2306

Sean,
Thank you very much for this most substantive ongoing thread (I'm one of many keenly watching/learning).
Three quick questions/clarifications:
- aluminum engine block?
- bladders installed by Dennis' shop?
-roll bar, Olthoff as well? 4 pt or 6 pt extending into cabin? 1.75" mild or 1.50" 4130?
Very Well Done,
Steve
 
Iron block so I can potemtialy vintage race. 4pt roll bar, the 6 point seemed to really restrict vision, custom seat and 6 point harness.

Bladders installed by Dennis.

Problems imo if you are going to do any type of tracking are the motor should be tied down from bellhousing to car from factory, and there is no reason not to do solids all around.

The brakes are not really up to the potential of the car, but then Gt40s never had great brakes. factory should offer a track brake upgrade option, something from brembo, baer etc.

Latest problem is the right front bearing loosend after 500 miles and is shot, will see if hub survived. Imo its a result of poor qc in SA.

I also would not do a 4bbl again. While the power is there, the car pulls enough gs on corners to cause one bank to flood while the other starves. That means a stumbling motor coming out of bends, whereas more precise power allows one imo to put it down sooner and acuratly hold the car at the limit on exit. 4bbl just seems too inprecise, but will try redo floats and primaries. However you cant prevent the fuel from sloshing to one side of the intake manifold on corners.

There is a reason they ran webbrs in period, More precise fueling, fatter and flatter tq curve even if h suffers a little.

That all being said, this is by far the most fun car I have owned. But its going to take 10-20k more and 10 days on track to be fully sorted as a strong really fast track machine.

Basicaly its undoing all the softenign spf did to make the cars streetable, most of that softening dosent do anyhting in term of streetability, and then relearning some things they learnt in the 60s..

As to the development I am doing now, thats what it takes to do a serious track machine.

While I was able to run down a new porche turbo at the track, this was more a driver thing, but the car as it is now is probably going to slay a regular 911c2s or new c7 vette.

I still need to loose another 12 secs per lap. Lets say 6 from sorting the car furtehr, maybe even 10 with brake ugrades, and another 5-7 secs from sorting the driver and bringing him up to speed.
 
http://willyscarb.com/.... holleys have had some clever people make them do stuff better in the last 50 plus years, this outfit is one of them, I have dealt with all the other pretenders with the glossy pages etc and it takes a bit to impress me, these carbs do.
 
Last edited:

Keith

Moderator
I ran a relatively unmodified 750 DP, on Al Unser Snr's Penske IROC Camaro on road racing circuits with no issues. As Jac says, there are some clever tweaks to Holley's these days and I must admit to being a fan of their maintenance free operation. Also one of the biggest pluses for me, was the ease of getting effective fresh air into the carb, not a simple feat with the Weber setup.

I am wondering if the real reason that Webers were used back in the day, was the sheer familiarity of the European race engineers with their common usage, although Alan Mann must have been very experienced with the US 4 barrel in his various Ford Galaxie/Falcon racing programs.
 

Rick Muck- Mark IV

GT40s Sponsor
Supporter
You can certainly upgrade the brakes if you wish, any number of calipers, i.e. Baer, AP, etc. will bolt to the upright brackets that SPF uses. The rotors are already beefier than the original cars used and naturally the choice of pads will have a large effect on the braking. The Wilwood parts were chosen to provide better than the era performance with off the shelf availability.

As to "softening" the suspension again the spring rates and shock valving used are not far from the specs FAV used. Certainly there have been huge gains in shock design and tuning since the 60s. Shock dynos were unheard of then and now many mid level race teams travel with a dyno and perhaps a shock specialist. In 1966 the crew guys turned the knobs on the Konis and waited for the driver to "yea or nay" the setting.

The GT40 is/was a heavy chassis compared to say a P4 or T70 and therefor reacts very differently to adjustments. It will take a much larger change to be noticed as compared to a T70.
 
The car is running a modified Holly built by Quick fuel, so maybe its just a matter of adjusting the floats or fuel flow. I also think that with the gs the car pulls on corners maybe the fuel is sloshing in the inlet manifold to one side.

