LE9 305 w ESC Performance upgrades '86 k5 Blazer

[Ricko1966]

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]

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]

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]

^^^ 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]

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.

 

[legopnuematic]

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]

I think you are correct I think there is a box behind the glove box which was the predecessor to the first ECM.
I've always said you could remove my '83 engine and the check engine light wouldn't come on


This looks like a good article on vacuum advance

https://www.motortrend.com/how-to/1601-everything-you-wanted-to-know-about-vacuum-advance-and-ignition-timing/

 

[Johnny Atomic]

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]

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]

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

 

[68post]

The restrictions in a 305 are it's awful bore size coupled with it's diminutive size with low compression, and you severely need compression @ 7,000'.
Not the heads which are normally just fine to boost compression on a 350, (unless you have the worst versions).
The cam is sometimes smaller than a 350 cam specs, but not always, and the 305 needs a very small cam to help to not lose compression - especially in a truck! But a BETTER cam always helps, Isky and Comp both make some very good tiny cams ( most truck 350's need these also).(A cam is down the list about 4th)
Add a K&N air filter to your stock airbox, but it will be expensive

Long tube headers always bring extra power and a mileage boost if you free up the remainder of the exhaust. A higher flowing single pipe system can be better than duals when done correctly with a hi-flow Y-pipe and low restriction muffler, (A mandrel bent 2.5" system). This would be priority one!

Set a new stock 350 installed with better exhaust and you'd likely gain mileage and definitely feel like double the power. And I'd use new/good 305 heads on that 350, 1.84 valves and all!!

 

[1979 K10]

Surprisingly the 305 with ESC holds up really well to a 350 until GM went to throttle body injection in 87. Only down 5 hp and 40 ft lbs of torque.

https://autocatalogarchive.com/wp-content/uploads/2024/08/Chevrolet-Blazer-1986-USA.pdf

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I hear you on 350 being superior.

We had a 95 TBI 350 and still own the 97 vortec 350. Big difference in power numbers and seat of the pants power between the two.

Also have a 327 aka LS 5.3 in the family. It doesn’t have the down low torque of the vortec 350 but comes alive higher in the rev range.

 

[1979 K10]

All original exhaust except the huge, power robbing catalytic converter is long gone so that has to help exhaust flow. No emissions testing where I live.

If I redo exhaust I’d like to keep it single and try using these better flowing manifolds. I read on another thread that someone switched from headers to these and thought these were better.

https://a.co/d/hanoBAJ

 

[68post]

All original exhaust except the huge, power robbing catalytic converter is long gone so that has to help exhaust flow. No emissions testing where I live.

If never redo exhaust I’d like to keep it single and try using these better flowing manifolds. I read on another thread that someone switched from headers to these and thought these were better.

https://a.co/d/hanoBAJ

No manifolds do better, and the corvette big Y manifolds would flow better than those $301.00 new ones. The stock exhaust is weak even w/o the cat.$.02

 

[1979 K10]

Here’s a do it yourself dual exhaust kit.
Pair that with some summit long tube headers + dual mufflers.
https://www.summitracing.com/parts/wlk-89005

Still looking for a single exhaust setup. I may try to copy the current design but using larger diameter pipe as mine is pretty dented up right by the front driveshaft and transfer case.