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dangfiat
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another question: for a tuned 650 or 700... an electric fuel pump or stick with the mechanical? I'm leaning to going electric
Tuning Stroker Crank
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Tuning Stroker Crank
the hobbler
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There is nothing wrong with the original mechanical pump---it will easily supply all the fuel that your carb will need. My tuned '659cc' engine still has the original pump--never had a supply problem. I will be keeping to a 'mechanical' pump on my '695SS' engine. Abarth never fitted an electrical fuel pump even on their most powerful engine--the 695SS. If you DO go to 'electric' pump, don't forget to fit an automatic "cut-off" switch in case of an accident. With a mechanical pump, as soon as the engine stops, the pump stops. With an electric pump, even if the engine stops, whilst the ignition is on the pump will continue to pump petrol. Keep to the mechanical pump--it is a heck of a lot less hassle!
Hi Daniel, Whilst I agree with Tom's reasoning in his last post it is after all a personal choice. I do use a small low pressure electric pump to feed my twin choke and a weber DGF 30 on my spare engine, I don't have any 'hot' problems and the carbs don't flood either. Remember the wilder the engine the more need for positive fuel feed at all times - and always carry a spare 
If you need any information on the type and make of pump I use please ask.
Ian.
If you need any information on the type and make of pump I use please ask.Ian.
I upgraded to an electric, Obviously they have their plus and minuses.
One key thing is to use a low pressure pump designed for low pressure carburated applications.
This is the one i am using.
Mr. Gasket 42S Mr. Gasket Micro Electric Fuel Pump
Gravity fed type pump with simple two-wire design. Works on 12 Volt negative ground systems only. Includes fittings and mounting hardware along with easy to follow DIY instructions. Pumps require approximately one amp average draw at maximum delivery. Flow rate is 28 gallons per hour (GPH) at 2...
www.holley.com
I believe rockauto and amazon has it also, the same unit is rebranded by a few of the holley brands. The 42S is the lowest pressure one, and the one you want. 2-3.5psi. They have a 12S model that does 4-7 psi. Too much pressure and the float will have issues trying to stop flow. But obviously it depends on the type of carb you have.
If you search "AUTOBEST 42S" you will find it.
Interesting to see what everyone has been up to regarding modding the motors, i started my project a long time ago and fitted a ported big valve panda head onto big bore standard crank motor, (800cc) 10.5 to1 cr 42/82 cam it made 52 bhp @6000 and 46lbs/ft @5500 on the dyno. A little disapointing tbh was expecting around 60 hp. Didnt know about Lavazza heads at that time..... Anyone on here know the gear ratios of the 126 gearbox?So. ive spent a fair bit of time looking and researching the progression of upgrades and performance for these cars. The D'angelo head is honesty very intriguing.
Im assuming your talking about the lavazza split head.. https://www.dangelomotori.it/en/pro...-head-complete-with-new-lavazza-tappet-cover/
Ive spent a few long nights browsing the Italian fiat 500 forum, trying to discover what secrets they have hidden there.
Ive come to the general conclusion that typically head modifications progress as follows:
-Std500 head
-Std 500 head with porting
-Std 500 head with porting and valve size increase
-std Panda 30 head with twin duct
-std Panda 30 head with port/polish, and maybe valve size increase.
Then racers start to get creative:
-Std 500 head that has been machined to accept a dual intake
-panda 30 head with significant port machining
View attachment 439057
View attachment 439055
View attachment 439059
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The most extreme versions are some folks who have made fully custom dual overhead cams for these little engines.
The lavazza head seems to take all these design trials and tests into a complete package if you want to go near full race.
Obviously these heads come with a price, but it would be nice to dream, who knows
Definitely looks like a well designed pc of kit.
View attachment 439058
With all of this said, i am disappointed in the fact that there are absolutely no test values or flow graphs for anything sold on the market for the 500. To me this is odd and uncommon, as most companies that sell aftermarket heads/cams in the North American car market typically have flow charts and actual dyno results showing some form of % increase. Obviously there's a lot of different customization options one could have as a completed engine for the 500 (displacement, cams, exhaust etc), but i wish the market had some sort of baseline comparison for those of us shopping for aftermarket goodies with actual comparative values, especially for the $$$ stuff like the lavazza head... nearly 2000€ but no real figures, like ??..
Im in the process of building a flow bench, and i have a stock 500 head, along with a ported one, one with larger valves and a few panda 30 heads (stock and modified), that i would like to bench test and share the research on the forum for folks to reference to. The italian forum likes to keep all this info hidden unfortunetly from what i could see.
Hi Mossfred, regarding 126 GB ratio's - 1st 3.250:1 2nd 2.067:1 3rd 1.300:1 4th 0.872:1 Diff 4.875:1 (8/39)
If you swap the standard diff for the 126BIS item you get 4.333:1 (9/39) The BIS diff in my gearbox will pull 60mph @ 4000rpm but I have 165x60 12 tyres.
Hope this helps.
Ian.
If you swap the standard diff for the 126BIS item you get 4.333:1 (9/39) The BIS diff in my gearbox will pull 60mph @ 4000rpm but I have 165x60 12 tyres.
Hope this helps.
Ian.
Hi Ian, thank you for the info… I already a have a 5th gear on my trans but it broke the other day.
I don’t know what the ratio of that gear is either but now you’ve given me this info I can choose more wisely!!!
My car pulls to the rev limiter in 5th very easily. It’s also quite scarey!!!
the hobbler
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A word of warning, as passed to me by Tony Castle-Miller (Middle Barton Garage)---the 5th gear should only be regarded as a "cruising" gear and NOT an "accelerating" gear. It would seem that in most of the 5-speed conversions, the 5th gear shaft is only supported at one end. I have a standard 126 box in my Fiat, and with 165 x 55 x 13in tyres, my car is geared to 14.54mph per 1,000rpm which translates to 87.24mph at 6,000rpm (or, 85mph at 5,882)
I’ll have a good look when it’s apart….
the hobbler
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Just as a matter if interest, your power output of 52bhp, was that at the flywheel or at the wheels? If it was "at the wheels", the "at the flywheel" measurement would have been nearer 60bhp.
It’s measured at the wheels but they calculate it back to flywheel power. I’m pretty sure the wheel hp is shown as well but I can find the graph at the moment.
Hi Mfred, I've had a dig around and found that the 5th gear would be around 0.7428:1 although I am unsure which maker that figure came from.
Ian.
Ian.
Hi Ian, got mine from D’Angelo. I’m looking for a Bis box now to give me the higher final drive ratio