Probably next summer we will put some 02 bungs in and see what its doing.

Running carbotech pads at this point, Imo the willwoods are fine for a hot rod. In 400 miles I had to replace one caliper and both master cylinders, plus the clutch master cylinder. In the end we started replacing these with tilton units. The calipers are simply ok for a street car, and farf rom what woudl be good on track. Even when they work, the modulation and bite is sub par. These are brakes for a hot rod, not a race car.
Would love to hear what woudl bolt on in their place, having lost brakes twice now.

My reference to softenign has to do with poly bushes and eliminating the attachements from the bellhousing to the frame, so the rear crossmemebr takes all the strain, and apparently deforms in spf cars. We are talking maybe $20 in parts the factory elimnated, you have to ask why, its pretty idiotic.

I can slo say that at 550 miles the right front bearing started to loosen, or I should say the retaing bolt did and the wheel was on its way to departing the car, the damage we will asess soon, possibly the hub.. Once again I have to say lackadasical QC in SA.

In short with 550 track miles the car has been unable to complete a full day, in each case its pretty much sub par componants or poor QC from SA.

I am slowly sorting and each day out the car gets better, but its frustrating and expensive having to deal with this stuff, and it should not be so.

As to suspension adjustments, its very sensitive, one click of rebound or compression noticably changes the car, and front end bite is phenominal.
 
I ran a relatively unmodified 750 DP, on Al Unser Snr's Penske IROC Camaro on road racing circuits with no issues. As Jac says, there are some clever tweaks to Holley's these days and I must admit to being a fan of their maintenance free operation. Also one of the biggest pluses for me, was the ease of getting effective fresh air into the carb, not a simple feat with the Weber setup.

I am wondering if the real reason that Webers were used back in the day, was the sheer familiarity of the European race engineers with their common usage, although Alan Mann must have been very experienced with the US 4 barrel in his various Ford Galaxie/Falcon racing programs.
Based on what peole here are saying, will def try to sort out the carb. We know the engine is loading up and missing coming out of bends. maybe fuel sloshing out the float bowels. Frankly between the brakes, crossmembers etc we have been focusing on getting the car dynamicaly sorted first, that part is getting really close.
 
I can slo say that at 550 miles the right front bearing started to loosen, or I should say the retaing bolt did and the wheel was on its way to departing the car, the damage we will asess soon, possibly the hub.. Once again I have to say lackadasical QC in SA.
One of my friend had the very same recurrent issue with his SPF, on front and rear bearings...
He had some sleeves machined, installed them on the hubs. This needed a change in the size of the wheel bearings (larger). Problem solved. Not a so heavy job, if you have a good machinist (PM me if you want his contact details, to get more info...)
 
ad some sleeves machined, installed them on the hubs. This needed a change in the size of the wheel bearings (larger). Problem solved. Not a so heavy job, if you have a good machinist (PM me if you want his contact details, to get more info...)[/quote]


Pm sent

Thanks
Sean
 
Last edited:
Sean,
Your problem sounds like the bearing retaining ring came loose. It is held by 2 small allen head screws. I would not jump to having the hubs machined with larger bearings unless the bearing fit to hub is truly too loose. The loose retaining ring would have affected your braking. I do agree we could use bigger brakes for track days, but it will never be like the 1400 lb. Lotus Europa I also track.
 
Last edited:
Dave

Thanks for the advice. Any other info you may have on track runnign one of these cars would be greatly appreciated. No need to reinvent the wheel.

Sean
 

Dave Hood

Lifetime Supporter
Holman Moody machined sleeves for my hubs. Why Superformance didn't do that at the factory is a head scratcher.

Dave
 
Ok our solution is a new locking collar that can be scverewed on before but with a small bolt in it so it can be clamped to the spindle, then we are also machining some bearing retaining rings out of better materials.

The locking collar loosened because the tab in the retaining ring failed.

So now the bearing should be held in place both by a locking collar, and a stronger retaining ring.

The question is why otherwise retained bearings come loose at all.
 
Top