Fiat TC Fast Road engine-a few questions.

Competition engines and 'live' projects only. Good photos to illustrate your post are expected.
Piotrek125p
Posts: 184
Joined: December 2nd, 2012, 3:45 pm
Location: Lodz,Poland

Re: Fiat TC Fast Road engine-a few questions.

Post by Piotrek125p »

Today I remove one of my inlet seat.
Sorry for bad photo, I have only cell phone.
Sorry for bad photo, I have only cell phone.
IMG013.jpg (653.34 KiB) Viewed 6771 times
The diameter of insert now is 43mm, according to GC draw from the last post I need to have a 45mm insert. In the lowest place of my seat place in head is 6.35-6.4mm. So, in my opinion, these no space for it in my cylinder head. If I understand correctly, I can bore 0.25mm deeper below old insert (0.010' mean 0.010 inch ?). I think it's a really limit, because it's really next to unmodified SSR (I would like to modify my SSR with GC style). So, if my new, OE Fiat seat wiil be stick out from combushion camber, can I make now set of thicker seats ? How thinnest seat can I use (of corse if I would like to have a 30-45-70 seats like GC suggest me) ? My old seat has 6.5mm thickness. In the workshop where I have a training, they have a plenty of very good cast iron which they use for LPG seats with very good results. Could I use it if I have to use a thicker seats ? They never made a seats of copper alloy, I think that you use a special copper alloy, because a normal copper alloy is very soft and to my knowledge, a material for seat must be harder that normal copper alloy.
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Guy Croft
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Re: Fiat TC Fast Road engine-a few questions.

Post by Guy Croft »

Crikey.

Just send it to me Peter

then you can teach all the machine shops in Poland how to do it properly ...

you will become rich and I shall be happy and not have to type every evening...


G
Guy Croft, owner
Piotrek125p
Posts: 184
Joined: December 2nd, 2012, 3:45 pm
Location: Lodz,Poland

Re: Fiat TC Fast Road engine-a few questions.

Post by Piotrek125p »

I want to learn as much as possible doing as much as possible with my engine. Everything was done with him yet was done by me. I'm only a simple student who want overhaul and tune up his engine by personally, but as it's in school, the good teacher is the key of success. So GC, could you help me with my problem ? Give my parts to someone else I can do at any ime, but I want to be engine builder, so I must do it personally how much it's possible.

Sincerely Piotr.
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Guy Croft
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Re: Fiat TC Fast Road engine-a few questions.

Post by Guy Croft »

UNDERSTOOD PETER,

UNDERSTOOD

G
Guy Croft, owner
Guy Croft
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Re: Fiat TC Fast Road engine-a few questions.

Post by Guy Croft »

You can bore down as deep as you like but remember the port region below the Fiat seat insert is only about 4-5mm thick! if you bore too deep you will break through the port on the long-side radius (port roof/valve guide side). I normally do not bore deeper than 0.5mm over standard.

The seat insert needs to be of depth approx. 4-5mm or you won't be able to cut the angles properly!

I would recommend copper alloy - Colsibro or Trojan.

Look up Columbia Metals on google....

G
Guy Croft, owner
Guy Croft
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Re: Fiat TC Fast Road engine-a few questions.

Post by Guy Croft »

pictures of how to do the short-side radius on a Fiat type TC head with 36-35mm ports.

This reply is about how to develop the curve on the central region of the short radius that has such a critical effect on lower lift flow - 0-5mm lift (or so..). This region is important because the inlet flow 'sees' that even twice in the cam cycle.

Captions to follow, sorry data lost last week.

G
Attachments
inlet SSR 43.5mm valve TC.GIF
inlet SSR 43.5mm valve TC.GIF (10.82 KiB) Viewed 6466 times
short radius region.JPG
short radius region.JPG (54.73 KiB) Viewed 6466 times
inlet SSR 43.5mm valve TC_01.GIF
inlet SSR 43.5mm valve TC_01.GIF (10.89 KiB) Viewed 6466 times
inlet SSR 43.5mm valve TC_02.GIF
inlet SSR 43.5mm valve TC_02.GIF (9.88 KiB) Viewed 6466 times
inlet SSR 43.5mm valve TC_03.GIF
inlet SSR 43.5mm valve TC_03.GIF (10.4 KiB) Viewed 6466 times
inlet SSR 43.5mm valve TC_04.GIF
inlet SSR 43.5mm valve TC_04.GIF (10.03 KiB) Viewed 6466 times
inlet SSR 43.5mm valve TC_05.GIF
inlet SSR 43.5mm valve TC_05.GIF (9.91 KiB) Viewed 6466 times
inlet SSR 43.5mm valve TC_06.GIF
inlet SSR 43.5mm valve TC_06.GIF (9.5 KiB) Viewed 6466 times
inlet SSR 43.5mm valve TC_07.GIF
inlet SSR 43.5mm valve TC_07.GIF (11.63 KiB) Viewed 6466 times
Guy Croft, owner
Piotrek125p
Posts: 184
Joined: December 2nd, 2012, 3:45 pm
Location: Lodz,Poland

Re: Fiat TC Fast Road engine-a few questions.

Post by Piotrek125p »

Thanks GC for an article about SSR modification. I wrote to you on the last PM. I wrote there that it seems to me that the optimal radius in my case, it depends on how deep will set the valve seat. Remind me, if there is such a relationship, or 4 mm radius is a constant in my case. (I could not read your article carefully, unfortunately). It seems to me that the value of the radius was influenced how deep will set the valve seat. At now a intake valve seat are 0.25mm deeper than original, but the valve seats still protrude above the head face about 0.2mm. it seems to me that in my case should preferably be used correspondingly lower valve seat (0.3-0.5mm below) since it is already the valve seat is very close to the SSR. I'm right ?

I have a new set of new Goetze piston rings, new Goetze cylinder liners and a set of Mondial 84mm pistons from 1800 (1.8mm dome). My pistons have some little damage due to storage, which type of Scotch Brite I have to use ? In your book I read that medium Scotch Brite will be best, but I really don't know which color of Scotch Brite is medium. The worst that the seller did not know they, Scotch Brite isn't very popular product in Poland.

Are the 0.05mm bore-skirt will be good for a cast Mondial pistons in a street/track day engine ? Or I should to use another clearance ? Are the flex hone
will increase the clearance ? I want to buy a Flex Hone SC 180 tool.

Sincerely Piotr.
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Piotrek125p
Posts: 184
Joined: December 2nd, 2012, 3:45 pm
Location: Lodz,Poland

Re: Fiat TC Fast Road engine-a few questions.

Post by Piotrek125p »

Do you still recommend to modify the intake valves in the way specified in your book? I want to do a 30 degree top cut , waist stem to 7mm and maybe modify a radius. You write here
viewtopic.php?f=2&t=199
that you modify a radius on the inlet valves. What is the radius ? Which radius I should to use ?
Do you still modify a exhaust valves by approx the radius from 9mm to 12mm ? Or you do another radius/modifications ? Do you do a top cut 30 or 45 degree ? Do I have to modify a seat angles like inlets (30-45-70degress with 30 top cut on the valve) or do another combo ? I found this draw on your site
Fiat TC 8v ex seat 70deg throat.GIF
Fiat TC 8v ex seat 70deg throat.GIF (14.11 KiB) Viewed 6289 times
I did not find this information on your website about modifications of exhaust port, valves and seats, could you tell me what seats with top cut on the valve I should to use ?
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