LE9 305 w ESC Performance upgrades '86 k5 Blazer

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,764
Reaction score
9,560
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
CAMSHAFT! and heads are the big restrictions on an LE9.

As far as you blue smoke at startup. If you have good oil pressure and compression it is probably jus valve seals.
That is an easy repair.
If it's got 416s or 601s they really are not bad heads, yes there are better,but there are much worse.
 

1979 K10

Full Access Member
Joined
Jun 8, 2021
Posts
80
Reaction score
135
Location
Flagstaff, Arizona
First Name
Terrell
Truck Year
1979, 1986
Truck Model
K10, K5
Engine Size
400, 305
If it's got 416s or 601s they really are not bad heads, yes there are better,but there are much worse.
I'll have to look for the head casting numbers where ever those are. The engine is caked in 40 years of oil and dirt.
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,764
Reaction score
9,560
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
I'll have to look for the head casting numbers where ever those are. The engine is caked in 40 years of oil and dirt.
More work than you want to do just to satisfy curiosity.. cast into the head by the rocker arms underneath the valve covers. Seriously if you want performance,change engines. Or put boost on that one. Swap your boost to the next engine when this one dies. Not kidding
 

Turbo4whl

Supporting Member
Supporting Member
Joined
Oct 30, 2019
Posts
3,190
Reaction score
7,471
Location
Downingtown, PA
First Name
Wayne
Truck Year
1974
Truck Model
Jimmy
Engine Size
350
^^^ BOOST^^^

When you think about newer vehicles, they mostly have smaller displacement engines. So how do they have enough power? Boost is the answer.
 

hack_man

Junior Member
Joined
Jan 2, 2025
Posts
5
Reaction score
4
Location
MA
First Name
Tony
Truck Year
1983
Truck Model
K10
Engine Size
305
Where is the ESC Module located? Does this work with the knock sensor to retard timing?

I remember there was a TSB back in the 80's, my 305 was pinging and the dealer installed two small canisters tied to the vacuum line at the distributor. I think they acted to delay vacuum advance.

I tried to get a copy of that TSB but they refused.
 
Last edited:

legopnuematic

Licensed Junk Dealer
Supporting Member
Joined
Oct 27, 2016
Posts
2,711
Reaction score
7,257
Location
MO
First Name
Spencer
Truck Year
1971, 1̶9̶7̶4, 1976, 1979,1̶9̶8̶5, 2002
Truck Model
Dart Swinger, Sierra 10, C10 Cheyenne, C10 Big Ten, Silverado 10, Ram 2500
Engine Size
225/6, 350 c.i., 350 c.i., 5.9l Cummins
Where is the ESC Module located? Does this work with the knock sensor to retard timing?

I remember there was a TSB back in the 80's, my 305 was pinging and the dealer installed two small canisters tied to the vacuum line at the distributor. I tried to get a copy of that TSB but I remember them refusing.
If I’m recalling correctly, the esc box is in the cab behind the glove box area. Wires should run from the large plug on the firewall above the passenger side cylinder head.

It works with the knock sensor to pull timing.
 

hack_man

Junior Member
Joined
Jan 2, 2025
Posts
5
Reaction score
4
Location
MA
First Name
Tony
Truck Year
1983
Truck Model
K10
Engine Size
305

Johnny Atomic

Full Access Member
Joined
Oct 18, 2019
Posts
84
Reaction score
203
Location
Little Rock AR
First Name
Johnny
Truck Year
1983
Truck Model
Sierra Classic 1500
Engine Size
350
If you start having intermittent starting problems that you can chase down to lose of spark, I would look at the ESC. You can buy a $20 bypass loop cable on ebay to disable/bypass the ESC, and leave all the ESC stuff in place. Check the timing after disconnecting the ESC, it will probably be a little too far advanced.
 

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
6,769
Reaction score
11,478
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
305
I can confirm that the ESC module is located behind the glove box. The best access is to clear out your glove box and remove the box itself.

I would advise against any kind of a bypass or elimination of the ESC, like the bypass loop mentioned in the post above this one. It's fine if you want to do that for testing purposes though.
 

1979 K10

Full Access Member
Joined
Jun 8, 2021
Posts
80
Reaction score
135
Location
Flagstaff, Arizona
First Name
Terrell
Truck Year
1979, 1986
Truck Model
K10, K5
Engine Size
400, 305
I can confirm that the ESC module is located behind the glove box. The best access is to clear out your glove box and remove the box itself.

I would advise against any kind of a bypass or elimination of the ESC, like the bypass loop mentioned in the post above this one. It's fine if you want to do that for testing purposes though.
Looks like the previous owner replaced the distributor. How do I check the timing since mine is ESC equipped?

I live at 7000 feet altitude so we usually advance timing for our elevation
 

Latest posts

Forum statistics

Threads
44,607
Posts
962,240
Members
37,132
Latest member
Jwedd
Top