Dave Stribling
October 9, 2018

Engine Block Prep

I want to put a 347 stroker together for my ’67 Mustang and I plan on assembling it myself. What do I need to have the machine shop do to the block before I assemble it? It is a 1990 5.0L roller block.

Robert Broady
Putnam, Illinois

The 347 stroker uses a 0.030-inch overbore from the stock 4.00-inch 302 bore and a 5.315-inch or 5.400-inch connecting rod, depending on which crank and rod combination you use (stock 302 rod is 5.090 inches long). Because of the longer rod length, most stroker setups require the bottom of the cylinder bores to be notched to clear the rotating assembly. Other than that, have your machinist do the following:

• Standard block prep includes cleaning, checking for cracks (magnetic inspection), and installing the cam bearings and core plugs
• Bore the block 0.030 inch over
• Notch the block for the 347’s rods
• If necessary, align-hone the block (often the mains will go out of round, so have the machinist check and see if it needs an align-hone)
• If necessary, deck the block (like the align-hone, the head mounting surface will probably need to be milled flat on many blocks)

For most street engines, this should get you a block that will run reliably for a very long time and will be ready to pull out of storage and ready to build. If you are building something with some teeth, then follow your machine shop’s experience when putting a lot of horses into the block. Good luck with the build!

Most 347 strokers require the bottom of the cylinder bores to be notched, as shown here. It allows the longer connecting rods to clear when the piston is coming around to top dead center. This is now a common modification, so your machine shop should have no problems with notching the block.

Leading Seams

Do you still lead-fill quarter-panel seams? My body guy says they don’t do that anymore.

Dane Rich
Via the Internet

I still lead them, but I can’t say for how much longer. Most auto body supply places don’t carry lead or the supplies to do it anymore. Eastwood still carries the supplies (lead is PN 31151) you need if you want to learn to do it yourself.

Most shops like the one you are using don’t lead the seams anymore because of the hazards of using lead. The biggest hazard is the acid—the acid is used to help the lead stick to the panels, but is gets everywhere and can cause problems and health issues. Inhaling lead and getting it on you is also quite bad. Finally, the fillers we have today are really good, so most shops use the fillers on the body seams rather than using lead. The lead is a much stronger fit, and some of the seams can be wide and deep, so I personally still lead the joints. I would say as long as your shop has a good welded assembly, the body fillers should work fine. It may be very soon that we won’t have the lead available to us anymore.

Lead going on this 1967 hardtop’s quarter-panel. We are using an oxy/acetylene torch—a leading torch uses acetylene only and makes for a much cleaner job. Note the width of the seam that is being filled. That’s a lot of body filler to crack!
Here the quarter-panel has been leaded up and is ready to grind down. The goo at the bottom is the tallow used to keep the lead from sticking to the wooden spoon or paddle used to spread the lead into place.