| Slant Six Forum https://slantsix.org/forum/ |
|
| Converter me https://slantsix.org/forum/viewtopic.php?t=56280 |
Page 1 of 1 |
| Author: | Boilermaker [ Fri Sep 26, 2014 6:11 am ] |
| Post subject: | Converter me |
Once and again the question is asked. Sorry for the repetition . Info: 68 dart convert, cam 268 duration, 447 lift, 110 lobe separation. 10.5 comp ratio, 158 psi cranking . Stock bottom end freshened. 390 holly, offy intake shorty headers 3:21 in a 8-1/4. I figure I'm at 3400 lb? I now have a stock converter done up for 2800 stall. On the break I get 2200rpm flash 2600rpm. With the lash at .016 and .018 timing at 18 deg at 800 rpm and 32 deg at 2300. The car has the hardest time to idle in gear. Motor is out at this time ,so the question I have is what stall to select. The car went 16.0 at 86 mph so far. Planning on going to a 3:55 or 3:73 later. Thanks in advance |
|
| Author: | Dart270 [ Fri Sep 26, 2014 6:32 am ] |
| Post subject: | |
I have never seen a converter do 2200 RPM on the brakes and 2600 RPM flash. Either your brakes are very weak, or the "flash" is actually wheelspin. With that cam, you should not have trouble idling with any converter. I would guess your valve lash is too tight, or you have a vacuum leak somewhere. Try loosening your valve lash 0.006" on int/exh and see if your idle (especially hot idle) improves. Where is your lash set now? With that buildup, and for fast strip times, I would really get a 9.5" converter from Midwest or Edge Racing that will stall at 3000 RPM. That will really make your car come alive. Also, I would set the timing at 28-30 deg max advance. You may pick up some time there. The 225 does not like a lot of advance, especially with high compression. Close up the advance mechanism so that you have 15-17 deg at idle. Where is the cam degreed? You want around 100 deg installed centerline for that combo. Happy building and racing, Lou |
|
| Author: | Boilermaker [ Fri Sep 26, 2014 6:56 am ] |
| Post subject: | |
Thanks Lou , Lash is at 19 and 23 . It does run quite well that way. Cam is at 8 deg advance. ( again motor runs great there). How will the 3000 rpm converter be in regular driving? I'm at 3200 at 65 mph on the highway. |
|
| Author: | Dart270 [ Fri Sep 26, 2014 9:52 am ] |
| Post subject: | |
If the idle is poor, then try increasing the lash to 0.023" and 0.027" and see if it improves. You can always put it back if it makes no diff. A modern 3000 stall will feel almost like stock until you hammer on it, then it will come alive. You might lose 1/2-1 MPG from a stock converter, but probably nothing if you are cruising at over 2800 RPM. Best, Lou |
|
| Author: | wjajr [ Mon Oct 06, 2014 7:43 pm ] |
| Post subject: | |
My engine and drive train combo is similar to yours with 3.55 rear gear turning about 3200 @ 65 mph. It idles in park around 1000 rpm, and 750-800 rpm in gear. I had a hard time getting it to idle in gear until the lash got loosened out to 0.024 to 0.028" at which point most of the lope is gone. I had to check compression psi of each cylinder, and adjust lash to equal out each cylinder's pressure to 162 to 165 psi. Vacuum gage wagging settled down and vacuum increased when in gear idling. Also correct A/F mixture will help idle vacuum quality, and off line performance. I ended up installing an o2 sensor and gage to aid carburetor tuning of a 390 cfm Holley. Oh, base timing is set at 13* and recurve holds that 13 degrees until rpm goes over 1400 rpm. My 67 ragtop goes 68.3 mph in 10.3 seconds in an eighth mile. No 1/4 mile track near by so haven't run one yet. |
|
| Page 1 of 1 | All times are UTC-08:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|