tri08sbc

A good friend of mine has a C4 85 and he was removing the thermostat housing when he broke one of the bolts off. After drilling the center out and inserting an easy out, he snapped that off also. Would a left hand drill bit help ? Or is that part of the intake which could be swapped for another intake ? It's a cross fire injection intake. I'm trying to help him find some help. The C6 group have been very helpful to me with my car, so I thought you guys may have some insight that could help my buddy. Thanks for your input in advance.

WVZR-1

Your friends '85 shouldn't have a cross-fire intake (not that it matters) BUT you might want to confirm the year or the intake type.

Has he been able to remove the easy-out?

There's numerous approaches to removal - the left-hand drill bit and progressing in size often works. Tools, equipment etc. that's readily available might influence the choices.

tri08sbc

Oops my bad. It's an 84 and he hasn't been able to remove the easy out. Thanks for helping me clarify that. Is that surface that the thermostat sits on part of the intake or the block ?

WVZR-1

The intake is a two piece (upper/lower) and the water outlet is into the lower base. A GOOGLE images search for "Corvette cross-fire manifold" or an eBay search should supply many images.

Depending upon your situation I'd think that if possible and there was someone with mobile welding capabilities you consider mig-welding a nut/washer or nut and complete the extraction. It's kind of a "who do you know" and what's available in the area. Your location hints there should be "many" that could help you.

tri08sbc

Thanks that was a great help. It looks like replacing the manifold for $199 is not too severe. You were a big help. While I have you helping me, I sold him my C6 stock wheels at a good price, but the rear ones will hit the rear suspension knuckles. What size spacer would clear that problem up ? I was thinking a 2" or less would do ? Thanks again for the words of wisdom.

WVZR-1

There's a good bit that goes along with an intake replacement. It wouldn't be my first choice. You also generally don't know what you're buying when buying "USED". There's other options and the MIG suggestion of mine in your part of the state shouldn't be expensive or difficult to source.

Wheel spacers? If your rears are still on the ground it might be good to confirm the wheel offsets from the wheel back-side. I don't generally assume anything!

This is maybe what you should expect on your wheels:

Front: 18 x 8.5 56MM offset
Rear: 19 x 10 79MM offset

Danlb

The same thing happened to me when I tried to change the thermostat on my '84. I pulled the manifold and took it to several machine shops and they all told me that a shop with wire EDM cutting capabilities would be the only place that could help because of the broken thread extractor. A buddy at a local hot rod shop took it to an aircraft machinist at the local airport and he had me back up and running the following day for about $100.

tri08sbc

I will let him know about the MIG welding solution as well. I would tend to agree on the used source. The mounted tires just seem to hit the rear suspension knuckles, I thought putting spacers on would bring the tire away from that. It doesn't look like it would take more than a 2" to do the job. I just wasn't sure of it. The fronts fit fine. The only thing in regards to the intake is that he decided to try drilling around the edges of the easy out and I think he put a bunch of holes on the intake itself. He showed me after he did this, so that's why I told him I'd try to get some answers for him before he did anything else to make it a bigger problem.

WVZR-1

The less he messes with it and the sooner he solicits professional help the easier the repair. At this point he may very well be able to TimeSert/HeliCoil the manifold. The more he "tinkers" the more expensive the fix is likely to be.

I believe that when mounting "base" C6 wheels on an early car 1" are suggested for a front and something 1 3/8 or very close for the rears. If 1 1/4 OR 1 1/2 were less expensive "off the shelf" it might influence the decision BUT if there were no monetary savings then the 1 3/8 I believe would be the choice.

tri08sbc

I'm going to let him decide on the intake thing and will suggest the 1 1/2 " spacers for the rears. The fronts have complete clearance. I will encourage him to join our forum though, so he can ask these type questions himself. You guys are very helpful.

WVZR-1

If you visualize the C6 wheels 1" further outboard of where they would mount now I believe you'll better understand the 1" spacer suggestion for the front.

Tom400CFI

At this point, it needs to be welded on, and removed that way...then if the threads aren't serviceable due to his drilling, it will have to be drilled larger and a cert or helicoil put in (which will be stronger than the original threads, BTW).

FYI, I have a Crossfire base for sale, if you want it.

tri08sbc

I see your point. It would be better.

tri08sbc

I will let my buddy know.

John A. Marker

This does not solve the current issue, but the reason the bolt snapped off is the prior owner did not apply anti-seize to the threads. Steel and aluminum will react overtime.

In the case of galvanic corrosion, the combination of two dissimilar metals with an electrolyte is all that is needed to form a reaction. The result is that the two metals bond together as if glued or welded.

tri08sbc

Very aptly put Sir. But he still has to either remove the snapped off bolt with the extractor inside or remove the intake altogether. Correct ?

John A. Marker

That is correct. He might get the extractor out if you use a center punch and tap it clockwise to reverse the way he was trying to extract the bolt. You have to catch a edge on the extractor in a couple of places and tap to walk it out. Or weld a nut to the extractor and get it out that way.

If you get the extractor out, then I would suggest to continue to use a drill going up the next size bit until you drill out the bolt. You can then weld up the hole and fill it in. Then re-drill and tap. Or use a heilcoil insert.

Cruisinfanatic

I did the exact same thing about 20 years ago. After a lot of calling around I decided to put it back together the best I could with 1 bolt and filled up as high as possible. Drove to the local Chevrolet. Next day I was ecstatic that they got it out at a cost of $150. I don't care how they did it

tri08sbc

Understood... Thanks

hcbph

I don't know if this is the same thing or not. There's a video on Youtube for Jay Leno's Garage on a company that uses some specialized equipment to 'vaporize' broken bolts and easyouts from holes without damaging the threads. IIRC it started with aerospace stuff and has gotten down to classic and unique car parts. I expect they'd be pricey but then again what does a replacement cost, assuming one is available?