Slant Six Forum :: Modifying 1bbl manifold to 4bbl?

SV162, very interesting! I was indeed thinking about something exactly like that (the red 4bbl manifold mod on pg. 4).

Most people do this by smoothing down the original manifold carb mount and opening the hole to accept a metal spacer (either 2 or 4bbl) to act as the carb mount, then trying to grind out some better distribution.....but...then instead of welding the plate to the manifold, some guys are using epoxy to mount them. I assume this is done to avoid the problems inherant in welding cast iron, particularly if the spacer is of a different metal (most spacers are aluminum).

I have actually and successfully done emergency manifold repairs using JB Weld, but is epoxy really strong enough to do a mod like this? Wouldn't the expansion properties of the different metals cause stress on the epoxy joint?

I didn't read anything about what epoxy was used. Any opinions? Thanks!

Author:	polkat [ Sat Apr 30, 2011 9:49 pm ]
Post subject:	Modifying 1bbl manifold to 4bbl?
A question for us loooow budget guys: This might be pushing it a bit, but I've seen many 1bbl to 2bbl manifold mods, but has anyone ever done a 1bbl to 4 bbl mod? Is there enough plenum space to cut a large enough hole to weld on a 4bbl plate, or 4bbl adaptor? I've seen what looks like different plenum sizes on 1bbl manifolds so I thought I'd ask. Thanks! ________ CANDIES4YOU

Author:	VDART [ Mon May 02, 2011 9:30 pm ]
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it has been done, article from a 1960's mag showed this mod, do not remember if they used the 196 aluminum intake or a cast 1. Lawrence

Author:	polkat [ Tue May 03, 2011 12:59 am ]
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VDART, do you remember what magazine it was, and if the article is on line somewhere (though i doubt it)? ________ California medical marijuana dispensary

Author:	SV162 [ Tue May 03, 2011 3:26 am ]
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This might interest you polkat. Some pics are part way down this page, with more info scattered throughout the thread. http://www.moparmarketforum.com/forum/v ... d&start=60

Author:	polkat [ Tue May 03, 2011 1:23 pm ]
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SV162, very interesting! I was indeed thinking about something exactly like that (the red 4bbl manifold mod on pg. 4). Most people do this by smoothing down the original manifold carb mount and opening the hole to accept a metal spacer (either 2 or 4bbl) to act as the carb mount, then trying to grind out some better distribution.....but...then instead of welding the plate to the manifold, some guys are using epoxy to mount them. I assume this is done to avoid the problems inherant in welding cast iron, particularly if the spacer is of a different metal (most spacers are aluminum). I have actually and successfully done emergency manifold repairs using JB Weld, but is epoxy really strong enough to do a mod like this? Wouldn't the expansion properties of the different metals cause stress on the epoxy joint? I didn't read anything about what epoxy was used. Any opinions? Thanks! ________ Blonde live

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Modifying 1bbl manifold to 4bbl? https://slantsix.org/forum/viewtopic.php?t=44795	Page 1 of 2

Author:	coconuteater64 [ Tue May 03, 2011 1:50 pm ]
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I countersunk bolts into my adaptor and sealed it with good old Permatex. Coming up on the 2nd year with nary a problem.

Author:	polkat [ Tue May 03, 2011 2:29 pm ]
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coconuteater64, I'm trying to picture this in my mind. Do you have any pics? ________ Live sex

Author:	coconuteater64 [ Tue May 03, 2011 4:20 pm ]
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What I did was grind the manifold flat, very carefully, then put a big 2bbl carb gasket on it where I thought the carb should go. Then I spray painted it and threw the gasket away. Whatever was not green was what had to disappear. So I drilled a series of 1/8" holes close together, smacked it with a ball peen hammer, and the offending metal broke free. A little Dremel work and it was ready for the adapter. I used the Indian Head gasket shellac on the adapter, not Permatex. Memory must be slipping a little.

Author:	polkat [ Tue May 03, 2011 4:49 pm ]
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Okay, I can see the countersunk bolts in the pic. So I'm guessing you drilled four holes in the manifold and then tapped them for the bolts? ________ Buy aromed vaporizer

Author:	Brussell [ Tue May 03, 2011 5:28 pm ]
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I recently bought a modified manifold off ebay, I assumed that he had done what was done above^ (coutnersunk and tapped studs etc) it was just the epoxy, when torquing down the carb the adapter plate came free from the manifold. i'd suggest do as many bolts/studs as possible. To do mine, I'm getting it machined flat, drilling as many studs in as possible and using an epoxy as a sealant.

Author:	selfie [ Tue May 03, 2011 5:57 pm ]
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Quote: SV162, very interesting! I was indeed thinking about something exactly like that (the red 4bbl manifold mod on pg. 4). Most people do this by smoothing down the original manifold carb mount and opening the hole to accept a metal spacer (either 2 or 4bbl) to act as the carb mount, then trying to grind out some better distribution.....but...then instead of welding the plate to the manifold, some guys are using epoxy to mount them. I assume this is done to avoid the problems inherant in welding cast iron, particularly if the spacer is of a different metal (most spacers are aluminum). I have actually and successfully done emergency manifold repairs using JB Weld, but is epoxy really strong enough to do a mod like this? Wouldn't the expansion properties of the different metals cause stress on the epoxy joint? I didn't read anything about what epoxy was used. Any opinions? Thanks! The red manifold on that page is mine... I have it finished but never got around to posting pics. I used Devcon epoxy but also have three socket head bolts that are tapped in to the cast iron of the manifold. I cannot give any indication as to how well/poorly it runs as I am still waiting on a carb.

Author:	SV162 [ Tue May 03, 2011 7:27 pm ]
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Well get on it selfie, and add the pics of the finished product to the MM thread..........ya slack bugger!!!

Author:	polkat [ Tue May 03, 2011 10:24 pm ]
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selfie, looking at your 'finished' image of the red manifold, I can't really see where any bolts through the spacer into the manifold would fit, other then on the sides. Do you have an image showing the bolts installed? I'm also looking forward to seeing how it comes out. Post it on this site if you can. How did you flatten the manifold? I think you said on the thread something about using a 7" grinder, but that's hard to picture. ________ California medical marijuana dispensaries

Author:	Charrlie_S [ Wed May 04, 2011 4:19 am ]
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I did a 4bbl "homemade manifold from a small block 2 bbl manifold. back in the 70's. I opened up the plennum and used a 2 inch open aluminum carb spacer. Fastened it on with "Devcon" plastic steel. The Devcon was strong enough to lift the engine, with a plate bolted to the carb flange. The manifold ran fine for over 5 years on a 12 sec 273 engine. I just sold that manifold 2 weeks ago. My 66 Cuda has a homemade setup made from a stock cast iron 1 bbl manifold. Milled the 1 bbl mounting flat, made a steel plate 3/8 inch thick, to match a Holley 2 bbl gasket, and "Spray" welded (no fasteners of any kind) the plate to the manifold. I did have to add a spacer between the carb and the plate, to raise the carb for clearence to the manifold. I made this manifold in 1979, and am still using it. Though I did add nitrous nozzels about 8 years ago.

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Author:	polkat [ Wed May 04, 2011 1:58 pm ]
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Charrlie_S, interesting stuff! I was looking on the web at the Devcon Plastic Steel, and noticed that it comes in two versions; a two part epoxy, or a one part putty. Do you remember what you used? Also, the data sheet for the product (the putty) says that it will resist up to 250 F heat. Is that really enough for an intake manifold? Thanks! ________ Buy Digital Scale