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420A Blown HG?

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Inkdlyfe

Proven Member
438
7
Feb 23, 2016
Summer feild, Florida
So I just did my HG not even 3 miles ago MLS with ARP torqued etc, I started it multiple times after this moved it maybe 3 miles total, started the car last night idles still for I'll so 20 mins started to get hot car is turboed so I figured that' ok with no Breeze or fan going just wanted to make sure i had no boost leaks or vac leaks checked out all good turnt the car off went to start it today and turnt turnt turnt nothing sounded like I was trying a compression test with the motor all together, thought the plugs came loose so checked them nope all good, and on time for sure, did a comp test first one read 0 no change at all got a new test and the 1st one read only 30 after 10 turns rest 0 maybe moved 1 cm, went back to the 1st and that one read 0, oil seems ok very very minor milky color on the cam cap bolt tops but not on vc, dip stick, or oil cap there all good looking, should I try another comp test ? What are the chances I blew a hg on I'll say 3 1/4 mile test runs ? Fully built motor just a fyi and yes head and block been decked when HG was installed
 
check the coolant and see if its low, that should tell you if the head gasket it leaking coolant into the crankcase. if your coolant level is good, take off the valve cover and turn the motor over by hand. make sure both the cams are turning. its possible that the locating pin on the end of one of the cams sheered off.
if you had both the block and head surfaced, and you torqued down the head studs per ARP's instuctions, the head gasket should be sealing properly
 
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check the coolant and see if its low, that should tell you if the head gasket it leaking coolant into the crankcase. if your coolant level is good, take off the valve cover and turn the motor over by hand. make sure both the cams are turning. its possible that the locating pin on the end of one of the cams sheered off.
if you had both the block and head surfaced, and you torqued down the head studs per ARP's instuctions, the head gasket should be sealing properly
Cams turn with the motor
 
So I just did my HG not even 3 miles ago MLS with ARP torqued etc, I started it multiple times after this moved it maybe 3 miles total, started the car last night idles still for I'll so 20 mins started to get hot car is turboed so I figured that' ok with no Breeze or fan going just wanted to make sure i had no boost leaks or vac leaks checked out all good turnt the car off went to start it today and turnt turnt turnt nothing sounded like I was trying a compression test with the motor all together, thought the plugs came loose so checked them nope all good, and on time for sure, did a comp test first one read 0 no change at all got a new test and the 1st one read only 30 after 10 turns rest 0 maybe moved 1 cm, went back to the 1st and that one read 0, oil seems ok very very minor milky color on the cam cap bolt tops but not on vc, dip stick, or oil cap there all good looking, should I try another comp test ? What are the chances I blew a hg on I'll say 3 1/4 mile test runs ? Fully built motor just a fyi and yes head and block been decked when HG was installed
Did you bleed the lifters down when you installed the head?
 
But another thing I don' get is the fact that I can for sure feel pressure coming out of each cylinder at each rotaton so, with that said why would the comp test only read flat out 0 noy jump alittle to 5 or even 10 vs stay at zero completely? Even hovering over the holes u still do feel pressure,
 
Alright so I did another test and now they all read 30 each
 
How would I have bent valves over night tho ? Car ran and drove after rebuild it ran the other day and then the next day it don't fire ?
 
But another thing I don' get is the fact that I can for sure feel pressure coming out of each cylinder at each rotaton so, with that said why would the comp test only read flat out 0 noy jump alittle to 5 or even 10 vs stay at zero completely? Even hovering over the holes u still do feel pressure,
Because air moving feels like a lot of pressure when in reality it isnt.
 
Try another tester, that one could have the schrader valve missing, could have jumped down at the crank cog, might have sheared the key.
 
So I found out
It stays at 30 psi don' drop slowly or anything
I am in time top and bottom.
But I just did find out I don' have spark
 
90° out of time fixed the problem top was inline bottom was too but not top to bottom it' running now
 
When the crank was tdc my cams was 5 teeth off when the cams was inline the crank was 90 off checked compression got 155 around that in each and runs and idles
 
You got lucky my friend! Congrats.
 
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