1987L69

So I have been running my LG4 in my 84 Z28 5 speed, which i believe to have original parts at the very edge of the timing tab, IE off the timing tab, I figured it was my old harmonic balancer, so Friday I replaced the one that was on it with a new one, thinking that it may have slipped, but it had not, I have tried setting the timing at the factory 6* and it has poor idle and performance, very hard to start when warm (not the starter dragging, just turning over forever). At the current timing, I get no starter drag or pinging under load. So my question is, where to go to from here? It has an edelbrock intake, edelbrock 600, non CC distributor and computer removed. The engine does not smoke at all, odometer shows 94K miles and is pulling right around 24 in of vacuum at idle.

sofakingdom

iTrader: (1)

Advance it.

Keep advancing it until it just starts to ping under heavy load in too high of a gear when fully hot. Then back it off until it quits.

Won't necessarily be "right", but it'll be ahelluvalot better than some "spec" from "book" that doesn't apply to YOUR car which IS NOT the car "spec" was created for (different, carb, dist, etc.), with the fuel YOU can buy in 2017 rather than 1986, doing what YOU do with it, to get it to run like YOU want it to.

Don't be a slave to "spec", life is too short for that.

zed-028

AlkyIROC

Are you unplugging the EST connection when you check the timing??

OrangeBird

iTrader: (1)

It appears he has deleted the EST .

I agree 100% with the "advance it till it pings when floored , back it off a few degrees at a time till the pinging can't be heard when floored , and then a few degrees more for safety's sake , and then drive it" approach to setting timing . Sofa has so rightly called it "giving the engine what it wants" and that really is the best way to put it , set the engine so it runs good despite what the book says for timing specs.

zed-028

seeing as though youve deleted the EST (well spotted) did you pull the vac hose off the dist before setting the timing?

AlkyIROC

The "non CC distributor" I assume is a large cap HEI with weights and springs in it plus a vacuum canister attached.

Trouble with timing marks and balancers is they're very inaccurate. Many, many years ago I was adjusting my timing at the dragstrip. I was up to 44* advanced and still making power.

Eventually, I used a piston stop and a degree wheel to see how accurate the timing mark was. When the piston was at TDC, the timing mark said it was already advanced 8*. An adjustable timing pointer solved the issue and what I thought was 44* was actually 36*.

Advancing the timing until it pings under load then back it off a few degrees isn't a bad option for a basic daily driver but isn't very good for any kind of performance setting. The base timing should be set to match the camshaft grind however how much total timing an engine requires depends on the actual engine. 2 engines with the same base timing may make more power with different total timing so what your engine needs depends exactly on the engine. Ballpark is anywhere from 32-38* of total timing. Once the base timing is set, you don't change it unless some major engine changes are done. Total timing is changed by modifying the weights and springs inside the distributor.

However you need to first get the engine running properly with the correct base timing. The factory setting may be 6* but even with a stock cam 8-10* will be better. I know you're going to hate to do this but I would recommend using a piston stop and degree wheel to check the accuracy of the timing mark first. If the marks are not accurate, your base timing won't be accurate.

zed-028

if you fancy a rougher more Aussie method, take plug #1 out, find the compression stroke by placing your finger over the hole and have a mate turn the engine by hand. when you feel compression, put a pen or a piece of dowel in the hole. have your friend turn the engine by hand a bit more, when you see the most of the pen out, you will be at tdc.

may not be as accurate as a piston stop and a degree wheel but it will at least let you know roughly if the balancer mark is worth a pinch of ****

1987L69

Yes I do, and I have it hooked to manifold vacuum after I get done setting the base timing.

Thank all of yall, now i know im not crazy with this engine, now my second thing, I wonder if the timing chain is installed correctly or if its still the factory one, if it jumped a few teeth........ I will find this out in a couple of weeks when i replace the timing chain and gears

redneckjoe

one possibility is a mis-match of parts. some SBC's used a 12 o'clock balancer and pointer, while others used the 2 o'clock version. it's possible your using the wrong pointer.
http://garage.grumpysperformance.com...-engine.11561/

i agree with Sofa's method 100% though. give the engine what it wants.

what kind of distributor are you running?

1987L69

It has a stock timing chain cover, with the timing marks at the 2 o'clock position for TDC, and the ballencer does as well.
Its an accell distributor, about 3 months old.

midias

Just for fun did you set piston #1 at TDC and make sure the rotor was actually pointing at it?

1987L69

no I did not. Im rather crafty with engines, I am a diesel mechanic in the Coast Guard and have always messed with engines. But all that would tell me is that it's at 0* correct?

midias

Correct but if the distributor was dropped in off a tooth or two it could be causing you some issues.

Also are you sure your hard hot start is not carb related? If you start with the pedal held down does it get easier?

1987L69

It does not matter where the accelerator is when it is at the factory timing. There is no way to have the distributor off a tooth or two, because you rotate it to set the timing, and that does not effect the center shaft.

midias

I mentioned the accelerator because I have seen edelbrock carbs leak fuel into the manifold when hot and flood the engine a little holding it down all the way helps the motor start letting more air in.