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Gary
Gary, Technician
Category: Car
Satisfied Customers: 11345
Experience:  GM master tech for 15 years/ASE master tech for 20 years
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gm 400: gm400, have spark and fuel. timing at 12 deg without

Resolved Question:

gm400, have spark and fuel. timing at 12 deg without vac advance. fireing order 18436572.
starts but wont run. sound like its running on four cylinders and pops thru the exhaust
Submitted: 1 year ago.
Category: Car
Expert:  Gary replied 1 year ago.
will it pop up through the intake also ?
your 100% sure when you droped in the distibuter it was on TDC ?
Customer: replied 1 year ago.


i have an 8" balancer the tdc mark is at approx 2:00 oclock. i checked for the compression stroke and stopped the mark at approx 15 degs on indicator. drpooed the distributor in with rotor between 1 and 2 degs. set the #1 plug approx in line with rotor. with attempting to keep it running, terrible with some dark smoke, i set it at 12 degs w/out vac adv.

Expert:  Gary replied 1 year ago.
is it also popping up through the intake?
what kind of rockers are you running? how did you adjust the valves ?
Customer: replied 1 year ago.


its a reconditioned engine i purchased from secon hand with 1500 miles. and it is not popping thru the carb. it has standard stamped rockers

Expert:  Gary replied 1 year ago.
before we go crazy here can you perform a compression test?if that is done its realy going to cut the problem in 1/2
now one quick thing when you dropped the distibuter in was the rotor pointing at the # XXXXX spark plug tower
also when you drop that distibuter in the crank balancer line should be at 0 degrees
Customer: replied 1 year ago.


i will do the test. the dist. was more towards the #3 plug and the timeing was at approx 15 degs

Expert:  Gary replied 1 year ago.
if the compression on all 8 is above 100 put it up on TDC 0 drop in the distibuter with the rotor pointing at the # XXXXX spark plug wire tower on the cap and try it
let me know ill be here when you need me
Customer: replied 1 year ago.


let you know for tomorrow

Expert:  Gary replied 1 year ago.
no problem.it more than likey will come down to the timing being off or low compression due to the valves not adjusted correctly
you can always get me back through this post at anytime with any follow up or questions with this issue even after you rate us here at Justanswer !
Gary, Technician
Category: Car
Satisfied Customers: 11345
Experience: GM master tech for 15 years/ASE master tech for 20 years
Gary and 15 other Car Specialists are ready to help you
Customer: replied 1 year ago.


reset the tdc and distributor last night. i moved it up oone tooth. before it was pointed at #3 now it is at approx 5:00 or juist past #1. going to check the compresion tonight. let you know tomorrow. you have done a good job, i will take care of the rating tomorrow.

Expert:  Gary replied 1 year ago.
no problem keep me up to date !
Customer: replied 1 year ago.


what is a good compression number?

Expert:  Gary replied 1 year ago.
120 or more
what do all 8 have ?
Customer: replied 1 year ago.


#1 was 160 still working on it

Expert:  Gary replied 1 year ago.
after you did the distibuter retime did you start it up yet ?
if they are all over 120 should be good
160 at all is outstanding
Customer: replied 1 year ago.


without the gage i have pressure on all but the #3!!!

Expert:  Gary replied 1 year ago.
all others have @ 160 ?
and # XXXXX has 0 psi ?
Customer: replied 1 year ago.


havnt gaged the rest yet, ill let yu know

Expert:  Gary replied 1 year ago.
ok find out how many are not at 160 tell me all cylinders and what you have for psi numbers
then we will fix the low or no compression cylinders
Customer: replied 1 year ago.

im not going to be happy if i have to pull the head off. the guy i baught it from better do it for me. ill keep you posted.

Expert:  Gary replied 1 year ago.
well it may be just a valve adjustment.dont worry yet
Customer: replied 1 year ago.


im hoping or is it hopping?

