Is this common?

-
ERACER

ERACER

Well-Known Member
Joined
Aug 25, 2008
Messages
48
Reaction score
0
Location
Oxford, ME
Recently picked up a set of "302" casting heads that appeared to be in very good shape. They looked to be essentially untouched. The smog ports have been blocked and possibly a light port on the ends of the intake runners. Other than that, they appeared pretty well stock. Much to my surprise, when I disassembled them, I found a repair in the 4/5 cylinder (depending which side you put the head on), on each head. On the other side of the repair is the heat crossover. If you look into the crossover, you can see the back side of the repair, which was poorly done with JB weld or something like it. Is the casting typically thin here? Even if so, why would there be a hole on an unported head? I haven't read anything like this on here before. Anyone else seen this?

heads 001 (Custom).jpg
 
Never seen it before... I would think JB weld couldn't survive in the exh port... interesting.
 
OK, so since I made my original post, I did some investigating on other sets of heads I have kicking around. I guess I had never noticed that the exhaust port in question actually opened to the heat crossover. My bad. I suppose I've never had something to draw my attention to it either. As far as I've seen, don't most after market intakes and gaskets block out this crossover?
 
No. Most leave them open. you can block them with gaskets... The Air Gap blocks them. The way to seal them is to weld or braze that up.
 
The little tin thingy in the gasket set usually burns through after a while. I have successfully filled them with tightly packed furnace cement, I would imagine JB weld would work too. Its not like filling the floor of the port or somehting, were the repair is exposed to high velocity exhaust gases.
 
What's weird to me is it actually looks like they did bring it all the way into the port. Not just plugging the crossover. Maybe its the picture tho...lol.
 
No, you're seeing it right. The filler actually begins in the exhaust port and runs part way into the heat passage, like it was packed in from inside the port. The intake manifold side is still open a little more than half way in.
 
It's a poor attempt at filling the exhaust crossover as you've already determined. Typically, it's done by melting aluminum until it's liquid, then pouring it into the port. When it cools, you grind it away to match the other ports. The reason for doing it is to eliminate the turbulence created by the open hole in the back of those 2 ports. Even if you block them with a gasket or sheetmetal at the intake, you'll get turbulence in those 2 ports. It's a nice trick if your car doesn't get any winter use.

I've done this a couple of times using old pistons and/or scrap aluminum.
 
Yeah, I can see where that opening might create some turbulence, but now that I look, most heads seem to have it and be just fine. The only uncertainty I have now is if I should just leave it, try to somehow make it a bit smoother, or try to remove it altogether. As far as removing it, I'm not exactly sure what it is and how easily it would come out without causing damage to the head. Not to mention this isn't the most easily accessible area. Also, not knowing what the filler material is, what would I use to add more material in order to be able to smooth this out?
 
I've never had to fill them myself. I'd ignore it and press on...
 
OK, I won't worry too much about it. It's apparent that these heads have been on a running engine since the passages were filled and the material has held up. I just hadn't seen anything like it before. Thanks for all the responses:thumbrig:
 
Agreed, most heads are fine with it open, but if you are trying to get the max performance from iron heads without regard to cold start issues, it's best to fill it in.
 
You must log in or register to reply here.
-

Back
Top