budget builder

iTrader: (3)

ok I didn't make it out of the yard. it idles at 1K rpm like clockwork but when you drop it in gear it chugs. I know this would happen since b/c of the rpm drop but when I hit the gas the motor drops out almost completely. the more gas the worse it is until it shuts off totally. and backfires. is it possible to be just one peg off after dropping in dizzy? or is this still just something simpler than that? I just read your post about absolutely nothing over 12 with the vaccum plugged and THEN the vaccume should work its magic. ok I had to park it in the backyard for now my timing light is toast. Then I have to rewire the choke to a correct 12v and ground neither of them were a good choice from my #Mechanic# the ground was and is too loose and now the hot is kinda baked. :_( I had no idea that tuning was such fun.

JaBoT

you need to adjust the idle afr screws with the car in gear and someone holding the brake.
Also sounds like you may have another issue like a vacuum leak somewhere

budget builder

iTrader: (3)

idle was set about 1000 and it was running. when I dropped it into gear of the rpom dropped and then it started chugging I khit the gas and ran worse a lot worse. it started shutting off the only way I could get it to catch up was to let off the gas. my timing light is toast. and I need to rewire my choke its kinda crispy plus my mech. left the ground really loose. I parked it in the backyard. but it idles in park beautiful when I get another timing light I will set it to 12. or should I wait until I can afford a dial back light? is it possible that i got 1 peg off when i dropped the dizzy in? nah! its running too good for me to have done that. idk but i will not be defeated this will not beat me i will be spinning a wheel by the end of next week b/c i have to soon start doing the body work. thanks to everybody that has been nice enuff to try to help this rookie.

budget builder

iTrader: (3)

ok will check for another vaccum leak. the best vaccume i could get is 15in but i did manage to get it to stabilize. and hey thanx for taking time to help. my timing light is toast cant get another one until Thursday.

JaBoT

even if the dist is a tooth off, if you are able to get the timing you want without the can hitting anything it doesn't really matter. The only disadvantage is the #1 plug may be a little off from the normal position of around 5 o'clock.

budget builder

iTrader: (3)

what about having it on the exhaust stroke instead of the compression stroke?

JaBoT

that would be 180 out and it would be popping and spitting and not want to run.

bestracing

He has the Mallory distributor which I believe should of had a spring kit with it, mine did.

Just as an FYI, Also make sure that the vacuum advance diaphragm doesn't take more vacuum to be fully engaged than what your motor has. Example your max manifold vacuum is 18" and it takes more than that to fully pull the diaphragm in.

JaBoT

the first post says he has a "hei dizzy"

All that will do is not give the full amount of vacuum advance at idle and or cruise. It will still be advanced from it's initial setting even thought the vacuum can is not fully engaged. Is it optimum, no. But you are making it sound like it won't work.

bestracing

I didn't say it would not work, I just posted it as an "FYI" since he is new to this and it is something he should check out when he gets the time. Yes it still will be advanced but the timing will not be stable. There is a post somewhere on here talking about setting the vacuum advance timing from an old GM engineer. It's good reading for the OP.

budget builder

iTrader: (3)

Hey fellas I found a huge chunk of the problem. I started not to do it but am really glad that I did get a piston stop. I followed instructions and loosened the rocker armms installed the stop and rotataed the crank one way then the other and guess what. No wonder I was going close to what looked like 20btdc the mark is off just that much I took a pic. Its at the bottom the blue are two marks one in clockwise the other in counterclockwise. And if I'm right TDC is in the center this is why when the adv looked high the car was still running better. I guess I should've said that it was the same balancer off the 20+ year ols 305 I pulled out of the car. I'll let u know the results.

