Well, it's clear there are several possible approaches when building some mani's which have very restrictive clearance at the weld joints.

I've pulled out the tungsten, squeezed in places, but the torch angle suffers, as does the weld.

So here recently I broke down a mani and seperated all the runners. I had given it alot of thought on how much movement the runner would see as a result of being welded free. Well, it was more than I thought...and fitment is gonna be a pain trying to get it back together.

So, it's obvious a jig is necessary. I knew that was the best approach at the time, but just figured I'd give it a shot to see for myself.

Well, my questions are as follows:

Anyone here using runner jigs, do you just basically locate the two ends firmly, or do you jig the entire runner to prevent any side to side movement also?

Secondly, I am aware that when the steel is heated the crystal lattice structure is affected, therefore quenching at various speeds locks the structure and affects strength, blah blah blah...I've been to school to. In the real world though, these aren't aerospace units, these are turbo mani's for my own Honda's along with some local guys.

So my question is, can constant water quenching after each small period of welding control distortion without having to jig the runner? I seem to feel that after the manifold is heated when on the motor, that it's going to experience a certain temper of its own anyway, therefore my quenching may not have a profound affect on the steel in the big picture.

Comments/answers/pics appreciated

 

I separate my runners from the two flanges and weld them up, I use sch40 mild steel, 1.25", and I found that if I tack each joint about 4-6 times with filler I can weld them without jigs. The first couple manifolds I build this way bit me in the *** because I didn't have enough tacks. Stainless is going to shrink even more though as will the thinner the material.

 

So, in theory the majority of movement would be a result of the joint to be welded, therefore if reinforced with more tacks it can be minimized.

I notice though you use this method with mild steel. Stainless has tendency to warp and move a bit more. Well, that's the first tip then either way......more tacks!

Bump for more info

 

i just did a sch 10 ss ramhorn for a 1.8t VW. I made a jig with 5/8" thick head and turbo flanges and did as many of my root passes while it was bolted to the jig as possible. I got at least 80% and only did 1-1.5" long segments and cooled them with compressed air. I was pleased to find the manifold under no tension when i unbolted it. After finishing my roots and doing a cap on each runner (after taking it apart) there was only one that didnt fit perfectly back inthe jig and it was off by less than 2mm. $.02

 

when i did this manifold i bolted all the flanges into my fixture and tacked the runners together. i hadn't even welded the collector completely. i would tack up one runner, then weld as much as i could with it bolted into the fixture- but not finishing the weld at the collector so i could break it off and finish the areas i couldn't reach. having individual flanges for the head made this easier to do as well... i could weld them completely. i did this for 5 individual runners, then finished welding the collector as much i could, then added the last runner (that was already welded up) to the collector because it would have impeded access to the bottom of the collector... that last runner to go on was the #4 runnner from the right. i'd do it this way again as it turned out well and wasn't that difficult to do.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dave@passenger &raquo;</TD></TR><TR><TD CLASS="quote">I separate my runners from the two flanges and weld them up, I use sch40 mild steel, 1.25", and I found that if I tack each joint about 4-6 times with filler I can weld them without jigs. The first couple manifolds I build this way bit me in the *** because I didn't have enough tacks. Stainless is going to shrink even more though as will the thinner the material.</TD></TR></TABLE>

EXACTLY how I do it. If you have gaps in your fitment...it ***** everything up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RC000E &raquo;</TD></TR><TR><TD CLASS="quote">So, in theory the majority of movement would be a result of the joint to be welded, therefore if reinforced with more tacks it can be minimized</TD></TR></TABLE>

Minimized but it will still move, it will still move even if you lay a single pass while its still in the jig, take it off and make a second pass.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dave@passenger &raquo;</TD></TR><TR><TD CLASS="quote">I separate my runners from the two flanges and weld them up, </TD></TR></TABLE>

weirtech brought up a great point before when I was talking to him, when you seperate the runners, weld the runners that are still attached to the collector, all the way around. Then break them off when done, then put the other two back on, and weld them while on the collector and head.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RCautoworks &raquo;</TD></TR><TR><TD CLASS="quote">weirtech brought up a great point before when I was talking to him, when you seperate the runners, weld the runners that are still attached to the collector, all the way around. Then break them off when done, then put the other two back on, and weld them while on the collector and head.</TD></TR></TABLE>

Bam....and that's the ticket. Funny how it's so easy to overlook the obvious solution...damn. Use the jig you've got....what the hell...I should have seen that one.

It just lures you in to breaking them OFF and welding them, that breaking some off to clear the connected ones to be welded in place is the best bet.