[NoVa-Corvairs] Noob May Need a Good Used Head

[Darrin Hartzler]

Hi all,

If I were going this far, I would pull both heads and put higher compression 110 heads on for more power with no other changes.   Low compression allows you to run regular gas, but does not give the excellent pep one expects from a stock 110.

I have several sets of 110 heads, a few of which I would be tempted to run as is.   

Just a thought as you are digging into the engine.  Seems a shame to me to spend money on deep seats for an open chamber smog head.

Best,
Darrin

-----Original Message-----
From: Novacc-list [mailto:novacc-list-bounces at corvair.org] On Behalf Of Bryan Blackwell via Novacc-list
Sent: Friday, March 03, 2017 10:32 AM
To: Northern Va Corvair Club
Cc: Bryan Blackwell
Subject: Re: [NoVa-Corvairs] Noob May Need a Good Used Head

Hi Dan,

A couple of thoughts:

First, you're right, the head has to come off.  The compression check shows zero.  On the leakdown test, it may just be you had it on the overlap instead of compression, don't forget it's two engine revolutions per cycle.

One other bit - as I recall you have an electronic ignition.  On those you don't want to pull plug wires for the test, it's better to sneak a probe down the boot on each distributor wire and ground the cylinders one at a time.

Finally, I've reached the point that I don't trust used unknown history heads.  IMHO, if the head is coming off, I want to put a rebuilt one with fresh seats in it's place.  In any case, you should verify which casting numbers are on the engine so both sides match.

--Bryan

> On Mar 3, 2017, at 12:04 AM, Dan Weiss via Novacc-list <novacc-list at corvair.org> wrote:
> 
> Pulling one plug wire at a time, removing the wire for #2 Cyl produced no difference, so it seemed the problem was the same cylinder the Ranch found in need of some attention.
> 
> Compression test was done on each cylinder.  First test was without having throttle open (forgot about that); second test was with throttle open for each cylinder.  Open throttle produced a range of 2 to 7 additional PSI of compression.
> 
> Here are readings:
> 
> CYLINDER			FIRST TEST			SECOND TEST
> 	2					0					0
> 	4					143					145
> 	6					150					157
> 	1					140					143
> 	3					157					164			
> 	5					151					156
> 
> Onto the leak down test.
> 
> Did the best I could to get cyl #2 to TDC by aligning the rotor under the cap with the #2 contact.  First attempts read close to 100%.  Further adjustment seemed to tighten things up and tests consistently read right on the yellow and red section divider at about 71% cylinder leakage. I made sure to turn the regulator so the gauge read 0% before connecting it to the cylinder. The gauge immediately read 71% leakage and stayed right there.  I turned the regulator clockwise to allow for airflow from the compressor, and the air was flowing out the exhaust pipe.  What surprised me was that if I did achieve TDC, with the air leaking out the exhaust, I thought the rocker arm in the pic would have been with the exhaust valve, but as you all already know, that is the intake valve.
> 
> Does it seem that the leak down test was done correctly?  
> 
> Obviously, regardless of the leak down test, the head has to come off to be replaced or repaired.   I plan to pull the valve cover off to see what may be going on under there tomorrow or Saturday..
> 

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