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Has anyone fabricated or modified headers for 318 poly in stock B body?

Evan Frucht

Evan Frucht

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I've done the research on this but not sure if I'm missing something. The TTI ones are too expensive and also they are bigger tube diameter (1 7/8") than I want. I've Seen a few messages on the poly 318 yahoo group but they are minimal, no finished stories or pictures that I could find. Haven't found much on here excpet people saying its too much trouble.

I'm leaning toward this options. I hear the new 1990's 5.7 L gen 3 hemi headers have identical port spacing (the flanges could be cut out and replaced with proper ones) They would fit on the head. But my questions are would they clear the power steering pump? That's seems like my biggest clearance obstacle but I haven't heard much mention of that. It seems people mainly worry about clearing the motor mounts and oil filter. Do people even attempt this in the b body ? Or do the people who try this have early poly pickup trucks with more clearance? Was thinking of trying these. https://www.summitracing.com/parts/psm-70-1374/make/dodge

Or if I become convinced the modification avenue is impossible I may try to make some that will fit from scratch with 1 1/2 or 1 5/8 tube. I don't even care if they are a little funky as long as it's an improvement from stock manifold. Does anyone know more about this picture I found online? Seems like someone made some... question is do they fit? If so I'd probably try to copy them.
318 Poly headers.JPG
 
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I personally don't like that 2-into-1 primary pipe design one bit. Your general idea sounds reasonable & if you're a top-notch welder and maybe have access to a tube bender, then go for it. If not, even with the tubes that are too big & the high price, the pre-fabricated headers will save you tons of frustration & likely a little money too. Just my 2-cents. Didn't '66 Coronets have poly 318 engines available? If correct, that would be the car I'd do my header search with (you probably already know this).
 
PurpleBeeper said:
I personally don't like that 2-into-1 primary pipe design one bit. Your general idea sounds reasonable & if you're a top-notch welder and maybe have access to a tube bender, then go for it. If not, even with the tubes that are too big & the high price, the pre-fabricated headers will save you tons of frustration & likely a little money too. Just my 2-cents. Didn't '66 Coronets have poly 318 engines available? If correct, that would be the car I'd do my header search with (you probably already know this).
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Just curious, why do you dislike the 2 into 1 design? Obviously it's not as good as individual tubes but I would think it would be a significant improvement over the small manifolds? or not?

I may try to to modify the header's I linked to. I'm thinking best case I will only have to cut it off at the flange and weld it to the proper one at a different angle maybe. Worst case I have to also cut out sections of 2 of the tubes to re-route them.

The TTI would be almost 1000 or more shipped, don't get me wrong they are nice but out of my budget.

The headers I might try to modify are 280, flanges off ebay are 60, and a few pieces of random mandrel bent tubing would be roughly another 60. Thats all including shipping. That's 400. Even if I go over another couple hundred I'll still cheaper. Plus I hear you need some $300 mini starter to make the TTI ones work. That's why it makes sense to me. The welding is no issue for me, sort of my specialty.
 
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Go for it and let us know the out come.
 
Evan Frucht said:
Just curious, why do you dislike the 2 into 1 design? Obviously it's not as good as individual tubes but I would think it would be a significant improvement over the small manifolds? or not?

I may try to to modify the header's I linked to. I'm thinking best case I will only have to cut it off at the flange and weld it to the proper one at a different angle maybe. Worst case I have to also cut out sections of 2 of the tubes to re-route them.

The TTI would be almost 1000 or more shipped, don't get me wrong they are nice but out of my budget.

The headers I might try to modify are 280, flanges off ebay are 60, and a few pieces of random mandrel bent tubing would be roughly another 60. Thats all including shipping. That's 400. Even if I go over another couple hundred I'll still cheaper. Plus I hear you need some $300 mini starter to make the TTI ones work. That's why it makes sense to me. The welding is no issue for me, sort of my specialty.
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I think you can do it....double check those donor header tube-to-tube distance and go for it!

In general, 2-into-1 tubes are more restrictive than single tubes (though I've heard good things about "tri-y" max wedge headers) and I think that's pretty obvious, plus the different exhaust back pressures cylinder-to-cylinder isn't a plus. I really have NO idea how the flow of those headers would compare to stock poly manifolds??? Just thinking out loud... have you looked into extrude honing stock poly manifolds & how those would compare vs. header flow? Also, is there any way at all (maybe inner fender notching) to use an individual primary tube for each cylinder with your engine/body?
 