JaBoT

Its actually not uncommon. The outer ring on the balancer spun. Just put a new balance on and you should be good to go.

budget builder

iTrader: (3)

Got the power back! Got it timed for 12btdc got close to 18in vaccum on manifold and got 900rpm in park and ~550-600rpm in drive with ~16in vaccum. I have not attached timing tape but it seems to have ~12 degree of mech. advance I attached the vacc. Adv and the idle went up to ~1100rpm so I idled it down to ~900prm again. It purrs. But I shut it off and it still diesels a little. I fired it up and shut off no dieseling do it again and revv it to ~2500 to 3500 and it dieseled again. I idled down a little more and revved it and it didn't diesel

budget builder

iTrader: (3)

Still has bog under load and light accl. Moving accelerator pump rod seems to have little effect. I'll keep trying.

budget builder

iTrader: (3)

Look at this the white mark is the "real" mark

budget builder

iTrader: (3)

I know i'm posting a lot but I have a question: do any of you think that the dieseling could be caused by 87octane gas? I have a tank full. look i'm no expert but I don't think the timing is too adv. or retarded. i don't think the idle is too high opening the throttle plates and i heard that if i up the octane that might take care of hot spots in the cylinders if that is the problem. i'm just asking. maybe i need to check float levels? heck man idk i'm just throwing ideas out there. I want to thank once again everybody that time out of their schedules to help me!

bestracing

Actually it looks like the balancer is for a timing cover that has the timing tab near 12 o-clock position and he has an aftermarket timing tab that is in the ~1:30 to 2 o-clock position. My 86 was like this but when I cleaned, painted and sealed my motor, I bought a new balancer and had to get a new adjustable timing tab because the stock was near straight up and the new balancer was to the side. I used a piston stop to find zero and then moved the red 0* tab to match. The new balancer has timing marks on it which makes it easier to read rather than trying to read the tab.

I hated trying to reach over the front of the motor to look down behind the water pump to time the motor. Now I can do it from the side.

Could be the gas but could also be your plugs could be too hot (R45 vs R43) or your idle mixture can be too rich now. You've changed a lot so your mixture settings might not be optimized now. Just a good practice to recheck these things after making multiple changes.

If the dieseling is really bad and you hate waiting for it to quit, you can leave the car in gear when you shut off the motor and that kills it right away then shift it into park while you are trying to figure this out.

I run 89 during cool weather and 93 during the "Dog Days" of summer because of where I have my timing set and the hotter the weather the more likely the motor wants to detonate "ping". Altitude, compression ratio, cam timing, ignition timing, octane, air temperature, carbon deposits, spark plug temperature range can all play a part in detonation.

JaBoT

O yea forgot about those. They really were a pita to lean over the front of the car.
Best bet is to just buy a new balancer and matching timing tab at the same time.

budget builder

iTrader: (3)

what would happen if I connect it back to ported vaccum? and right now the idle is at 1000rpm in park and about 650 in drive. maybe its b/c of the loud exhaust but that sounds a little high to me can let me know what you all think. I have it hear because it seems to make the most vaccum but maybe with some tweaking I can get it to idle a little lower. I don't like having to hold the brake pedal this hard at stop signs and lights just to keep it tamed.

bestracing

Per GM specs it should be 500 RPM at warm idle (open choke) in drive. With mine adjusted to ~800 at idle I'm about 550 to 500 in drive. My cam makes it bounce a little in gear.

JaBoT

How much vacuum is it making at idle?

And no don't put it on ported otherwise it will idle even worse. Since you are asking this I'm guessing there is someone there who says it's not supposed to be that way?

Also what stall converter do you have?

budget builder

iTrader: (3)

Ii have a stock converter and yes when put to ported vaccum it did idle worse just as u said and your right me and some other guys thought it should idle a lot lower but it makes ~18in vaccum in park at ~1000rpm. And that's about the best I could get it I also learned something interesting today. I was going to change my metering rods and step up springs and checked the owner manual. The manual said the base jet is 1432(.110) and rod Is 1459 (075x047) well when I took them out they were really 1451 (070x047) which according to edelbrock.com pdf is 2stage lean on cruise and 3stage lean on power which means it probably has had a jet change too! Anbody got an idea where I need to start to fix this mess? I was trying to go 1stage rich on power and cruise from base which now would put me 4 stage rich power and 3stage rich cruise from where it is now since its not at bse like it should be. HELP!!!!!!!!!!!!! And how hard is it to change jets? Oh and step up springs are orange I think

JaBoT

Tune the a/f screws with the car in gear and the brake on. It makes a difference.

