exhaust studs versus helicoiled 8 mm holes

[alexblack13]

Hi Guys,
What does the team think?

I took the studs out through the manifold flanges to help remove the manifold. With the removable x member this turned out to be possible with a bit of fiddling. Whilst the engine is on the bench, I was thinking..Just thinking mind..don't shoot! of drilling and helicoiling the manifold stud holes to M8 with 2 x d length inserts.

Advantages are as I see it. More torque on the fasteners and easier to remove manifolds etc. Thinking of using good quality (Umbrako) 8mm dia Allen caps. Could be a handy mod this. Replacing gaskets for E.G.would be a bit easier. And of course fitting and removing the said pipery

Originality is my main don't do it... Any others?.. Should I forget it? Refitting the studs is an easy job.. I put the pipes in then fit the studs back through the flange holes.

Flame suit fitted and buttoned up....

[paddy]

So how often do you replace your manifold gaskets?

Paddy

[john.p.clegg]

It's a good engineering solution to a problem...if you have a problem.

John

[CBUEB1771]

I was thinking..Just thinking mind..don't shoot! of drilling and helicoiling the manifold stud holes to M8 with 2 x d length inserts.

The notion of helicoils does not bother me at all from the originality perspective. But I am quite curious about M8 rather than 5/16" UNC, the latter being original. True, the differences between the two are pretty darn small dimensionally, but I am bothered by making slightly mongrel Elans (as determined by fastener standard) significantly more mongrel by adding metric fasteners to the engine.

[alexblack13]

Yep.. OK.. Anymore?

5/16'' no problem. Just have m8 in stock is all, and you won't tell the difference without picking up the two fasteners and reading the info...

Exhaust flange gaskets have been known to give up. Recent posts from ? asked about replacing as he could not get the manifold off the studs.

Keep it coming. Together we will make a decision..

Thanks guys... There is no problem by the way john. That's why I am swithering ( Is that a word?)...will I? wont I? ..a stripped out stud would force the issue.. But mine are all fine.

Al'

[oldelanman]

Hi Alex,
Seems to me you are looking to fix a problem that doesn't (yet) exist. If you want to make it easier to replace the gaskets and/or remove the manifolds and the threads in the head are OK, why not just use cap screws in the existing threads. If those threads do get damaged then would be the time to fit helicoils.

Just my thoughts......

Regards,

[alexblack13]

OK.. An option I suppose but I would like to put a bit more torque on the fasteners too. One of the main advantages for me that & Helicoils would allow 1.25 x normal torque.. A few times out of and into the std threaded holes is not a good idea in cast ally.

Just an idea at the moment mind. I might well just refit the studs thro' the flange holes as normal, and use some new brass nuts.

AB...

[Gray]

Hi

Threads in alloy can become a bit loose over time without stripping as the studs often come out. I have a head which has had a stud thread stripped and oversized stud fitted by previous owner, which I hope is not too large to helicoil. If you have the equipment and time to do it, a good idea helicoil with bolts/capscrews holding the manifold in my view, makes taking the manifold off much easier.

Regards Gray

[alexblack13]

That's a one for and a few why bother(s)

Hmmm.. I think I'm going to do it while the motors out.... maybe,perhaps..

Any one else?

Al'

[stugilmour]

Alix, I used 5/16" UNC socket head (Allen?) screws into the original threads as I had a couple of the original studs that were nasty to remove. I believe I saw several posts in the archives with this mod recommended. Would definitely stick with 5/16" UNC Heli-coils as well to make everything reversible if desired. I think I Heli-coiled one hole on mine during rebuild (probably should have made a note to myself ). Used lock washers as well. Lost one screw during shake-down run, but I think it was inadequately torqued as opposed to a failure of the modification.

The header install was easy enough with the engine in just the chassis, but when the body is in place the screws make the header job way easier, particularly around the thermostat casting. Socket head screws work well with a swivel type wrench (ball shaped where it engages the screw head). At least some of the studs have to be removed in any case with the body in place because of clearance issues when using my formed header (Dave Bean SS), so the Ali threads will get a work-out if the header needs to come off with the engine in place.

Any thoughts on the metal type to use for the screws? Mine are just the regular black one's, nothing exotic. Not sure what they are though. Could easily be changed out if recommended. Used anti-seize in the holes. Not sure if these fasteners are available in SS, or if SS is recommended in contact with Ali?

I checked my Bean catalog, as I thought he recommended the screw mod, but I was mistaken. It does list 5/16" exhaust studs that are shorter for quicker installation of the header (presumably shorter on the UNF end). No steel grade provided for the studs though. He also lists a SS plain washer and a thin looking flex lock nut in SS with moly or silver plating to prevent seizing. This is all for the stud type design.

Giving the Bean catalog info a bit of thought, the shortened studs with the thinner mounting flanges of the SS header seems the best solution. I expect the shortened stud would allow sevicing of the gaskets without removing the studs or the header assembly from the lower Y pipe with the engine in place, but I have not tried this myself. Would also expect the shortened studs may not work with a cast header or manifold due to the thicker mounting flanges.

I expect drilling and Heli-coil install with the engine in place would be a bit dodgy for clearance with the drill, so understand why you would consider now with engine out. Maybe with and 90 degree angle drive air drill it might be possible, but clearance and steadying the tool would be hard I expect. My car has two brake boosters in the way as well, so even less room than the Elan. I figured if the screws torqued fine I would leave well enough alone, and so far so good (1000 miles only).

OMG, I think I am shifting into fourth gear on my next post!

[garyeanderson]

Hi Alex

You need a new project to mess with. Leave your Elan alone and go buy a Coupe and cut the top off if you want to stir the hornets nest up. Put a Zetec/duratec in it and it will have all of those lovely metric fasteners already...

Gary

[stugilmour]

Hi Alex

You need a new project to mess with. Leave your Elan alone and go buy a Coupe and cut the top off if you want to stir the hornets nest up. Put a Zetec/duratec in it and it will have all of those lovely metric fasteners already...

Gary

Love it Gary! Alix would also get the MT75 five speed and could sell his Lotus box!

[Gray]

Hi

Whats wrong with chopping the roof off?

Reagards Gray

[alexblack13]

LOL....

Behave the lot of you...This is a serious discussion don't you know.


I'm getting closer to doing this mod'. I would use 5/16'' unc helicoils methinks. As stated, easy to stick a new set of studs into.

Umbrako fasteners for Allen caps.. The best. The spec' is available online but I have not checked. I won,t use SS I don't think as the screws are getting expensive. Another reason for the m8 was I have loads of umbrako m8 fasteners... Ah well. If I decide to go with it I will order the fasteners with Mrs B soon. I will have to buy minimum 50 thereof.

Keep them coming, I'm all ears..

Al' .....

[Spyder fan]

Is chopping a roof off and fitting a Duratec controversial?

Okay... steel studs threaded into soft aluminium allow you to anchor securely and then apply torque using a steel nut on a steel thread. Using steel hex headed bolts to thread into the soft aluminium to apply torque is a recipe for disaster, I really don't think I am wrong here. Helicoils into the soft aluminium would act like a stud so no problems using hex headed bolts, M8 might allow a bit more torque to be applied, but is it necessary and will it cause controversy amongst us purists?

Regards