420A No compression...

[Inkdlyfe]

Before i start yes i understand there is many treads on this subject and Ive read up on most of them even on different places but still cant seem to get this answer...
ok so i did a full rebuild on my 420A-T went all out with it spent alot more money then i really wanted to buying
head bolts and bottom bed plate bolts
-crower springs and valves
-Wisco .50 over pistons with wisco 50 over rings (matching the piston specs)
-Eagle H beam rods
-Kings main and rod bearings
along with new
-Crank shaft
-oil pump
-water pump
-idler pully
-tentioner
-lower sprokets
and ALLLLL new seals completely even ones recently installed and new sensors through out the whole engine
yes everything is torqued down and nothing was short cutted outta anything done the right way and took my time with it, when finally getting the motor done and dropped in i went to crank the first time and nothing, found out the problem fixed it there was a plug connecting the starter to the main harness it wasnt connected to did that and bam started up....BUT it wouldnt idle on its own i would have to keep the throttle open in order to keep the car running,,,, came back to the car the next day did the same thing couldnt figure it out then the next day it wouldnt start at all no crank nothing found out my CAS was bad from the store. replaced that now fired up but now sounds like a reallly bad misfire like a helicopter is behind me if you try and reve it up it dont wanna do anything in response to how it should due to throttle postion, and then would randomly spike to 4k and hold there then die out, yes Ive tried removing the tps does the same thing and yes i do have a new tps.... so i figured compression test is now called for, got s compression test and now this is where i am now and stuck more then ever cuz there is ZERO compression at all... but engine was starting? yes i have fuel yes i have spark and yes ALL the timing marks are in line for sure and started at tdc, but u can feel air coming from each clyinder while cranking wiht no plugs... after doing like 4 compression tests on each one i decided to fill the cylinders with air instead and this lost me ... try to follow me on this its bout to get confusing

in time 1st clyinder is tdc when filling them with air this is the results

1-air in intake 4 air in exhaust
2 and 3 air in valve cover

1/4 turn now 2nd tdc

1 and 4 valve cover
2-inatke 3 exhaust

1/4 turn

1 intake 4 exhuast
2 and 3 Valve cover

1/4 turn

1 and 4 valve cover
2 exhaust 3 intake

ive done this order 4 times and been the same each and every time im not sure if i wasnt paying attenon right but i coulda swore the first time i done it when 1 was exhuast 4 was also vise versa each time for each cylninder not diff each time,,,, and keep in mind when the air was coming out of the valve cover a extreme amount of air exited out of the tester tube,,, after putting eveything back into the right loaction i went to start and now the car dosnt even want to fire.... cant figure out why at all... it cranks and cranks and cranks nothing i am getting spark for sure though after cranking a few times it like i dont know struggles on good time and like poofs and crank crank crank again and poof like a large ammount of air coming through the exhaust,,,, YES all timimg marks are in line for sure... what is going on here ,,, ????

 

[dsmcrzy]

Have you pulled the valve cover to make sure all the head components are where they should be.

With air coming up through the valve cover like you are describing could either be piston rings or the head gasket not sealing correctly.

Little confused as to how you did the compression test. Sounds like you did a make shift leak down test.

What were the compression test results for each cylinder? Did you do them with the plugs in all the other cylinders or did you do it with them all out?

 

[dsmcrzy]

You don't cover it in your post but did you have the block or head resurfaced at all?

For the head and bed plate bolts are they ARPs or just oem replacement? When converting to ARP bed plate bolts it's require to get the block line honed because the ARPs will deform the bed plate differently than the OEMs once they are torqued down.

Have you changed the oil? Any tell tale signs of failure? Flakes in the oil or anything?

 

[Inkdlyfe]

I stated up top there wasn't any compression. I used the one from O'Riley I pulled all the plugs and then also did it w all the plugs in

 

[dsmcrzy]

How about the block and head? I think you missed my second comment because we posted st the same time.

 

[yoscoobie]

just do a cylinder leakdown test and post what happens

 

[dsmcrzy]

I believe he did that. That's what he's trying to describe above.

 

[Inkdlyfe]

Correct i did a leak down test and i reserfaced the block and head yes

 

[dsmcrzy]

Do you have pics of the surfaces? Were they good and smooth or rough? The head and block surfaces should look like this:

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[Inkdlyfe]

Yes maybe not that silver looking but it was damn sure smooth like glass for sure made sure there was nothing left of the old gasket at all and smoothed it out.

 

[Inkdlyfe]

My walls are so much thinner then yours is your stock mines .50over

 

[dsmcrzy]

No mine is 40 over.

 

[dsmcrzy]

I didn't even think they made 50 over pistons.... do you have pics during the build?

If timing is good and everything is where it should be in the head... you are probably going to have to pull it out and go through it.

 

[Inkdlyfe]

Yes wisco .50 over and yes I do I'll have to post them I'm really not trying to pull the head but I guess imma have to any guesses ?

 

[miliman13]

What you describe sounds like your valves are leaking, the seats to valve angles are not seating properly.
*Based on degree statement.

What is your ptw clearance, ring gaps? its normal to be loose and thus have blow by at first, with warm up this clears up as things tend to expand.

 

[Inkdlyfe]

Haven't really had a chance for a warm up tbh the motor only ran for maybe 15 mins total that's not 15 at once nor if my valves where to be leaking wouldn't they leak all the time during a leak down test using a air compressor ? Not only during the rotation they are ment to be open ?

 

[miliman13]

leaking should be minimal at TDC or when all 4 valves are in the closed position.

 

[Inkdlyfe]

If 1 is tdc and time is aline there's a large ammount of air in take I believe n 4 exhaust or vise versa it's stated at top but intake for sure got alot of air but it's the same no matter what one is tdc same amount

 

[Inkdlyfe]

Air being herd in vc is that valves closed ?

 

[ThunderChild]

Air heard through the VC under a leak down test is blow-by past rings, unless the valves hanging open and it goes past the valve seals.
I have a hard time discerning what you're describing, but it sounds like a timing issue and/or possibly the valves hanging open.
Need to have a way to check values on everything else, without a logger or tuning solution that's difficult.
Last 420A i rebuilt ran like crap for the first few min, then cleaned up after getting to temp. idk if certain sensors need a calibration period maybe (tps for instance) on the 420A.

 

[Inkdlyfe]

Imma assume the reason why the engine doesn't want to start but turn over is a simple sensor problem well Imma hope but since the piston rings have yet to ever expand you think maybe the leak down test isn't a good test as of right now because the engine has yet to ever even get hot ?

 

[Inkdlyfe]

And I don't see how it could be a timing issue only cuz both my cam marks are facing each other; one dowel is up other is down; the holes on each cam shaft are both up; and my lower crank marks are lined up and block was tdc on 1 when installing the head

 

[Inkdlyfe]

And I found the problem! Both cam gear dowels snapped clean off and the shafts where not spinning with the gears how did this happen... ???

 

[ThunderChild]

Cams may be messed up, not allowing smooth rotation when installed. then when you tried to start it, it snapped them off.

might want to start tearing it back down to inspect everything. very least, remove the cams and so a leakdown/compression test to make sure no valves are bent as thats another possibility of cause.

 

[dsmcrzy]

That actually happened to another 420a on this forum. So weird.