Rebuilding my 54 year-old Pontiac V8 properly after someone used gum wrappers as bearings

I’d just blown up the stock transmission on my Pontiac and was laying in defeat under the behemoth. Reaching up, I playfully tugged on the back of the flexplate and my whole world fell over.

The clunk I heard was the crankshaft moving fore and aft in the block, otherwise known as “end float”. A little bit of end float is OK. The couple of inches I had spelled disaster for the engine I had up ’til that point thought was OK to run a few more years.

It was time to pull it out and go through it. What started with the idea that I’d just throw some new rings, bearings and a slightly fatter cam into quickly became a full hot tank, sonic test of the 54-year-old block, machined crank, new pistons and rods, rebuilt later model cylinder heads, roller rockers and much, much more.

The pic below shows the engine bay of the car when I got it, covered in surface rust and built up grime on the engine. It was a stock 1964 Pontiac 389, with a single four-barrel Carter AFB carburettor and a gross output of 303hp (pretty good for back in the day). It would have been lucky to have 200hp through the restrictive log exhaust manifolds and intake.


It was a sad day to be pulling this car down. It had been a long journey to get here, starting with the restoration of another Pontiac from 2013-14 that ended with it burning in a shed fire. This was meant to be my running, driving car. It seemed like a huge step backwards at this point.


The original 389 in this car was caked in inches of dirt, and everything looked very old and tired. I want to drive my car so I decided to replace much of it, and not tempt fate by using unknown alternators and wiring.


Excuse the bodgy pic, but A moment of triumph was celebrated here (below), lifting the engine out while the bonnet was attached! I did cheat and remove the cylinder heads because the decision had already been made to throw them away thanks to a lack of aftermarket support for pre-1965 Pontiac parts. Many bolt patterns and updates happened for the 1965-on model year, so I purchased some ’66 GTO cylinder heads off a mate and that is how this whole snowball started rolling…


July, 2015. Having checked the main bearings it confirmed the crank would have to come out, as there were two down to the copper lining.


August, 2015 and the block was fully torn down, crank, con rods, and pistons all removed and inspected. It was this delay (due to my workload) that led to me approaching Dan and Phil of Peninsula Engineering in Brookvale, Sydney, to machine my parts, and build the long motor for me. I dropped it off to Dan and Phil in October, 2015.


The bores were okay, but after Dan and Phil checked it they advised they wanted to bore it out to make it perfect. Thankfully, Pontiac engines can take a huge over-bore and stroke as pretty much all Pontiac V8s have the same block, from 301 cubic-inches to 455 cubic inches. Peninsula Engineering would bore my engine +.060in (15mm) to measure 4.120in (104.6mm) while retaining a 3.75in (95mm) stroke, as this was considered to be budget-conscious (and I didn’t want a million horsepower).


There was a delay getting standard 400ci pistons from Keith Black so the short motor (bottom-end) was together by March, 2016. I had ordered a Rollmaster timing chain, new pushrods, a Comp Cams flat tappet cam (224/230/110), full ARP bolt kit (including upgraded con rod bolts), and a new oil pump.

Dan and Phil got the 1966 GTO #92 heads on by April, 2015. Fresh valves and springs, plus the aluminium oil filter relocation block (see below) to clear the cast iron long-branch headers from Ram Air Restorations. I wasn’t in a rush for the engine, so I was very happy for them to take time to put it together.


Here was where we struck trouble, with the rockers. I had bought Comp Cams stamped steel units with a 1.65 ratio, the same as Pontiac’s high-performance Ram Air IV motor, but for an unknown reason the rockers would not line up with the pushrods or valve tip.


My rocker issue was fixed with 1.65 aluminium roller rockers from Yella Terra. These are actually an Australian product, and as soon as they went in it fixed the geometry problems. Another upgrade was the new timing cover, as the original item was an old iron item that used a 4-bolt water pump often known for overheating. The new aluminium piece had a much better 11-bolt pump which the boys shimmed for tighter clearances, improving cooling.


To prepare for the momentous arrival of my fresh engine I had removed the front-end off the Barge so it would be a simple manner of craning the fresh donk out of my ute, and sliding it straight into the open engine bay… or so I thought.


I got the call from Dan to come get my big iron lump in mid-July, 2015. They had run it for 45 minutes on the engine test stand to break the flat-tappet cam in, a vital step involving holding the motor at 2000rpm to avoid killing a lobe off the new cam. They had rebuilt my Carter AFB 4-barrel and strapped it on to the brand new Edelbrock Performer dual-plae intake manifold, installed an HEI electronic distributor, and fitted the new (and modern) starter motor.


So purdy, I was hyper-stoked to see it all together at last.


Unfortunately, the weight of the all-iron Pontiac V8 meant even just getting the motor out of the ute was a saga, as the engine crane couldn’t fit under the back of the now-slammed car. Eventually I got it out, bolted the TH400 transmission up, and got the whole lot into place (after I removed the Ram Air Restorations long branch headers to make it easier to get the engine mounts in). It was so late by the time I finished that Friday night I took a pic the next day!


Wearing the now-400cui engine and TH400 auto I honestly thought I’d be driving the car in just a few months’ time. This was July 2016.


This photo is the last pic I have of the iron 400 together. Ryan and I had just finished dummy-fitting the Vintage Air A/C, while I’d thrown on some old school Edelbrock finned valve covers to see what they looked like. The engine cover is the original, powdercoated black. It was looking good compared to how I first got the car (see top of page).

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s