As far as the carb. I am assuming its used. If not call edelbrock and they will send you the right stuff.
I would start with the carbs base jets, rods and springs and make changes from there. They should get you relatively close.
The bog you have is probably because the carb was leaned out to much.

budget builder

iTrader: (3)

ordered the original base metering rod so I can start fresh. in meantime will tune carb for idle in drive and see how much vaccume I stillhave or lose. thx

budget builder

iTrader: (3)

got the rods its been raining almost everyday for about a month here in north Carolina so if I can 1. get off work in time 2. keep my wife from finding me something to do i'll take the 8 screws out of the air horn take out the 2 jets install the proper 2 jets install the air horn then install the proper rods and see happens from there

budget builder

iTrader: (3)

Ok I changed the rods and jets. I found out that The jets were already the original .110. Nyway I changed them to the new ones anyway. I checked the secondaries and made sure that they were opening. They are. I took it down the road and man the difference! This thing will fly! The power picked up dramatically but the bog is still there. Its not quite as bad or last for as long but it is still very much there. I want to check for vaccum leaks again b4 I step up the rods again. oh! I also stepped up the springs to the plain. Could the fuel octane still be part of the problem? Should I change to premium b4 I step up the rods again? Any advice is appreciated. Thx

SmallblockCh3vy

I need help I'm new to the forum and I have a 1990 camaro rs 305 carburated and the cars running rich as soon as I shut the car off it smells strongly of gasoline I also have a disconnected pipe in front of the cat behind the headers could that be a possible suspect?

skinny z

I've been following your thread and it's great to see you're making progress. I know little about the style of carb your tuning so I've had nothing to contribute.
I'd like to touch on the full manifold vs ported vacuum advance you mentioned. AT THE RISK OF HAVING SOMEONE JUMP DOWN MY THROAT...try making the switch if you haven't already. Check your total timing at idle with your full manifold vacuum hooked up, change to a ported source but advance your initial timing (now just the base timing) to where or near where it was with the full vacuum advance hooked up. Adjust your idle speed as needed via mixture and curb idle (yes, I'm aware that this may present some problems of it's own regarding the transfer slot)
It would be interesting to see if your light throttle hesitation diminishes in any way.
If it doesn't make a difference, you can change it back and proceed form there.
Nothing ventured nothing gained.

budget builder

iTrader: (3)

I know very little myself as I am still learning maybe one of the veterans will step in and offer an opinion. hey I don't mind on this thread if someone needs help and somebody can help bump the subject matter help out and speak on it welcome to thirdgen.org

budget builder

iTrader: (3)

interesting!!!!!!!!!!!!!!!!!!!!!!!!! I guess its worth a try and if it don't work just change it back
but will that put me too far advanced when ported vaccum kicks back in?

bestracing

I doubt it but are you having any Pinging, knocking sounds, kind of like the knock of a diesel idling, when you accelerate (detonation)? If yes then you should raise your octane. If it is a definite no, then higher octane is just a waste of money. With some cars it could be hard to hear or know if your car is having detonation issues

Higher octane will not increase your performance if the motor is tuned right. For people that say it improved their performance , they must of had some detonation robbing them of power and the higher octane got rid of the detonation or some other problem and just by chance they fixed something the same time they tried higher octane fuel.

