Author Topic: Intake manifold bolts stuck  (Read 1343 times)

Offline 81vee

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Intake manifold bolts stuck
« on: January 06, 2018, 05:08:10 AM »
Howdy guys. I have another conundrum for you today.

I recently purchased an Edelbrock 2701 manifold for my four bolt late block 350 engine. The frame and drivetrain are from a 74-78 k20. The other one was Chinese and I suspect it was giving me trouble ;)

However, upon installation, all four of the bolts directly sitting near where the carburetor would usually rest are now seemingly stuck. I tried torquing them down and all they do is turn and turn and turn and turn.... You get the point. I can't even remove them now. If it helps, I costed them with RTV silicone sealant as per the installation instructions that came with the manifold. I'm in a bit of a pickle about what to do now.

Any suggestions?

Thanks,
Mike
1981 C10 w/ '74-'78 K20 frame 350 crate 4.10 rear SM465 4" lift
'05 Colorado LS Z71 crew cab victory red

Offline FlatBlack77

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Re: Intake manifold bolts stuck
« Reply #1 on: January 06, 2018, 07:13:44 AM »

That is not good. the bolts closest to the front and back of the engine go into closed holes. the inner ones go in holes that end in the lifter valley. that is why you need sealer on them. see pic


It sounds like what happend is the threads stripped out in the holes and the part of the bolt that sticks out the bottom is not stripped so they will not back out. You are going to have to somehow cut the heads off the bolts then remove the intake manifold and collect the leftovers. then tap them for new bolts and clean everything very well before putting it back together. Not saying that you didn't do it but make sure to fallow the proper sequence for torquing intake manifold bolts

"When you are a hammer, everything looks like a nail"
'77 C/10 - 350/350 mild street motor

Offline Peter S

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Re: Intake manifold bolts stuck
« Reply #2 on: January 06, 2018, 08:31:43 AM »
Cutting the heads off of the bolts will not help unless all off the problem bolts are on the same side of the intake. The bolts are at an angle so even without the bolt heads, the intake cannot be lifted straight up.
-Peter

1978 K10 stepside

Offline FlatBlack77

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Re: Intake manifold bolts stuck
« Reply #3 on: January 06, 2018, 08:59:18 AM »
if they are loose enough to spin free then they will probably drop out the bottom. unless they arent long enough to  come out the other side. they may need punched out
"When you are a hammer, everything looks like a nail"
'77 C/10 - 350/350 mild street motor

Offline VileZambonie

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Re: Intake manifold bolts stuck
« Reply #4 on: January 06, 2018, 11:14:10 AM »
Use an air ratchet and a swivel socket to back them out. Slide a pocket screwdriver under the heads to apply some upward pressure and they will walk themselves out.

For the record, it is critical that you follow the tightening sequence and torque values to properly seat the manifold. Also do not use RTV on the threads, use permatex thread sealant with teflon. Use RTV in lieu of the end seals and over the corner of the gaskets so that there is a total seal. Lower the manifold into position, start all bolts and then begin tightening them in sequence. Repeat the sequence 5 times or until the final torque value is achieved.

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Offline 81vee

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Re: Intake manifold bolts stuck
« Reply #5 on: January 07, 2018, 06:50:54 AM »
Thanks guys for all of your help! I'll definitely try all of what you guys said, and take your advice the next time I do the intake. One quick question, however. If I didn't put any sort of sealant on the four bolts next to the carburetor, would that cause issues?

Thanks,
Mike
1981 C10 w/ '74-'78 K20 frame 350 crate 4.10 rear SM465 4" lift
'05 Colorado LS Z71 crew cab victory red

Offline VileZambonie

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Re: Intake manifold bolts stuck
« Reply #6 on: January 07, 2018, 07:01:55 AM »
oil will work its way up past the bolt and pool on the intake.
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Offline 81vee

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Re: Intake manifold bolts stuck
« Reply #7 on: January 07, 2018, 02:51:15 PM »
oil will work its way up past the bolt and pool on the intake.
Thanks, makes sense.  ;)  I thought that might have been the solution to another problem i'm solving. Just wanted to ask.

