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Studebakerboy
06-07-2007, 09:17 PM
I've had a lot of trouble keeping exhaust gaskets on my SBC motor home. I'm currently doing manifold work on my brothers 73 and my sons 72 Avanti ll.

I'm using French locks for the front and rear cylinders, but can't find any available for the center cylinders. I've used blue locktight and lockwashers on the centers, but the bolts keep backing out.

I've gone to my Standard Aircraft Hardware book and found that an AN course bolt is available with drilled head. My thought is maybe safety wiring the center bolts together, and keep the gaskets from blowing.

Any secrets to keeping them from blowing out? Are french locks available for the center cylinders. I've searched and can't find them. The one I have came from Ecklers Corvette. I want to keep the Avantis' from having the same problem.

Regards,

Kevin

Kevin Edwards

http://airlandandseaparts.com

N8N
06-07-2007, 09:33 PM
I wasn't aware that Chevy *used* gaskets on cast iron manifolds. I've always just put a little smear of hi temp silicone on there and called it good.

You could try Summit, Jeg's et. al. or even your local Chevy dealer for locking plates for the bolts. They did have them on there from the factory.

nate

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55 Commander Starlight
http://members.cox.net/njnagel

Neal in NM
06-07-2007, 10:21 PM
Have you checked to see if the mainfold gasket surface is flat? If it is not then have a competent machinist grind it flat. Neal

Studebakerboy
06-07-2007, 10:58 PM
Yes sir, they're good and flat. I think it's more a problem with the bolts backing out. May try a high temp RTV and glue them in.

Chevy didn't use gaskets at the factory, but replacement gaskets are available.

Does anyone know about french locks for the centers?

Kevin Edwards

http://airlandandseaparts.com

Dick Steinkamp
06-07-2007, 11:05 PM
I don't have any experience with these Stage 8 ones, but they sound like the hot setup...

http://www.stage8.com/auto.htm

http://www.jackit.com/headers/stage8_bolts.htm

http://home.att.net/~benmlee/stage8/stage8.htm

I've owned a lot of SBC's...some with stock cast iron exhaust manifolds, and some with headers. I've never had a bolt loosen up. I don't do anything special. The 327 in my '54 has generic block huggers. FLAPS 3/8" head bolts. Star lock washers. Generic FelPro gaskets (the kind that come in any overhaul or head kit) Going strong after 30,000 miles.

http://thenobot.org/images/s2d/s2d_01.jpg

Studebakerboy
06-07-2007, 11:27 PM
Dick:

Your the Man! Those are cool! I'll look into ordering some in the morning.

Part of my problem may be that I replaced these bolts with new grade 5 or 8 (not sure) from the local hardware store. The 20 pound feet in my Chevy factory RV manual is called out for the torque. Seems a little loose, but what the heck.

One of my new neighbors went to take off in his RV 7 and had no airspeed. I had him taxi over the hanger and I cleaned out his pitot system. Bugs had gotten in it over the weekend. Got my first ride in that little hot rod. Took only 20 minutes to circle the lake in that thing!

Anyways, back to the Cheby, the airplane mechanic in me wants to switch out the bolts to something I can safety wire. Blew out another gasket climbing the plateau into Crossville last night.

I've never personally seen french locks on the center cylinders and can't find them offered for sale on the internet. That may be no surprise, because I usually don't own anything until it's run out and all that stuff long gone. My Packard in the 56J has them on all.

Kevin Edwards

http://airlandandseaparts.com

Tom B
06-08-2007, 07:58 PM
Are the manifold bolts really cap screws?

Take them out, drill 1/16 holes through the heads, put them in, torque to specs and thread mechanic's wire through them all. keep it tight between the cap screws, they shouldn't back out.

[img=left]http://www.alink.com/personal/tbredehoft/Bothcars.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe
'60 Lark VI
'05 Legacy Ltd Wagon
All three Indiana built OD cars

N8N
06-08-2007, 09:13 PM
http://www.firstgen.com/catalog/Ricks-234-257.pdf

scroll down to page 250

HTH

nate

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55 Commander Starlight
http://members.cox.net/njnagel

Studebakerboy
06-08-2007, 09:48 PM
Nate:

Way to go! Great catalog. I think we may be getting close, but I think (not being a big block owner in 25 years) that those are still just the fore and aft cylinders. Maybe not, does anyone know if the locks depicted in the center of the ad shown on p 250 are big block fore and aft cylinders or the center pair? I think since 4 are shown, they are big block fore and aft.

Just looked at used RVs on Ebay and several big block rigs had blown exhaust gaskets mentioned in the ad.

Kevin Edwards

http://airlandandseaparts.com

N8N
06-08-2007, 10:56 PM
I think the pic is for a SBC. probably have to call and ask.

nate

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55 Commander Starlight
http://members.cox.net/njnagel