Author Topic: heat shields on a tunned engine?  (Read 12938 times)

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alapimba

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heat shields on a tunned engine?
« on: February 13, 2011, 10:38:18 PM »
hello

i have a 650cc engine with a 35/75 camshaft, -35,7/28 valves -lower 2mm head, and a record monza replica exhaust, 28weber.

Should i use or remove the engine heat shields? I mean the metal "floor" that goes above the dinamo.
Also can anyone please show me where should i connect the earth strap?

Thank you

DEYAN IYI

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Re: heat shields on a tunned engine?
« Reply #1 on: February 14, 2011, 09:36:17 AM »
Hi!

I wouldn't remove that thing - bad aerodynamics and dirty engine room :) I'm not sure if it helps cooling at all.

The earth strap - buy long enough piece of it. I have it connected on alternator case (also you can fix it on one of the 4 bolts on the holder to the block but for dynamo not a good idea), then on the left wall of the engine room on the bolts of the relay. It was the easiest way to do it, without making something special. I don't like the idea to be fixed on the bolts of the engine mounting "spar".

Your tuning kit sounds lovely :D But do not spoil it with the original carb :oops:

Greetings!  :)

alapimba

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Re: heat shields on a tunned engine?
« Reply #2 on: February 14, 2011, 10:30:01 AM »
eheh i'll keep the original carb for nwo because it was the cheapest way as i already had it with me.
I'll mdo some trips like this and then improv a bit maybe with a weber 32 dcof, not sure yet...

The engine mouting "spar" is the bar that bolts on each side of the car and where the engine sits on?

alapimba

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Re: heat shields on a tunned engine?
« Reply #3 on: February 14, 2011, 10:31:42 AM »
picture of the engine:



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DEYAN IYI

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Re: heat shields on a tunned engine?
« Reply #4 on: February 14, 2011, 11:42:32 AM »
 :D

Yes, the "spar" I mean that "bar".

'Bout the "budget"  part of the thing I can imagine :-X

Now I see, you got a 500, so if you worry about the hot air,
you can enjoy the old nice "open hood" Abarth look.

 :)

alapimba

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Re: heat shields on a tunned engine?
« Reply #5 on: February 14, 2011, 11:45:37 AM »
yeah i forgot to mention that it's a 500. but as all the mechanics is 126, including gear box :)

Rusty's Uncle

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Re: heat shields on a tunned engine?
« Reply #6 on: February 14, 2011, 02:13:35 PM »
 :D Hi the 500 has a plain metal , non vented cover as opposed to the 126 that has deep louvres cut in the section below the dynamo & cooling housing to encourage air flow. I have fitted a 126 cover as they are interchangeable if you trim a little metal from the rear left hand corner of the cover to match the shape of the 500. The standard earth strap on a 500 is a slightly heavier duty brown wire with lugs that bolts to the underside of the dynamo mounting casting bolts. Then connects to the bodywork at the lower nearside "spar" mounting stud. See picture  [-/
Two good reasons for refitting the Weber 28 IMB carb are that you know it will fit  :D
Then it will give you a chance to get to grips with all of the mods and see how well you can get it running before you try to blow the roof off.
One thing is for sure , you are going to notice a huge change from the stock 499ccs engine you started with. Have you checked out the carb number & jet sizes  ???

alapimba

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Re: heat shields on a tunned engine?
« Reply #7 on: February 14, 2011, 02:20:47 PM »
Hello, thanks for the picture. it helped a lot.
One doubt about that cover, the deep louvres were not supposed to be on the oposite way to get fresh air from under the car?

I didn't noticed that under the dinamo i could connect anything. Not i got the idea thanks.

About the carb i didn't checked the jet sizes, i just bought a kit from poland that had smaller jets than the ones fitted so i kep the original and replace only the gaskets.

By the way one doubt... the starter has 2 cables only that both attachs to the same place? It gets ground from the gearbox/block connection to the chassis? Is that?

Thanks

Rusty's Uncle

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Re: heat shields on a tunned engine?
« Reply #8 on: February 14, 2011, 06:25:35 PM »
I had to have a think about the direction of the louvres myself & came to the conclusion that there will either be a + or - air pressure under the back of the car when it is in motion so either way there will be air movement into the engine bay.
As for the main & air jets on the 28 IMB they seem to have gone through a bit of a roller coaster ride in terms of size throughout the range & as you say the later Polish carbs had the smallest jet sizes of all. As I found out biggest is not always best and the key thing is the balance between the main jet that will meter the fuel and the air jet that will control the mixture. One of my pet projects at the moment if you look in the 500 section on the forum.
The main black battery lead goes on the starter motor connection along with the thick brown wire that runs up to the control box. As you say the starter motor earths out on the engine etc  [-/

alapimba

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Re: heat shields on a tunned engine?
« Reply #9 on: February 14, 2011, 06:38:08 PM »
well it seems that i have everything well connected.
I just need today to put the fuel pipe from the pump to the carb and the car is ready.
I'm a bit of afraid to test it lol.
The engine had worked before out of the car but i'm afraid that i have done something wrong putting it in place  :oops:

i guess the starter is too close from the pipe that take the air from the engine to inside the car.
Probably because the gearbox is from a 126 and the car is a 500?

1973/126

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Re: heat shields on a tuned engine?
« Reply #10 on: February 14, 2011, 06:52:11 PM »
 I think you are right about that heater channel. I had to replace it for a 126 one when I done the same on my 500.
 Have you got a pull leaver starter, or the later type?
1972 Fiat 500
1980 Fiat 126

alapimba

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Re: heat shields on a tunned engine?
« Reply #11 on: February 14, 2011, 06:55:55 PM »
it's a pull lever starter.

by the way.. the anti backfire thing it's supposed to be installed inside the pipe that goes from the valve cover to the air cover???

it's suposed to have fire in that area?

Allan

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Re: heat shields on a tunned engine?
« Reply #12 on: February 14, 2011, 07:27:45 PM »
Flash supressor. My SLR had one on it in my Army days.
In reality it has two effects. One is to stop any problems caused by a backfire and the other is to stop the oil mist from clogging up the air filter. They need cleaning on a regular basis too.
Allan

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Re: heat shields on a tunned engine?
« Reply #13 on: February 14, 2011, 08:10:08 PM »
Good luck with the start up  [-/
As for the "backfire" thing , I think that component is wrongly described and it is more of a fairly crude scrubber ( don't get excited boys! ) that is there to catch oil mist & droplets and return the oil back into the system hence the angle on the outlet of the standard rocker box cover.

alapimba

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Re: heat shields on a tunned engine?
« Reply #14 on: February 15, 2011, 10:01:16 AM »
the backfire should be place in the end near the air filter or in the end near the valve cover? or in the middle of the pipe?

also the connection from the carb to the air filter.. originally it has a metal pipe between this 2 parts, theres anything wrong in use only one rubber pipe from one side to the other? (like in this picture)



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