I am trying to fine tune my 350, that is 030 10:1 comp with an edelbrock C3B intake, and holley 600 vac sec,plus GM single point dist. It seems to want to ilde,and get better vacuum with more advance (static) like 12-14 and at about 3000 it is at 35 (total) with vac advance plugged. Idles ok but it seems like it could pull more when driving ( aluminum PG with a stock( I know) converter and manual shift. With the static at 12-14 and total at 35 it will idle and drive OK, like I said it seems like it could pull off the line more but my cam may not be in yet RPM wise, however after runninng it for awhile and trying to restart I get a real lazy start, and at 14 static I get a real hard start when hot. My question is if I back the static off to like 8 or so and with the 20 that is in a GM points dizzy with stock weights but aftermarket springs would i have enough total timing? Or could I have another problem? http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=110551&lvl=2&prt=5
I time all my motors by ear, then check with a lite to see where it's at. 9 out of 10 i leave what i find with the lite alone. Anyway, 35 total's in the ball park, but i suspect it may handle a little more without pinging. Trial and error. If it idles better at the 12-14 initial, and it starts OK and it's not pinging on the ohther end, leave it. Now, the Powerglide's almost like taking off in second gear on a TH 350, so don't expect much THERE. Also, what cam's in it? Maybe it don't like the PG's 1st gear and the stock converter. Many things to consider. Also, what rear gears are not complimenting the PG's 1st gear? on and on. I just read some more. Can you overcome the hard cranking with a heavier battery (more amps) and leave timing there? I've run more initial than that w/more compression
OK, i'm slow.I just read cam specs. The stock converter/PG's ****ty 1st gear are not all too compatible with your cam choice. How heavy's the car, and what ring and pinion's in it?
I would check the operation of the advance machanism in distributor to confirm it is working as it should. Next I wonder if you have a good quality set of ignition points for sure??
The rear end is a 56 chevy, and from what I was told it is a 370 gear. The dist points look new, a club member set it up for me. Advance works as i can see it move up with the light. The car is a 1936 Ford cabriolet and I am not sure of the weight. Fwiw I just changed the weights on the dist and va can withan adjustable one from Crane cams. It used to take 3000 plus for the timing to come in and with the springs I have on it now i can see a huge difference in how fast it comes in. I also noted that when I was driving it today at real low RPM my headlights went dim, and then they cmae back at idle, I may have a bad alt and that could be causing the slwo start when hot due to a low batt...
"IF" it's 3.70's, you're good there, no doubt, but double check. But big gains with 2500-2800 stall and TH 350. No ****, the 1st gear in the PG's maybe within 10% of the TH 350's second gear, and a bunch away from it's 1st gear. Tweak on your timing, DON'T use the vacuum advance with that much initial, and consider a slight stall AND the TH 350 for big gains
PG 1st gear 1.76 or 1.82. TH 350 SECOND gear 1.52. TH 350 1st gear is 2.52. Rest ***ured, this a BIGGER difference than you think. It's very noticable going from a 2.20 Muncie to a 2.52 Muncie. Imagine 1.76 to 2.52!!!!!! This will be your biggest bang for the buck. Same driveshaft/yoke, and x member location, different flex plate (very important)
Listen to Groucho. I changed from a race-prepped Powerglide with a 2500 stall converter to a TH350 and a similar converter and improved 3 tenths in the 1/8th mile. And, that was with a 3.70 rear end and a 2,000lb car.
I am wondering if, on top of all the tuning, could I have a bad alt? According to my ammeter it does not charge at low PRM, or idle, idle is about 900 RPM. It was also stalling when in gear, something it had not done before, and at idle or in gear the headlights dim, but come back when the motor is revved. The only accesories I have are the fan and electric fuel pump. The fan draws about 18 amps and I have no idea how much the pump draws. Drove the car last night and when I got back from a 5 min ride it would not crank. I charged the batt, and it was low and then it cranked like a SOB, same thing this am after being left off of the charger all night. Could a bad alt cause some of this?
You try to sneek up the initial advance for throttle response, and smooth out that cam a little bit. That combined with the vacuum advance will put your total advance too high
It sounds like either a bad alternator, or it's just not strong enough to keep up with the accessories you have. If it's not charging at idle, and your idle's fairly high at 900 RPM, somethings not kosher. Do you have a big reduction pulley on the alternator? Anyway, fix your charging problem so it'll crank when hot and find yourself a good used TH 350 from someone installing a 700R or something, get a 2500-2800(?) stall converter and you should be golden. If you get your stall (which your cam card RECOMMENDS), don't forget a better trans cooler. And don't waste your money on a stall for your PG! It's NOT gonna make you as happy as a TH 350
Sounds like your total advance is right about where it needs to be. You can get more mechanical advance in a stock gm dist. by either removing any bushing that is present on the advance limiting pin in the dist. or filing the notch that the pin goes in. If backing off the timing allows it to start better when its hot then this will help. If it still is turning slow due to the compression then you need a higher cranking amp battery, bigger cables, better starter, or all of the above.
Its common for total advance with the vacuum hooked up to be up around 50 and around 20-25 at idle. This is only to improve idle quality and economy when cruising. Doesnt hurt a thing as far as performance goes. When your starting it or when your foots in the throttle the vacuum is zero and your just working off of the mechanical. I always vacuum advance on everything but a drag car.
I'll go along with you on the mechanical advance, but vacuum advance backs off when throttle is applied whether it's sourced to manifold vacuum or ported vacuum. Running vacuum advance doesn't impinge on the engine's power producing capabilities. The extra advance gained from running vacuum advance sourced to manifold vacuum allows the engine to run cooler at idle due to, time is required to burn the lean mixture. A lot of race oriented stuff can cross over into street engines if a little bit of thought is exercised toward a more reasonable - milder - choice of components. Imo and experience a race-o, mechanical advance only distributor doesn't belong on the street.
We can go at this all day long. FIRST-i never said vacuum advance "impinged" on power. TWO-vacuum advance should be run ported NOT manifold vacuum, so i wouldn' affect idle as you noted. THREE(and i'll stop here)-mech only has no place on the street? He chose this cam, and some might say it has no place on the street either. But, in my opinion, to get any semblence of response with his chosen combo, he'll have to squeeze as much initial out of that thing, and adding the vacuum advance "might" push his total too high. The total can be restricted, but now you've added to an almost solved issue. So, i didn't get into that. This is just my opinion
Thanks for the link as well. I am sure I have several issues at stake here, and I am trying to fix one at a time, although they can all be interelated. I am going to set my timing again. 12-14 initial with 20 in the dist, all in by 3000 Go through the charging system to make sure I can crank this pig over. The cam was chosen awhile ago, and I realize that the different parts may not be super compatible. so I need to get working with what I have short term, and look at some options long term ( ******, converter etc). Then go through the carb.
The higher the amp rating on an alternator the lower the output and lower rpms. Also points distributors will "float" and depending on coil voltage output and how you have it wired you may not be getting enough of a spark. Pretty much the reason why high performance ignition systems were invented, not to mention the dual point distributor.
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