diff --git a/I650/tests/i650_test.ini b/I650/tests/i650_test.ini
index 21011779..051c5cb3 100644
--- a/I650/tests/i650_test.ini
+++ b/I650/tests/i650_test.ini
@@ -14,7 +14,7 @@ set mt debug=cmd;data;detail;exp
 set dsk debug=cmd;data;detail;exp
 
 :: Limit maximum diagnostic execution time
-runlimit 2 minutes
+runlimit 50M instructions
 set on
 on error ignore
 on runtime echof "\r\n*** Test Runtime Limit %SIM_RUNLIMIT% %SIM_RUNLIMIT_UNITS% Exceeded ***\r\n"; exit 1
diff --git a/PDP18B/tests/pdp9_test.ini b/PDP18B/tests/pdp9_test.ini
index 545ed475..45d9e431 100644
--- a/PDP18B/tests/pdp9_test.ini
+++ b/PDP18B/tests/pdp9_test.ini
@@ -9,7 +9,7 @@ set cpu eae
 cd %~p0
 :: Limit maximum diagnostic execution time
 ::
-set runlimit 2 minutes
+set runlimit 10M instructions
 set on
 on error ignore
 on runtime echof "\r\n*** Test Runtime Limit %SIM_RUNLIMIT% %SIM_RUNLIMIT_UNITS% Exceeded ***\n"; exit 1
diff --git a/PDP8/tests/pdp8_test.ini b/PDP8/tests/pdp8_test.ini
index 02b37ed5..6f76ba91 100644
--- a/PDP8/tests/pdp8_test.ini
+++ b/PDP8/tests/pdp8_test.ini
@@ -7,7 +7,7 @@
 cd %~p0
 
 :: Limit maximum diagnostic execution time
-runlimit 2 minutes
+runlimit 1500M instructions
 set on
 on error ignore
 on runtime echof "\r\n*** Test Runtime Limit %SIM_RUNLIMIT% %SIM_RUNLIMIT_UNITS% Exceeded ***\n"; exit 1
diff --git a/SEL32/tests/sel32_test.ini b/SEL32/tests/sel32_test.ini
index 7e2976e7..a5947824 100644
--- a/SEL32/tests/sel32_test.ini
+++ b/SEL32/tests/sel32_test.ini
@@ -23,7 +23,7 @@ set env HOST=sel32
 ;======================================================
 ;
 ; Set run limit of 2 minutes
-set runlimit 2 minutes
+set runlimit 750M instructions
 set on
 on error ignore
 on runtime echof "\r\n*** FAILED - SEL32 Test Runtime Limit %SIM_RUNLIMIT% %SIM_RUNLIMIT_UNITS% Exceeded ***\n"; exit 1
diff --git a/VAX/tests/vax-diag_test.ini b/VAX/tests/vax-diag_test.ini
index 1cd6a661..902663e5 100644
--- a/VAX/tests/vax-diag_test.ini
+++ b/VAX/tests/vax-diag_test.ini
@@ -18,7 +18,7 @@
 #set cpu hist=20000
 #break A3B4 SHOW HIST=40
 cd %~p0
-set runlimit 2 minutes
+set runlimit 600M instructions
 set on
 on error ignore
 on runtime echof "\r\n*** Test Runtime Limit %SIM_RUNLIMIT% %SIM_RUNLIMIT_UNITS% Exceeded ***\n"; exit 1
@@ -125,8 +125,8 @@ expect "DS> " send "ATTACH KA820 HUB KA0 4096 0\r"; go -q
 expect "DS> " send "ATTACH DWBUA HUB DW0 4 5\r"; go -q
 # VAX 8200 simulates the floating point accelerator which then 
 # inspires tests to use it.  This takes more time.
-set runlimit 3 minutes
-call Common
+set runlimit 600M instructions   # Override prior runlimit
+call Common 
 call do_test EVKAB "VAX Basic Instructions Exerciser"
 call do_test EVKAC "VAX Floating Point Instructions Exerciser"
 #call do_test EVKAE "VAX Privileged Architecture Exerciser"