all Aluminum 2point8 prototype race engine???

p8ntman442 · Post by **p8ntman442** » Thu Jun 30, 2005 12:07 pm

But my pitch is 1.5. will a 12 x 1.5 tap right into the 11 x 1.5 threads? anyways, I did some testing on a 1/2 inch piece of alluminum with 11 x 1.5 threads in it, it held 95 ft lbs fine. I think there are still enough threads in all the holes to supply ample holding torque. Now I need help finding head bolts that are longer than what I have by about an inch to an inch and a half. with all the sbc heads made, there has to be a set of head bolts available. Forget studs, Its only going together once, then when it comes back apart, it will need sleeves and Ill have new holes and threads machined then.

off to find some 11 x1.5 bolts in 5 1/2 and 4 1/4 inches long. wish me luck. (I may just use the long head bolts I have in the short holes as it is.

Kohburn · Post by **Kohburn** » Thu Jun 30, 2005 1:19 pm

I doubt that peice of aluminum is of the same alloy as the block

aluminum alloys vary in strength tremendously

and yes a 12x1.5 tap would thread into an 11x1.5 hole

The Dark Side of Will · Thu Jun 30, 2005 9:08 pm

12 - 1.5 = 10.5

11 - 1.5 = 9.5

So the tap drill for a 12 x 1.5 hole is only 0.5 mm smaller than the major diameter of 11 x 1.5 threads.

Doug Chase · Post by **Doug Chase** » Thu Jun 30, 2005 10:33 pm

The Dark Side of Will wrote:Tap drill = nominal diameter - pitch

12 x 1.75... tap drill = 10.25

I hadn't seen that rule of thumb before. Nice. Thanks.

p8ntman442 · Post by **p8ntman442** » Fri Jul 01, 2005 12:38 pm

northsar head bolts are 11x1.5 by 173.78 mm which is 6.84 inches long.

add a few washers and Looks like im in business. Take the long head bolts and put them in the short holes and take the n* bolts and put them in the long holes. Shimming where necessary.

Kohburn · Post by **Kohburn** » Fri Jul 01, 2005 1:17 pm

The Dark Side of Will wrote:12 - 1.5 = 10.5

11 - 1.5 = 9.5

So the tap drill for a 12 x 1.5 hole is only 0.5 mm smaller than the major diameter of 11 x 1.5 threads.

yes but when retapping a hole larger you have to look at the minor diameter of the smaller hole - because the major diameter will be getting removed by the tap -
as long as the minor diameter of the threads left in the hole is equal or less than the tap drill then it will be like a brand new tapped hole.

Kohburn · Post by **Kohburn** » Fri Jul 01, 2005 1:17 pm

p8ntman442 wrote:northsar head bolts are 11x1.5 by 173.78 mm which is 6.84 inches long.

add a few washers and Looks like im in business. Take the long head bolts and put them in the short holes and take the n* bolts and put them in the long holes. Shimming where necessary.

I'd rather shorten the threaded end as required than shim anything

p8ntman442 · Post by **p8ntman442** » Sun Jul 03, 2005 8:04 pm

uhh, have you read this thread for the last few pages? Im trying to get as much thread as I can on these bolts, I dont think Ill be cutting any threads off. I will most likely have threads cut onto the other end to make studs if possible, not sure if you can do that on grade 10.9. my die cut into my stock head bolts. This may be a solution, until I know for sure, im not declaring the problem fixed. The problem with the shimmed n* bolts is the oil catch in the valve covers. But they can be removed, so not much of a problem, the bolts will clear the rockers no matter what.

The Dark Side of Will · Mon Jul 04, 2005 9:31 pm

Studs are made by rolling the threads onto round bar. Cut threads are not as strong as rolled threads. The working of the material makes it stronger, for the same reasons that undercut rolled fillets on crank journals make the crank stronger.

p8ntman442 · Post by **p8ntman442** » Tue Jul 12, 2005 12:17 pm

Im picking up my new head gaskets and 3.4 tdc bolts today at napa. Then off to fastenal for some grade 8 washers to remove the excess length. Depending on the amount of thread on the bolts, I may remove some from the threaded end, but most likely will use 3-4 washers to make them fit. looking at .57" too long. If this dosent work, Im going 1/2" and making studs cut to length.

p8ntman442 · Post by **p8ntman442** » Wed Jul 13, 2005 12:11 pm

Well the 3.4 bolts are nice and long with plenty of threads. I had to make spacers rather than cut threads off each bolt and remove 1/16" off the diameter of the head flange. I was gonna use nice machined spacers, but what the heck, a stack of nickles with a hole drilled in them should work right MTA? I would have had a report on if it worked however the crappy head gaskets napa got me dont work because its an open deck, and the gasket dosent seal the water jacket on the outside edge.

