Sunday, January 26, 2014

The Front Bumper Tuck

In 1973 Chevrolet was required to increase the crash resistance of the bumpers on its vehicles. This began the era of the "big bumper" Novas. In order to be able to accommodate an up to 5 mph impact, the bumpers were pushed out away from the body 2-3 inches which made the bumpers look really bulky.

Big Bumper Nova owners wishing to clean-up the look of their 73-74 Novas have two choices. They can swap the nose trim, grill and bumper for a 69-72 setup which is a basically bolt on swap as the fenders are the same, but this is not cheap swap and it changes the personality of the 73 nose. The alternative is to perform the "bumper tuck". This is fairly quick and cheap.

On the front and rear, the bumper tuck eliminates the 2" plastic/vinyl trim that is suspended between the bumper and the grill or end panel and moves the bumper back to sit abutted to the grill or rear panel. On our car the rear bumper tuck was performed by the previous owner (who told us he also replaced the rear bumper with a 1974 bumper).

Since I had the front grill removed for paint, I decided to reassemble the front end with a front bumper tuck. Step one was to notch the bumper bracket. These bolt to the frame and when you slide them back without the notch they will run into the radiator support.

After several tries and test fitting, this is the final cut I used. 4-1/2" from the rear edge and 4-1/2" wide. (You can follow the slope of the detent in the brace in for the last 1-1/2".)

Bumper Tuck
Next Drill the new holes in the frame with a 1/4" or 5/16" bit and then finish the hole with a 1/2" or 9/16" drill bit. I only had a 1/2" so I needed to the clearance the holes so the bolts would slip through. The brace is now bolted to the frame using the first two bolt holes on the brace.

The #3 bolts are no longer bolted through the frame because the frame bends in away from the bracket. Here I just used an old bumper (carriage) bolt to tie the bumper bracket together with the outside bumper bracket.
Bolt the bracket to the frame in the new bolt hole location and you will have a bumper tuck that sits up over the lower grill trim and above the bottom of the headlight trim.

Lower Bumper Tuck Alternative
I also wanted to see how it looked if I bolted the bumper below the lower grill and headlight trim. The upside is you can move the bumper further back about 1/2", the downside is the 2" gap between the bumper and filler panel that would need to be filled.

To do this I added another elongated hole lower on the frame rail. (This pic is before I connected the two holes.) For the back bolt I used the existing slot in the frame.

If you use this bumper tuck you don't need to notch the braces but you definitely will need to fab filler panels for the side trim. Also with the bumper pulled this far back I found my front tire ran into the rear edge of the brace so if I left it this way I would have needed to trim the back of the brace.
It seems everyone goes with the upper tuck and I concur, even if the gaps weren't there the lower grill trim now becomes a visual element and it changes the look of the front end.

I'm thinking a Spoiler by Randy might be a good addition to the front...

Saturday, January 18, 2014

Freshen Up the Interior

Since I had everything apart I decided the interior of the Nova needed a little freshening up as well. The dash pad, door panels and front seat were shot but the carpet, headliner and back seat were fine.So I decided to "freshen" the interior. Here's the before shot:
While I was working on the heater a new dash pad was put in and I rattle canned the dash. The door panels were replaced with new ones from Classic Industries and I took the front seat to Marce at Surf City Upholstery to have him match the velour that is on the back seat from the previous owner's recover.

I've still got to find a door pull and trim for the door panels,and there are lots of little pieces that could be replaced, but its looking much better. Here's the result so far.

Sunday, January 5, 2014

The Heater Undelete

At some point a previous owner had the heater core go bad so he removed the A/C and Heater equipment under the hood and bolted a steel cover over the air inlet on the firewall. By removing this he also eliminated the Defroster. So for the last 10 years its been a little cold and foggy in the Nova during the winter months.

I decided this finally needed to be fixed. In addition to this my son also noted that there were no lights on the dash, so at night he was running dark. Since we were going to send out the seat to have it recovered I figured this would be the perfect opportunity to get under the dash and fix this as well.

First I completely disassembled the dash. How is it possible all this stuff fits under there?

Next to get access to the mounting location for the heater blower motor I removed the passenger side inner fender well from inside the engine compartment.

There are a couple of companies that make "AC Delete" covers for the 3rd Generation Novas. The top piece is made from fiberglass and looks like a factory cover but I found it wouldn't fit without cutting the cover just above the top hose outlet. So I opted for the simpler looking ABS cover.

The next item was the wiring the PO had snipped off the wires that passsed through the firewall and I had this to work with. See the 5 neatly cut wires? They go through the firewall out to the AC/Heater components. The other end of this harness goes to the AC/Heater controls on the dash.
I bought a new Blower Motor, AC Relay, and AC Resistor and from the factory service manual I figured out how to wire it. The key to success was to buy all AC components. The AC components are all heavier than the Heat-only and the firewall on the AC cars are different than the firewall on the heat only cars!

 The resistor was mounted inside the AC delete panel and wired out to the AC relay which feeds the blower motor. This all is routed through the firewall in the big grommet just above the valve cover.
You can see the new Heater core coming through the firewall. The first test was to try the blower motor and it worked on all speeds. All I need now is a couple of hoses and the Heater install will be complete.

In reassembling the dash I cleaned all of the connections and replaced all the bulbs and two undersized fuses and now we have all the lights on the dash as expected!

We added new door panels a new dash pad and had the seat recovered and the interior is like new.