I have started cleaning up a set of 205 Darts. I must say that the "as cast" title is a little miss-leading. These things overall look really good. There is not a lot that needs (or can) be done to improve their flow.
My question concerns a casting technique that may be common on aftermarket heads, but looks odd to me. While polishing the intake runners, I noticed what looked like a hole in the side of the intake port. It turned out to be the hole for the rocker arm bolts (drilled from the top of the head).
I realize that the " rocker arm bolt bulge" is a flow restriction on the stock LS1 port, but will there be any issues with it being removed and the hole exposed?

 

There are at least two things to be concerned about:

1) The hole will disrupt the flow along that port wall.

2) The hole must be sealed so it doesn't create a vacuum leak.


I would call DART and tell them of your concerns. They may offer to send you another head without the hole.

.

 

I have Darts as well, all rocker holes are exposed as they are in stock ported heads. Due to rocker locations and port requirements, I think it is just a fact of life unfortunately. You can seal your rocker bolt with some Permatex pipe sealant (Teflon type) or silicone. I am going to try screwing in the bolt to see how far down it protrudes, I think it is going to be right inside the hole though. One option I thought about but haven't checked yet is putting in the bolt, packing the lower hole with JB Weld, then once hard shaping it to the port. Problem is if it ever falls out it is going right into the cylinder.

So, at the end of the day, I am going to just seal the threads.

 

wht about a tricky weld job? or using epoxy or something?

 

I would use epoxy before JB weld, the opoxy will at least burn up in the combustion chamber when exposed to high heat if it comes loose, not sure about the JB weld.

 

That's what I was thinking as well. I thought about epoxing the hole, but I've heard too many stories of the epoxy breaking loose and coming out.
I'm not too concerned about the leak as long as I seal the bolts, I was a little concerned (like PB stated) that the hole might cause slight turbulance and disrupt flow.

 

Just bolt them on with some sealer.

I seriously doubt you'll see any power lost from that hole.

Ed

 

Don't worry about it. It happens in alot of aftermarket heads. Some heads (sbc,sbf,bbc) have rocker stud holes exposed before there is porting started. There is no need to worry about vacuum leaks there will be a bolt in the hole, and the open end of the hole does not really restrict airflow to any degree. Just make sure to thoroughly seal the threads on your rocker bolt or it WILL cause an oil consumption problem, silicone works good(not ultra blue/black), I've also seen guys use teflon from a can.

 

I am using an aftermarket stud mounted rocker, the vendor calls for red loctite to make sure it stays in place. Anybody got a feel if that will seal the hole?