why don't people like helicoiled bolt holes in intakes

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str12-340

str12-340

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I have seen several ads and posts that make a big deal about the bolt holes not being helicoiled in an intake manifold. I don't get it. I've had many manifolds that have carb stud holes helicoiled and even one that had the themostat housing holes done and never had a problem out of them, what gives???? Some of the coolest manifolds haven't been made for 40 or 50 years.
 
Some aluminum engine parts come with inserts installed new. They've never bothered me at all. In aluminum, it makes the bolt hole stronger. If someone has a problem with a properly installed thread insert, I question their intelligence.
 
I prefer keyserts to coils, but either is better than raw aluminum threads IMO.

The only reason to leave raw aluminum threads is cost, and rarely space limits.
 
I don’t get it either. I suppose some peeps want an untouched item? Yet some of those same peeps complain when an untouched intake (that’s over 40 years old) is being sold for a fortune.

I bought a LD4B intake a few years ago that was in great shape except one of the thermostat threads needed to be hélicoïded. I had both thermostat threads hélicoïded before I installed it and am actually more content with that since the odds of me removing the thermostat down the road is likely.
 
I agree when they are done right but I have seen a few done wrong/crooked, maybe that's where the hesitation come from.
 
We race ATV's nationally for several years. Every hole had a helicoil installed on the engine covers. The clutch would have to be replaced every run on 2 and 4 strokes. They worked great.

spoiler pics 744.jpg


spoiler pics 745.jpg


spoiler pics 739.jpg
 
Maybe it’s just a psychological thing when someone reads that the bolt hole(s) have been heli-coiled. Something was “damaged” at some point and “repaired” so it must be less than it was. Imagine if aluminum cylinder heads were treated the same way.:rolleyes:
 
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12many said:
Maybe it’s just a psychological thing when someone reads that the bolt hole(s) have been heli-coiled. Something was “damaged” at some point and “repaired”. It is less than it was. Imagine if aluminum cylinder heads were treated the same way.:rolleyes:
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Heli-coils, if done right, are stronger and better than aluminum threads.
 
66fs said:
Heli-coils, if done right, are stronger and better than aluminum threads.
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Of course. I’m speculating as to what a doubter might be thinking. It must be compromised, (must be less than it was) in their mind, who knows?
I clarified my post.
 
I've used them for years with no problems but I've never really understood how Heli-coils are stronger when the threaded insert is threaded into the aluminum.
 
Heli coils don't bother me as much as an intake that had been milled and then will only fit correctly on ONE engine, that a usually won't come attached to that intake....
 
moparmarks said:
I've used them for years with no problems but I've never really understood how Heli-coils are stronger when the threaded insert is threaded into the aluminum.
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Heli-coils are stainless steel and the OD is now larger, more strength, and now the threads will not wear. I would not Heli-coil good aluminum threads, but I have no problem installing and using them. When I worked in Quality, Government reps had to approve any repairs on certain contracts. Heli-coils were considered rework and no approval was needed. Studs are the best thing to use in aluminum since the steel or stainless steel full length threads of the studs are in the aluminum. The studs would then take any wear or cross threading.
 
66fs said:
Heli-coils are stainless steel and the OD is now larger, more strength, and now the threads will not wear. I would not Heli-coil good aluminum threads, but I have no problem installing and using them. When I worked in Quality, Government reps had to approve any repairs on certain contracts. Heli-coils were considered rework and no approval was needed. Studs are the best thing to use in aluminum since the steel or stainless steel full length threads of the studs are in the aluminum. The studs would then take any wear or cross threading.
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1st order of business in my new aluminum intake............studs & Loctite in every bolt hole.
 
When you machine a part out of aluminum, all holes should be heli-coiled or have some type of thread insert installed. To not do so is just a short cut.
 
I recently worked as an engineering contractor for NASA. We used a lot of aluminum to make stuff that flies on the International Space Station but my main project was a propulsion control system for long range exploration.

EVERY tapped hole in aluminum utilized thread inserts, no exceptions except for super light duty usage.
Not Heli-coil but Keensert style. Many of these were #2 or #4 screws. Everything was built to Mil-spec standards.

Another thing, lock washers are never used. Everything was loc-tited or used locking type fasteners.

GM stopped using lockwashers more than 20 years ago. My engineering manager at a different company around 2000 was a GM retiree and one of the first things he did was eliminate lockwashers. This was for HD off road equipment.

I've adopted these practices in my own junk.
 
The starter bolt holes in my 727 are heli-coiled. They have held up to starting my 10.5:1 compression 440 with timing locked @ 38 degrees for a couple of years with no loosening of the starter. I think Heli's and keyserts are great solutions.
 
Kia/Hyundai have block failure head bolts pull out and give you the same symptoms of bad head gasket , the fix is thread certs. Terrible Quality control don’t buy one there junk . The car not the repair .
 
KosmicKuda said:
I recently worked as an engineering contractor for NASA. We used a lot of aluminum to make stuff that flies on the International Space Station but my main project was a propulsion control system for long range exploration.

EVERY tapped hole in aluminum utilized thread inserts, no exceptions except for super light duty usage.
Not Heli-coil but Keensert style. Many of these were #2 or #4 screws. Everything was built to Mil-spec standards.

Another thing, lock washers are never used. Everything was loc-tited or used locking type fasteners.

GM stopped using lockwashers more than 20 years ago. My engineering manager at a different company around 2000 was a GM retiree and one of the first things he did was eliminate lockwashers. This was for HD off road equipment.

I've adopted these practices in my own junk.
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Many areas there is no room for a insert. The best insert if you are an engineer is a time-sert. Most boosted EVO engines done here require time-serts. Every hole in a race engine where time-serts are not needed get helicoils. Even if the threads are perfect. My new Indy heads, All the holes are Helicoiled.

Aluminum block head studs are Time certs.

++ TIME-SERT Official Threaded inserts for stripped threads, blown out sparkplugs,
 
AJ/FormS said:
I know what you mean, those lil 5/16 holes look awful puny. Funny thing is I have lifted the entire front of the car off the floor using a carb-plate bolted onto my Airgap.....
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A rough calculation says a 5/16" bolt can carry 500# x 4 =2000# (10:1 safety factor) . A grade 5 bolt would be a little higher. Its not the bolt we worry about though.
 
If everybody would use studs instead of bolts on the t -stat and carb there would be as many heli-coils needed. I am guilty as charged with using bolts especially on the t stats. When was the last time I checked for bolts bottoming out? Shame on me. :lol:
 
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