Head change with issues

H

hamck

Member
Hi Grumpy
I'm new here so please excuse me. I recently Installed some aluminum heads on my 350 small block that raised my compresson from 8:1
to 9.5:1. Im having a lot of oil through the pcv entering the manifold and can't figure why. I've tried numerious baffles in the valve cover and different pvcs with no results. Blow by was my first thought but a compresson test showed all cylinders at 210 psi +- 5 pounds.
210 psi is kind of high, don,t you think? I'm planning on removing the engine for a cam change and check the rings over the winter,so what do you suggest I look for when i tear it down? That 210 psi and oil consumpion has me stumped .
Thanks
 
did you verify that the old head gaskets and new head gaskets had the same holes and passages opened and blocked? by design many headgaskets block off certain ports for coolant and oil and allow others to flow based on the generation of the motor. i will defer to a better answer from someone more knowledgable but this could be an issue
 
air pressure at sea level is generally considered to be measured at about 14.7 psi, if your getting 210 psi on a compression test.....210 psi divided by 14.7 = roughly 14:1 compression
now you may not have quite that much compression but you surely have exceeded 9.5:1compression, if your at 210 psi readings, on a compression test.
and as pointed out the oil drain back passages may be and most likely are blocked or partially blocked by the head gaskets, blocking the drain back oil passages, allowing oil to build up to a level in the heads that causes the valve seals to have problems compensating with it, rather than draining off as it should rapidly,and at a far lower level before draining, back into the lifter gallery so that will need to be carefully checked and generally new valve seals should be installed.
I'm sure a careful inspection and some detailed measurement, of the cylinder head combustion chamber volume, quench and head gaskets, can bring to light the cause and eventually lead you too the correct cure to the issues your seeing here!
http://www.steigerperformance.com/products/sp90005.html
IVE ADDED A GOOD DEAL OF RELATED THREADS AND INFO THAT SHOULD HELP

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http://victorylibrary.com/mopar/cam-tech-c.htm

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Thanks Grumpy
I assume dcr has the deciding effect on cranking psi. I came up with that figure with an on line calculator . My scr= 9.5 and my dcr =8.16
with an intake closing point of 55 abdc. Now I can verify that when I remove the engine. Mabe the cam was installed wrong. Ill have to see.
As far as the oil issue, The drain holes in the heads seem small to me, and that crossed my mind. They are new heads and I didn't even think of that when I installed them. I do have a lot of oil pressure ( 80 psi ) at crusing speed, always did.
Thanks for your input
Harry
 
Hi John
I recently installed Dart SHP 180s During the install, I noticed some lifters that looked a little funny on the bottom. It looked like they weren't turning.
So that's why I'm removing the engine ,to change the cam (currently a comp xe grind )
and what ever else that maybe wrong. The 210 psi cranking pressure has me stumped.
 
Looked funny on the bottom like concave if that is the case there is a good chance your cam is being gobbled up. Do you run zinc additive or a high zinc oil? I just changed my cam for that reason ate all to hell from lousy oil. Plus I installed new heads bought complete which came with stronger springs that sped up the process of the cam being ate up for me. You can check the lift numbers off your cam the same way as degreeing it. I did my swap in car but I was working on Chevelle plenty of space but still had to pull radiator and ac condensor.
 
They had a wear mark like a line across the bottom. They weren't tight in the bores, but weren't turning. Yes ,I used vr-1 oil high zinc.
I have a 76 corvette so its easier to remove the engine than the rad.
 
Help Grumpy Its been a while but I finally removed my engine. I checked the drain holes in the heads and there not blocked,. I did a leak down test at TDC and BDC with the rockers removed. This is what I got #1 6% top / 5% bottom #8 6 / 7 #4 6/6 #3 10/8 #6 10/10
#5 7/10 #7 5/10 and #2 9/5 If you recall, I had a cranking pres. of 210. Are these good numbers or should I re ring? I will be replacing the cam and lifters. Is it possable that the oil pump pressure / volume is too high and flooding the heads with oil , causing it to be drawn into the PVC system? I also checked the valve timing . The cam is 2 deg. advanced. I'm a little lost at this point. What would you suggest?
Thanks, Harry
 
