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914World.com _ 914World Garage _ 914 and 550, both T4, One Cold Starts, the Other Doesn't, Why?
Posted by: Tastyplacement Jun 24 2017, 08:11 PM
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.
Posted by: Rand Jun 24 2017, 08:13 PM
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?
Posted by: jvmarino Jun 24 2017, 08:21 PM
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.
Posted by: thelogo Jun 24 2017, 08:28 PM
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 
Posted by: arne Jun 24 2017, 08:47 PM
What cams in each?
Posted by: Tastyplacement Jun 24 2017, 10:38 PM
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.
Posted by: Tastyplacement Jun 24 2017, 10:40 PM
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
Posted by: thelogo Jun 24 2017, 10:57 PM
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
Posted by: Perry Kiehl Jun 25 2017, 11:38 AM
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.
Posted by: rhodyguy Jun 25 2017, 12:54 PM
Feather the throttle a bit on the big engine when it lights up. It will settle down. Typical.
Posted by: r_towle Jun 25 2017, 01:31 PM
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.
Posted by: Tastyplacement Jun 25 2017, 06:04 PM
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.
Posted by: Racer Chris Jun 26 2017, 09:31 AM
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.
Posted by: Tastyplacement Jun 26 2017, 11:23 AM
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.
Posted by: porschetub Jun 29 2017, 11:34 PM
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 
Posted by: Rav914 Jun 30 2017, 08:29 AM
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
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.
Posted by: Racer Chris Jun 30 2017, 08:38 AM
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.
Posted by: Edward Blume Jun 30 2017, 09:47 AM
Somebody had to do it. Lets see the 550 Rep. 
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