap to fill it up again.

Then I took it for a spin down the road a ways to check for speed. Stopped at a light and steam was coming out from under the hood again! I had forgotten to put the cap on and boiled 4 gallons out onto the street.

After filling the system again, we went for a ride and there was a bad vibration at 35 mph, then again at 55. Looked underneath and the passenger side header was hitting the frame, so I notched it slightly. (the frame!)

While working on this, I noticed a small leak in the seam of the end cap of the radiator. Removed the radiator, flushed with fresh water, melted off the end cap solder, then added flux to the entire seam and sweated solder into the seam again properly.

Vibration is lessened but still there, so I changed the motor mounts. (I know, should have done that in the first place!) Now she's running perfectly.

Listen to the almighty forum Gods when they say things like "Change the Motor mounts every time you remove the engine, they're 7 bucks a piece." or "Make sure you check the radiator cap before you close the hood."

This is good advice!!

Dan

Re: Engine Upgrade on my 71 !
 

Awesome you got it all in there and running good. The little stuff is just that. Little stuff. Glad you have her back on the road and you are happy with the swap.

Re: Engine Upgrade on my 71 !
 

Great Job!!!

Inquiring minds want to know where the tired 402 is going?

Re: Engine Upgrade on my 71 !
 

Hey guys,

Thought I would share how things are going and update the build. We've moved from Colorado Springs to Penrose, 35 miles south from the city to a small homestead where I have more room for my toys and a pasture for my daughter's horse. The truck has been running fantastic the whole time. I pulled a 2 axle horse trailer full of all my crap about 20 times back and forth between the two cities with no issues except horrible gas mileage.

My brother sent me Custom Camper badges for my truck and I don't know the exact placement for them so I'll need some of you to post pics for me please.

One problem that has never gone entirely away is the vibration. I changed all the mounts including the tranny, but there is still a nagging vibration there at idle, and at certain rpm increments. I've been giving it some thought and i have an idea about what it might be. The engine I installed was from a 1 ton dually which was a standard transmission with a huge hulking clutch plate. It occurred to me that since they have this huge balanced clutch plate instead of the flex plate which is now on it, that there might be a difference in the stock harmonic balancer between automatic and manual applications. Can anyone tell me if there's a difference?

Oh, and FYI I still have the 402 on an engine stand in my new garage.

Thanks guys,

Dan
:gmc2:

Re: Engine Upgrade on my 71 !
 

nice.............. big block power

Re: Engine Upgrade on my 71 !
 

454=torque=terrible gas mileage....But fun has no price IMO..

Good job. On the swap. As far as the vibration. Is the driveshaft indexed? I would check the U joints. Sounds like one is giving up the ghost.

Re: Engine Upgrade on my 71 !
 

Dan, where did you get the flex plate that currently is on the 454? The 454 is externally balanced & requires an externally balanced flex plate (or flywheel in the case of its previous life in the 83 1 ton). The lack of that wee little balance weight on the flex plate will give you a bunch of weird vibes for sure...

Re: Engine Upgrade on my 71 !
 

Flex plate came off the old 402, which I don't remember having a vibration issue.

Re: Engine Upgrade on my 71 !
 

you will probably require a new flexplate, the one off the 402 was not balanced like the one on the 454 should have been. you need one off of a 454 or one built for a 454 with the external balance

Re: Engine Upgrade on my 71 !
 

External balanced:

http://www.summitracing.com/parts/SUM-G102SFI/?rtype=10

Vs.

Internally balnaced:

http://www.summitracing.com/parts/SUM-G100SFI/?rtype=10

See that weight welded on to the externally balanced one? Thats what you're missing. A relatively easy fix, it's just going to involve pulling the transmission to change out the flexplate.

http://www.eaglerod.com/index.php?op...d=27&Itemid=25

Re: Engine Upgrade on my 71 !
 

402 is internal balanced, 454 is external balanced. Do not drive/run the truck until you change out the flexplate for one the is for the 454. You did use the balancer off the 454....right? The balancer must be extrenally balanced on a 454 just like the flexplate. It can kill the crank and or bearing in the engine if you keep running it with the wrong flexplate.

Re: Engine Upgrade on my 71 !
 

I did keep the harmonic balancer from the 454. I've been driving it this way for over a year, recently hauling a trailer for the move. Guess I'll tear it back down.....

Thanks for the help guys!