Lo-Buck Head Job ideas...


Top Poster
Quit sniggerin' :LOL:

This is a project idea to help out an impoverished mate. No, not in NZ...

I want to work to a rigid timetable if possible, just to see what can be done, and what the SOTP results are. No show pony, just a daily driver.

Plan is to take the head (a 221 log), strip and sandblast, port/polish and install with Weber adaptor. External costs would be for spark plugs, carb adaptor, blasting, gaskets, stem seals, welsh plugs and carb. It should come in under USD$100 back on the car, BUT:

I need opinions on whether the sandblasting will appreciably damage the CI valve seats - which are in OK condition currently. Or will the slight "resurfacing" bed in quickly? My blokes use a refined garnet for this type of blasting work.

What kind of tolerance (unit to unit) on the valve springs can I accept, for stock valvetrain?

Thanks, Adam.
I don't snigger at people from Australia.

Some-one help the man out. My mate works at a sandblasters, but hes on holiday.

My 221 head and block got skipped last winter. Garnets, you say, (sni**er,sni**er), sounds refined all right. You've not ground up some ladies aniversery ring, have ya addo?
Go for a "soft" blast medium like walnut shells or plastic beads. They strip rust nearly as well as garnet and will not harm the underlying metal in thenslightest.
or you could put heavy layers of tape on the seats and try not to blast them. or if you do just a quick lap job....snicker....

Just my personal preference; I'd blast the livin' he** out of it, go after the whole thing with hot, soapy water, scrub everything in sight, generally make it clean enough to eat off of. Rinse, towel off, dry with compressed air, and then spray it down with WD-40 before it can start to rust. (If you're not going to paint it)

A real good valve job is in order at this time. I wouldn't skimp here at all.
Some mechanics will work after hours, just slide 'em a case of the beer of their choice. Put the money in new stock springs, and bronze valve guides, if you can afford 'em. Hopefully, the valves can be re-ground along with the head seats.

Good Luck with it!!
Ta for the feedback. One problem with mechanical workshops here. They're either s**t-house, or overpriced, or both. :roll: And I mean overpriced. :shock: The valve seats and margins are better (used) than some places could accomplish new, and blowing the budget is not an option here.

My manual says seat runout can be up to 1½ thou, and valve margin the same again. This in theory gives 3 thou of peek-a-boo until the impact reshapes things. Or is this the point at which a rebuild is imperative? This isn't made clear - whether it's machining tolerance, or maximum wear.

SR - I don't know anyone who uses walnut shell here. Plastic media, yes. It's pricey, too. What do you think of glass beads?

XE: I don't grind up people's rings. ;)

Also, some comments on the springs would be great. I plan to clamp them end-to-end in the vice, and measure deflections, tabulate, use strongest as benchmark and remeasure. Even under hand pressure they feel different. Is 10% OK? 20%? 30%? I don't want to shim unless really needed, as that will just about be the end of the timing set, which has to last another 12 months or so.

As a semi-related issue, I am going to post some valve size questions in Hardcore Tech.

Regards, Adam.
Heh Addo, glass beads are just fine, that's what I use all the time, just turn the pressure down to about 30 psi and don't hold it on the seats for a long time. Glass beads will eat away metal just as well as abrasives if you hold it in one spot for any length of time, especially at high pressures. When you are done just put the whole thing in a tub of hot water and detergent soap and slosh it around, the soapy water will cause the glass beads to release their hold and fall off. Spray with wd-40 and or paint to avoid rusting.