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Topic: More exh manifold questions

in Forum: C3 Fuel, Emission Control, and Exhaust Systems

More exh manifold questions

Posted: 5/7/12 11:05pm Message 1 of 9
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Vette(s): 1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
A few "mounting and locking" questions related to the original (center-dump/rams horn) manifolds.  1) Did the two center bolts have any form of locking mechanism?  I know the two pairs of bolts at either end share a "French lock" or whatever it's called, but was wondering if I should use a split ring lock washer under the two bolts in the middle.  That leads in to my other question: 2) I don't seem to have enough of the thick washers that bear against the hole in the manifold.  Should every bolt (12) have one of those?  I probably lost a few somewhere, but just making sure.  Any reason I could not use a split ring lock instead of those thick ones or should I order a set from one of the vendors?  



 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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Re: More exh manifold questions

Posted: 5/8/12 6:05am Message 2 of 9
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
No locks on the center manifold bolts.
The thick washers were only used on the bolts that seat directly on the manifolds. If there is a bracket that the bolt goes thru, then no (thick)washer was used. I wouldn't use lock washers(split)...if absolutely needed, I'd use a regular flat washer....maybe two, if I had to.  Thumbs Up



Joel Adams
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Re: More exh manifold questions

Posted: 5/8/12 7:55am Message 3 of 9
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Vette(s): 1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
Thanks, Joel.  That makes sense about the bolts that go through brackets.  Assuming you mean a bracket like the AC compressor support?  What about the smaller brackets that just hold the ignition shielding on?  Should those get a thick round washer?  

Split rings are not recommended because they'll rattle loose or is there another reason?  




 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Re: More exh manifold questions

Posted: 5/8/12 11:53pm Message 4 of 9
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Vancouver, WA - USA
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Vette(s): 1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
It looks like Corvette Central sells a kit that only has 8 washers in it - that's about how many I have.  Wish I could remember which bolts had washers when I took things apart.  I have my AC bracket, but there will still be two bolts without washers if I only have 8.  



 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Re: More exh manifold questions

Posted: 5/9/12 4:33am Message 5 of 9
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Don't think any of the shielding bolts up to the manifolds, does it?
The A/C brackets, and I think either the P/S, or Alternator brackets on the other side will not have the washers...basically the four bolts on the front.

I don't like using lock washers on the exhaust because they tend to dig in, and make it harder to remove the bolts....which is usually a hard enough job as it is. It's rare that a bolt with a flat washer will back out, anyway, plus, you have the French locks. But that's just me... Big smile



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Re: More exh manifold questions

Posted: 5/9/12 11:12pm Message 6 of 9
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Vette(s): 1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
Joel, here is one of the shields I'm talking about:



I AM putting the washers underneath those crazy little brackets for those shields (there is also a similar shield on the other side, rear.  My car didn't come with shields for either side in the front.)  I am NOT putting washers under the bolts for the A/C bracket you see on the right side of the pic.  I think I've got it figured out now, thanks for bearing with me on this rather inane line of questioning.  Also, FYI - no P/S or alt brackets attach to the manifolds on my car.  They connect directly to the block or head on the drivers side.  




 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Re: More exh manifold questions

Posted: 5/10/12 6:58am Message 7 of 9
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Hmmm....never seen shields like that, that bolts up to the manifolds....learn sumptin new every day around here!Thumbs Up

and, fyi..the French locks should go over the top of the manifold, normally...like "n" instead of "u"...don't really matter tho...just throwing that out there to bug ya....LOL
It's lookin gud, and you'll be back drivin that thing afore ya know it!Clap



Joel Adams
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Re: More exh manifold questions

Posted: 5/10/12 7:20am Message 8 of 9
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Vette(s): 1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
Good tip about the french locks.  Everything is still loose, just in the fit-up stage, so it'll be pretty easy for me to change that.  Interesting that the shielding on the earlier cars bolts up differently -- I thought those were unchanged until '78 or so.  

Thanks for the help and encouragement!




 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Re: More exh manifold questions

Posted: 5/10/12 9:59am Message 9 of 9
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Duncanville, TX - USA
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Dadgummit!  I'm loosing my eyeballs or sumptin here.....
I can barely see now that what you have is two metal brackets that bolt to the manifold, and then the chrome shielding is attached to those brackets with the wingbolts. Originally, it looked like it was a one-piece deal... once AGAIN....I'm rong....but I'm getting used to it. Sorry, but what you have is typical...I just wasn't looking at it very well. Might be time for me some new eyeballs....Cool



Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

in Forum: C3 Fuel, Emission Control, and Exhaust Systems


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