Author Topic: 1966 389 in a 1979 403 T/A?  (Read 798 times)

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Offline 1tinindian

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1966 389 in a 1979 403 T/A?
« on: March 11, 2010, 01:18:36 PM »
I have a 389 that I'd like to use in my T/A and would like to know what engine mounts and shaker assemblies and A/C brackets I'd need to make this swap work, and look somewhat factory installed.

Anyone here ever done a swap with he older engines or have a link to such an undertaking?

It'd be nice to have some Pontiac power in my Pontiac!

Thanks for your help.

Leon

1979 WS6 Trans Am
1983 WS6 Trans Am

Offline Mr. P-Body

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Re: 1966 389 in a 1979 403 T/A?
« Reply #1 on: March 11, 2010, 02:25:48 PM »
Leon,

   The motor mount adapters are readily available fom Ames Performance or Performance Years.  Get on their site and query them.

   The 389 heads are a liability. Using later 400 heads is a much better propostition.  Static compression needs to stay under 9.5:1 for using 93 octane gas.  Heads with chamber volume of around 80 CCs are ideal for the 389.  Hard to find. using 72 CC heads with a "dished" piston is the most common solution.

   Upgrade the timing cover/water pump assembly to '69-newer 400 stuff.  If you can find an engine with all the pulleys and brackets, that would be a big help. It can be a real bag of worms.

   Replace the connecting rods with good forgings!

   If you would like more specifics on how to upgrade the Pontiac, just say the word! Virtually everything that "fits" 400 or 455, "fits" 389 (except bore-related).

Jim

Offline LilSki

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Re: 1966 389 in a 1979 403 T/A?
« Reply #2 on: March 11, 2010, 04:38:47 PM »
I have a '69 428 block in my 79 with the engine mount adapters. I wasn't all that happy with the fit of the adapters but I got them to work. I actually bought two sets from two places and I liked the set from Ames the best.

You have to watch out a bit though as it can throw off your shaker alignment. I am using the WFO drop base shaker so I was able to move the shaker back about an inch as my engine seems to sit a bit forward in the car. This worked for me but the stock shaker base does not allow any adjustment.
Kevin
79 Trans Am: (77 nose), WS6, M-21, 461, Hotchkis TVS, PTFB Contol arms. 
85 Trans Am: Vortec 350 w/LT1 cam/T56, TPI conversion w/Megasquirt II.

Offline 72blackbird

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Re: 1966 389 in a 1979 403 T/A?
« Reply #3 on: March 11, 2010, 05:13:21 PM »
I built a 389 for a customer w/ a 65 GTO recently- the original numbers matching block had been bored .090 to fit standard 400 pistons and the crank was already cut .020 under, so I ended up sourcing a replacement block and crank for this project.

The owner wanted his 389 to be as period-correct as possible, so we used the original 8-bolt timing cover- for your application the later 11-bolt timing cover would be much better (no pulley alignment problems w/ the later model p/s pump and alternator). You'll need to use a later model balancer w/ this timing cover as well. We also used later model no. 11 heads to keep the compression pump gas friendly.

Ordering forged pistons for the 389 will take at least 4-8 weeks, so plan ahead. I also put the forged 5140 replacement rods in the motor and had all of the usual quality machining processes done (blocked bored and honed w/ torque plate, had the rotating assembly balanced, decked, align honed, etc.) to ensure this motor would live a long life.

Geno

Offline 1tinindian

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Re: 1966 389 in a 1979 403 T/A?
« Reply #4 on: March 11, 2010, 08:29:18 PM »
Thanks for all the great feedback guys, but I'm a little disappointed now.
From the looks of it, the heads, rods, pistons and timing cover are no good,right?
That leaves me with a block and a crank.
Not as much to work with as I thought!

Oh well, it was  just a thought, thanks.

Leon

1979 WS6 Trans Am
1983 WS6 Trans Am