Installed ported head & dropped comp. on two cylinders

[BLACKCAT]

Recently I put on a ported head on the 7MGE using ARP studs & did a compression test today as it did not perform as good as I hoped:
160, 165, 130, 170, 100, 170.
With the old head it had very good consistent compression.

Wet test #3 stayed the same & #5 only went up around 5 psi so I assume the rings are still good.

Does not overheat or use coolant.

Sticky valves?

Did not do a leak test as I used the same valves that came with the head which were in very good condition once cleaned.

Apart from removing the head is there anything else to check?

 

[IJ.]

What's the valve lash like?

 

[BLACKCAT]

Intake at around .20 mm & exhaust around 0.20 to 0.27.
Will remove the cam covers tomorrow & double check.
Installed new springs so dont know if the increased seat pressure would have anything to do with it either.

 

[IJ.]

If anything the heavier springs should lessen any chance of the valves being off the seats.

Head didn't spend anytime face down with the cams installed by any chance?
ie: on the bench (It's a bit odd the 2 low cylinders aren't 2 grouped though)

 

[BLACKCAT]

Dont think so but I had to take it to two different workshops for the shave as the first place did a real rough finish that would have resulted in a BHG within minutes of startup.
The shim clearances were all over the place & I had to change most of them.
Maybe I made a mistake in checking one.:nono:
There were two or three buckets that did not rotate as freely as the rest so will check that as well.
Its amazing how the little things come back to bite you big time.:3d_frown:

 

[IJ.]

Yep tell me about it.....

I got 13 Km's out of my last build

 

[AJ'S 88NA]

Dont think so but I had to take it to two different workshops for the shave as the first place did a real rough finish that would have resulted in a BHG within minutes of startup.
The shim clearances were all over the place & I had to change most of them.
Maybe I made a mistake in checking one.:nono:
There were two or three buckets that did not rotate as freely as the rest so will check that as well.
Its amazing how the little things come back to bite you big time.:3d_frown:

The buckets not rotating freely, if they don't how would they operate freely up and down? Could be your problem IMO. You need to find another shop, with the clearences all over the place would scare me away.

 

[Zach]

Do a leakdown test and see if you can hear air coming through the exhaust or intake manifold, that'll tell you if your problem is with the valves or the bottom end.

 

[Setheroo]

When you had it flowed... what did your CFM flows turn out to be for each cylinder? I am kinda curious as to how much can be gained from a port job on our heads...

It looks like you have some valve seating issues though for real. Not too much fun to have to deal with.

 

[amichie]

It's the Toyota 7m-ge law of diminishing returns.

Did you lap the valves in with valve grinding paste etc or just clean them and install them??

 

[BLACKCAT]

Well I have been stuffing around with the head for the last few hours, its damn hot around 40C:icon_mad:
Pulled the cams out & replaced the three buckets that were a bit tight.

Checked the valve clearance::icon_bigg
I - 20 22 25 20 24 22 20 23 24 24 20 18
E - 25 25 22 25 22 25 21 26 25 23 22 25

When I installed the new studs, using the molly lube, I tightened them 30,45,60 & 75 loosened & tightened again three times before finally following the above tightening sequence the fourth time.
I checked the readings twice on two seperate days before the engine was started & they were all at 75.

Now you would not think some would be looser after driving the car for seven days.
Well 1 certainly was, ie the third stud I checked which just happened to be around cylinder #5. Moved about an 1/8 turn.
I tightened the whole lot to 80 & checked twice.
Not happy Jan:3d_frown:

I used the Toyota bolts on two previous head gasket replacements & they never changed their readings, even the last lot which were in there for 16 months installed at 80 with ordinary engine oil.

Have to do some shopping:biglaugh: so will do a compression test shortly when I come back to see if there is any improvement in the two cylinders.

Here is some info on flowed heads (not mine):

 

[BLACKCAT]

Just did a compression test & there is no change %()&^^!!!!!:cry:

The only other thing that I changed was the two intake manifold gaskets with some really thin aftermarket ones:nono:

I will buy genuine Toyota ones & see if thats the problem otherwise I give up:3d_frown:, beaten by the 7M demon.

 

[AJ'S 88NA]

Just did a compression test & there is no change %()&^^!!!!!:cry:
The only other thing that I changed was the two intake manifold gaskets with some really thin aftermarket ones:nono:

I will buy genuine Toyota ones & see if thats the problem otherwise I give up:3d_frown:, beaten by the 7M demon.

Don't give up look at IJ, he just keeps on ticking.

 

[IJ.]

< Timex

 

[BLACKCAT]

Took the car for a 20km drive & it goes quite good apart from the rough idle which is a combination of the cams & loss of compression.
There is a noticeable air leak behind the alternator area.
Just wondering how much horsepower it will loose at the next dyno meet (10rwkw?).:nono:
Probably what I gained by putting in the BC cams but the ported head should make up for some so my estimate is 110 rwkw.

 

[cuel]

Hmm.... Sounds like a valve issue. Not seating properly for some reason. Did you have a valve job done, or just lapped in?

 

[BLACKCAT]

Well I pulled the head again & took it to a machine shop to check for leaks & #3 & 5 were definately leaking at the valves.:3d_frown:
Had them machine all the seats & valves.
Just finished putting it back this evening & will do a compression test tomorrow.
The machine work threw out all the valve clearances & took me a while to get them fairly good as some of the shims had to be as low as 2.30 mm.
Thank goodness for aftermarket parts as Toyota only has them as skinny as 2.50mm.

Initial valve clearance following machine work:
Ex:
0.25 0.22 0.08 0.24 0.21 0.25 0.23 0.23 0.13 0.26 0.23 0.19
In:
0.18 0.16 <0.04 0.16 <0.04 0.16 0.15 0.15 0.05 0.20 0.16 <0.04

Final clearances after a lot of measuring, swearing & swapping::naughty:

Ex:
0.25 0.23 0.30 0.25 0.25 0.25 0.23 0.24 0.30 0.26 0.23 0.26
In:
0.18 0.20 0.20 0.20 0.23 0.16 0.19 0.18 0.20 0.20 0.16 0.20

67097mgte:
I 25 20 20 20 20 20 20 19 20 20 16 23
80 90 91 61 94 92 99 92 93 93 66 88
E 25 25 26 25 29 27 30 26 29 30 30 28
80 80 78 80 85 80 84 81 67 67 73 86

 

[Tire Shredder]

nice work sir. dyno time!

 

[BLACKCAT]

Just did a comp. test & the two cylinders are up to 170 so problem solved.
Had some exhaust mods done:
2 1/4 to 3" after the first muffler flange straight through to a rear 3" muffler.
Sounds a bit louder but not as bad as I anticipated, around 88db at 3000.
Will see how the new setup performs on the dyno in a few days.

On a much sadder note looks like I lost my cat which was with me for over 10 years.
It was dying from kidney failure & it did not want to eat anything at all yesterday.
Once I finished the engine yesterday I went to look for it but could not find it anywhere, even looked under the house.
Appears that it just went away to die somewhere.:nono:
It never missed a day of not greeting me when I came home in all that time & I will miss it for a very long time.
God thats just another topic I will raise with you in due course.:icon_evil