Intake air temperature, ignition timing, octane level, compression ratio, engine temperature and engine deposits will effect if a motor will detonate or not.

skinny z

I haven't followed all of your timing numbers and at this point I'm not certain where you are regarding the same.
I'll tell you how I have it set up at the moment and you can decide from there.
My specs: measured 10.25:1 iron headed 350 (RHS Vortec heads), smallish cam but larger than any stock profile. I have compression test pressures in the 190 psi range. The reason I'm listing these details is that they all make a difference in how you might set up an ignition advance curve and that will all relate on how you set up your carb tune.
My initial advance is set a 14° btdc. Maximum mechanical advance in the distributor is 20° and that starts at 1400 rpm and is all in by 2800 rpm. I've adjusted my vacuum advance to start at about 10" of vacuum and it's all in by 15". Total there is 20°. This is connected via ported vacuum so at idle, I only have 14°. Any SBC builder will tell you that it will easily tolerate a lot more advance however this is my setup. This means at cruise (in 3rd gear or "little d"), I'm at 3000 rpm, and am pulling more than 15" of vacuum. At this point I have 14°+20°+20° for a total of 54° advance. Is that too much? There's an argument in itself but I get over 20 mpg on the hi-way and it's not pinging. In fact it runs like a freaking freight train and I love to keep it there as long as it's practical.
To answer your question, depending at what point your vacuum advance starts and how much it is, it's a fairly safe bet that it won't be too much. To pull enough vacuum for the advance to start (assuming nothing's messed up in this area) you're probably going to be at light throttle and not putting too much demand on the engine.
This is why an AFR gauge is so important. If for example you ARE in a light acceleration mode, and the advance is starting to become greater, it's essential that you know that the AFRs aren't too lean. If it is, then detonation is a possibility.
There are so many variables, just as there are opinions and experiences, that's it's really difficult to say exactly how your engine might behave by changing the vacuum advance source.
However like you said, you can always try, and then put it back.

JaBoT

54 deg isn't to much for cruise if your engine likes it. For best mileage give it as much advance as it likes.
The easiest way to figure out how much timing at idle your engine wants is to keep advancing the timing at idle until either the idle rpm stops getting higher or till you reached max vacuum. The bigger the cam the more timing it needs. A stock engine at idle doesn't do anything past like 10 deg.
Now depending on how much timing it needs at idle and the distributor you have it may not be possible to get more timing at idle without going over what you want for total mechanical advance. For example the smallest bushing for a msd distributor is 18 deg so if you want 36 total the most you can have at idle is 18.that's where the vacuum can hooked up to full vacuum comes in. An hei dist is even worse without serious modification.

budget builder

iTrader: (3)

ok I don't understand anything u guys said. its all greek to me but it sounds like I need to go to a muffler shop and have them weld in a bung for a wide band o2 sensor and go ahead and spend the money or go get a dyno tune which I don't know how much that would cost. but It looks like I would at least need one of those to get it completely dialed in. although I would like to know what hp I am putting out. thx guys 2day I've got church but starting 2morrow I will get back at it. I have to put my timing tape on the balancer and go from there

bestracing

Really depends on the MSD distributor. On our 67 race car we had a total of 24* of mechanical advance for our MSD distributor. so our idle timing was set to 12* and total timing was 36*

JaBoT

Unless it is a msd "hei" distributor (which is an exact copy of a gm factory hei distributor with an msd name on it and a fancy billet shaft) you can change bushings in it to go between 28, 25, 21 or 18 total.

budget builder

iTrader: (3)

off brand HEI dizzy. bought from jegs on sale $41 switched to a Mallory ignition module and got a 50K flamethrower coil. AND how do I install a afr one last "?" where is a chassis dyno near 28334 four oaks, nc. nevermind mayhem motorsports in raliegh,nc told me 3-400 dollars for tuning and dyno. good deal yes/no

budget builder

iTrader: (3)

20.4miles needed 1.7gals of gas is this right? I did the distance by gps. I filled up and when I made to my destination I filled up again. this is a little low (mpg) isn't it?

five7kid

iTrader: (14)

Too much slop in that measurement. Go 200 miles, then fill it up. That is a better test that will reduce the error in the tenths of a gallon to full.

budget builder

iTrader: (3)

just got me a jewel of a body and since i'm changing the body the motor is in i'm thinkin about changing the carb to a 650 holly double pumper and selling the edel 750cfm what do you all think?