you also do not necessary go to a larger bolt, you can install helicoids' inside of each other. I have seen quite a few helicoids' inside of helicoids' on old harleys, personally id go for JB weld it only has to hold 30lbs. Plus its an intake, isn't that what they make clear lacquer for, get it running and hot then coat the seam with clear lacquer (old used car trick)

 

Raining this morning, went to NAPA (we don't sell anything except the short coils and nobody stacks them), Advance (we don't carry 7/16 kit, just a few 7/16 coils), Orielly (7/16 Helicoil kit in back, they don't stock the drill bit or longer coils).

I figure since every time I wanna wrench on it we get rain, and the local farmers must be sneaking by when I'm gone and wallowing out the holes.

 

On the Full Torque, the nice lady on their 800 number tells me they only sell direct, ship from California.... I was hoping with all the truck repair around me they would have a stocking distributor. Savanah has a big container port and the paper industry, which means we are a magnet for semis of every state of disrepair. You really don't want to tail gate a pulpwood truck, they get paid by the load, haul freight all the time, and parts as well as chunks of wood come off.

lhscouts is also right about the tired.

 

Try mcmaster, they ship very very fast. http://www.mcmaster.com/#standard-th...nserts/=nlaxg0

or

MSC industrial: http://www.mscdirect.com/browse/?sea...rdrct=helicoil


Here is a way to use 3/8" bolts with your stripped holes. You need to drill and tap the heads for 9/16"-12 or 1/2"-13 (thick vs thin wall)and put this insert in: http://www.mcmaster.com/#standard-se...nserts/=nlaxq1. The only issue I see, that are 1/2" long. look at the surface area of the threads holding the insert to the heads should be vs. the threads holding the helicoil in the heads.

 

Don't believe we have enough material for those sizes. The head is not continuous, it has open areas to save metal. Note pix of original head before machine shop, and there seems to be some smooth area in that hole as well. From another angle each hole boss is visible, and 1/2 would not leave much.

Since only top of hole was stripped, tried a new helicoil all the way to the bottom. Which was threaded with the tap. And a second coil (about 1/2 of that stuck out) on top. Trimmed of below flush. Tested with a bolt and washers, got to 25 NM. Repeated with partial coil removed. Had aluminum on the theads, which must come from the area of the hole where tap had not cut out to full size. I suspect the issue is that the 25/64 original bit is just too large for aluminum...

That metal rod poking thru is the one and only oil channel to each head. A second passage is drilled, but does not exist on the engine block. This allows heads to be universal rather than left or right hand.

 

Decided to go with 7/16; drill to size "U"; and thread for new bolts. First one done, and tests to 40 nm. The bolts are drilled slightly off from 90 degrees. This tap is the closest commercial model to what ihscouts described as the way to go.

Plus rain. At this rate of progress, which is an embarrasment to me, I should be done by Labor Day. Others put up one post and describe how they rebuilt a Series Rover, and swapped engines twice; in one paragraph...

 

ehh we all make mistakes from time to time but I am sure in the end it will have been worth all this extra work, and I thought mine took to long to do

 

I don't know how it will be worth all this extra work (nothing is being improved) but it's a good learning experience for our mod when the noobs post up about head gasket replacement. Whoa, those will be lengthy what-not-to-do replies.......

Yeah Buzz, the blind tap is fine. It can be modified to cut thread all the way to the bottom and a pocket for the shavings with each flute sweeping them to the middle, the hollow.

Just go with what ya got.....and keep the faith.

 

As I expected, got to the hole that had been drilled and helicoiled for 3/8 with a 25/64th bit. Drilled out with the U bit, and tapped for 7/16. But since hole was too large to start with, I was basically threading a portion on old threads, never a good idea. Result failed at 20 nm with 7/16 bolt. This one I will have to drill out a bit larger and use a 7/16 helicoil (bought today).

A couple of the original holes held before, I seem to recall they were the corners, this would help on the two rear ones where drill placement, firewall, and hood might not mix well.

Rain has blessedly stopped work in early evening.

Of course I keep trying to figure out the common problem, and I believe it must be related to valley gasket skewed off, and in trying to get the bolts in I got most of them cross threaded the second time. Kept thinking with another turn the gasket would pull down. As for the first ehlicoil that failed, I'm convinced that the drill bit stated was for use in steel, and aluminum requires a slightly small bit.

So I plan to use a smaller bit than speced by Helicoil for the 7/16 insert and tap that I bought today. Hoping won't have to modify mount holes in intake manifold for alignment.

As for lessons learned, good judgement comes from experience. And experience comes from bad judgement. I am indeed fortunate to have so many supporters on the forum, ready to add their insights, research, and occasional much needed kick in the rump.

I plan when done to collect the problems, and edit them into the first page, so that others won't have to read the whole thing to get the laundry list of what to do and what to do differently. And of course others will add to it.

 

I kinda skimmed through alot of this page, so apologies if this info isnt relevant anymore...

Autozone has a good selection of coil sets and Menards has a good selection of drill bits.