Let's Get Something Straight

Consider the following scenario: You're out in your shop working on a project. It's getting late and you're tired but there's just one more thing to get done. Now, at this point your mental clutch begins to slip and you take a shortcut, even though in the back of your barely functioning mind you know better—unfortunately this series of events usually ends up in the “no act of stupidity goes unpunished” category.

Recently we had the need to drill and tap the accessory mounting holes in a very expensive aluminum head. The existing holes were 3/8-inch diameter and the bracket we were mounting to the head required 7/16-inch fasteners. Armed with the correct 23/64-inch bit for a 7/16-14 tap we decided to drill the holes oversize freehand. Not a good move. Predictably we drilled the hole crooked, so to fix the problem we had to do what we should have done in the first place and used a drill guide.

When a drill press isn't an option a drill guide is a viable alternative. Basically a thick block of metal, they can be used against a flat surface to keep the bit straight. We've made them from aluminum and steel and now have a selection of them on hand. In this instance the hole was drilled straight, but it was now oversize so a thread insert was installed. In the end we got the job done, but as the saying goes, we went the long way around the barn.

1. A drill guide with various size holes is easy to make out of flat material. It can be used to keep bits straight and aid in starting taps properly.

2. With the guide clamped in place we managed to straighten out the wonky hole and drill it the proper size to be tapped.

3. The same guide had the correct size hole to start the tap for a thread insert.

4. Threaded inserts can be lifesavers. They come with the proper drill, tap, steel inserts, and an installation tool.

5. After applying thread-locking compound the insert (which has inner and outer threads) is screwed into place. Aluminum parts can often benefit from thread inserts if the fasteners are to be removed and replaced on a regular basis.


Keep On Truckin'

In the July Shop Manual column the origin of Chevrolet's W engines was discussed. As part of that the use of Pontiac and Buick engines in GMC pickups was brought up. Although we were aware that GMC pickups used Pontiac V-8s from the second series in 1955-59, we were unaware of Buick engines being used in trucks.

Since that column was published we've gathered more information from our readers and our archives. Here's one of the letters we received.

Hi Ron,

Regarding truck engines, my 1963 Motors Truck Repair Manual lists several '56 and '57 Chevy truck models with a 322 Buick nailhead. The overhaul kit that I used for my '56 nailhead was actually listed for a '56-57 Chevrolet truck. It's also listed for a Chevrolet school bus chassis from 1957-59 with a 322 nailhead. Several '58-63 Chevy truck models were listed with a 348 (W engine). The GMC section did not list any Buick or Chevy engines up to 1963.

You have probably received numerous replies on this subject by now, but if not, hope the above is helpful.

Have enjoyed Street Rodder for many years, keep up the good work. Have been on several of Jerry's road tours and plan on another this summer. Fords Forever!

Rick Rickard
Via the Internet

Thanks for your letter, and you're absolutely right about Buick engines in big Chevrolet trucks (a number of readers brought this to our attention). As we were focusing on pickup trucks our research stopped there, but we've sure learned a lot since.

From what information we've gathered, in 1956 and 1957, Buick's 322 V-8 was available in Chevrolet's heavy-duty trucks and chassis destined to go under bus bodies. Beginning in 1958, the trucks got 348s while it appears the 322 was still used in school bus applications through 1959. To make things even more interesting—it appears that GMC used Oldsmobile engines in some of their big trucks from 1957-62. So, why should this be of interest? There are a number of reasons—these trucks may be an untapped source of vintage engines; it's likely that they will have some desirable heavy-duty internal components (although the compression ratio is probably lower); and wouldn't a Buick, Olds, or Pontiac-powered truck make a cool hauler?