evilminds

ok first off i no longer have the camaro..but i did manage to get it running decent enough thanks to everyone here :-) un fortently selabrations were short lived after i loaned to my nephew..yup he wrecked it..totalled it..that's been a while awhile back..but

Now for the new project..i know this is a camaro forum, but since i got good info here the last go around i thought maybe you guys might be able to help me out with my 89 GMC truck..

Ok , i got this used and in non running condition. was told it was 305,,after charging the battery, and cleaning the motor, i got it started only to here the dreaded rod knocking sound.. so much for a quick fix.

So i went out and got a rebuild kit for a 305,,After pulling the heads off i notice that it's not a 305 but a 350,,so back to the autostore i go to exchange the 305 rebuild kit for the 350 rebuild kit.

not only was it a 350, but 1,3,5, and 7 pistons look as if a band of mice had been chewing on them..the other pistons were fine...wait for it there's more ;-)

sent the block and heads out to be machined and cleaned, only to hear the block is cracked,,,Cracked! grrrr

ok at this point I'm looking at all the possible SB i have lying around the garage..just something to put in this truck so i get moving again..didn't have another 350 so i settled for a 305 which i knew the block and heads were good on..

Ok here comes the problems i worked around.

Block is a one piece rear main seal just like the 350 i pulled out..so other than it being a 305 the crank should work since there both the same stroke..that takes care of that.

head that were on the 305 however is a different story..the heads are 14014416 58cc heads..
So in order to make the intake off the 350 work on these heads..i had to angle the left and right center bolt holes on the intake so they could be bolts onto the older heads..and i guess that fixed that issue lol

now for problem i can't seem to get around
Ok motor is all installed..i set the base timing to 0..engine wants to stops running almost as soon as it starts..
plugging the ecm back up after setting the base..the idle is about 1000 to 1200 with a constant up and down in RPM..and wont idle lower than 1000 in park.

of course i dont have to tell ya what the motor does when ya put it in drive at this RPM..ok i'll tell ya anyway hehe ok RPM at 1000 and in drv IAC opens fuel gets poured in and the RPM sky rockets..putting it back in park the idle is now twice as high as it was when it was in drv.

a friend of mine came over and suggested that the timing sounded like it was off because when he pumped the gas in N it backfired thru the TBI..so without disconnecting the wire you normally disconnect for setting the base timming he adjusted the dist so it didnt back fire and it would take the gas ok..that brought the idle down somewhere around 850 or so.

checking where the timing was actually set after he was done revealed that timing was at 12D BTDC oh and i'm using 305 chip AJUK which has a base setting for 0..so now i'm scratching my head.

It runs ok like this,,still tries to throw gas cause the idle is still abit high when its in drv,,but something just doesn't sound right to me.

I've never turned the distro on any of computer controled vehicles without disconnecting the wire for setting the base timing.

So if the ECM is set for a base timing of 0..but the distr is actually set for a 12 BTDC..shouldn't cause even more problems than just the rogh idle and the high RPM the lowest map it gets like this is around 30 to 35 @ ~850RPM..

So if i set the distro for the base timing of zero like the ECM is set for,,how would i add the 12BTDC that it seemes to be somewhat happy with lol

oh and another question if i may..been so long i cant remember.
when vewing the spark advance table..adding to the existing numbers is bringing it further into the BTDC? or is it taking ATDC?

Sum up this motors components.
Stock 305 block (around 86 i think) 1 Piece rear seal
Stock crank..3.48 Stroke
stock Cam( non roller)
58CC cast heads
Aluminum intake center holes drilled for correct angle to bolt to heads.

If anyone has any idea's i'm all ears..right now it's burning rich both before and just as soon as Closed loop is reached..but not as bad when the distr is set to 12 BTDC.

Damon

The ECM does not know what the base timing is set at. It assumes 0* becuase that's what's programmed into the chip. So it's going to be 12* more than it thinks it is at all RPMs and loads (unless it's tickling the knock sensor which will cause it to pull the timing back).

First thing I'd verify is that the indicated TDC is actually true TDC. You've thrown together a Franenstin of parts from different motors so it's best to verify things like this absolutely first.

Fortunately, ALL SBC gen1 cranks, regardless of year or displacement, have the crank keyway in the same place (pointing straight at the #1 crank throw) so the only mismatches possible are between the balancer and timing tab. Plus the possibility that the old balancer has slipped the outter ring which throws everything off. Hence the need to verify indicated TDC against actuality.

