Does anyone know what diameter U-bolts were used on the exhaust clamps at the header pipe/secondary pipe junction and at the muffler/tip junction on a factory LT-1 exhaust system? The JM says what TYPE of clamp that's used (open/closed design) but I can't find the actual U-bolt diameter anywhere. I don't trust the repro's YET....Thanks In Advance!!
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Re: 1970-1972 LT-1 Exhaust Clamp Sizes
Jeremy,
Like the LS-5 exhaust the LT-1's used a 2 1/2 inch exhaust. The difference is in the header pipes where LT-1's were 2 inch at the exhaust manifold and enlarged to 2 1/2 inch as the left the manifold. LS-5's were 2 1/2 inch all the way. A standard 2 1/2 inch clamp slould do the job. -
Re: 1970-1971 LT-1 Exhaust Clamp Sizes
But do you know what the actual diameter of the U-bolts are? I've seen 2 1/2" clamps with U-bolts ranging from 3/8" diameter to who knows-what. I've got three 2 1/2" clamps, and all three have different diameter/length U-bolts. Even the saddles are different....one is thinner than the other two. The one closed-style 2 1/2" clamp I have that I believe to be off of an old (my Dad's) Corvette has a U-bolt that is flat through the radius, and roughly 1/2" diameter at the threaded ends. The other two that probably came from Napa in the '70's are like 3/8" or so. THE NCRS IS CORRUPTING MY BRAIN!!!!!!!!!!!!!!!!Can't I just put on headers & Cherry Bombs with Autozone clamps and still get Top Flight? LOL!!!Comment
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Re: 1970-1971 LT-1 Exhaust Clamp Sizes
Jeremy,
Sorry, I misunderstood your question. I have a couple of cars that have what I believe are original clamps but they are buried in the garage so I can't look very easily. My recollection is the size of the U-Bolts are on the smaller side but I'm only visualizing. The more modern clamps that I see are a larger diameter. The clamps used at the exhaust tips have a flat portion at the radius but I'm not certain on the center clamps. Make sure the center clamp has enough length to go over the center hanger and clamp the pipes too. Maybe someone else can jump in here and provide some better details.Comment
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Re: 1970-1971 LT-1 Exhaust Clamp Sizes
Like Dave I am not in a position to measure the diameter of the clamps on my car, nit I would guess they are 5/16 X 18 threads.
Most of the clamps used at the transmission are round for their full length, like the drawing in the TIM&JG, but I have seen a few apparently original cars with the flattened top clamps at that position.
I believe the clamps holding the tips on are 2-inch, but otherwise Dave has described them well. There is a commonly available reproduction for this clamp that is probably as close as you will get, short of finding an original. All of the clamps on the exhaust system are worth only a few points, do the best you can and move on to more productive areas.TerryComment
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Re: 1970-1971 LT-1 Exhaust Clamp Sizes
Thank you for (and all future) the responses. I have a mess of old GM exhaust clamps, and I just want to know which ones to use and which ones not to. I have several that fit the JM description, but I don't want to put retardedly wrong clamps on an NOS LT-1 exhaust.After going through all I'm going through and the $$ spent, IT'S GONNA HAVE THE RIGHT CLAMPS!!!!LOL!!!Comment
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Re: 1970-1972 LT-1 Exhaust Clamp Sizes
Jeremy-----
The original u-bolts were 5/16" and used 5/16-18 thread size on the ends.In Appreciation of John HinckleyComment
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