I have a set of gaskets that are (gasket/sheet metal/gasket/sheet metal) top to bottom. Im gonna try to use them with some type of sealer on the bare metal on the bottom. Any sugestions on what seals metal head gaskets best?

Kohburn · Post by **Kohburn** » Wed Jul 13, 2005 12:24 pm

ive never seen anyone use sealer with MLS head gaskets - at the most some spray tack to help hold em in place

p8ntman442 · Post by **p8ntman442** » Thu Jul 14, 2005 12:01 pm

SHIT!
well 11mm didnt hold in one hole.
Im going all out. 1/2" grade 8 studs all around.

I used spraycopper gasket stuff and it worked well. Recomended by a machine shop.

off to call fastenal

The Dark Side of Will · Thu Jul 14, 2005 5:27 pm

What did you do to this hole?
Your head bolts were 11mm originally, right?

Was this a virgin hole?
Remind me what you did, again?

Kohburn · Post by **Kohburn** » Fri Jul 15, 2005 7:15 am

I dunno if you have enough material for 1/2" thread - but for a 12MM with a thread pitch matching that of the 11mm you should have enough material..

depends.. did you strip a hole out? thats what it sounds like, i think you may have to use a threaded insert like a timesert

p8ntman442 · Post by **p8ntman442** » Fri Jul 15, 2005 12:06 pm

[quote="The Dark Side of Will"]What did you do to this hole?
Your head bolts were 11mm originally, right?

Was this a virgin hole?
Remind me what you did, again?[/quote]

same hole that was problem b4. There were still threads at the bottom therefore I was looking for longer bolts. The threads that were left were not enough apparently because the 3.4 bolts went to the bottom and still the hole stripped out. 1/2 is bigger than 12mm I dont think retapping a 12mm into an 11mm (stripped) leaves more than short flat threads that dont hold.

My son could be born this afternoon, or anytime this week, so that leaves me with no time for the car. So I will make it another dilly dally project, and do it right. 1/2" studs are gonna cost $$$$$$$ so im gonna look into borrowing a timesert kit and get some long n* 30mm inserts. Those may work. Cant seem to find the minor dia, and od of the timesert tap though.

Kohburn · Post by **Kohburn** » Fri Jul 15, 2005 12:11 pm

yeah 1/2" = 12.7mm

but with the thread pitch being completely different your starting minor diameter is 12mm

definately time for a threaded insert -

oh and congrats on the rugrat btw :thumbleft:

p8ntman442 · Post by **p8ntman442** » Sat Jul 16, 2005 7:10 pm

well, ive been on the timesert site timesert.com and looking at the engineering data, Im thinking to do this and only have once chance at saving this block, I have one good option.

12mm timeserts. A lil pricy for a college kid with baby, but a big savings in the long run. I think it will work fine holding the motor together in the future when its sleeved, decked, and boosted. It will also allow me to never have to look for 11mm bolts again. What a pain in the ass.

I was thinking about 1/2" but thats about the same price to make studs as it is to buy the timesert kit. Another related thought was that 1/2" bolts may not fit throuh the holes in a 3.4 tdc head. (I had a set of heads but cant remember) Wish I didnt sell them for 50 bucks. Im not even sure of the feasability of making this block a dohc, but why do anything to definatly rule it out, so another good reason to go with the 12mm timeserts. 12 x 1.75 timeserts require a 1/2" drill and a .552 major dia. tap. so the threads holding in the insert will be virgin and complete

no rugrat yet. still waiting.

Kohburn · Post by **Kohburn** » Mon Jul 18, 2005 7:53 am

yeah dunno about the dohc swap onto that block - but I imagine it'd be a good swap for a 3400

p8ntman442 · Post by **p8ntman442** » Mon Jul 25, 2005 12:43 pm

well I actually went 7/16-14 inserts, just ordered them today, as well as the bolts. I drilled all the holes and tapped 3 of them so far (easy tapping very soft aluminum). I had to just order a bottoming tap for the kit because the holes are blind and I didnt know if the long inserts would work without fully formed threads. 1.5" holes 1.25" inserts. That only cost 21 bucks for the tap. They are not regular sized taps so I couldnt get one at a parts store.

My girlfriend is set to get induced friday morning, and I doubt the parts will be here by then, so this may take a while.