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Exhaust Manifold Replacement Question - Zip Corvette
hi all,
I’m replacing the exhaust system on my 73 and so far the process has been easier than I expected (no rusty broken bolts!!).
I purchased my parts from Zip and they’ve slowly been coming in as they ship.
Last week I received the the first shipment which included one of the manifolds (the second has shipped today) and I’m a bit concerned with the quality control of it since I paid $250 for a US made GM Licensed reproduction vs. cheaper Chinese reproductions that would cost about a third of the price. Speedway Motors has a pair + studs and bolts and gaskets for a little over half of what I paid for one manifold alone and the seams have been smoothed and prep'ed.
What is the community’s opinion? The inside, as far as I can see seems ok, but those dirty seams on the exterior and the brown rust(?) spots are just straight bugging me, although I know that is normal for any cast iron. It just doesn't seem like something that a GM licensee would sell.
Last edited by stefansangreal; Aug 20, 2018 at 08:02 PM.
I got mine several years ago from rock auto about $80. Looks the same as yours. Came with studs gaskets. They’ve worked fine so far. Made by atp. Good luck.
cast parts will always have some variation, I personally would go ceramic coated over bare cast for appearance. but both have their pros and cons. biggest concern with quality of parts is to inspect all the mounting holes and surfaces, ensure none are oblong or flat surface is warped. also inspect for any casting burrs on the inside, ive had a few new ones that had to be touched up with a dremal on the inside edges, not that it matters much but I have noticed some headers are not edge ground inside and some are.
the second picture does have a oblong bolt hole care should be taken in torque, that one will have to be re torqued an extra time.
Last edited by sambrand; Aug 21, 2018 at 08:08 AM.
AS you have stated...raw cast iron will rust and can flash rust really quickly. I myself would not worry bout it due to IF you do not apply a coating on these manifolds they will rust all over adn these areas will no longer matter.
IF you are planning on having a coating put on them NOW is the time BEFORE you install them.
When I do new manifolds or originals that a e not worried about critical judging. I take my die grinder and sander and grind and sand all of the casting edged smooth so when the manifold is coated...it is really nice looking and these raised casting edges can not hold dirt or crud.
And I use all correct bolts, thick washers, French locks, studs and gaskets to get them installed also.
Went ahead and coated the manifolds as suggested. Brushed them off with a wire brush bit on a drill and a brush bit on a handheld rotary with brush bits for the smaller crevices.
Then applied vht primer and vht cast iron paint for coating. My first attempt didn’t hold up to my expectations (due to being a rushed job), so I went ahead and started from scratch again and fortunately the second procedure was much better.
The manifolds have been cured and installed, torqued to 25 lbs.
In the process I decided to install new spark plugs and wires (because hey, why not? I figured I’d do it while I’m down there.)
I’m now at the stage of installing the new exhaust system. It’s a Mike Allen chambered exhaust.
Anyway, both manifolds from Zip turned out great. I'll post pics of the manifolds once I get everything installed.
Last edited by stefansangreal; Sep 16, 2018 at 03:09 AM.
Exhaust Manifold Replacement Question - Zip Corvette