What would you guys personally recommend for solving threading issues, seeing that this is one? I'd hate to have to tap one a size bigger, who knows if that might cause other issues.  :-\

Appreciated,
Mike
1981 C10 w/ '74-'78 K20 frame 350 crate 4.10 rear SM465 4" lift
'05 Colorado LS Z71 crew cab victory red

Offline zieg85

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Re: Intake manifold bolts stuck
« Reply #8 on: January 07, 2018, 02:55:50 PM »
Heli-coil... Best fix I can think of.  Below is one example

http://www.stanleyengineeredfastening.com/brands/heli-coil/screw-thread-inserts
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 4.56 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline VileZambonie

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Re: Intake manifold bolts stuck
« Reply #9 on: January 07, 2018, 06:56:53 PM »
Odds are you damaged the bolts which are softer than the heads. Run a thread chaser through them
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Offline 81vee

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Re: Intake manifold bolts stuck
« Reply #10 on: January 08, 2018, 07:20:27 PM »
I checked the threads on the head and they are solid. It ends up someone screwed up in the bolt pile and mixed metric and standard bolt patterns, which caused them to get stuck, seeing how they are different sizes. >:(

Unfortunately, it also seems like the bolt holes don't line up correctly for the intake to the heads. I think if I recall correctly that someone put TBI heads on this motor? Would that change the bolt locations? All of the others seem fine, minus the four near where the carb would lay.

If I were to drill some of the intake manifold bolt holes out some to accommodate for this, would that be a smart idea?

Thanks,
Mike
1981 C10 w/ '74-'78 K20 frame 350 crate 4.10 rear SM465 4" lift
'05 Colorado LS Z71 crew cab victory red

Offline VileZambonie

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Re: Intake manifold bolts stuck
« Reply #11 on: January 09, 2018, 05:48:14 AM »
Are your heads center bolt valve covers or perimeter bolts? If you have mismatched the parts which it sounds like you have, yes you can drill or elongate the 4 center holes in the intake. The seat angle will be off so you can either buy a set of bushings or make your own to compensate. Click the link

https://www.ebay.com/itm/Professional-Products-52110-Angled-Adapter-Bushing-Set-of-4-/282781283934?_trksid=p2385738.m4383.l4275.c10
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Offline Jerr-conn

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Re: Intake manifold bolts stuck
« Reply #12 on: January 09, 2018, 09:53:18 AM »
I've done a lot of this in my day. Here is what I would do: if  the bolt angle does not interfere
With the carb mounting flange, i would center punch , as close to the center of bolt head as
Possible. Following the bolt angle , drill a 3/16" hole the depth of the manifold plus the head
Thickness 1/8" into head. Change drill bit to 7/16" and drill to same depth. By this time you
Should have the removed the bolt head. Do all 4 like this. Now you should be able to remove
Manifold. Now put some clean rags thru ought tha lifter valley to contain all drill chips.next,
 drill  3/16" hole thru rest Of bolt. Try an easy ought to see if you can back bolt out. If not, use a 5/16" bit and drill all Way thru. Remember to drill at same angl as bolt. Then retap threads for
3/8-16 threads. If you have to, drill and tep for 7/16-14 thread. If going to 7/16 , then drill these 4holes In manifold To 1/2" for clearance. REMEMBER ---center of bolt and angle. If you need to
Use 7/16 bolts, and the head of bolt interferes with manifold, try socket head cap screws.
Jerry

Offline 81vee

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Re: Intake manifold bolts stuck
« Reply #13 on: January 12, 2018, 04:44:40 AM »
Alright, thanks for all of your help, guys.

I'll try to do that. The other manifold I had did something similar in its design, although I'm not sure if that could be the point of failure, where coolant was leaking into the oil. Either that, or I have a cracked block. So many different things could be wrong with my predicament  :-\

I'll try, but if I get bad results, I guess I'm gonna have to look through a catalog and dig deep into my pockets for a new crate motor.

Thanks,
Mike
1981 C10 w/ '74-'78 K20 frame 350 crate 4.10 rear SM465 4" lift
'05 Colorado LS Z71 crew cab victory red

Offline Jerr-conn

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Re: Intake manifold bolts stuck
« Reply #14 on: January 17, 2018, 08:39:20 AM »
The more I think about it, I would try what Ville suggested on Jan 06. Pry up on bolt heads as you try backing them out. I think somebody put in metric bolts instead of English bolts. Is the head size
9/16"? That's what a 3/8-16 bolt should be. Should be using  gr 5 or gr 8 bolts.now you have a few ideas, keep us informed.
Jerry