At the risk of posting this, and letting the whole world know how clueless I am, I am certain I am not the first person with this question.

OK mechanic types, I need some help.

I have a 409 SBC I'm installing in a 1967 Donzi Ski-Sporter (16).

I had initially purchased some E-Top CMI headers for this engine, but they proved to be about 3.5" too tall to fit under the hatch. I was able to sell them, and bought some new style CMI shorter (not equal length runner) E-Top headers. I got spacers to give some additional clearance for the new (not yet installed) Edlebrock aluminum valve covers.

As an aside, I would like to give some KUDOS to Eric @ Teague Custom Marine. I ordered the CMI exhaust through them, and he really went to bat for me in getting me what I actually ordered. CMI initially sent the correct headers, but with brackets I didn't order welded to the top.

Now my question. If you look at the picture showing the 12-point bolt, and the very minimal clearance between the bolt head and the water jacket tube, how are you supposed to tighten these bolts? A 3/8" 12 point box wrench fits it perfectly, but you can't get the wrench on the bolt head. And the other end of the open end wrench won't fit on a 12-point bolt head.

I'm sure you could use Vise-Grips, but that seems like a really wrong way to go.

What tool do you use to tighten these. These are the bolt supplied by CMI for the installation.

I would change the problematic bolts to hex (6-point).

Damn nice lookin Bill, I expect to see some pics of the completed install!!
My 18 has been crying for a set!

Steve, they would look mighty fine on your spectacular 18.

I went with unpolished, as nothing else in the engine compartment is polished. I think they look just great.

Can't wait to hear how they sound!

Regarding my "issue." I'm going to try a couple of things. I bought a long 3/8" 12-point box wrench that I am going to grind down to about 1/2 it's original thickness and see if I can get it to slip past the tight spot.

In case that doesn't work, Eric from Teague is sending me some stainless socket bolts.

The problem with hex bolts is that they need to be small head. The size of a normal hex head is that it actually prevents the bolt from being able to go into the hole. So they use small head 12-point bolts, or perhaps socket head bolts driven in by a ball ended allen socket.

I would check with ARP, I think they would make a 3/8's bolt to fit that, like a regular "header" bolt.

studs?

This is what I mean by hex; six rather than twelve point, you can get these in stainless too.

its a 408 bill a 408 lol...

Use these and an "open end" wrench.....just be careful and don't round the shoulders.

BTW...keep the valve covers...gives it that "Bad Ass Sleeper" look.

SFOcean, I did a quick look for some hex head ARP s/s 3/8 bolts. I'm using spacers, so the bolts need to be 1.5" long, which I didn't come across. Most maxed out at 1". The ones I have are ARP 12-point s/s header bolts.

I bought a couple of 3/8" 12-point box wrenches to destroy. I ground the end of one of them down to about 1/2 the original thickness, and it still wouldn't fit over the bolt head, so I rounded off the top of the bolt head into a dome shape. The (2) center bolts are still a problem. I had to grind the shoulder off the bolt head, to get the bolt to even make it past the water jacket header tube. And yes, the holes are slots, probably for that reason; so the bolt can be angled in.

I might fiddle around with it a little more, but I have some s/s allen cap bolts coming, and I believe a ball allen socket will get them tightened without issue.

Those are actually the original valve covers from when this engine lived in a 1972 Caprice.

Keith used them when he broke the engine in on the dyno. He told me he thought they would leak, but they didn't.

I have some Edlebrock finned aluminum covers to put on. However, it they don't fit, I know these work.