Ok/ I'm really tempted to just buy those and try but waiting to hear more info (if its out there) about the challenges others have faced, before I decide on the exact route I want to go (ie which headers will I choose to modify or will I go a full custom route like the picture.) Another thing is, I can't tell from the pic of those gen 3 hemi headers exactly what would interfere with what. I may just have to try it and worst case return it. and I don't think I'm trying to mess with the fender wells on this one.
 
after examining the engine bay more thoroughly I've decided it will be too troublesome to make those modern hemi ones work. not impossible perhaps but not worth the trouble. If the engine was in a car with more room to work with, then those headers (or many others) could be adapted easily, but it would be to hard to make them fit in a 64 b body, which clearly was not designed for headers.

I've decided I'm going to make my own headers to fit the car. I will have to comprise the design, maybe they cant even be called real headers,... they will be, short, basic and hug the block pretty close. I mocked up a little drawing on the computer of my concept. if anyone sees a reason this design would be worse than the stock manifolds let me know.

THE FRONT TWO PORTS WOULD BE CONNECTED IN MY DESIGN TO MAKE ROOM FOR STEERING BOX AND MOTOR MOUNTS.... so they would not be true 4 into 1 headers. I'm thinking it would be a major improvement over stock manifolds, especially if they are the same on both sides.​

318polyheaderidea.jpg
 
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Drop 1 to 3, 5 to 7 and 1-3, 5-7 to collector going up in pipe size with every pipe joining. Joining cylinders at the port would be no better than the poly log. Worked on poly header configurations for two years. Pulled the poly and installed a BB problem solved. I had even looked at the older Hemi exhaust designs which I would think port design and spacing would be closer than the new stuff.
 
mopar 3 B said:
Drop 1 to 3, 5 to 7 and 1-3, 5-7 to collector going up in pipe size with every pipe joining. Joining cylinders at the port would be no better than the poly log. Worked on poly header configurations for two years. Pulled the poly and installed a BB problem solved. I had even looked at the older Hemi exhaust designs which I would think port design and spacing would be closer than the new stuff.
Click to expand...
what do you mean? even if just one cylinder is joined at the port it still wouldn't be any better? This motor is not upgraded much, it has a reground cam, and a four barrel, but I think it could still benefit from breathing better. I'm about to put a dual 2.5 inch exhaust on it. Figured I wanted more volume than the manifolds provide? and having semi separate head tubes would also be a plus. BTW the new hemi gen 3 headers have the exact same port spacing, its IDENTICAL. it would be easy on an poly that was going on an open hot rod or something. I don't think the old hemis you mentioned are the same port spacing as the polys,... but I know for sure that the new 2004 5.7L hemis have the exact same exhaust port spacing as a 1964 poly 318.
 
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It kills 2 cylinders ( 1 & 3 ). I think you will find a better design if you look at the old hemi small cube exhaust.
 
mopar 3 B said:
It kills 2 cylinders ( 1 & 3 ). I think you will find a better design if you look at the old hemi small cube exhaust.
Click to expand...
Do you have a picture of or link to the headers you're talking about. The reason for connecting those two ports is that there is very little space around the steering box. And motor mounts to work with. I'd have to go over the top or something like tti's
 
I'm no expert on this but there is truth in the 1-7 2-8 for port excavation. Look at tri-y header design. The Schumacher shorty Big Block header is designed that way and work darn well even with 1 5/8 tubes. I ran them on a 451 stroker with great results.Just a thought for you to research.
I think it's great that you are up to this challenge.
 
Now I'm starting to think it may not even be worth it. I'm not sure how much flow the stock head will even allow (does anyone have any opinions on this?) And there's no way I could afford head porting and machine work at the moment. The PO did say the the heads had been machined but I think they may have just cleaned up the valve seats, and did not do much porting if any. The PO also said the cam was reground by the same shop. The car has a 625cfm AFB.

Are the stock 318 heads restricting this motor more that the stock manifolds are?
 
I'm no fabricator, but if you have the flanges could you just mimic the tti?

20180410_164211.jpg
 
matthon said:
I'm no fabricator, but if you have the flanges could you just mimic the tti?

View attachment 679310
Click to expand...

Ya, but whats the fun in that? Lol. I do see your point and it is a good one. If I thought they were perfect and just too expensive I might try to copy them. But honestly I want something "better" or more appropriate for the 318 small block. Also one of th main problems i have with the TTI ones are
- too big, they are 1.75... I think 1.5 would be better for close to stock 318. IMO 1.75 head tube's should be for a 440 BB... not a small block. It's almost a joke.
- Need to lift motor to install
- would need a new mini starter
- possibly need a 90 degree oil filter adapter
- spark plug boot clearance might be an issue.

