72 240Z question and mechanic in North Dallas needed

[jtay]

Finally got the 72 put back together and have been doing a few test drives.  Unfortunately this is an automatic and very original car with 75K miles so I do not want to change to manual right now.  With the automatic it is difficult in D to get above 3500 RPM.  I have seen it once jump to 4500 when I floor it and other times are always 3500 when I floor it.  I really think it should drive stronger so I need someone to check my work and tune as needed.  I have added newly rebuilt Ztherapy SUs, spark plugs, valve job, ceramic coated header, exhaust, resonator, and other misc things.  I know about the person in Fort Worth but that is very far away from Allen TX.  I would like a reliable engine mechanic that is closer to Allen who understands the L24.  Let me know your thoughts and if there is something I can check to get this engine running strong.  Compression check is 142 140 145 125 125 135.  The engine has never been rebuilt.

[Zed Head]

Sounds like your kick-down is not kicking down.  Could be at the transmission or it could be at the gas pedal.

[siteunseen]

How long since a fluid and filter change? That seems to help once the filer clogs and won't allow flow.

Start with the simple/cheap stuff.

[jtay]

Thanks guys.  I have checked the kick down and it clicks under the pedal and at the tranny.  The kick down line did have to be removed and bent to allow it to work with the new Euro style bar from Ztherapy.  Pic below.  I also found this part that I have no idea how to tell if working correctly.  The kick down line goes into this Valve S30.

https://zcardepot.com/products/automatic-transmission-modulator-valve-s30?_pos=1&_sid=619e5bf2f&_ss=r

As far as fluids, the tranny fluid is new and the antifreeze but I have not changed the oil yet.  I have all receipts and it shows an oil change last year but less than 100 miles driven.  Guess I better do that and new filter.  What about distributor points?  The car does hesitate a bit on acceleration.

 

PIC of kick down and distributor.

 

[Zed Head]

Do you think it's an engine problem or a transmission problem?  Leave it in 1 or 2 and you should be able to rev it up and accelerate, without it shifting at low RPM.

[Mark Maras]

Addressing the acceleration problem, grab a repair manual (any will do) and tune it up. It's quite easy to learn and do. The tuneup includes resetting the valve lash which may bring those compression #s up. They should be above 165. 

[jtay]

I did adjust the valve lash and have not done the compression test after that.  Those numbers were done when the engine was cold. I will take back out for a drive and see about 1 and 2 when it cools down.  104 here today and I do not have the AC working yet.  The person that had it before me did extensive work on the body(no rust) and interior is brand new but he did not spend much time on the mechanical restoration and that is where I come in. I think there are multiple things going on and I would like to make sure the engine is good before I go down a slippery slope of rebuild.  I certainly expect more out of this engine than what I am getting.  No torque what so ever.  Steadily climbs to the speed I need but I expected more and need to drive another 240 to compare.  

[Mark Maras]

 Be sure to hold the throttle wide open when testing the compression.

[jtay]

Here is the update.

Took it out this morning and in 1 and 2 I get pretty good torque and can take the RPMs up to where I want.  I stopped around 5K.  When in D it drives very conservative and shifts around 3K.

Went home and did oil change and new filter.

Got up to temp and then did the compression check and held throttle open.

140 142 142 145 143 142 with 4-5 revolutions

I did one more test with 8-10 revolutions and it would get up to 150-160. When driving the car does hesitate when the accelerator is pushed and then it kicks in.  Let me know your thoughts and thanks.

[Mark Maras]

 As the car is hesitating while pushing on the accelerator, gradually add a bit of choke and see if the hesitation goes away. 

[zed2]

Texas Retrosports 

2637 Oakland Ave. Garland TX 75041 

(972) 278-7651

They have deep knowledge of the Datsun Z

Good luck.

Keith

[jtay]

Keith do you have any other places to recommend?  I look them up on Google Maps and it shows as permanently closed and last update on Facebook was early this year with their website down as well.