installed HKS 264 cams, headgasket, now crappy compression

[quote Sleepy probably didn't allow the lifters enough time to extend.



My money is on the head gasket. I'll bet a nickel that that's the problem. Any takers? If the car is in time, valves shouldn't be an issue. Even after taking the lifters into consideration. If compression is lost, it's probably due to head warpage or other head gasket problems. I just can't see having even compression across the board prior to work done, and then have two different sets of even numbers on alternating cylinders after head gasket is replaced and the cams were swapped out. Just doesn't make sense. Got to be gasket. Not valves.

 

[turbowop]

A head gasket would have to be pretty bad to show zero compression. Even then, usually they blow between cylinders giving each of those cylinders similar compression numbers. Or into a coolant passage. It would have to blow out the side to give zero compression and that would be painfully obvious if that were the issue.

So in other words, I'll take that bet. /ubbthreads/images/graemlins/grin.gif

 

I think the best bet at this point is what has already been suggested. Go get you a leakdown tester and go from there. I think Autozone loans them. Either way get one and you will know for sure what in the world is going on. Any chance you degreed the cams when you installed them?

 

I bet its your lifters also, its quick and easy to bleed them. You just take a paper clip, bend it straight and stick it down the hole and push down on it until it bottoms out, then push down on the tip of the lifter itself. You will notice the lifter start to bleed down and oil oozzing out of it. I should do a write up in the how to section. I think its one of those things thats over looked all the time.

 

[turbophein]

if you want to make a cheap leak down tester, take a old spark plug, break off the porcelain and punch out the center of the plug too... then take a air hose fitting and weld it onto the rest of the plug, in the 4g63 case, i would weld on a 6" tube and then the air fitting to fit into the head, and for good measure if your welding skills are not the best, put a little jb weld over the welds to make sure it is air tight...

there you go, a cheap leak down tester!

 

[toybreaker]

Quoting BOOSTIN HARD:
I should do a write up in the how to section. I think its one of those things thats over looked all the time.



Why yes, yes you should, with like, pictures 'n sh*t. /ubbthreads/images/graemlins/wink.gif

I too, am a believer in bleeding the lifters down anytime the cams are out.

Of course that means during re-assembly there is another step...

Bleeding the lifters down means they are effectively empty, and that can spell trouble for you big cam guys.

During the [effectively] dry start the lifters will bottom out, and the valvetrain will get shock loaded something fierce. This is especially bad because the rocker arm geometry will be all caddywampus working against the [effectively] short lifter. This means the rocker arm and valve stem tip will be at an awkward and un-natural angle, and may be working very close to the edge of their intended contact area. With a big cam/smaller base circle regrind, this can easily lead to burrs, gouges and other damage on the valve stem tip or end of the rocker arm.

Obviously, that would be bad....

So, before you put the t-belt on, set both the cams dowell pins up, and rotate the crank counterclockwise 90* for valve clearance.
Spin up the oil pump with an electric drill or cordless screwdriver (no impacts!).
Rotate the cams slowly 360*, one at a time, and return them to dowells up.
Line up the crank, install the t-belt, and fire that bitch up!

silence /ubbthreads/images/graemlins/smile.gif

It should be noted that the lifters won't allow fresh oil in if they are loaded against a cam lobe, so you have to turn them with the pump spinning to fill all of the lifters. You can get away with just spinning the pump without spinning the cams, but you'll have a couple lifters that will be pissed, and they'll let you know about it when you fire the motor for the first time, (like fingernails on a chaulkboard /ubbthreads/images/graemlins/banghead.gif )

If you're in it that deep, just take the time and do it right.

 

[toybreaker]

Quoting turbowop:
First off, you need to rule out why you're getting such low compression in those two cylinders. Time for a leak-down test.



nailed it, first post!

Quoting Nemesis:
If you have a quick coupling by the gauge on your compression tester (most do) screw that bad boy into the motor, and hook it up to an air compressor. Once it's connected it'll leak like crazy.



Good post!

Most of the good compression testing set=ups have exchangable hose ends, and many of them use a traditional style quick release end. Coupled onto the end of the air hose in your shop, it will allow you to blow air into the cylinder and listen for where it's leaking. It's not a perfect test, (because without the gauges, you don't know the actual leakdown) but it'll give you a quick indication of how bad the repair is going to hurt.

