Exhaust manifold bolt question
Thread Starter
TECH Enthusiast
iTrader: (10)
Joined: May 2013
Posts: 500
Likes: 19
From: Van Nuys, CA
Exhaust manifold bolt question so this might be a stupid question (tried searching but too much random stuff comes up) but can you or has anyone drilled and tapped their exhaust manifold hardware to a larger bolt/ stud? seems like theyre a common problem with snapping or stripping. also think its kinda stupid to have that much weight resting on such small hardware.
my heads are currently off and im in the process or removing some of those broken studs (which i havent been able to) well i got 1 of 3. lol. Ive done soo many swaps and these always seem to be a pain.
my heads are currently off and im in the process or removing some of those broken studs (which i havent been able to) well i got 1 of 3. lol. Ive done soo many swaps and these always seem to be a pain.
There are several videos on how to remove them with a welder, The heat it put into the broken bolt helps break them free.
By the way it's not the weight that's the problem, It's the reaction that happens when you bolt something together using dissimilar metals. Aluminum and steel don't play nice together over time.
By the way it's not the weight that's the problem, It's the reaction that happens when you bolt something together using dissimilar metals. Aluminum and steel don't play nice together over time.
Thread Starter
TECH Enthusiast
iTrader: (10)
Joined: May 2013
Posts: 500
Likes: 19
From: Van Nuys, CA
oh ive already welded the studs and that. thats how i got one out.
i was just asking if there would be any issues installing bigger hardware. also think some of mine are stripped/cross threaded by previous owner. im not a fan of heli coils so id rather just drill a size bigger and tap it for a bigger bolt/ stud.
i was just asking if there would be any issues installing bigger hardware. also think some of mine are stripped/cross threaded by previous owner. im not a fan of heli coils so id rather just drill a size bigger and tap it for a bigger bolt/ stud.
Yes, essentially you may drill and tap; however, you have to consider the fact that you may have to drill the exhaust manifold to fit the new bolts. Additionally, keep in mind not to drill to far in or to large of a bolt as it can create other issues. Not to mention, if the bolt or nut is too large then you will continue modifying. Really not worth the headache.
It does happen a lot, but the best fix is, ARP studs. A little expensive, but gives piece of mind and you won't have that problem again.
In my opinion, I would try to clean out the tread the best I can and see if I can get a bolt to catch on a few threads. It may be enough to keep a good seal. Again, buy the studs if you can. If this is no go, I would helicoil. Drill and tapping to a larger bolt would be last resort.
It does happen a lot, but the best fix is, ARP studs. A little expensive, but gives piece of mind and you won't have that problem again.
In my opinion, I would try to clean out the tread the best I can and see if I can get a bolt to catch on a few threads. It may be enough to keep a good seal. Again, buy the studs if you can. If this is no go, I would helicoil. Drill and tapping to a larger bolt would be last resort.
Last edited by rising_4rm_ashes; Sep 25, 2019 at 05:44 PM.
You're putting steel threads in to an aluminum base. Makes it stronger than original. What's not to like? For cast aluminum parts that I might want to R&R in the future (Like a cast front cover), I add heli-coils during initial assembly. Makes for a better more durable part.
TECH Senior Member
Joined: Jun 2016
Posts: 22,293
Likes: 3,617
From: Central Cal.
You're putting steel threads in to an aluminum base. Makes it stronger than original. What's not to like? For cast aluminum parts that I might want to R&R in the future (Like a cast front cover), I add heli-coils during initial assembly. Makes for a better more durable part.
Trending Topics
TECH Addict
Joined: Dec 2017
Posts: 2,182
Likes: 970
A bigger bolt doesn't address The Real Problem; the weakness of the aluminum itself. In addition to making a head (or other casting) that's altered that way, instantly and permanently incompatible with every part out there in the world that needs to bolt up to it.
Heli-Coils are the way to go.
Not sure how "not being a fan" figures into REALITY, or how such a thing would even get started. They're really BY FAR the best way for most typical people like us to improve on the obvious weakest feature in a whole engine. I recall getting FSMs for Chrysler vehicles in the 60s, where in the transmission section, the first step in prepping for a rebuild after teardown was, "Heli-Coil all bolt holes".
Heli-Coils are the way to go.
Not sure how "not being a fan" figures into REALITY, or how such a thing would even get started. They're really BY FAR the best way for most typical people like us to improve on the obvious weakest feature in a whole engine. I recall getting FSMs for Chrysler vehicles in the 60s, where in the transmission section, the first step in prepping for a rebuild after teardown was, "Heli-Coil all bolt holes".
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
I always make sure I tap the holes out or chase them before I install any bolts. The leftover crap from the GM applied threadlock on the stock manifold bolts is a bitch if you dont clean it out. I usually go pretty wild with high temp anti-seize when torque the bolts, too. Ive used ARP 12-point bolts on each of my LT installs and havent had a problem yet.
Thread Starter
TECH Enthusiast
iTrader: (10)
Joined: May 2013
Posts: 500
Likes: 19
From: Van Nuys, CA
I always make sure I tap the holes out or chase them before I install any bolts. The leftover crap from the GM applied threadlock on the stock manifold bolts is a bitch if you dont clean it out. I usually go pretty wild with high temp anti-seize when torque the bolts, too. Ive used ARP 12-point bolts on each of my LT installs and havent had a problem yet.
yeah i usually try and clean any of the holes out pretty good. but these were already snapped inside when i bought the motor.
I got ya. Im a mechanic on mid to large construction equipment myself. Have to deal with tons of broken bolts. Depending on how broken the bolt is I center punching each each, drill them down the center, weld a washer and nut to what’s left of the bolt, let them cool some then try to back them out. Drilling the hole gives the bolt a bit of an opportunity to shrink slightly once it’s welded on. That usually works unless it’s broken too far below the surface it’s threaded into.