The Stovebolt Site Forums The Shop Area Engine Shop Fenton headers and Offy intake

Does anyone know if you can use the tapped holes on the bottom of the Fenton’s to heat the Offy? I was going to put a plate on the bottom of the Offy and pipe one side to the front Fenton and the other side to the back one, hopping that some exhaust would flow between them; also I am considering powder coating the Offy black to absorb more heat. Have any of you guys done this or is there a better way? Don't want to use engine coolant to do the job!

Thanks Again
Erwin

That's the way you are supposed to do it, although engine coolant works a lot better.

Erwin, The key words in your post are " Hoping that some exhaust is going to flow between them "..

I had a conversation with Tom Langdon of Stovebolt Engine Co. about this subject. He said the original Fentons had a baffle to force the hot gases through the tapped holes and up into the intake plate.. The reproductions don't have the baffle. He told me I could hook up the pipes and " hope " ,,, but that is not going to heat the intake..

There is a reason the intake manifold manufacturers make heated water intakes..

Maybe I'm simple-minded but how can there be a FLOW of exhaust gases when the exhaust gases are fed from both both exhaust pipes (which are both pushing out heated gases)? There might be heat transfer but where is the gas going to flow to?

I understand that the heated water set-up has water going into one side of the bottom opening of the Offy intake and moves to the front of the intake, then the water travels to the other end of the intake, and then the water exits through the other side of the opening on the bottom of the intake. Look at the bottom of the Offy intake and you will see the divided chamber. Thus, there is flow in, around, and then out of the intake. The intake is designed for flow, but in order for flow to occur, the fluid (or heated gas) must go in one side and out the other. Am I wrong?

Heated exhaust gases will help but heated water-flow is much more effective.

By the way, I think you want some sort of heat to the intake at all times, not just for faster warm-up. The heat is needed at all times because the change in pressure of the the carburetted gases results in cooling of the gases, which cools the intake, and might cause condensation of the vaporized gasoline. It could result in cooling to the point that you can feel a cold intake (if it is not heated with exhaust gases or warm "coolant" water). Once again, is my understanding incorrect?

Thanks,

Tim

I have exhaust heat tubular headers which are similar to the fentons. One port is located in a straight part of the manifold and the other is located on a bend. I think the idea is that there is a siphon effect on the straight port and a pressure effect on the port located on the bend. I can't comment on how effective it is, however, as it seems the most heating effect comes from heat conduction from the head.

Borla (some) have an finned aluminum block that bolts to the bottom of the intake.It heats up quickly and works o.k.
I have thought of a heat riser tube that comes
from the outside of the exhaust header pipe(no flow).The other end will attach to the finned aluminum block increasing the heat transfer to the intake.

There will be a little bit of flow due to the fact that the cylinders fire in alternate banks and you will never have the flow of the two banks exactly matched, so some gas will flow between the two. Also, if you use copper tubing you will get some heat flow from conduction. Water heat is much more uniform though. It has the advantage of being at a constant temperature no matter what the load on the engine or the timing setpoint.

Got the headders and the intake on this weekend. Man what allot of grinding and fitting! Looks real good but there is NO space to put on any plate between the headders and the intake. These things fit together real close about 3/16 of an inch between them. I guess the intake will be heated by conduction like it or not!!

Do you have a picture you can post a link to?

I will send you one via e-mail tonight. Need to take a few for Pop's anyway to let him see the progress.

Erwin --

Sounds about right most of those plates as far as I've heard are about a quarter inch thick and often have to be trimmed and ground on for the headers to fit. :p

Those pics show a lot of detail and they are REALLY close to the bottom of the Offy manifold.I would still use an aluminum cover plate on the bottom of the intake.Have someone heli-arc some "fins" on the plate for heat absorption.
You could use some cereal box cardboard to use as templates for the fins.

Erwin, do you want me to put the pics on picturetrail and post a link to them? that engoine you are building is looking really good

Go ahead and post them if you like. I am new to this site and am a little overwhelmed with all the great info there is to be had here. Have not got to the gallery yet, but I can't wait.

This is a link to Erwins 235 Chevy Engine

235 Slide show

http://www.picturetrail.com/gallery/view?p=12&uid=683118&gid=1175851

Erwin--

That engine is purty .... looks very nice -- you did a heck of a job. In your initial post on this thread u indicated that you wanted exhaust heat, I think its a good idea. I would point out that Pat Smith who wrote the Multiple Rochesters article for inliners in their tech section claims to have had good results with exhaust heat, In that same article, Smith shows an exhaust plate he made using the intake gasket as a template. Whatever you decide---nice work pretty engine.

Erwin,

Nice job with that engine.

Have you checked the alignment of the holes in the headers with respect to the exhaust ports in the head? As I recall, a few of the mounting "ears" on my similar intake/exhaust setup on a 261 were better aligned if I ground some metal off the bottom of a few ears (in particular, ears on the rear header). This lowered the header and not only made space for a heating plate but also decreased the amount of stock that needed to ground off the bottom of the intake (in order for the intake and exhaust to be installed without touching each other, usually resulting in an intake and/or exhaust leak).

Earlier this summer, I removed the Offy intake and Fenton headers to cure a newly painted manifold and the carbon markings on the manifold gaskets indicated good alignment with my trimmed-ears headers.

Has anyone else had to lower the mounting ears on the Fenton headers?

Tim

Erwin, your engine looks great. What kind of a vehicle are you going to lower it into ??

Thanks Guy’s, I really appreciate all the kind words. I did have to do a little grinding on the ears to get the headers over the ports real nice and so they wouldn’t squish the bumped out part of the gasket. The motor is out of a 55 delivery sedan cast October 28 1954. The 216 my truck had in it was beyond my ability to fix at that time (Boy I sure do wish I had kept it). Anyway my 235 will be dropped into a 53 Chevy 3100 ½ Ton pick up truck. This truck was my dad’s he bought it from my uncle when I was 10 or so. Learned to drive on this baby and loved it! It got me everywhere I wanted to go and some places I didn’t need to be. No one else liked to drive it because the 6 volt system was VERY temperamental and the clutch stuck when the humidity was up. If it rained the wipers wouldn’t work when you gave it gas as somebody replaced the fuel pump with one that didn’t have a vacuum assist. It went down hill from there and mostly sat until I needed a truck to haul stuff. Dad was going to junk it three years ago so I didn’t give him a chance to change his mind. I flew over there to get it, spent a few days getting it to run and drove it home. Decided I REALLY wanted a truck and this was it. I am in the progress of a frame off restore to something I can drive and enjoy for the rest of my life. Hope this didn’t bore everybody to death. I am getting some photos together of the restore to post on the projects page in a few days.

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