cams, head work, or high compression pistons?

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valkyrcustoms
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Joined: Wed Aug 28, 2013 10:56 pm
Your car is a: 1975 Fiat 124 spider
Location: Austin, TX

cams, head work, or high compression pistons?

Post by valkyrcustoms »

So I am getting my 75 a few things to give it a little boost up from plain stock condition but I would like to plan ahead for future additions and so I can start researching what parts I would need for each step.

I just got a 36 ADL and will be installing it in the next week or two. I am also looking for a less restrictive exhaust at the moment to complement the bigger carb since I have the more restrictive 4-1.

My question is, what should I do after that? Cams, head work, or which compression pistons? Any suggestions on how I can go about any of these is appreciated. Keep in mind, I do want to drive this car a lot, maybe not as a daily but certainly with the ability to perform daily duties if I so desire.

I do plan on bigger(???) Cams and high comp pistons in the future just trying to find out which I should do first. As for head work, not sure if it is needed or worth the cost for the increase in performance you get. By head work I mean thins like port/polish, larger valves, however many angle valve job.

So any suggestions on how I should proceed are welcome. If you can give me reasons why I should go one way over another, that would be awesome as well.

On a side note, I did also just purchase a single 45dcoe with manifold from another member here, so if any future upgrades at better suited to that setup please take it into consideration.

Thanks in advance.
-Rudy O.
1975 Fiat 124 Spider (1756) [Jackie]
1975 Kawasaki KZ400 [Sofia]
1982 Honda CB750f [Amelia]
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azruss
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Re: cams, head work, or high compression pistons?

Post by azruss »

without ever going into the engine, you can add a lightened flywheel, aluminum crank pulley....the big cast iron one that drives the alt. Adjustable cam pulleys and an high performance ignition like computronix.
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RRoller123
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Re: cams, head work, or high compression pistons?

Post by RRoller123 »

I can say that the lightened flywheel I just had installed made a great difference in my 80FI; it really zips around now, much faster than it was before. Next is performance head and cams, then higher compression pistons.
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engineerted
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Re: cams, head work, or high compression pistons?

Post by engineerted »

You should start with a good base. That means HC piston first. Then every thing else will just be add on's. You may have heard this before, " Power is made in the head" when you increase flow thru the head you increase power, so bigger valves, larger cams, and beter port flow.
Ted
1978 124 Spider, Complete Restoration
1974 Fiat 124 F Production Race car
baltobernie
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Re: cams, head work, or high compression pistons?

Post by baltobernie »

My vote is to spend your money on dialing-in your new carb/exhaust setup. For this you need the services of a chassis dyno and a mechanic who understands Weber carburetors. We get a LOT of cars in our club that the owners have spent good money on upgrades, but leave a bunch of performance and driveability on the table. Sometimes, a truly skilled mechanic can sort out a modified car. We're fortunate to have such a guy, but most of you will have to make do with numerical data such as A/F ratios and WHP.
So Cal Mark

Re: cams, head work, or high compression pistons?

Post by So Cal Mark »

until you add some compression you'll be limited to cam selection and the amount of head work that is beneficial. The light weight flywheel is a great way to add performance without going into the engine
valkyrcustoms
Posts: 63
Joined: Wed Aug 28, 2013 10:56 pm
Your car is a: 1975 Fiat 124 spider
Location: Austin, TX

Re: cams, head work, or high compression pistons?

Post by valkyrcustoms »

You make a good point, Bernie, and I had not even thought of that. Does anyone know of a good shop or local member in Austin, TX that could dial my new carb in? If not in Austin, then Houston or Dallas areas, since they are relatively nearby?

So then the general consensus seems to be compression before cams/head work. I will be looking into the other suggestions to get some lightweight goodies and hi-perf ignition first though.

Anyone have suggestions on what exhaust I should go with. Factory 4-2-1? Abarth style header? Allison's snake tube headers? I would like to go with one that will not become a choke point in the future after final upgrades. I think at that point I may swap in that 45 dove. Sound like a good idea?

