What is needed for connecting the exhaust pipe to the exhaust manifold on a 59 235? Pipe was loose on the two mounting bolts and when I removed it there was the remains of a metallic donut. I'm assuming I'll need that, but do I also use a two hole gasket for the flange as well? Napa site shows both the donut and a gasket, and I think my 1963 Master Parts books does as well if I'm reading it correctly. Thanks.
1959 Chevrolet 3800 Pickup 1937 Chevrolet GC Panel Can you still call it a barn find if it's your barn?
More than likely the surface material on your metal donut is gone. That's why it is loose. Buy a new donut. A two hole gasket is used on joints that come together flat (parallel) which can be hard to make fit without leaking.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
Kerwin that 3 hole gasket goes above a heat riser like a v-8 would be,your 59 is 2 bolt with a pucker in the end of the pipe to accept the donut then 2 hole flange brass nuts to finish it. Sorry I muddied the water on 3 hole gasket ignore that.
Looks like the local NAPA will have the donut for the flange. Someone had used bolts to hold the flange on to the manifold instead of the usual studs, originality aside, is there any clamping difference between bolt/washer vs. stud and brass nut? As far as new studs and brass nuts, should they be pretty universal for GM from that period such that NAPA would have them as well?
1959 Chevrolet 3800 Pickup 1937 Chevrolet GC Panel Can you still call it a barn find if it's your barn?
Original steel nuts rust to the studs and the studs snap when trying to remove the nuts. A brass nut doesn't rust so it's easier to remove but it can be stripped if over torqued. It's a personal preference. You can also use a brass jam nut if your are worried about holding power. Your FLAPS will have repair kits with brass and/or steel studs and nuts.
You can drill out the old studs in the manifold and re-tap the hole and screw-in a threaded stud. If the manifold is cracked/butchered you can use an epoxy like JB Weld to repair and secure a stud. The hard part is doing the work from underneath the truck. I suppose the best way is to remove the manifold and repair on a work bench. Unfortunately you remove the bolts with spreaders that hold the intake as well. Refitting is a balancing juggle to get alignment rings in place, intake and exhaust manifolds in place with new gaskets.
Last edited by buoymaker; 06/12/20211:17 AM.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
When reassembling manifolds to engine, do not tighten the inter manifold bolts all the way until all the manifold bolts with brass nuts on them too have been tightened.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
