How to modify the exhaust manifolds???

I have a set of manifolds laying around and my brother took them to the machine shop to have them honed out some. The guy at the machine shop says that he can do little for them, but I know guys around here that have had some serious work done on their manifolds.

Are you guys having the heads "extrude honed"????:confused:
If so how do I contact them?

What should I ask for when I go to the machine shop with these manifolds?

Dirtybird91
 
The machine shop is absolutely right, there isn't much you can do to them. The only place you can remove a decent amount of material is the collector portion, which can lose about 1/4" up to about 4" in from the bottom. I have my stock manifolds ported about as much as they can take, but they aren't exactly "modified" as if the confirguration or shape has been changed. They are just ported.
 
I bored mine out on the mill table.I had a peice of steel that would bolt
to the mill table .That I was able to bolt to the collector .It was a jig made
up for another job.And I was able to bolt the collect to.Then I bored the
collector out to 2.125 inches and about 3 to 4 inch deep or past the inside end
of the collector,with a boreing head.Then i blended in with a grinder.

The collector cleaned up nice.But I still have the bolt bosses sticking out
inside of the header .Blocking the exhaust gasses.I ground down the bolt
bosses and tried to taper them a little to areo them from the exhaust gas,
At the head flange.

I don't know if it helped or not.I sure it did,but have no dyno proof.

You can port them with a drill with a flap sanding disc .use about a 120 to 80 grit
flap sanding disc.And get the flap sanding disc of 2 inch or small diameter.And it
will take about 2+hours each header to port, when doing the sanding method.

I did my own because I didn't have the money to send to T-BIRD 88.if you got
the money have him do it for ya.

RANDY
 
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A jig made to hold the header collector,will take time and material cost.
the jig cost could could take 4 + hours to make. After that it take about
2 minutes to bore each header.

It may be cheaper to send to t-bird 88,or do yourself.FLAP sanding disc
cost about $5.00 each you will need one or two.

RANDY
 
hmmmmmm........

Randy,
I would send the manifolds to t-bird88 (Wynne) but my brother needs something to happen really fast.
I will head to the machine shop with the information that you and Bill gave me.
I think it will all work out.:D

Dirtybird91
 
Get em flowbenched...

If the machine shop has a flowbench, get a baseline of how much each manifold flows. Compare the % difference for each exhaust primary. Compare the difference of each manifold (right to left).

I wouldn't be surprised to see some serious inbalance of flow, both cylinder to cylinder and bank to bank.

Although, they may not be able to get the manifolds to flow a large percentage more than what they already flow, they can certainly balance the flow out. That can make differences in and of itself.

You may want to do the porting yourself but utilize their flowbench to match stuff up.
 
That is why I opt. to machine my collector,instead of hand port. To make
sure they were the same bore through out the collector.And be balanced.
Not much can be done with the head bolt flange end.With the bolt boss on
the stock header.Except go with after market headers.

I have a flow bench.I did not flow the headers because it would take to
long to make a fixture on the bench, to bolt and seal the headers to flow.
And I just didnt want to take the time to bolt the heads with the headers
on the bench to flow the headers that way either.And I am not building
an all out race car,so I didnt take the time to flow them.I kinda wish that
I would have flowed them though.

Frank: I would think the fastest way to get the headers ported would be
to do it your self.You can buy flap sanding disc at tractor supply,rural king.
A place that sells welding supplys, farm stores.

RANDY
 
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Randy

So what you are telling me is that the part that the machine shop will can do the most work on will be the collector side. Not much can be done with the side that bolts to the heads right?

Frank
 
Frank: your right.Yes .

I think it would be faster to do your self.

It would be cheaper to do yourself

You will be able to stick your chest out farther if you do it yourself.

And you will have beer money left if you do it yourself.

You need to port them out to the point that tha flat edge is gone on the end
or tip of the collector.Or port out to 2 inch ,If 2 inch is the size of the down tubes.

RANDY
 
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Randy N Connie said:
Frank: your right.Yes .

I think it would be faster to do your self.

It would be cheaper to do yourself

You will be able to stick your chest out farther if you do it yourself.

And you will have beer money left if you do it yourself.

RANDY

Thanks again Randy!:cool:

Frank
 
Randy N Connie said:
Frank: there are some ported stock headers for sale,in the parts for sale section.
RANDY

Randy,
I dropped those off today! I will cross my fingers that the machine shop does a good job. The guy said that he will be basicly honing out the "lip" inside the collector and doing a little work on the head-side.

Cross your fingers for me!:D

Frank
 
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