HELP! All Mechanical Eliminated- Wont rev past 4K

[Arne]

At this point, I think we can agree that the timing on this motor is all forked up, and I don't think we should assume that anything is correct. Here is what I think I'd do at this point if it were mine, and in exactly this order:

1.) Pull the plugs and cam cover. Find true TDC on #1 compression stroke via piston movement.

2.) While at true TDC, verify cam timing (both #1 lobes pointed up in ears) and check for correct cam chain tension. Correct problems as needed. (I have concerns that the head may have been excessively milled w/o having the cam towers shimmed. This could seriously affect the cam timing.)

3.) Still at true TDC, compare timing mark on pulley to marker on timing cover. If wrong, correct by moving marker or creating new mark on pulley. If a new mark is made, always use it forevermore.

4.) Still at true TDC, remove distributor cap and see where the rotor is pointing. If it doesn't point to the front of the car (approx. 8:30 assuming 12 o'clock is straight up towards the engine), the distributor drive gear is incorrectly installed. Remove the distributor, drop the oil pump, re-index the drive gear and re-install pump and dizzy.

5.) Set static timing by hand to approx. 0 degrees (true TDC). Start the car, warm it, set timing to 5-10 BTDC and test.

[ChrisZ]

What Arne said also check that the oblong grove is towards left of the location notch according to fig. EM-64 in the FSM.

Didn't you state in #1 that your mechanis is a special Z shop !!.... he should know this.

Chris

[Seanw987]

Thanks guys. I'll pass this info On. The shop pc crashed this week.

[=Enigma=]

Thanks guys. I'll pass this info On. The shop pc crashed this week.

Time to replace that old 80386 and 14.4.......nerds will get it.

[sblake01]

Time to replace that old 80386 and 14.4.......nerds will get it.

I'm not a nerd but I get it. An 80386 likely had a slower modem than 14.4. Something in the 300 or 1200 or maybe 2400 baud range.

[Trys_Hard]

What Arne said also check that the oblong grove is towards left of the location notch according to fig. EM-64 in the FSM.

Didn't you state in #1 that your mechanis is a special Z shop !!.... he should know this.

Chris

We do and there is nothing in this thread that we haven't tried. Sometimes twice.

[Seanw987]

Yes, I must admit. These guys at the shop are really being put to the test. I gave them a mystery build motor made with parts from every type of Z. They werent expecting this to be such a complicated swap but they are keeping thier cool (they still let me in the shop) under these extenuating circumstances. The time they are spending on the car has been more than I've been charged for and they refuse to give up.

I hope to have the car back daily but I know I wont get it back until its Right.

Thanks Again Guys

Edited March 18, 2009 by Seanw987

[doradox]

We do and there is nothing in this thread that we haven't tried. Sometimes twice.

I think a little more specific information might help. What shop equipment are you using i.e. tune up scope, 4 gas analyzer, etc. Is the dwell consistent across all 6 cylinders? What is the secondary voltage at idle ,2000, 4000 rpm, max voltage available at each plug? Coil oscillations look normal? What are the CO, CO2, O2, and HC readings at various rpm. What vacuum readings do you get at various rpm? What is the timing (vac advance disconnected) at 1000, 1500, 2000, 2500, 3500 rpm? Have you artificially leaned and richened the mixture and noted change in rpm. Being a Z specialty shop I am assuming you have known good parts to swap. Carbs, distributor, coil, wires, etc. These things have been tried? Was the intake replaced at some point? I know it sounds stupid but was anything accidently left in the intake ports? I typically stuff them full of rag or paper towel when working with the intake off to prevent foreign objects from getting in the ports.

Steve

Edited March 19, 2009 by doradox

[ChrisZ]

I think a little more specific information might help. What shop equipment are you using i.e. tune up scope, 4 gas analyzer, etc. Is the dwell consistent across all 6 cylinders? What is the secondary voltage at idle ,2000, 4000 rpm, max voltage available at each plug? Coil oscillations look normal? What are the CO, CO2, O2, and HC readings at various rpm. What vacuum readings do you get at various rpm? What is the timing (vac advance disconnected) at 1000, 1500, 2000, 2500, 3500 rpm? Have you artificially leaned and richened the mixture and noted change in rpm. Being a Z specialty shop I am assuming you have known good parts to swap. Carbs, distributor, coil, wires, etc. These things have been tried? Was the intake replaced at some point? I know it sounds stupid but was anything accidently left in the intake ports? I typically stuff them full of rag or paper towel when working with the intake off to prevent foreign objects from getting in the ports.

Steve

Wuh...

[WingZr0]

Sooooo..., just so we're all on the same page here, we can all

blame this on Datsun Parts LLC right? :pirate:

Sho of hands, NOW! ! !

~Z~

Edited March 19, 2009 by WingZr0

[=Enigma=]

Sooooo..., just so we're all on the same page here, we can all

blame this on Datsun Parts LLC right? :pirate:

Sho of hands, NOW! ! !

~Z~

That fact certainly doesn't help matters but I'm not sure we can conclude that just yet.

[Seanw987]

I poked my head in the shop yesterday.

A stock cam has been tried with no noticable difference. It just sounded wimpier than when it had the perf. cam . no improvement to rev range. Vaccum readings were taken, im not sure what they are but they seemed normal, it was noted that when the balance tube vaccuum lines were removed, the idle went up, not down.....