the leak down numbers are certainly not exceptionally bad,in fact Id say about average ,any time you have issues it helps to step back and think logically, in this case,
have you calculated your dynamic compression? what is your plenum vacuum read at idle and at wide open throttle? whats your ignition advance curve and ignition timing?
Think about where can oil enter the cylinders, well obviously it could be getting past the rings but those leak down numbers are reasonably low so I'd look at other options, I'd suspect the valve seals,or loose valve guides, even if NEW might need to be checked carefully, and might need replacing or the intake gaskets are not sealing the ports completely,when the heads and intake are bolted on,allowing oil from the lifter gallery to seep into the intake ports, if thats the case you should see some indication of oil stains on the intake runner floors and walls, can you post clear pictures?,
check clearances, carefully if the valve spring retainer comes close too contacting the valve seal it will leak oil careful inspection of the engine components should provide clues to the source of the oil entering the cylinders, but keep in mind a higher compression engine will tend to use some oil, the amount it consumes should be reasonable, if its under a quart every 5 tanks of fuel Id just add oil as needed and consider it standard maintenance.
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Isn't this the correct graphic when measuring for coil bind??? If there was .060 inches
between each coil, then the total would be close 1/4 inch.



 

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yes that picture is deceiving, you need .090 clearance between the retainer to valve seal and a TOTAL of .060 clearance MINIMUM on the valve spring coils from spring bind, or solid stacking the spring coils

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Hi Grump, Sorry for the delay. I took some photos , but there not too clear. The runners in the heads are clean as new. If you noticed, the gasket I used has the heat crossover blocked. All I can think of is there had been a leak of exhaust entering the valley area, creating positive pressure in the crankcase forcing oil into the PVC system. That would give the impresson of blow by past the rings. ???? I'm just guessing now. The other photo are the valve tips. Does that pattern look ok to you? There about 3/32 wide. I thought valves rotate. Theres only mabe 4 hours on the heads.
Thanks for listening Grump
Harry
 

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Hi grumpy
Its been a while, but I have my engine back together and in the car.
The oil issue I contribute to a bad intake gasket install. I also changed the
cam, and now my cranking pressure is 180. I went to an intake closing of
64 A B D C from 56 A B D C. Of course I gave up a lot of that low end torque
that puts a smile on your face. I'm still tinkering with the timing, looking for that
sweet spot but the big issues I believe are gone. You were right about looking
for the obvious, some times the simple things are over looked.
Thanks to everyone that commented.
Harry
 
Hi grumpy
I would like your opinion on cam timing. I installed my Isky cam straight up as per the directions. Doing so, I lowered my dcr .
If I advance it 4 deg. , I could raise it to around 8:1 but The intake would be opening at 24 BTC (at .050 -1 BTC ) currently ,
LSA is 112 and ICL is 112 . What affect would opening the intake earlier have ? Would it create too much reversion and lower my vac. at idle?
Its not too big of a deal pulling the front off and changing the timing but I don't want to do it twice if it doesn't work.
The cams an isky 264/270 mega with 112 lobe center. What's your opinion, go or leave it alone?
thanks, Harry
 
http://www.summitracing.com/parts/isk-201264-27112
Would it create too much reversion and lower my vac. at idle?
Assuming a constant lobe center angle?
Click to expand...

the only difference your likely to notice, from a 4 degree advance in cam timing is a slight increase in off idle torque and MAYBE a bit less tolerance for crappy low octane fuel

Longer duration
more peak power, rougher idle,
higher fuel consumption,
higher emissions,
less torque at low RPMs,
power peak occurs at higher RPM,
power rpm band widens and moves up

Shorter duration
the opposite of the above results


Assuming constant duration

Tighter lobe centers
more peak power,
higher fuel consumption
rougher idle
more torque at low RPMS,
peak power occurs at LOWER RPM,
higher emissions,
power RPM band gets narrower and moves DOWN

Wider lobe centers
opposite of above


Assuming constant lobe centers and cam duration

Advancing the cam
slightly improved low rpm torque,
slightly reduced peak power
imperceptible change in emissions, idle & fuel consumption
advancing the cam 4 degrees generally moves the whole power curve about 150 rpm lower in the rpm band

Retarding the cam
opposite of the above
 
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Thanks Grumpy Seems like a lot of work for only 150 rpm shift. Does DCR increase with RPM? I've read a lot of your
sub links but I may of missed that part. I'm about 7.6 when using an online calculator. I thought with a higher RPM , it
could get higher. If so could you point me to that sub link please?
Thanks Harry
 
yes theres a small increase in efficiency of the cylinder fill efficiency as the port velocity and exhaust scavenging become more efficient within a limited rpm band.
generally from about 3000rpm and up the inertia of both the intake and exhaust gases produce a more effective fill of the cylinders
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