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Vintage Racer Build

Posted: Tue Aug 13, 2019 12:02 am
by ST3Racer
There have been a few mentions of my current project, which is a re-body rebuild of my old EP/ST3 124 Spider Racer into a Vintage Racer. This build was necessary as Vintage requires an all-steel ( or all stock shell) body shell. My old EP racer had the Baucom FG body kit (for sale.....), and could not be easily used for the Vintage build, so hence, the new body. I am building to the SVRA Group 3, D Production spec, and will be racing in Colorado, and Texas.

The body I picked up is a '79, already stripped for racing, but never progressed past the stripping phase (perfect for me), and sitting for the past 15 years. This is being backdated to '72 trim (rear is done, front is not, yet), to conform to the Vintage rules, and powered by a full-race 1756cc engine. Most of the rest of the old running gear is being moved over to the new body. The Wilwoods will be left behind for FIAT brakes, by Vintage rules.
forlorn, but solid, and rust free 12/15/18
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newly built full-race engine
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70's cage in new body, 7/15/19
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front, not backdated yet
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fuel cell fabrication
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rear, backdated for older tail lights
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Re: Vintage Racer Build

Posted: Tue Aug 13, 2019 8:47 am
by friedman
That is a serious looking roll cage, looks like you could go over Niagra Falls and survive.
I note you run the gooseneck for an external thermostat, is that your plan and is there an advantage to that over an in-head thermostat (which would be easier to use restrictors instead of a thermostat)?

Like most of us non-racers, I find threads like this very interesting so keep posting and excuse my questions if they seem simplistic.

Re: Vintage Racer Build

Posted: Tue Aug 13, 2019 11:01 am
by ST3Racer
In considering this re-body build, I knew it would be important to keep the roll cage from the old chassis. It is the vintage provenance of this build as it was originally built by E.J. Trivette out of Jacksonville, FL in the early 70's. There were two bars added to comply with SCCA rules from the mid 90's, but it is mostly original, and has historic significance. It was a PITA to get it torched out whole from the old chassis, however. I DO feel very secure in that nest of tubing, while driving in competition. Ironically, the cage doesn't conform to SCCA rules post 2007, where there has to be a certain length of horizontal tubing in the main hoop....

What is pictured on the engine is a stock in-head t-stat housing, with a modified filler connection. I use a dual-pass aluminum racing radiator that has no filler neck. The modified filler gets the fill point to the highest point possible, to make it easy to fill and remove any air bubbles. The brass fitting goes to overflow. I use a standard (but modified) in-head thermostat. It all works.

As far as the questions go, ask away, as I am pleased to answer.

Re: Vintage Racer Build

Posted: Fri Aug 16, 2019 3:39 am
by ace124
What are you doing about oil surge control? I see your running an OEM type wet sump, i assume with some trick internal baffling?
Even with an Accusump ive never been able to totally eliminate oil surge on corners with mine. Even on street tyres, let alone semi slicks i race on.

Re: Vintage Racer Build

Posted: Fri Aug 16, 2019 8:48 am
by friedman
When I did track days on my stock sumped spider I always overfilled by one quart and that got rid of oil starvation in hard least for my driving level on street tires.

Re: Vintage Racer Build

Posted: Sat Aug 17, 2019 2:10 am
by ST3Racer
John, Carl,
I wrote a good reply this morning, and then fiddling with a sideways picture caused my reply to evaporate.... So, I will try again.

A good but simple oil system will make all the difference on the FIAT TC engine, for fast road or race driving. The most important thing to do is to install an oil cooler. This will improve the oil capacity, oil delivery, and oil temperature (in that order). Use a sandwich plate that is available from Summit Racing. This plate fits in between the oil filter housing, and the filter. It will allow the use of a Toyota filter from WIX, readily available, and also available as a NAPA Gold part (also made by Wix). A 16 row cooler for the street, and a 25 row for racing, will do wonders. The addition of an Accusump will complete the system for a racecar. Proper install on the accumulator is to remove the insert plug on the Main Oil Galley on the exhaust side of the engine and tap for a -8AN fitting to connect a hose from the accumulator to the fitting. For racing, I use the 3 quart manual valve unit which is mounted on the passenger side alongside the tunnel. There is no Passenger seat. For the street, a 2 quart Accusump can work mounted sidewise right in front of the passenger seat. Precharge the unit with 10psi of air pressure, and fill the sump with the normal capacity. Start the car and run up the pressure after the valve is opened to 60 psi and shut off the valve and the engine. Then check the oil level, and over fill about 1/2 qt, but no more. Ditch the Veglia oil pressure gauge for a good one when you place your Summit order. An Autometer is just fine, and you can get one to match the other gauges.

I run a stock oil pan on both cars, with no added baffling. I have done this for more than 25 years with no oiling or oil pressure problems. Simple but effective. Simple Oil Cooler install. Simple Accusump install. The fitting location on the block is the key to the accumulator install, but the real difference I believe is the oil cooler.

