914 and 550, both T4, One Cold Starts, the Other Doesn't, Why? Options

[Tastyplacement]

This is baffling to me. I have two type 4 cars, both have 914 motors and have a lot off commonality to them. My 914 starts cold no problem. My 550 replica is a total hassle to start cold.

The 914 which cold starts very easily:
-1.8 liter motor
-twin IDF 40 with no choke and no cold start circuit
Main Jets are 115
Idle Jets are 55
carbs were recently completely rebuilt
-Pertronix Ingnitor 1 points replacement

The 550 replica:
-2.3 liter motor
Main jets are 155
Idle jets are 65
carbs seem great, but haven't been thoroughly cleaned recently
-twin IDF 44 with no choke and no cold start circuit
-Pertronix Ignitor 3 points replacement

The 914, I pump the pedal once, car starts every time and is immediately steady. The 550, I have to pump the pedal 4 or 5 times and It'll fire quickly and die quickly. Once I do this a few times it'll run if I keep it at about 2000rpm by feathering throttle. Once it is warm, it's awesome.

[Rand]

I've never had luck with carbs and no choke being a friendly cold start combo. Surprised the 914 works so well. Does it run really rich after warm up?

[jvmarino]

Maybe the spark plugs. My carb'd 914 2.0 was tough when cold and I recently installed new plugs (after 20 years on the Platinum plugs I put in when I did a rebuild), and the cold idle is much smoother. The old plugs still ran great when the car warmed up.

[thelogo]

I would think the more performance oriented
Your engine is

The less flexibility it will have

Having just switched from a 1.7 to a 2.3 myself

2.3 wants to be warm and at wot

1.7 will do whatever you wanted just not with
Much power .


Like a formula 1 car , doesnt like to idle
At a stand still (IMG:style_emoticons/default/beer3.gif)

[arne]

What cams in each?

[Tastyplacement]

What cams in each?

Actually, that's a good point because the 2.3 has a particular cam, 307 Dur. x .500" lift, not sure how wild that is.

[Tastyplacement]

I've never had luck with carbs and no choke being a friendly cold start combo. Surprised the 914 works so well. Does it run really rich after warm up?

Yep, actually I think the idle circuit in the 914 is really rich, while it leans out in the main circuit. My a/f gauge was reading 8.5 at low RPMs, which seemed really rich and then 12 or 13 at WOT

[thelogo]

I always thought cold start
Meant like cold climate
Alaska ,Minnesota Wisconsin

But even southern ca 96 deg
And texas .

Cant imagine what cold start in
Real cold would be like



And you said you had a 550 replica



. And how tall is the car

Im 6ft 2 in a 914 .

Having a felling 550 is a bit tighter

[IronHillRestorations]

Performance cams usually mean less than stellar cold start properties. Hold it at about 2000 rpms until it gets up to temp.

From the info you've shared, the 550 is a much more radical engine and cold starting will never be great on an engine like that.

[rhodyguy]

Feather the throttle a bit on the big engine when it lights up. It will settle down. Typical.

[r_towle]

I may be wrong, but I think one of our vendors sells a throttle handle that allows you to set the throttle at a higher speed from inside the car when you start it up....its something that the six has, but I recall someone making it for the four...not sure.

For cold start, that camshaft will require some extra revs to warm it up prior to letting it idle...just normal.

[Tastyplacement]

How about going up one jet size (+5) on the idle jets?

I looked tonite and the Spyder has 50 idle jets, not sure why I thought they were larger.

I may be wrong, but I think one of our vendors sells a throttle handle that allows you to set the throttle at a higher speed from inside the car when you start it up....its something that the six has, but I recall someone making it for the four...not sure.

For cold start, that camshaft will require some extra revs to warm it up prior to letting it idle...just normal.

[ChrisFoley]

The 50s are too small for the 2.3L.
55 would be better, and probably is enough to set the idle mixture for easier cold starting.

[Tastyplacement]

Thanks chris, I am going to try the 55s, which I have on order.

By the way, I got your shift linkage put in my 914 recently and it truly is spectacular...

The 50s are too small for the 2.3L.
55 would be better, and probably is enough to set the idle mixture for easier cold starting.

[porschetub]

Wow huge jets...why,those mains are massive, what vents are you running ,if that makes it go your vents are too big.
Bigger is not better,camshafts are the same (IMG:style_emoticons/default/sad.gif)

[Rav914]

Wow huge jets...why,those mains are massive, what vents are you running ,if that makes it go your vents are too big.
Bigger is not better,camshafts are the same (IMG:style_emoticons/default/sad.gif)

I'll buy that. I had 32mm vents on my 1911. Cold start, idle, and starting from a standstill required lots of throttle in order not to stall. I switched to 28mm vents and problem solved.

[ChrisFoley]

Wow huge jets...why,those mains are massive, what vents are you running ,if that makes it go your vents are too big.

Those aren't too large for a 2.3L with a long duration camshaft.
It might even call for bigger mains and bigger airs.
I wouldn't hesitate to put 36mm venturis in those 44s if the engine is configured for top end performance.

[EdwardBlume]

(IMG:style_emoticons/default/thisthreadisworthlesswithoutpics.gif)

Somebody had to do it. Lets see the 550 Rep. (IMG:style_emoticons/default/cheer.gif)