[Joes] [Joes]
Help 127: Rebuilding Heads


Rebuilding Heads is not difficult. The key to a successful build is cleanliness. Joes Garage uses a old school technique, manual tools for the actual rebuild. Joes Garage always uses new, modern valves, springs, and valve guides during a rebuild. Everything is done on site.

First, bead blast the head. Do not use quartz sand to blast the head. Sand causes scratchs that can cause scratches that can cause cracks. Clean the head. A pressure cleaner is helpful and fast.

Second, remove all the valves and guides. Keep track of which valve and guide comes out of each hole. I number each with a perminate marker. The following tools I find to be simple and efficient.

Note the punch has a cup on it. Take the cup off to push out the guides. Use the cup to insert the guides. When you have all the tools assembled remove the springs.

Prior to pushing the valves guides out of the head, heat the head to 350 degrees or so. I use welding gloves to handle the head after it is hot. By heating the heat it will minimize the damage to the guide holes caused when extracting the old guides. Clean the guide holes and head.

[cartoon]

Third, assemble the head. Use a Micrometer to measure the guides. Guides can come in many sizes. Standard sizes for Triumphs is about 0.5 inches. As heads are rebuilt the holes open up. Many over sizes are available. If the old guides came out tight, then buy the same size guides. If the old guides slid out easily, then a larger size is needed. Each hole in head maybe different. so you may need several different oversize guides. Number and keep track of each guide.

New guides should be the correct size for the valves. Try inserting the valves into the guides prior to installing the guides in the head. Valves should easily move up and down easily. Also, a slight side movement can be noted. Get a feel for the valve in the valve guide prior to install. If you push in over-size guides, the hole that the valve goes in may be distored. If this happens the hole can be honed or reamed to accommodate the valve. Heat the head up again to 350 degrees and place the numbered valve guides in a cup of ice cubes. After a short wait, put the welding gloves on and remove the heat from the toaster oven and quickly place each new guide into the head using the punch with the cup to insert valve guides.

[cartoon]

Guides are in and it's time to install valves. Valves should easily move up and down, try them. The following tools are necessary to dress the valve seats so the valves will seat correctly. The seat is cut at a specific angle to accept the valves.

[cartoon]

[cartoon]

After the valve seats are cut, the valves need to "seated" into the seats. The following tools are necessary. The Valve grinding paste needs to be placed on the valve seat, then the valve placed in the valve guide. The suction cup tool is placed on the valve, then the valve is rotated/back and forth on the head seat. This matches the contour of the valve to the seat in the head. Observing the seat after a few minutes one can see when a thick line has been etched into both the seat and the valve. Clean the head and valves.

[cartoon]

Look carefully at the next picture.

[cartoon]

That's water in the combustion chamber. This is the test to assure the valves are seated well. If water leaks past the valves, get the suction tool and valve grinding paste out again and seat the leaking valves. If it holds for a few minutes that's good. Note each valve location has a number and each valve in numbered.

Clean and oil the valve as you put them in. Use motor oil on the seats, valves and stems. Can't use to much!

[cartoon]

Wash the caps and valve keepers that hold the valves closed. Use the spring compressor to put the valve springs on the stem of the valves. Place valve keepers on the end of each valve as the spring compressor holds the spring in place. I use a hemostat to hold and insert each valve keeper half. All done!

If you want to give it a go and do your own head, I can help. Bring the head by and I will coach you!

[cartoon]

Keep it in the saddle!

Mike


Return to BBC Home Page


Copyrightę1997JOES GARAGE No Rights Reserved