Fiat twincam project coming off the stand

[Nut124]

Slowly, but surely, my covid-19 Fiat twincam project is getting ready to go back in to the car.

This is a -78 1800cc twincam. Goal is 145-150 modern HP at 7000-7500. Dual Weber 44IDFs.

10:1 static CR. Steel top ring, alu whywheel, 4-2-1 header.

This was the engine/car used by Fiat in the World Rally Racing circuit in 1972-76 with some pretty good success.

[englertracing]

looks cool
does it use downdrafts because side drafts will interfere with the chassis?

[Nut124]

Yes. The brake booster/cylinder is in the way. Side draft would be ideal and cool.

[AC sports]

Looking good buddy!
The cam gears look to be from VAS. I've had a flange come off one of them. Check the screws holding the flanges on. Maybe loctite if need be.
How did you go with the sump?

[Nut124]

Looking good buddy!
The cam gears look to be from VAS. I've had a flange come off one of them. Check the screws holding the flanges on. Maybe loctite if need be.
How did you go with the sump?

AC, thanks. Yes, I replaced the VAS sprocket flange screws with longer ones and locktited them. They, VAS, should really use longer screws and locktite. I'm using a lot of locktite.

On the sump, I may regret it, kept the volume the same. I added baffles along the sides of the pan, 3/8" from the rim, about 1.5" wide. These needed to have relief cuts for the rod bolts. If you google "crank scraper" you'll see examples. Not sure if it makes any difference. I never had oil pressure problems on the track but did have oil coming out of the breather.

I drilled holes high up in the oil return tube to prevent crank case pressure from pushing oil up the tube under heavy load.

I am adding a 4-row oil cooler, which, with hoses, adds some volume. I also got a catch tank from VAS.

Installed billet aluminum flywheel from AASCO and Valeo clutch today. Planning on dropping her in with trans mounted this weekend. Will need to recruit some help.

Header fitting, mating to my custom exhaust is going to take some effort. It's hard to find good shops to do custom exhaust work here nowadays.

BTW, I got a set of head studs, nuts from ARP. Expensive but impressive. Very predictable, progressive torque development compared to the old torx head bolts.

[AC sports]

Glad to hear it coming along.
To be honest everything I ever bought from vicks was pretty crappy. Most of their stuff is manufactured in china.....nothing wrong with that....but they dont qc it when it gets to the u.s.
If your using their header, I suggest you check it against a gasket. One I took off a car had a 5mm mismatch. Gasses were hitting the flange.
I've never seen the AASCO flywheels.
I had one made from steel locally here for the race car.
Watch your oil pressure gauge on left turns. To be honest I've never used a crank scraper on a fiat tc. I played around with different sump designs and settled on either winged trapdoor type for track and slicks, and the type I emailed you for events on street tyres.
Do you have the part number for the stud kit you used? I'm with you on its advantages over bolt type attachment. Bolts are only convenient if your removing the head with block in car. Impossible to do with studs.

[Kevin Johnson]

...
Watch your oil pressure gauge on left turns. To be honest I've never used a crank scraper on a fiat tc. I played around with different sump designs and settled on either winged trapdoor type for track and slicks, and the type I emailed you for events on street tyres.
...

It has been ages but I believe Guy Croft developed a scraper. If you search that forum it should come up.

[AC sports]

As far as I know he too uses a gated winged sump . Never seen a scraper in his parts list.
Yours is the only commercially available one I know of Kevin. I dont think it does much for surge in a fiat though. I've no doubt it strips excess oil from the crank. The issue with the oem fiat tc sumps is lack of capacity, too much oil storage in camboxes, slow drain back and the pickup location not being central. Factory windage tray is only suited to mild road use. It's a shame because the bottom ends are immensely strong if fed oil!

[Kevin Johnson]

As far as I know he too uses a gated winged sump . Never seen a scraper in his parts list.
Yours is the only commercially available one I know of Kevin. I dont think it does much for surge in a fiat though. I've no doubt it strips excess oil from the crank. The issue with the oem fiat tc sumps is lack of capacity, too much oil storage in camboxes, slow drain back and the pickup location not being central. Factory windage tray is only suited to mild road use. It's a shame because the bottom ends are immensely strong if fed oil!

I think this was about 16 or 17 years ago on his forum. I might be mistaking a forum member constructing one for him having done so. I believe it was made from sections of 2mm steel that were welded to complete the pan flange.

[Kevin Johnson]

Guy just wrote back to me -- no, it wasn't him.

[Kevin Johnson]

Guy just wrote back to me -- no, it wasn't him.

A little bit of searching.

Here are Guy's thoughts on crank scrapers:

http://guy-croft.com/viewtopic.php?t=56

Here is where I remembered seeing it on Guy's forum:

http://www.guy-croft.com/viewtopic.php? ... t=15#p1971

It was actually fabricated by John Beardmore for a dry sumped 2.0:

http://www.beardmorebros.co.uk/website% ... _page1.htm

Back to work...

[Nut124]

My scraper baffles are pretty simple and have plenty of clearance.

[AC sports]

Some memory you have there Kevin!
Nut, that scraper / baffle looks good to me. Let me know how it is on left turns.
Are you running original weber 44 idfs or chinese versions? I've got a car here I set up on chinese ones and amazingly it runs really well. Only done around 20,000km though.
The only issue I've found with them is some jets are not as stamped I.e. a 50 idle jet could actually be a 70 . Also the throttle shaft bearings can be loose fitting and leak after a while. Had both occur in the past on customer cars.

[Nut124]

I have the Chinese Webers. Companies here in the US litigate about who here owns the Weber mark. Mine are labaled Weber but are not the Spanish or south american ones.

I went thru and stripped, inspected, deburred all parts thoroughly as needed.

I did have a problem with improper heat treatment of the throttle shaft where the threads are. Too brittle. Threads snapped off. Vendor replaced the carb.

What is a good initial setting for the bleed screws at the bottom flange?

[AC sports]

If you mean the air bypass screws with 8mm locknuts, I suggest you close them and try balancing the carbs. If your throttle shafts are not bent and your engine vacuum even, then they will balance without needing to compensate using the bypass screws.
As far as I know the italian firm sold off the business to spain and they are made there. I'm aware some of the smaller types were made in south America but IDF, DCOE should be made in Spain if current production. The chinese ones I've used were cast Fajs. They needed correctly calibrated jets only and worked well. Although the throttle shafts on a pair of DCOE types started leaking. Upon inspection, the shaft bearings were spinning loose in the housing and there was no air seal.