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> Rough Running 2 Liter, Is it just the cam?
newdeal2
post Mar 14 2005, 09:11 PM
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I have finally had time to re adjust the valves after a test drive gave me the quivers. The car ran too "choppy" in the mid range under load so I figured the .004 on the exhaust valves were causing the problem. I re adjusted to the "safe" clearances of .006 intake and .008 exhaust.

Now it runs better but here are my concerns: The car runs like crap if I don't let it warm up to a decent temp...say 5-10 min's. Then it runs pretty strong. If I crank it up and just drive it's pretty choppy on the low end and get's up and pulls in the higher rpm range.

As you all may know I have euro pistons, Raby designed Webcam [73 grind] for stock D jet and that's about it. I have done timing, checked plug and point gaps [tried different variations], check all hoses [both systems]. Compression is pretty good [130-145 and still under 100 miles on the rebuild].

So...if it needs a good warm up, runs choppy in the low rpm range but grunts above the 2,000 range is it just the fact that I have a hotter cam than stock and it's just the nature of the beast?

Feel free to analize this!
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Demick
post Mar 14 2005, 09:46 PM
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I have a 73 webcam. It runs great - not choppy at all. But the idle is not as smooth as stock - and I attribute this to the cam. I keep the idle at 1100 or so and it is good - but drop it down below 1000 and it gets a little rough.

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newdeal2
post Mar 14 2005, 09:58 PM
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Yep...same thing. I find 1100 to be good too. Do you warm up you car before driving or can you get up and go cold [meaning 60 or so in FL]?
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redshift
post Mar 14 2005, 10:03 PM
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Dood... NEVER DRIVE OVER 3 GRAND UNTIL IT'S WARM, AND I MEAN REAL WARM.

Do not short shift. Do not run in fifth gear below 2700 rpm. EVER EVER EVER.

If it's choppy... you are destroying your motor.

Sit in the parking space on the first start of the day for at least 90 seconds with the revs at 1500-1800, then proceed carefully, until warm..



M
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Rhodes71/914
post Mar 14 2005, 10:07 PM
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From my experience with my 914 and other Type IV engines I've had they all need a little warm up time. Even in fairly warm temps they need a few minutes to warm up from sitting overnight.
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Demick
post Mar 14 2005, 10:12 PM
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My motor needs no more than 30 seconds or so of warmup. Of course I don't drive it hard when cold, but it runs just as smoothly cold as it does warm.

Demick
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Jake Raby
post Mar 14 2005, 10:15 PM
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That cam isn't choppy at all... My version of the 73 runs as smooth as stock, sometimes smoother.

Are you running stock or Chromoly pushrods?

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newdeal2
post Mar 14 2005, 10:18 PM
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Not to worry...the only time I notice it is when I am moving the car out of the driveway and it's a "gentle persuassion". Just ran the car once or twice with a short warm up and notice a difference if I don't let it get up to temp. I never push the car dead cold.
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newdeal2
post Mar 14 2005, 10:22 PM
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Stock pushrods. I cleaned and checked them prior to install I think I have to get back to basics and see if I missed something. I also noticed one or two of the insulators on the wire set are broken at the plugs. Could be the spark arching to the heads?
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nebreitling
post Mar 14 2005, 10:27 PM
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my bet is that it's ignition related. and definitely replace those plug wires...
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JoeSharp
post Mar 14 2005, 10:29 PM
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Camed D-Jet. What did you learn?
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newdeal2
post Mar 14 2005, 10:34 PM
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Yea...I'm thinkin in that direction now. New wires and a good Petronix may be the ticket.

BTW...why the hose clamps on the runners?
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JoeSharp
post Mar 14 2005, 10:39 PM
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PARANOID!!!!!
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Jake Raby
post Mar 14 2005, 10:40 PM
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Big No No...

The stock pushrod is never optimal when used with a 73"ish" camshaft. You are probably lacking a ton of the potential lift that the 73 offers by using that stock pushrod, designed for a stock cam.

When the cam changes, the heads are flycut, the deck height is altered, or a different lifter cup height is used you MUST reset the rocker arm geometry...

Do some searched here and on the STF for details.

It can definately make that cam choppy.
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JoeSharp
post Mar 14 2005, 10:42 PM
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Geoff gave a good reply to my Suppeduped D-Jet, you may want to look at it. Talks about adjusting the D-Jet.
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newdeal2
post Mar 14 2005, 10:49 PM
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QUOTE (Jake Raby @ Mar 14 2005, 08:40 PM)
Big No No...

The stock pushrod is never optimal when used with a 73"ish" camshaft. You are probably lacking a ton of the potential lift that the 73 offers by using that stock pushrod, designed for a stock cam.

When the cam changes, the heads are flycut, the deck height is altered, or a different lifter cup height is used you MUST reset the rocker arm geometry...

Do some searched here and on the STF for details.

It can definately make that cam choppy.

Hmmm... changes in geometry...never came up in any of my "prep" questions. Given the changes it makes lots of sense. I will have to think about this when I go in to change the adjusters. A builder up in New York suggested I will have a real hard time getting my valves adjusted properly with worn adjusters [another no no on my part].
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Jake Raby
post Mar 14 2005, 11:13 PM
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These days not even a stock cam can get away with stock pushrods... If even a .010 change is made to any aspect of the width of the engine it can effect the geometry by up to 1.3 times the change...

I am making up some "Engineered valvetrain kits" very soon that will have all the pieces that you need to oufit the arrangement correctly, including the valve springs and pushrods. I am doing these for my most popular cams.
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newdeal2
post Mar 14 2005, 11:27 PM
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Geeez! By the time I consider everything I "should have" done I will be splitting the case again. Hmmm...is this just an excuse (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

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nebreitling
post Mar 15 2005, 12:24 AM
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Jake, when you say that "stock" pushrods are not sufficient, do you mean uncut "stock-length" pushrods, or do you mean pushrods of all lengths (even properly setup) made from "stock"?

just wondering if i shouldn't get some chromolies "while i'm at it"...
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