Datsun Roadster Forum-311s.org

Also, if the head gets surfaced make sure you shim the cam towers the same amount. I am no expert, but there are geometry issues to be aware of that MAY have an influence on where the cam rides on the follower (I encourage others with machining etc experience to chime in). The cam and follower have created a wear pattern together, and shifts in that MAY potentially lead to rocker pad wear or (less likely) cam wear. If you look at the rocker you will see the wipe pattern. When you put the engine back together you may want to check this pattern again to make sure it is consistent. I really don't know if a mm or so difference would cause problems or not. The wear pattern should be close to the middle of the pad, and certainly not off the ends. They used to sell a tube of "bluing" which was a thick grease-like stuff you could use to wipe onto the rocker so that when you spun the cam it would clearly show the wipe pattern. I used a dry erase marker the last time I did this but it was not as easy, but I could use it to select the correct lash pad (new rockers, different and reground cam which results in a different base circle).
One option if you are concerned would be to send the cam and rockers (maybe just the rockers) to Isky in CA, or to Delta cam in Tacoma to have the cam checked and to touch up the rockers to remove any pattern so that they create a new wear pattern when you re-install and break in the cam (cam break in is a specific process). I personally did not have a lot of success using reground rockers but mine were pretty old and my cam particularly tough on valve-train components.

Oh, never mind! Gonna run a different cam!

Gregs672000 wrote: Thu Jan 03, 2019 11:04 am Yes, agreed with above... don't be the guy that says "Its better to look good than to feel good...". Nothing makes a Roadster look better than a shift from second to third at 6500rpms...

YEEEEEEEHAAAAAAAAA

haha it should be fun doing that with the C-Cam!

Pjackb wrote: Thu Jan 03, 2019 3:04 pm

2mAn wrote: Thu Jan 03, 2019 2:07 pm Im pretty sure its chrome... it wouldve been done in the 70s/80s prior to the car being parked in '87

Rub some polish on it with a cloth (any polish really) if it turns black after a while it’s polished if it only cleans without turning black it’s coated

Its chromed, and I tried to clean it up with a buffing wheel. The bad chrome came off, the better stuff stayed. It doesn't look good, but it looks better than it did. That said, the chrome that is on there isn't going to come off easily. I think the only way to remove it would be to media blast it, but then you are faced with hour upon hours of sanding with increasingly finer sandpaper, then wet sanding it, then putting it on a buffing wheel for a few more hours worth of work. If it were mine, I'd be looking for a better one that just needs a polish, and keep this one as a backup spare.

As for skimming the head, why? Clean the gasket surface well and call it good. (Scrub with a scotch bright, then wipe it down with acetone till its clean.) It will seal just fine. Assuming there is no damage to the underside of the head, there is no reason to skim it.

Will

I believe you can take it to a chrome shop and have it removed.

Why not just paint the thing ? lightly sand it then add a light coat or 2 of self etching primer then put the high temp paint color of your choice

Pjackb wrote: Fri Jan 04, 2019 7:17 pm Why not just paint the thing ? lightly sand it then add a light coat or 2 of self etching primer then put the high temp paint color of your choice

I think Im actually going to do this, but not the entire thing. I will spend way too much time masking the raised letters and painting those and leave the rest as-is ... for now anyway

Ok, so I’m replacing the smog plugs on my 1970 U20 with new ones to hopefully eliminate the chirpy exhaust. Previous plugs are short square-head brass ones. Three of them came out with no problems. 4th one has broken the square head off. Do I risk drilling this out (carefully) or do I try to forget that one of these things is not like the others and save any further headaches, no pun intended.

Matt

https://drive.google.com/file/d/1jyPjSr ... p=drivesdk

It looks like there is enough of a lip left that will allow you to use a flat ended punch to tap on. Soak it with PB Blaster or such for a day or so and then tap on the far right corner of the lip to rotate it counter wise.

Do you have clearance to get drill onto it? If so I would drill a very small pilot hole, then follow up with a left-handed drill bit of approx. 1/4. I have had very good luck with them. If that doesn't bring it out I would follow that with a square extractor, not the spiral EZ out ones that always break.

impact wrench with flat screwdriver bit?? Ideally tightening

Remember, that often, screwing something in (tightening just a BIT) will solve the problem.

Thanks everyone. I tried cutting a slot and screwdriver but the brass is too soft and yes, tried to tighten also. No dice. I’ll soak and try the left handed drill bit next. Vice grips worked on the first three but the fourth was no bueno.

I have to about drilling it and tapping it with a left hand taper tap, then a bottoming tap and then using a left hand bolt. Of course in this case you would have to be careful not to drill through.

I'd try to heat the area around the plug and drip a candle on the plug. The melted wax wicks in and helps break the bond.
If nothing else works, make a centering bushing to fit over the stud to guide the drill bit.
Dan

Talk to me metallurgy people.
heating a brass bolt in a cast iron block will make for uneven expansion, right? I don't know which side expands more but shouldn't it break any bond caused by corrosion?
nest question, After heating would a shot of spray nitrogen carefully directed onto the brass cause it to shrink faster than the block?
Trying to think outside the block.