I would welcome any questions or comments about this, as I truly believe that these modifications make the FIAT TC engine vastly more reliable under hard running conditions.
-8AN fitting into the main oil galley
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Re: Vintage Racer Build

Posted: Sun Aug 18, 2019 1:11 pm
by ace124
Its interesting to read about your setup. Mine is similar but with a 2 quart accusump through a sandwhich plate above the oil filter. I used to run it as you do direct into the exh side oil gallery, but there was limited room for the alternator bracket, and i didnt like the hose been so close to the exhaust.
What oil viscosity do you run?
Are you running oil restrictors in the block or head to restrict flow to the head?
Have you lowered the oil drains in the head?
Interesting to compare.

Re: Vintage Racer Build

Posted: Mon Aug 19, 2019 12:23 am
by ST3Racer
The simpler the better. I would use the oil cooler sandwich plate just for the oil cooler, and not plumb the Accusump through that device. In/out short runs to the oil cooler and back. Simple - works. I use a 16 row on the Street car, and that’s it. I believe that this is the most important modification you can make to the oiling system for fast road driving. I track the car and tour with it as well, and have had no problems in more than 20K mostly hard driving.

If you wish to have an Accusump (accumulator), either for fast road use or for racing, I would not run the plumbing thru the sandwich plate, but direct to the main oil galley. One simple hose run. The simpler and shorter run benefits the system by keeping most of the oil in the engine, where it belongs. I also would not run the plumbing as shown in Guy Croft’s book - too much hose, and too much complication. Keep the oil inside the engine.

I didn’t think fitment of the one hose to the main oil galley would be a problem until you mentioned it as I only run the accumulator on the racer, and it has no alternator - total loss electricals run from a deep cycle battery that as a system has worked perfectly for more than 20 years. In light of your reply, I took a look at the street car engine to see the clearance issue.
street car oil galley plug
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Looking at it from the standpoint of having done a lot of AN fitting plumbing on my cars as well as customer cars, I think it would be tight, and not doable with the straight port fitting I use, but a 45 degree port fitting pointed up, would route the line up and over the alternator, and would allow routing over to the frame rail and back from there through the firewall to the accumulator. Same approximate length run of hose. Direct, simple - works.

I use Schaeffer’s 7000 20W-50 racing oil in both cars. It is an excellent oil that I sold like crazy when I had my dyno shop. I sold that business 2 years ago and the new owner still sells Schaeffer’s like crazy. It is available on-line, and through speed shops. Like any racing oil, it will work well on the street, but needs to changed out often. I change the street car oil every 2-3000 miles, and the racer every 2nd race weekend.

I run oil restrictors on the oil runs UP to the head, in the head, using old weber main jets drilled out to 1/16th inch. Easy to find these jets. Drill them out, tap the holes and screw them in and forget ‘em. Tap in far enough to allow for re-machining for any future rebuilds, or possible head gasket blows.
oil restrictor in the head
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I also lower the drains in the cam boxes.
cam box drains mod
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The real reason for this restriction UP, and relief DOWN is that with sustained high rpm, the FIAT TC engine pumps too much oil up to the cam boxes and fills them up to point that it will force oil out of the gaskets and oil cap. Too much oil up in the cam boxes, and not enough for the main/rod bearings. Bad. Some folks have tried to plumb in vents in the cam covers to cure this inherent problem, but that just pumps the oil out of the engine..... The stock set-up is perfectly fine for street driving, but not racing. With these modifications, the FIAT TC engine can be made to be bullet-proof. I got this great intel years ago from a write-up done by the late Bob Swenson of PBS Engineering. His firm in Cali was a go-to for FIAT racers years ago for his cam grinds (I have an F2 inlet cam), his machined flywheels (one in my Stradale), and other FIAT TC goodies, as his shop raced FIATs. I got a chance to speak with him before he passed on, and will remember his insights clearly. He didn’t care for the 2L, but thought the 1.8L was FIAT’s best, and as both of mine are now 1.8L engines, I keep his write-up in my racing notebook. These days, PBS makes sequential racing transmissions, and parallelogram racing jacks that they developed many years ago (yep, like in F1..).

Re: Vintage Racer Build

Posted: Tue Aug 20, 2019 4:50 am
by ace124
Cheers Bill
All standard Fiat racer stuff we do over here as well. I prefer to restrict in the block though. That way less oil pressure goes through the head/block connection and in theory less chance of a head gasket oil leak. In theory though as ive never known head installed restrictors to be an issue.
What bearing clearances are you running on mains and rods?
I read your running chevy rod sized bigends. I went another route and used a VW 136mm rod and reground the crank rod journals to suit. Cheaper rod option and better bearing selection. And less friction from a smaller journal...again in theory.
How do you chamfer your chev bearings to fit?

Re: Vintage Racer Build

Posted: Wed Aug 21, 2019 1:14 pm
by ST3Racer
Where is 'over here' ?

The rod bearings for the Vintage engine were supplied by Pauter, the rod supplier, and a modified type to fit the chamfer requirements of the FIAT crank. There are many different bearing configurations of the chevy rod bearings (wide, narrow, etc.), but using these on custom rods provides supply advantages you can no longer get using FIAT derived rod bearings.

I investigated the VW option on the rods, but I always use a stock dimension journal crank. It is my understanding that the 2L crank is forged, and should NOT be ground undersized, and that the hardening on the 1.8L and other FIAT cranks is surface only, and those should also not be ground.