The Stovebolt Site Forums The Shop Area Engine Shop bad offy intake???

does anyone have a clear shot of the heat plate area under an offy 2x1 for a chevy 235/261, model #1035. just got mine today and there is some pretty rough cating in this area and holes on either side of the two sections of the heating area and they appear to connect to the inner rail of the intake.

pics i have seen don't look like what i have.

that is my best description. here are some pics

http://pic80.picturetrail.com/VOL1958/10783339/19208600/351321285.jpg

http://pic80.picturetrail.com/VOL1958/10783339/19208600/351321281.jpg

http://pic80.picturetrail.com/VOL1958/10783339/19208600/351321280.jpg
http://pic80.picturetrail.com/VOL1958/10783339/19208600/351321296.jpg

Just wondering, is this a new intake?
Joe

hey 6,

yes this is "brand new in the box". auction bought from an online parts supplier.

i would like to find a heat plate for mine 292 4 brl but those people will not talk to you ,guess i will have to make one .

I don't recall the underside of mine but the casting was a little rough in that it had extra flashing around the bolt holes where the intake meets the exhaust.

check exeter auto. talked w/ them the other day and they were very helpful.

http://www.exeterautosupply.com/

Ed,
here is a picture of my 2 x 1 offenhauser intake. I purchased it from jim carter.

2 x 1 offenhauser intake

Well; the next problem you are going to have is those round holes where the aluminum was cast will leak. They're the ones with the steel plugs spotted into them. You can see them in Tim's picture. Mine leaked like a sieve when I put water through it. I had mine welded shut. I assume that they'd leak exhaust too, just not make such a mess.

For the heat plate, have you considered Tom Langdon and his Stovebolt Engine company? You can find him in the links section.
His heat plate sells for about $35, give or take. I plan to use one on my Offy 4bbl intake on a 250 L6.

Best wishes,

Les

Jerry,
you are looking at aluminum slugs i made.I had my welder weld them up solid.I set the intake up for water heat,if i decide to ever go that route.The picture is before i had them welded in place.

Ed, my intake did have some jagged edges from casting.I used a small file to clean them up.

I bought my Offy dual from Tom Langdon. I looked at your pics and don't see any problem with the "innards" but you need to make sure that the sealing flange is smooth and good. I bought one of these and have documented the installation as well as the mating of the Fenton headers on the engine rebuild album on the website below. Hope the pics help you!

thanks all. did not expect something as rough in a brand new state. once you get things home i guess they always look a little different.

That really surprises me.
I bought an Offy about five years ago and it is very nice. I have been told that they will leak water if using water heat, but I think Offy's were intended to be used with exhaust heat. That's why the bottom of the intake is made to match up with a stock exhaust manifold or Fenton headers with a heat box cast into them.
Well, I hope you can make it work for you, Ed. Good luck!
Joe

hey tim,

do you have a direct link to a picture of the aluminum slugs you had welded in the offy? i was looking at your pics and the only one i saw was the steel plugs on the offy bottom, just like i have now. thanks

big ed

Ed,
I will link some pictures later today.

Just a suggestion.....although many trucks are running water heat, I've found that using exhaust heat (if your running Fenton Headers) is a viable option. Using Langdon's heat plate and some compression fittings makes plumbing in the exhaust heat a much simpler install and you don't have to make any modifications to the heat circuit of the Offy intake. Secondly, you eliminate the potential for water leaks which could leave you stranded beside the road.

I've got nearly 8000 miles on my 235 engine and haven't had any issues with the exhaust heat. The pressure differential created by the firing order of the 235 DOES provide rapid heat transfer. I have pictures of the install in my Webshots albums. Check it out as you may agree that it is a proven viable option.

Dave

I don't think you can call it a "bad" intake as the hand work that's always required with castings has merely been overlooked. A cylindrical carbide burr in a die grinder will fix it in no time. I agree that what you purchased was designed for exhaust heat but can be made to use with coolant if properly modified. To me the whole point is the quick heat exhaust provides.

I have a question about the exhaust heat setup. I understand that there is pressure differential from one header to the other but it seems that it would pulse the gas back and forth unless there is a check valve to create one-way flow. I've never worked on something like this but I plan to set up my 250 this way and I'd like to understand it better.

In my opinion, the lesson regarding exhaust to be learned is in the answer to this comment.
Originally, Fenton headers were offered with what some call a "heat box" on the rear header. This "box" had the same configuration on the top of it as the stock exhaust manifold and bolted to the bottom of the intake. This "heat box" was nothing more than an open passage way from the rear header into the box where the intake attaches, keeping continious heat to the intake. Later, because of the configuration of the 216 versus the 235 intake, Fenton went to the more common header set without the heat box and developed the plugs in the headers with the two tubes that attach to each header and run to a plate on the bottom of the intake, suppling heat to the intake. In so doing, the exhaust is "shared" between the two headers, or between the two sides. Here is where the equalization of the exhaust from each side works to together. It's not so much the lack of a one way flow as much as just the equalization of the exhaust from side to side to creat constant a heat source.
It seems to work for a heat supply, but I agree, it doesn't seem like an equal flow would take place. I would suggest a plumbing pipe nipple pointing down on one exhaust pipe and above it another plumbing pipe nipple pointing up. Take the exhaust from the one pointing down, to a plate on the bottom of the intake and send it back out the other pipe to the nipple pointing up to create a circular motion of the exhaust to the heat plate. This would do more to move the heat and it would avoid the equalization process or the build up of any pressure between each side of the exhaust. I used this method on my truck for awhile and it seemed to work well. I now have a heat box rear header and, frankly, I'm not sure I could claim it works as well as the circulating set up. It heats fine, but it seems to take longer.
Finally, mixing the sides, or the front headers and the back header, by use of the tubes from each header does another thing.....something I do not like. I destroys the "rap-rap" sound of the Chevrolet six, the sound I originally fell in love with many years ago. Obviously, this means that method is not even a consideration.....at least for me.
Joe

Ed,
here is the link to the pictures you requested.
I welded mine up,just in case i want to run water heat to them.
The exhaust heat seems to work just fine on my engine.
aluminum slugs

I did machine the fenton headers to mate with the offenhauser intake.
49geezer has some really nice pictures of how he did his.

A bit of correction, it's not so much as the difference between 216 and 325, but more the difference between the Chevy engine and the GMC. All current production Fentons are mad without the heat riser on the rear header so that the same casting can be used on either engine. Otherwise, there would have to be 2 different castings for the rear header to make up for the length difference.
On a side note, I recently put exhaust heat on my Offy/Fenton combo (fabbed it myself) and notice no difference in how it sounds. But then again, mine doesn't have the "rap-rap-rap" sound, it sounds more like a cammed up Smallblock.

BigEd

I have some pictures of what it takes to replace those steel plugs with some aluminum slugs at
http://community.webshots.com/user/OldFartEd

Hope this may help.

Old Fart Ed (another Ed)