Once again, all suggestions welcomed and considered. Thank you to all who have responded and will respond in the future.
-Rudy O.
1975 Fiat 124 Spider (1756) [Jackie]
1975 Kawasaki KZ400 [Sofia]
1982 Honda CB750f [Amelia]
valkyrcustoms
Posts: 63
Joined: Wed Aug 28, 2013 10:56 pm
Your car is a: 1975 Fiat 124 spider
Location: Austin, TX

Re: cams, head work, or high compression pistons?

Post by valkyrcustoms »

On a side note, I apologize for being so long winded. Just like to give as much info to get the best responses.
-Rudy O.
1975 Fiat 124 Spider (1756) [Jackie]
1975 Kawasaki KZ400 [Sofia]
1982 Honda CB750f [Amelia]
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azruss
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Re: cams, head work, or high compression pistons?

Post by azruss »

from what i have read, the factory 4-2-1 gives good performance without issues of excessive heat and other such nuances.
vandor
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Re: cams, head work, or high compression pistons?

Post by vandor »

>So then the general consensus seems to be compression before cams/head work.

Well, that is ideal, but a lot of people have put hi-po head, cams, etc on stock compression engines because they did not want to touch the block. It will be faster than stock, but not up to its full potential.

>Anyone have suggestions on what exhaust I should go with.

Depends on what level of performance you want. The Abarth style header works very well on the 1800.

I think you have a good chance of finding some local Fiat heads and get a tech session going to get your carb dialed in. I think there is an email list for the Austin Fiat group?
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toplessexpat
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Re: cams, head work, or high compression pistons?

Post by toplessexpat »

vandor wrote:>So then the general consensus seems to be compression before cams/head work.

Well, that is ideal, but a lot of people have put hi-po head, cams, etc on stock compression engines because they did not want to touch the block. It will be faster than stock, but not up to its full potential.
... and being one of those people - it's pretty quick .... plus I can still kid myself that I'm waiting to put forced induction on it and so need to keep the compression low :)
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joelittel
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Re: cams, head work, or high compression pistons?

Post by joelittel »

I too am one of those people. I have a hip-po head, lightened flywheel, performance cams, adjustable cam pulleys (cams degreed at 109 per cam spec), header and a larger free flowing exhaust. This has all made a nice difference in how the car feels. It's quick and impresses everyone who rides in it.

I will be adding high compression pistons down the road but because of the financial commitment I have always put it off and gone for something I could get right away.

Knowing what I know now about the car (after 5 years of ownership), if I had to do it all over again I would have started my mods with the higher compression and built up from there. Everything I have done has made an improvement, but like Csaba said, the mods are not operating at full potential without the higher compression. So as it works out for me, being impatient with my modification purchases will cause me to wait longer to feel the full potential of everything I've already put into the car! Ha ha ha ha there's one of those stupid life lessons in there somewhere.
So Cal Mark

Re: cams, head work, or high compression pistons?

Post by So Cal Mark »

we've built loads of cars with cams, headers, carbs and they do show marked improvement. But since this thread was about the ideal way to start, I'd suggest getting the compression right at the beginning. If you don't NEED to build a complete motor and have a budget, then go with the bolt-on improvements
valkyrcustoms
Posts: 63
Joined: Wed Aug 28, 2013 10:56 pm
Your car is a: 1975 Fiat 124 spider
Location: Austin, TX

Re: cams, head work, or high compression pistons?

Post by valkyrcustoms »

Thank you all for your suggestions and ideas. I will definitely have to put more thought into this subject before spreading my limited wealth across the web. Lol. I will probably go with the ignition upgrade first and them some light weight bolt ons before getting to block or head stuff.

Buy for the moment, mark, can you tell me how much improvement may be experienced with one of your snake tube headers over a 4-2-1 OEM system? Or what each one is better suited for?
-Rudy O.
1975 Fiat 124 Spider (1756) [Jackie]
1975 Kawasaki KZ400 [Sofia]
1982 Honda CB750f [Amelia]
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azruss
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Re: cams, head work, or high compression pistons?

Post by azruss »

if you are looking for more than just motor performance. I highly recommend a rear sway bar
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