Manifold machining

JackA

JackA

Senior Member
Hi,

I have my manifolds off for gasket replacement and the Les Andrews book says to face them. Does this mean machine facing or with a flat file. They look fairly ragged to me and were leaking in several locations. Any ideas, experience?:confused:
 
Machine facing is more accurate. Leave them bolted together and let a professional do the job. It's cheap enough.
 
Now is also the time to check the condition of the two bolts holding your manifolds together. Many are rusted to the point of snapping right off if you look at them sideways. If you feel they are good and tight, don't touch 'em. There is no gasket between them to worry about either. A snapped one will ruin your day. Have the assembly planed at a machine shop. Should cost around $60-$75 bucks. Use only the copper gaskets with Ford cupped washers, concave side facing engine. Don't over-tighten nuts.Check 'em regularly for the first few months of driving. I don't tighten them when engine is hot.
 
Always have a machine shop resurface manifolds. You will find a file is extremely inaccurate.
NEVER take the manifolds apart after machining. Always ask for just the bare minimum to be removed. Check the end of the exhaust manifold nearest the front of the engine. They can get very thin in that area.
 
Nothing wrong with the steel /asbestos gasket , in fact we have the best results with them apart from showing. Also on a right hooker one should machine more off the top edge than the bottom , not much but it kicks the muffler end out a fraction which gives more clearance with the clamp etc.
 
If #4 exhaust droops (as many do) you might want to buy a new ex manifold rather than spend money on your warped one.
 
If you take the manifolds to a machine shop as suggested, I'd also ask them to machine the bolt ears to the same height on both manifolds. Each pair of ears should be the same height with repect to the engine/manifold mounting surface. All four sets of ears don't have to be the same height. Just remove what is needed to make each pair the same height. This will eliminate the possibility of breaking one of the ears off when you re-install. It will also help keep the torque the same on both manifolds and help alleviate leaks.
 
Tom, I considered buying new intake and exhaust manifolds, but then wondered if I would have to face them as well??
 
JackA said:
Tom, I considered buying new intake and exhaust manifolds, but then wondered if I would have to face them as well??
Click to expand...

i have never needed to resurface a new intake / exhaust manifold combo yet. IMO thats the way to go, beats messin with an old pitted piece and get that clean look. also ck out the new ceramic coated exhaust manifold from snyders.
 
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$30 is all that Majewski machine in Trenton, NJ charged me to Blanchard grind my manifolds. This shop is not a automotive shop, but They're experienced in automotive work. $40 to cut .030 off the head. Good Father and son shop to deal with.
Terry


Mitch//pa said:
i have never needed to resurface a new intake / exhaust manifold combo yet. IMO thats the way to go, beats messin with an old pitted piece and get that clean look. also ck out the new ceramic coated exhaust manifold from snyders.
Click to expand...
 
Jack,
Put along straight edge across them. I have a bonified old style cylinder/head flat straight edge for checking. If you have access they are best, if not use a long carpenters square on edge and use a feeler gauge. If it's out more than .005 surface it. Almost all need some cleanup....It helps insure that you get a good seal for intake and exhaust and helps to keep from cracking any ears on the manifolds. If the edges are pitted it may be a problem. Use a straight edge across the ports and make sure they line up well. If sagging too much on #4 It may be best to buy a new Exhaust manifold. The new Snyders ones are very good. We are lucky to have them available. Even with the new manifold I would mate properly to the block for alignment, tighten two 5/16 bolts holding the two together.. and check for straightness on the bench as described above. I would surface them no matter what.... but then I do my own so I'm use to having the equipment at my disposal. $40 to surface one very reasonable...

Happy Model A Motoring...
Larry
 
A while back, maybe a year or two ago, somebody posted that they used a tool from Harbor Freight for resurfacing model A manifolds. Is there anybody here familiar with this tool ???
 
80 grit takes along time. the machine shop route is best. replacing the flat file after the job is about the same price. Spend the time on proper installation instead of filing, or my slate and 80 grit approach.
Bob
 
I recently had my "heater" exhaust and intake manifold resurfaced. Unfortunately now I cannot install my heater cover because there is not enough room going toward #4 cylinder. It hits the distributor and I don't want to grind the cover. It is an Auto-Lite heater which was in very nice condition other than alignment. When I called him on it he said there was "no way" to mount for resurfacing so he used a belt sander. On a more positive note he told me to find another exhaust manifold heater and he would see what he could do about reimbursement. Only time will tell.
 
In my case there is no machine shop near by that can resurface manifolds and heads. Automotive machine shops are sort of becoming a thing of the past. There is a half azz shop about a sixty mile round trip from me with a terrible reputation that I wouldn't trust with my model A parts. Besides that, I've never seen a machine shop that will do an operation while I wait. This causes two trips and usually a few months waiting period.This is why I have resorted to using a file. If a person knows what they are doing and has the patiants and staying power , some manifolds can be done with a large flat file. I've got a belt sander in my wood working tools but never thought about using it on a manifold , I may try it. Son in law borrowed it and probably ruined it because he hasn't brought it back. Replacement is usually the best way to go.
 
Purdy and Cape Codder, The shop I used, Majewski Machine, Has a fixture for holding the manifolds. I didn't see it but I know Blanchard grinding when I see it and both the head and manifold were done on a Blanchard. I would suggest that possibly the man who ground your manifolds "tipped" it slightly and took a little more off the top and that might account for it being so close. I also want to say that there is is a guy in Souderton, Pa,(A&I eng.) who wanted $90 to do the head, alone! (Knuckin' Futz)
Purdy, There must be a shop in or near Birmingham that will do it.
Good Luck, Terry
 
Just for general information, I am posting a fixture that I made to do my own 'match milling' after I had a number of poorly done efforts at automotive shops. If you are not careful to make the carb mounting surface perpendicular to the manifold sedge when you match mill the intake and exhausts together. tha combination will not be vertical when installed and not fit the RS engine pan or fit the flare on the exhaust very well. Hand held grinding was NEVER correct when done for me that way.

In addition. I did NOT want a real smooth gasket surface as it makes the gasket easier to 'squirrel it's way out of the edges. I chose to use a fly cutter and adjusted the feed speed to leave just a very minor 'irregularity' so that the gasket would have a grip to the manifolds.

As always, this is just a thought.

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