Expert:  Gary replied 1 year ago.
if any are 0 we pull the valve cover and check the valve adjustment and go from there
Customer: replied 1 year ago.


got it

Expert:  Gary replied 1 year ago.
ok
Customer: replied 1 year ago.

ok, if youre there, 180psi in all but #3


if i remember correctly you set both valves closed, loosen the rocker until they are loose, tighten the rocker to slight push rod snug andb then 1.5 more turns on the rocker, yes?

Expert:  Gary replied 1 year ago.
turn the engine over so the push rods are not pushing # XXXXX valves
loosen rocker untill the pushrod is loos
tighten slowely until 0 lash is there
then go 1/2 turn down
pay attention when doing this and make sure the lifters are NOT pushing down when you do this adjustment
do that and see what the psi is after you adjust # XXXXX valves
Gary, Technician
Category: Car
Satisfied Customers: 11345
Experience: GM master tech for 15 years/ASE master tech for 20 years
Gary and 15 other Car Specialists are ready to help you
Customer: replied 1 year ago.

i hooked up a jumper fro the starter to help me and in the doing fried me ignition switch and screwed up the tumbler. how do i replace them.


 


all cyls are now 180psi

Expert:  Gary replied 1 year ago.
great im glad the compression is good now
what year and make and model is this vehicle ?
Customer: replied 1 year ago.


78 GMC truck C2500

Expert:  Gary replied 1 year ago.
i do not have any information on something that old
its a matter of buying a new ignition switch and ignition lock and installing them both
Customer: replied 1 year ago.


you have been great, thank you. how do i contact you?

Expert:  Gary replied 1 year ago.
look me up by name anytime
Customer: replied 1 year ago.


whats your name?

Expert:  Gary replied 1 year ago.
GMwrench
Customer: replied 1 year ago.


i thought i gave you a rating, but just recieved a request. are we ok?

Expert:  Gary replied 1 year ago.
yes we are thank you for the good rating
Customer: replied 1 year ago.


well its finaly running but have some abnormal vibration. this was an engine swap, whan i hooked up the alternater it charged for 5 minutes and then burnt up and quit, what do you think was the cause?

Expert:  Gary replied 1 year ago.

is this an internal regulator alternator?

one big power wire to the back and how many small wires go to it ?

 

Customer: replied 1 year ago.


yes

Customer: replied 1 year ago.


yes one power and one connecter w/2 wiers one red and one white

Expert:  Gary replied 1 year ago.
more than likey this alternator failed internally
these are self chaging alternators
big wire should have 12 votls from the batter
the white i think is for the charge light and what is the red wire reading next to the white wire ?
Customer: replied 1 year ago.

red wire reads 12 v

Expert:  Gary replied 1 year ago.
ok that alternator more than likey internally failed at full charge due to the internal voltage regulator stuck on
these just need to big power wire with 12 volts and the red small wire 12 volts for it to change
Customer: replied 1 year ago.


did you get my last comment/

Expert:  Gary replied 1 year ago.
yes i did
that alternaotr more than likey failed internally
you have the 2 powers for it to work and it is internal self charging and regulated internally
Gary, Technician
Category: Car
Satisfied Customers: 11345
Experience: GM master tech for 15 years/ASE master tech for 20 years
Gary and 15 other Car Specialists are ready to help you
Customer: replied 1 year ago.

i got another and the same results

Expert:  Gary replied 1 year ago.
the new alternaotr worked fine for a little while then blew up ?
Customer: replied 1 year ago.


yes, have any ideas?

Expert:  Gary replied 1 year ago.
what year and make and model is that alternator out of ?
Customer: replied 1 year ago.


its a street rod truck 78gmc w/gm400 and 700r4 2 alternators purchased from seperate sources one new and one rebuilt

Expert:  Gary replied 1 year ago.
this is an odd one
lets see if another expert knows more about this
hang on another expert will replay back to you
Customer: replied 1 year ago.


tx

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GM master tech for 15 years/ASE master tech for 20 years