HELP! All Mechanical Eliminated- Wont rev past 4K

[Stickerman]

that he bought from Datsun-Parts, LLC. It was assembled with a hodgepoge of different year motor parts.

Without opening a huge can of worms again, there is your problem. Who knows how it was put together coming from that guy.

[doradox]

Here's a long shot idea. Weak valve springs. Valves float at 4000 rpm. Datsun-Parts, LLC? Maybe not so long.

Steve

[hls30.com]

While I would never recommend your chosen vendor, DatsunPartsLLC , I do have a couple of questions:

1) Have you contacted Datsun-Parts, LLC? Being that you are close enough to take it personally and with out too much drama, why don't you take advantage of their warranty?

2) If you are outside of their warranty, Why?

3) What sort of hodge-podge oddities have you and your mechanics noticed?

I am sorry you are having a problem with a product bought from Datsun-Parts LLC.

Will

Edited March 3, 2009 by hls30.com

[rxsleeper]

I am going to offer up that it is the carbs, and most likely the throttle shafts or an air leak at the carb isolator. I chased the same problem on the race car. Replaced everything in the fuel system from the cell, FP regulator, lines, and then went to work on the ignition. Replaced MSD, Pertronix, swapped dizzy's, wires, plugs, caps, rotor, timing, etc.

I am not the only one to have this problem and I conferred with another ITS Z that was having almost the exact same problem. We chased this for several months and I even thought it was related to bad engine ground since I could make it quit by hitting the rumble strips exiting a couple of turns at Carolina Motor sports park. Even then, it would come back in 2 laps or less.

Long story short, rebuilt carbs from Z-therapy and no more problem. I can easily rev to 7k and even more. Of course, when you do that you will pop rockers off in a race. Don't ask me how I know that.

If you haven't replaced the carbs with some known good ones, I would try that before investing an enormous amount of time in other things.

I will not comment on the "new engine" builder. I think enough is already known about their "quality parts."

EDIT: Went back and checked my notes. One of the other guys with problems found that his float levels were too high. No fix when I lowered my float levels but it did gain a few rpms. Also, my buddy saw "cold" EGT's from the front carb (measured at the header) when he was chasing the problem.

Edited March 3, 2009 by rxsleeper

[sblake01]

We did get his prior motor running past 4k, before we put in this new motor that he bought from Datsun-Parts, LLC.

Er...check please!

[Zs-ondabrain]

Datsun-Parts... Nuff said. Sorry for your trouble. Guess you were one of the UN-forewarned.

Sorry,

Dave.

[ChrisZ]

Oh yeahr, stay the he.. away from that guy.

Now next time you get to the car, make a list of the part #, what is stamped in to the cam, distributor and so.

Chris

[Trys_Hard]

Oh yeahr, stay the he.. away from that guy.

Now next time you get to the car, make a list of the part #, what is stamped in to the cam, distributor and so.

Chris

The customer bought the motor prior to all the posts on Classic about Datsun-Parts, LLC. According to the ad the cam is a stock regrind.

[Seanw987]

True that I didnt know about The reputation of Datsun-Parts LLC. I had purchased a few smaller items from him on ebay prior to the motor purchase.

My dad offered me alot of the same advise posted here with a few extras.

He told me to take off the air cleaner and light a cigarette. Hold the cigarette so that the smoke is drawn into the carb. Watch the way the smoke is drawn in. If it glides in seamlessly then its good. If if staggers or pulses in, then the chain /cam timing is off and the valves timing is screwed. Also recommended that the tach be removed from the circuit and jumpered in this case to eliminate it as a suspect. Also said removing other fuses to other circuits and noting any changes in performance is worth a try. Squirting gas into the carbs and seeing if it would rev out more. bypassing electrical by jumpering from battery directly to coil, i think this was already tried. Recommended I install a clear inline gas filter so I can watch level changes at 4K- see if it runs low... all sound advice.

The original owner of the car said that the old 2.4 motor was doing the same thing when he parked it last.

But it was revving up to 5800-6000 range before i brought in the "Nice New Motor"

I only came here as a last resort for information. I know mike and art have put alot of time and effort into making my car right. I think I threw them a wicked blind curveball.

One last word of wisdom my father bestowed on me tonight was this, "When you find out what it is, It's going to be something simple that was staring you in the face the entire time." Thanks Dad.

Thanks Mike and Thanks Art and Thanks to all that posted here so far. This will have a positive end. Keeping you posted...

Sean

Edited March 4, 2009 by Seanw987

[ChrisZ]

The customer bought the motor prior to all the posts on Classic about Datsun-Parts, LLC. According to the ad the cam is a stock regrind.

A stock re grind !!.... i have several stock cams and none of them needs re grind, have a cam ground to stock specs sounds silly to me, it must have been worn out alot to do that.

Anyway if the old motor had the same symptoms it must be somewhere else.

Sean is there any parts from the old motor that is still in use ?

Chris

[doradox]

One last word of wisdom my father bestowed on me tonight was this, "When you find out what it is, It's going to be something simple that was staring you in the face the entire time." Thanks Dad.

Sean

Your father is a wise man.

Steve

[Seanw987]

The Cam is a performance grind on old stock.not just stock re-ground to stock - Not sure if thats even possible.