Looks like basically a clone of the stock 305 TBI engine with one exception- NON-swirl port heads. That right there is going to throw things off a bit since the older heads will want more timing than the swirlies. I can't say that they'll want 12* more becuase of the difference in design, but they'll want more. Certainly just the head change alone is enough to throw off the rather touchy (and crappy) tune of the stock TBI programming by probably a noticable amount.

I'm assuming no codes, no check engine light? If so, figure out why and fix it first before worrying about the tune or final base timing adjustments.

And, of course, welcome back!

evilminds

Hi, ya Damon,
i agree with you about the harmonic outer rings sometimes moving,
i learned everything i know about engines,,what little i know anyway lol from my older brother,,recently pasted away..
First rule was never assume the line on the harmonic balance is correct without first physically checking it.
your also correct about the key way too.
the timing marks on this engine are correct tho :-)
been thinking about what you mentioned about the heads,,so you think this 12* might be ok for now the way it is,,there was only 1 knock count using ALDL and that was when it was first started up.
I haven't taken it for a test drive yet, and monitored it using ALDL because i still have yet to find a laptop that's within my price range(FREE) hehe

evilminds

had a chance today to start the engine when it was cold..kinda sluggish like the timing is a bit off,,when it does finally fireup it quickly stops running,,but giving it abit fuel for about 1 to 2 min or so let's it stay running but then it idles up and back down,,for about 45 sec or so before it finally idles out.
which brings me to this question:
when the engine is in open loop,,is there a timing chart that the engine runs on before it goes into close loop? i didn't see anything in tunerpro.
also would it be a good idea to just start with the BLM chart first.to get things under control there before moving onto the other area's .
or should i just get the engine into closed loop first,and just try to get the map up in the lower RPM's to lower the RPM at idle?

Sorry for all these questions which i'm sure are covered in other posts here,,but i wanted to try and get the answers first hand as opposed to pulling the info from another post only to have that info apply to a different situation,or engine etc.

thanks in advance,Rick
Sorry Damon i forgot to thank you for the welcome back :-) it's a pleasure to be back among ppl who know more than i and try there best to give honest and to the point info without sounding like a rocket scientist lol that helps ppl like myself who only work on maybe 1 or 2 vehicles a year,,,.at the most :-)

evilminds

hmm, ok i have to admit something my memory at late has quickly become as short as my johnson,,so someone please refresh my memory for ok?

In open loop does the engine run off of the "Main Spark Advance table" at all?
also I went back to the 350 chip ANLW since the motor seemed to like it better than the 305 AJUK bin i picked..so If my Distributor base timing is set at 12* and i'm running with the ANLW bin..is my advance going way too far in any cell..i only ask because i forgot how to add up the total timing lol sorry guys,,i tried searching the forum but appearrently i didn't use the correct key words or something

evilminds

ok i got the idle pretty much squared away,,i found the table for startup timing,,so now it cranks cleanly and starts up soon after with no problems...
idles gradually drops to around 700 or so and runs very steady with no hickups
I put the base timing back on zero,,or pretty close to zero anyway changed the startup table around working at .2 intervals,,and thats about it :-)
I think my radiator is clogged up tho..with the thermo installed the temp goes to well over 225 with a 195 thermostat..with the stat taken out it still rises but not as quickly..

I guess the next step is working on the spark table while in CL,,but have to fix the temp thing first..
i'll attached the last log i did before i shut it off..just kept it simple tho..just the sensor data only..
would really help if someone could look over what data there is and let me know if i'm at least heading in the right direction

evilminds

ok the idle is now not wanting to go below 850 now for some reason..even after the ECM has kicked in..could someone with a 305 and just mild upgrades or just stock 305 do me a big flavor and post your bin file and datalog at idle up to temp range of about 150 or so..i just want to compare your IAC count and map sensor readings with the ones i'm currnetly getting on this engine.
I don't see any knock counts,,BLM refuses to budge from the 133 range INT stays at 128.
or just a datalog at idle would work too..then i could just try and change the timing until i get in the ballpark of what they should be average on a 305.
i tried looking thru the forum for uploaded datalogs but couldnt find any that had already been tuned,,or had been tuned close enough to say alomost finished etc.

thanks in advance, Rick