You do need to remove the schraeder valve from the end of your adapter hose first though. /ubbthreads/images/graemlins/wink.gif

Quote:
Then just turn the crank manually until it stops leaking out of the valves.



carefully...

The crank can give a quick spin when it goes over tdc, so don't let it bite you.

 

Quoting toybreaker:
Quoting BOOSTIN HARD:
I should do a write up in the how to section. I think its one of those things thats over looked all the time.



Why yes, yes you should, with like, pictures 'n sh*t. /ubbthreads/images/graemlins/wink.gif

I too, am a believer in bleeding the lifters down anytime the cams are out.

Of course that means during re-assembly there is another step...

Bleeding the lifters down means they are effectively empty, and that can spell trouble for you big cam guys.

During the [effectively] dry start the lifters will bottom out, and the valvetrain will get shock loaded something fierce. This is especially bad because the rocker arm geometry will be all caddywampus working against the [effectively] short lifter. This means the rocker arm and valve stem tip will be at an awkward and un-natural angle, and may be working very close to the edge of their intended contact area. With a big cam/smaller base circle regrind, this can easily lead to burrs, gouges and other damage on the valve stem tip or end of the rocker arm.

Obviously, that would be bad....

So, before you put the t-belt on, set both the cams dowell pins up, and rotate the crank counterclockwise 90* for valve clearance.
Spin up the oil pump with an electric drill or cordless screwdriver (no impacts!).
Rotate the cams slowly 360*, one at a time, and return them to dowells up.
Line up the crank, install the t-belt, and fire that bitch up!

silence /ubbthreads/images/graemlins/smile.gif

It should be noted that the lifters won't allow fresh oil in if they are loaded against a cam lobe, so you have to turn them with the pump spinning to fill all of the lifters. You can get away with just spinning the pump without spinning the cams, but you'll have a couple lifters that will be pissed, and they'll let you know about it when you fire the motor for the first time, (like fingernails on a chaulkboard /ubbthreads/images/graemlins/banghead.gif )

If you're in it that deep, just take the time and do it right.



Very good post John.

 

[dmj]

Road race engineering has a good write up on their site. Listed as 4g63 cam installation tips, easy to read and comprehend.

 

[sleepyvr4]

Quoting turbowop:
A head gasket would have to be pretty bad to show zero compression. Even then, usually they blow between cylinders giving each of those cylinders similar compression numbers. Or into a coolant passage. It would have to blow out the side to give zero compression and that would be painfully obvious if that were the issue.

So in other words, I'll take that bet. /ubbthreads/images/graemlins/grin.gif




HEAD GASKET. VALVES ARE FINE.

Head is off - checks out fine. Well, head is out 2-3 thousandths max - we used a felpro headgasket aka more cushion for the pushin. I wanna blame stock head bolts - Idunno. Was spit shining comb cham and puking out back of block yesterday. Headbolts were torqued to 85lb/ft (doubley checked). LMFAO.

Got ARPS - and because I know a few ninjas - getting a 2g head and intake mani (perfect for this setup) for free practically. Gonna make some sweet midrange with this turdburglar. It'll be together shortly.

Parts:

SBR SS Manifold, SBR Street FMIC, SBR IM Spacer, FP Downpipe, 3" straight exhaust, hacked 2G MAF & intake, 14b w/ EVOIII Turbine & O2 housings, 780cc, 255lph, ACT Fly, Custom Clutchnet 6 puck (for Curt Brown), slimfan, SBR mbc, SAFC, MMCD, ARPS, 2g head, lifters and mani, 264's, lightweight mods

Most of this guff was a hookup or super cheap. 92 Laser 6/4 aka "Project Donor"

 

[turbowop]

Well, f*** me. /ubbthreads/images/graemlins/hsdunno.gif

At least I was correct in saying it would have to be pretty bad and blown out the side to be the HG.

 

Quoting sleepyvr4:
also - if you bend a valve, doesn't it look like this afterwards:





If you smack a valve off of anything there will be no compression to speak of - unlike Eric Stoltz's cranium in that movie...



Glad to hear you got it figured out. ^^And thanks for the nightmares.^^

 

[sleepyvr4]

I shot a wedding last night - and made out with a hot red head lol....

 

Reminds me of that movie wedding crashers, where he sleeps with that chick on the beach haha.

"I always thought my first time would be on the beach."