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A Weird Roller Rocker Question
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Author:  ryandcovalt [ Tue Feb 16, 2010 7:15 pm ]
Post subject:  A Weird Roller Rocker Question
Hi guys. some of you know my setup, but for those who don't. I currently have a 72 Dart street car, a 225 with 10.6:1 comp. ratio, I also use a re-grind cam at .510 lift 282 duration. my problem is that even with the timing set way back it still pings under acceleration unless I mix in a few gallons of racing fuel. I am going to adjust the vac advance pod on the distributor and see if I can keep the timing advance from coming in so soon, hopefully that helps some. My question is will 1.6 ratio roller rockers help the situation? My thinking is that the increase of valve lift/slight duration increase would possibly help lower compression slightly. I would like to get 1.6 rockers sometime anyway, it would just give my a good excuse to buy them sooner if it would help. Let me know what you think. Thanks,

Ryan
Author:  Dart270 [ Wed Feb 17, 2010 5:27 am ]
Post subject: 
Ryan,

I doubt that will give you much help. Have you recurved the dist? What is your total mech advance? If your vac advance is holding too long, that could be it. Try unplugging vac advance (and plug manifold/carb port) and see if it goes away.

Anything over 30 deg total mech advance (no vac) and you are way too high. For that build, 26-28 deg is where I'd set it, and recruve dist to give you 12-15 at idle.

I made the mistake of too much timing for years, and finally got smart. One day, I got to the track after tuning my timing "by ear". Ran 15.5 1st pass, started retarding timing, and made it to 14.5 just by retarding timing 6-10 deg.

Lou
Author:  Charrlie_S [ Wed Feb 17, 2010 5:43 am ]
Post subject: 
I agree with Lou. Work with your timing. As for your cam question, the 1.6 rockers will not change the effective duration enough to make a difference. The amount of lift has no bearing on the dynamic compression. If you need to do anything with the cam, I would try retarding it a couple of degrees. After ignition timeing that would make the most difference.
Author:  Dart270 [ Wed Feb 17, 2010 6:29 am ]
Post subject: 
Yes, cam timing is the other biggie. Where is your cam degreed now, and what are the duration @ 0.050" and LSA? 282 deg advertised does not sound like a lot - need to go by 0.050" numbers.

I'd like a ride in that car at Hagerstown and see how it sounds/feels! Do they allow passengers down the track during t'n't?

Lou
Author:  Rick Covalt [ Wed Feb 17, 2010 1:14 pm ]
Post subject:  Cam
Lou,

I think Ryan's cam is installed 4degrees advanced, and it is 110 LSA if I recall correctly. I'll have to see if I have the grind sheet from Erson for the at 50 number. Maybe Ryan has it? On second thought, not ! :lol:

Rick
Author:  Rick Covalt [ Wed Feb 17, 2010 1:25 pm ]
Post subject:  Found it
The LSA is 110 and the duration @ 50 is 246.

Lou, I don't know if they allow passengers? They did 25 years ago in street cars. I will have to check.
Author:  Greg Ondayko [ Wed Feb 17, 2010 1:28 pm ]
Post subject: 
Quote:
Yes, cam timing is the other biggie. Where is your cam degreed now, and what are the duration @ 0.050" and LSA? 282 deg advertised does not sound like a lot - need to go by 0.050" numbers.

I'd like a ride in that car at Hagerstown and see how it sounds/feels! Do they allow passengers down the track during t'n't?

Lou
They allow passengers at Pittsburgh During TNT nights.

FWIW.


Greg
Author:  ryandcovalt [ Wed Feb 17, 2010 3:19 pm ]
Post subject: 
Thanks for posting the numbers dad, your right I would never have found them on my own (without calling you atleast). If I remember correctly at mason dixon we were started at 32 total advance and at the end of the day we were back to 28 total. After the race I set it back up to 30 degrees total 10-12 initial (cant remember exactly) and drove it for a while with a mix of race fuel. I have set the timing back to 6 degrees initial now and it still pings. It doesnt ping bad, just at wot in the lower rpm range. I haven't tried unhooking the vac advance completely, but I will try that next and see if it helps. Lou you are more than welcome to ride (if they let us), or even drive my car at mason dixon, and see what you think. I have done almost no tuning or adjusting at all, even the 600 edelbrock has never been touched, so im sure there is plenty of room for improvement.
Author:  emsvitil [ Wed Feb 17, 2010 3:43 pm ]
Post subject: 
The 1.6 will make the cam look longer by about 2 degrees (advertised and @ .50)....

282 will look like 284
246@.50 ~ 248@.50
Author:  bigslant6fan [ Wed Feb 17, 2010 9:29 pm ]
Post subject: 
Also check that your spark plugs aren't too hot of heat range
Author:  ryandcovalt [ Thu Feb 18, 2010 7:10 pm ]
Post subject: 
I will check and see what spark plugs I have, I changed them in the summer to a plug recommended on this site (cant remember the ngk number) Is there an NGK number you guys would recommend for an engine build like mine? Thanks
Author:  Dart270 [ Fri Feb 19, 2010 5:46 am ]
Post subject: 
If old style head, then try NGK GR5.

OK, that cam should work OK with 10.5:1 and premium.

Are you using MP advance springs? They advance too quick for most.

Lou
Author:  Rick Covalt [ Fri Feb 19, 2010 11:51 am ]
Post subject:  Head
Ryan's head is a peanut plug head. and the distributor is just a stock dist I got somewhere and then installed the advance arm (proper name?) in that had the slots welded up to have about 14 or 16 degrees advance.

Rick
Author:  ryandcovalt [ Fri Feb 19, 2010 9:17 pm ]
Post subject: 
I didn't get to pull a plug and see what the ngk # is. I know at in the summer I was running NGK UR5 plugs, and I thought I went one heat range colder to a UR6 would either of these plugs be ok, or a better one recommended? What spring should I have in the distributor, or is there a kit with various springs? Thanks for the help.
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