IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: Scoobum on September 16 2018, 01:44:31 PM
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While the engine was out this year I swapped in a new exhaust housing...cuz the other one was pitted to hell from the race gas on the flange affecting puck sealing. I smeared orange silicone on the puck this week and mocked it up to port the wastegate hole. What I found is the puck was sealing no more than a 16th of an inch around the 4 to 5 o'clock mark. I'll assume Precision drilled the hole a little off from my old exhaust housing. I took the DP to a local machine shop this week and had them drill the DP flange holes slightly larger. I was able to move the DP towards the right bottom corner more. Checked it again for seal...and I had a full 1/8th inch sealing at the 4 to 5 o'clock mark. If you ever swap exhaust housings with the same manufacturer check it. Don't assume the hole is drilled in the exact location as the previous one.
A quick thanks to Dan Keller for supplying the new housing to me free of charge.
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I have not seen many that were out quite that far but they are usually not centered. I think they just ream out the existing hole and stay on center...would not take much to be off for sure.
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My GT3255 with a stock hole was waaaaaaaay off from my THDP (a real one).
I was so bad I pulled the housing and put it on a mill. If I'd just enlarged it, it would have ruined the housing.
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I have yet to see one that is centered even somewhat closely.
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RJC has a plate for that :cool;