I want something that bolts in easily like the manifolds. I also don't expect much of a performance upgrade. Mostly for the coolness factor, and to say I did it... But if it would literally not benifit performance at all I may not go through the trouble
 
Don't need a oil filter adapter with the TTI's Filter fits fine.
IMG_1426.jpg
( Photos just for reference.) No the head flows fine for 318 Cubic Inches. Those ports look similar to the Hemi.I would say that you will be very happy with the results with the plans you have stated. Just Intake, Carb, and Exhaust Made a BIG difference when I had mine.That was with a stock cam and valve springs. I added 3.55 gears over the factory 2.76.The car would light the tires.
That was WITH the stock manifolds to 2 1/2'' exhaust before the TTI's

IMG_1389.jpg
 
Darter6, what intake and carb did you put on your 318 poly?
Did you need a kickdown rod/bracket specific to a 4 barrel?

Isn't there a guy on here that takes a driver side exhaust manifold and turns it into a pass side manifold?
Could you pattern them both off of the driver side manifold?
 
matthon said:
Darter6, what intake and carb did you put on your 318 poly?
Did you need a kickdown rod/bracket specific to a 4 barrel?

Isn't there a guy on here that takes a driver side exhaust manifold and turns it into a pass side manifold?
Could you pattern them both off of the driver side manifold?
Click to expand...
Darter6 may have his own answer but I was able to modify the stock two barrel kickdown linkage to function with the Carter AFB 625cfm (casting number 9636a). Its not beautiful but it kicks down and there's enough room to adjust it. (spent lots of time with vice and hammers to get it in the right shape where it wouldnt hit the block when fully forward, but also so it would push back enough to fully open the kickdown lever on trans. Also I was lucky enough to buy my Fury with an original cast iron 4 barrel intake that the PO already installed. The car runs like a champ... They have weiland four barrel intake for poly 318 but they don't make them anymore so you'd have to find a used one which could be expensive ($500-700). also TTI currently makes a four barrel intake for the poly($675).. probably only appropriate for strip cars as its very tall and expensive. personally I think you would be happy with the cast iron one. wait to find one for $300 or less. that probably a good price, sometimes the price gets a little jacked up for those on eBay because lots of people bid. try to find one on here or craigslist/swapmeets. those are it, 3 options...

Also yes there is a guy who advertises those manifolds. I sent him a PM a week or so ago but he hasn't got back to me, the thread is also "not open to further replies" so maybe he stopped having them made. I think its a good idea he made them, but honestly not enough of an improvement for the money IMO.
 
Darter6 said:
Don't need a oil filter adapter with the TTI's Filter fits fine. View attachment 679336 ( Photos just for reference.) No the head flows fine for 318 Cubic Inches. Those ports look similar to the Hemi.I would say that you will be very happy with the results with the plans you have stated. Just Intake, Carb, and Exhaust Made a BIG difference when I had mine.That was with a stock cam and valve springs. I added 3.55 gears over the factory 2.76.The car would light the tires.
That was WITH the stock manifolds to 2 1/2'' exhaust before the TTI's

View attachment 679334
Click to expand...
thank for the input
couple questions,

When you put in the 2.5 inch exhaust did you notice the car lose any low rpm torque over the old exhaust system (...what was in the car before the 2.5 duals?)
did it feel like it lost even a little of its "bottom end" power?

also did you upgrade the exhaust, carb and intake at the exact same time?

What difference did you notice after adding the headers alone? was it a big improvement over the manifolds. and again, did you feel any losses at the bottom end?

I doubt I'll ever take this car to the track, or need the extra HP I'm going for. This will be a street rod, so top end gains are not so important to me. I want it to be very responsive and take off quick tho.

I would like to be able to whoop a few 'stangs if the need or want arises ,.. as they say
 
Edelbrock 600 with a Weiand intake. No real change on the bottom end. As you know the manifold exhaust flanges are 2'' so from the manifolds to about 18'' the exhaust pipe was 2'' and then 2 1/2'' on back.
Yes bottom end torque was less with the header/cross over pipe thru the 2 1/2'' pipes to the back bumper.Could also be to the fact that the Weiand intake is a single plane.
One thing that I didn't do,but wanted to was replace the valve springs.A offer was made on the car and I sold it.


In the photo is the engine with the Chrysler Power wind tunnel intake($650) and a stroked 390 Poly that a friend has with a 750 Edelbrock, all the new Poly goodies and TTI's and full exhaust. This thing flat out flys and will give a Big Block a run for the money.
IMG_2722.jpg
 
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