My long tube headers are in the way of several things, so I thought I’d replace them with the shorty headers. Figured I would lose performance, but didn’t care. I like the look. So I’m installing the passenger side and the fit is TIGHT. About 3 sheets of paper between one tube and the crossmember, and the edge of the collector touches the oil filter housing. Nothing pressing or causing figment issues - but touching. Here’s a picture taken from below looking up into the collector. Is this a problem? Am I overthinking it? If I didn’t have a date with a paint shop Monday morning, I’d order replacement factory manifolds. The contact area seems to be about 1/16”. Thoughts?

 

Loosen the header and get a small piece of high temp gasket material in there. Get it to the paint shop Monday and think on it.
You could use a Dremel on the oil filter housing and header to gain clearance. You can loosen the header, move the collector up and retighten the bolts.
Others will chime in.
Good luck.

 

First, are you sure those are for a small block(maybe they sent the wrong ones)
If the are the correct ones, mark the header with a black marker where you have contact issues. Remove header, heat area with torch, tap with ballpeen hammer to create dimple for clearence where needed.
You dont need to cave the tube in, just enough so you have about 1/8-3/16's inch

 

OK - both good ideas. I have to say that after getting that side installed, it's not that much harder to take off than a regular manifold. After three times off and on, I was getting lazy lol. For sure these are the small block - I've had them for two years, before they made the BBO models. The driver's side was awful to get installed - I finally got it in place and I'm taking a break. Headers used to be a 2 hour project in the driveway - what happened??? So far, I'm not a big fan of these, but they look better than the rusty ones that were on there before. Thanks, guys

 

I don't remember headers ever being a 2 hour project.

 

word!

 

I didn't have any issues when I installed my Thorton headers. I went out and looked at my installation and sure enough the headers came pre-clearenced. Hard to tell from my photo below but that area you are having issues with has been flattened out on my pair. BTW I was able to install these headers on the engine stand and drop the motor into the car with them attached.

Thorton Oil Pump Housing Clearance

 

Absolutely. We did them in the driveway after walking home from school in waist deep snow, up hill. Maybe times has blurred my clock memory.... But dang, I was 8 hours on the car last evening, and I'm going out again this morning to see if I can get it wrapped up in the next 2-3... Maybe doing it myself instead of having 4 car buddies around is slowing me up. Or maybe that I'm old and fat? Nahhhh......

 

I have one of the very first sets - even though it has taken me two years to get them on... I'm sure early installations got Thornton plenty of feedback to make some changes. I'm still not sure how in the world I made the driver's side slide into place - I was certain I would have to raise the engine, but didn't. Still, for shorties, these are way tighter fitting close to the block than the long tubes. I'm a bit disappointed. After I get the driver's side finished, I'll take the passenger side back off and do the clearancing myself.