weber progressive, cam Options

[blauer]

I'm new to the porsche game. I have a 73 with a 1.7l. It all was in a box. I've had experience with Type 1 bug motors but not 4. I have bought the weber progressive carb kit, planning on ordering the svda 034 from hotspark. Is the camshaft a big issue since it was an injected motor? Any info will help. Thanks.

[realred914]

I'm new to the porsche game. I have a 73 with a 1.7l. It all was in a box. I've had experience with Type 1 bug motors but not 4. I have bought the weber progressive carb kit, planning on ordering the svda 034 from hotspark. Is the camshaft a big issue since it was an injected motor? Any info will help. Thanks.

yup, big issue, teh FI system has a special cam need, cause the FI runs of vacuum singal, any changes there will effect teh tuning, and the FI has a really limited ability to be tuned. There are some aftermarktet non-stock grinds that will work with the stock FI (Jake Raby sells one that wworks, made for imporved prerformance but still works with stock FI)

in general a carb type cam will not work with the D-jet FI, dont do it!


unless your going for high performance, the stock FI is very nice, drivable and still capible of decnet perfromnance. however if you want a lot more power, the stock FI is limited. I prefer the Fi over carbs for a daily driver on a stock ish or slightly bigger than stock motor. for much more power you need to go aftermarket FI or Carbs. but the big bucks for that upgrade means it only makes sence if I do all the other things to get big power boost over stock.

have fun with yoru box of parts!!!!! keeps us posted on teh project, good luck!!!!!!!!!!!!!!

[smontanaro]

I'm new to the porsche game.

Actually, you are new to the NARP game. If all you've owned is a 914, you haven't really owned a Porsche, dontcha know? :-)

Welcome...

S

[VaccaRabite]

First off (IMG:style_emoticons/default/welcome.png) !!!!

Now, I am going to proceed to rain on your parade, but just a little.

1) Return the Weber Progressive carb. They are suitable for Pintos and for use as boat anchors, but not with T4 motors. The intake runners are too long, and fuel will fall out of suspension between the carb and the head intake. The result will be super shitty performance and increased fuel usage.

2) Cams are really important in the choice to either carbs (note, plural) or FI. Carb cams tent to be more aggressive, and the stock FI cam is mild.

3) A FI 1.7 with a good tune will make about 80 hp. A 1.7 with a FI cam and a progressive carb will make maybe 60hp, if you are lucky.

4) BUT YOU ARE STARTING FROM A BOX OF PARTS! This is FANTASTIC news. Why? Because the stock 1.7 bottom end, with a good cam and dual IDF carbs makes a 1911cc motor with 115 - 120 hp. And all you need is headwork (which you would have needed anyway) and 96MM pistons and cylinders. This will give you a revvy motor with a lot more power then stock, but with almost no extra building work, and not a whole lot more money in machine shop labor and parts.

5) And if the case is split to swap that cam, you can put the crank from a stock 2.0 in there, with your 96mm pistons and cylinders, and have a 2056cc engine. Similar HP to the 1911, but more low end torque (and what I built for my car.)

So, I rained a little, but also blew some sunshine. If you know your way around a T1, a T4 will be easy. Except that doing it right will probably mean little to no chrome. :-)

Zach

[jcd914]

(IMG:style_emoticons/default/welcome.png)

914's are sickness you will probably never recover from.

I don't think your cam choice matters much if you are going to use a single progressive carb on a type 4 engine. The single progressive carb does not work well on a flat 4 engine. The fuel drops out of the air flow at low engine speeds and collects in the intake runners. You end up with irregular mixture and poor driveability.
You are better off with FI or dual carbs.
If you go carbs and stick with the original FI cam you will be leaving some performance potential behind.

If you spend some time searching thru the site here you can find a lot of threads on cams, carbs, FI pros and cons.

Good Luck

Jim

[markb]

First off (IMG:style_emoticons/default/welcome.png) !!!!

Now, I am going to proceed to rain on your parade, but just a little.

1) Return the Weber Progressive carb. They are suitable for Pintos and for use as boat anchors, but not with T4 motors. The intake runners are too long, and fuel will fall out of suspension between the carb and the head intake. The result will be super shitty performance and increased fuel usage.

2) Cams are really important in the choice to either carbs (note, plural) or FI. Carb cams tent to be more aggressive, and the stock FI cam is mild.

3) A FI 1.7 with a good tune will make about 80 hp. A 1.7 with a FI cam and a progressive carb will make maybe 60hp, if you are lucky.

4) BUT YOU ARE STARTING FROM A BOX OF PARTS! This is FANTASTIC news. Why? Because the stock 1.7 bottom end, with a good cam and dual IDF carbs makes a 1911cc motor with 115 - 120 hp. And all you need is headwork (which you would have needed anyway) and 96MM pistons and cylinders. This will give you a revvy motor with a lot more power then stock, but with almost no extra building work, and not a whole lot more money in machine shop labor and parts.

