I had to get a new head for my Fiat twincam 1800 project due to suspect looking ex seat w some corrosion in the original head.
This is a good used 2L head that has never been worked on.
My plan is to do port work per Stage II of the Guy Croft manual. A die grinder with 60 grit drums cuts aluminum like butter at low speed setting.
As of now, I'm done with dimensional work and port matching. Waiting on some flapper wheels to finish.
Manifold to port match is just about perfect now with the aid of a bore snake cam.
Port work on a Fiat 124 2L head
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Re: Port work on a Fiat 124 2L head
Those Exh port outlets at the flange look really big for that throat size I see in those Exh port bowls!
I would bet that welding up the floors of those Exh runners to make them a tad smaller would pick up bunch of mid range Torque and help the motor to rev faster and not drop off any top end power to boot!
I would bet that welding up the floors of those Exh runners to make them a tad smaller would pick up bunch of mid range Torque and help the motor to rev faster and not drop off any top end power to boot!
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Re: Port work on a Fiat 124 2L head
They do look huge. What are the dimmensions you are working with?
Those heads look like an Alfa head with quench pads.
Those heads look like an Alfa head with quench pads.
-Bob
Re: Port work on a Fiat 124 2L head
Port dimensions at flange are pretty much OEM, unchanged.
What I did was open up the smallest dimension of the port, mostly at the sides leaving the roof and the floor rather untouched. The average port min diameter was increased by about 1.5mm IN, 1mm EX.
Seat inserts are original.
Port dims:
Intake at flange: 35.8mm
Intake seat insert ID: 37.6mm
Port minimum diam: 33.0mm avg (34horiz, 32vert)
Exhaust at flange: 35mm
Ex seat inser ID: 32.7mm
Port min: 28mm avg (~33 wide, ~23high at the guide bump)
What I did was open up the smallest dimension of the port, mostly at the sides leaving the roof and the floor rather untouched. The average port min diameter was increased by about 1.5mm IN, 1mm EX.
Seat inserts are original.
Port dims:
Intake at flange: 35.8mm
Intake seat insert ID: 37.6mm
Port minimum diam: 33.0mm avg (34horiz, 32vert)
Exhaust at flange: 35mm
Ex seat inser ID: 32.7mm
Port min: 28mm avg (~33 wide, ~23high at the guide bump)
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Re: Port work on a Fiat 124 2L head
If I where you I would really want to get the head flow tested now so you know what the Exh to intake ratio has changed to!
On the few of these motors I have worked on ( flow wise at a shop I used to help out at) even with the head in stock form then intake Manifold was the main choke point in the whole flow system, so doing any work to the head is a waste of time.
On the few of these motors I have worked on ( flow wise at a shop I used to help out at) even with the head in stock form then intake Manifold was the main choke point in the whole flow system, so doing any work to the head is a waste of time.
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
Re: Port work on a Fiat 124 2L head
I would have no baseline, nothing to compare flow bench data with. I'm following the instruction in the book by G Croft who built these engines for racing in England for decades.mag2555 wrote: ↑Wed Jun 24, 2020 5:35 am If I where you I would really want to get the head flow tested now so you know what the Exh to intake ratio has changed to!
On the few of these motors I have worked on ( flow wise at a shop I used to help out at) even with the head in stock form then intake Manifold was the main choke point in the whole flow system, so doing any work to the head is a waste of time.
For manifold, I have a nice IR with 44 IDFs.
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Re: Port work on a Fiat 124 2L head
Did Guy share flowbench results for each of his porting Stages?
-Bob
Re: Port work on a Fiat 124 2L head
That is correct. Mine came from Pierce Manifolds and is as good as the space allows.
Re: Port work on a Fiat 124 2L head
Would bike carbs fit in?