5) And if the case is split to swap that cam, you can put the crank from a stock 2.0 in there, with your 96mm pistons and cylinders, and have a 2056cc engine. Similar HP to the 1911, but more low end torque (and what I built for my car.)

So, I rained a little, but also blew some sunshine. If you know your way around a T1, a T4 will be easy. Except that doing it right will probably mean little to no chrome. :-)

Zach

(IMG:style_emoticons/default/agree.gif) for the most part. If you can go back to the stock FI, I suggest to go that way.

(IMG:style_emoticons/default/welcome.png)

This quickly becomes an addiction, and there is no cure. Enjoy the ride. (IMG:style_emoticons/default/biggrin.gif)

[Mike Bellis]

(IMG:style_emoticons/default/agree.gif) with Zach and Mark

GET RID OF THAT CARB! IT'S A P.O.S. You will be very unhappy with the flat spot bog down as the secondary opens. If you must stay carbed, get some Dell's and a good cam to use them.

(IMG:style_emoticons/default/welcome.png)

[SUNAB914]

OK I got to say it. I'm tired of people dogging these carbs. Every 914 I've owned that was road worthy was carb'd, after the FI was pulled for bullcrap. All but one, I used the progressive carb, my other is duel weber. Not one that had the injection worked right, plus I watch you spends tons of money on parts all the time. How fast does it add up, plus over what a simple progressive carb cost. I live in NC as you can see, and yes it may not get below freezing for a very long time, but I use my cars as daily drivers and they are very reliable. Even in 30-40 degree weather, she's ready to go. Gas milage, I get 25-27 all day long in city traffic. Keep spending that money and replacing parts! Maybe Gasman will let me drive his one day and I can see what I'm missing. Until then stop giving onesided bum scoop.

[VaccaRabite]

If you need a car to get from a to b, the single progressive will get you there.

If you are looking at the car as a 30 year old sports car toy, the progressive ends up in the dust bin.

It all boils down to what you want.

[blauer]

okay, educated me. What is NARP? Yes, in your world, I AM obviously that stupid. Let's see... my dad had a karmangia... that he died in a crash. Every stamp and lable has VW on it. Realy, I asked a simple question because I thought this was probably a reliable site for REAL answers. I guess not. Have a nice day. Brent!

I'm new to the porsche game.

Actually, you are new to the NARP game. If all you've owned is a 914, you haven't really owned a Porsche, dontcha know? :-)

Welcome...

S

[Spoke]

NARP = Not A Real Porsche

About the center progressive, my 71 1.7L started life with me with a center progressive. It mostly ran good although in the winter it could be hard to start after running for a while because the carb would cool in the winter's cold temps and then I was trying to start a warm engine with the electric choke closed.

Besides that, it ran all the time. I couldn't run wide open throttle since all it did was blow out black smoke (inefficient combustion).

I bought another engine with a set of IDF40 Webers and put them on. The difference was eye-opening. Although a little harder to start from cold since it didn't have a choke, it ran all the time like the progressive.

The big difference was the more complete combustion under WOT. Now I was able to run WOT and not blow out a cloud of unburned hydrocarbons. The engine pulled much much harder (That's what she said) than with the progressive.

Bottom line if I were buying a carb, I would definitely stay away from the progressive and go with a pair of dual carbs. Not only do you have very short runners but each cylinder has its own carb situated directly above the cylinder intake.

[ArtechnikA]

okay, educated me. What is NARP? Yes, in your world, I AM obviously that stupid.

First, calm down.
Second, welcome.
Third - no one said 'stupid.'
Fourth - this is the right place for reliable answers, although the reality is that some of it may not be what you want to hear...

'NARP" - Not A Real Porsche.

The widely-held perception that the 914 is "not a real Porsche."
(The whole history is available here and elsewhere - the facts are plain enough. I will say no more.)

99% of the people here don't actually care if it's a Porsche or not, and 99.5% don't care what anybody else thinks. So just consider it a term of endearment...

There are thousands of pages of excellent technical information on this site.
Learn how to use 'Search' - it is your friend.

Most of the information in this thread is spot-on, but yoy may not be able to tell which is which is yet - you will, soon. Just as we're not calibrated on your experience yet, so some of the responses here may not be as well directed at the could have been.

If you're bringing up a project car, please - first - check for rust! Everybody wants to dive into the engine. You may discover after spending a lot of time, effort, and money on the engine that you have way more work ahead of you getting the chassis and suspension sorted. And it's no fun fixing rust with an expensive rebuild sitting under a tarp glaring at you...

[SUNAB914]

I couldn't run wide open throttle since all it did was blow out black smoke (inefficient combustion).
Something else was wrong with your car if this happened, not the carb.
Someone else posted fuel dripping down by heads. Must have forgot gaskets? or using wrong fuel pump.
flat spot bog down as the secondary opens. No flat spots on either of mine? Its called tuning your engine.