Valve Adjustment Method For Duntov Cam
#1
Melting Slicks
Thread Starter
Valve Adjustment Method For Duntov Cam
I need the correct and most accurate method for adjusting valve lash on my '61 283 with the Duntov cam. I have heard that it differs from other solid adjustments. Thanks
#2
Race Director
#3
Melting Slicks
I thought the Duntov 30/30 should be adjusted running after the engine is warmed up. I think there is another way but it seems it isn't the standard TDC adjustment.
Last edited by narlee; 06-17-2009 at 10:08 PM.
#5
Team Owner
Here is what I use...all the time with NO problems or hassle. You only have to move the engine twice. This works perfectly for the Duntov cam...the 30/30 cam is a different matter because of the grind on the lobes..
If you want the MOST accurate then you have to adjust the lifters "hot" ... meaning with the engine running and oil splashing everywhere...good luck with that..
If you want the MOST accurate then you have to adjust the lifters "hot" ... meaning with the engine running and oil splashing everywhere...good luck with that..
Last edited by Frankie the Fink; 06-17-2009 at 11:17 PM.
#6
Race Director
It will put you right on the heel of the lobe your adjusting. The lash is a little controversial on the 097 however. I know its been mentioned as 12-18 but I seem to recall 08-18 somewhere..... but its been a long time since my 61 was around.
#7
Team Owner
The first two sentences in the document I attached above explain the valve lash change in specs on the intake. It was supposedly tightened up for 'weekend racers'...
#9
Racer
I took this out of the Vette Vues Magazine about 20 years ago. If you can read it, it's the easiest, clean easiest and almost fool proof way to adjust your lifters. I takes about 10 to 15 minutes. I've been using this for years on my 65' 365hp.
#11
Team Owner
Basically, the same method that I use except you are turning the engine over more.
Its also prob harder to hit exactly 180 deg from TDC if you don't have timing tape around the balancer than just hitting TDC twice where it is clearly marked.
Believe me I've tried different methods and mine is the simplest, especially if you don't have the big bolt on the front of the cranshaft pulley to help turn the motor easily (which I don't) !!
I have to 'bump' the starter and then bust a gut on the generator fan belt to get the motor positioned just right so moving it only twice makes me very happy.
Its also prob harder to hit exactly 180 deg from TDC if you don't have timing tape around the balancer than just hitting TDC twice where it is clearly marked.
Believe me I've tried different methods and mine is the simplest, especially if you don't have the big bolt on the front of the cranshaft pulley to help turn the motor easily (which I don't) !!
I have to 'bump' the starter and then bust a gut on the generator fan belt to get the motor positioned just right so moving it only twice makes me very happy.
Last edited by Frankie the Fink; 06-18-2009 at 09:23 AM.
#12
Race Director
TDC does not put the lobe on the base. Best method is the "opposite" from full lift. For example, to adjust #1 intake you bring #6 intake to full open position, then adjust #1. You match the opposite in firing. Use the following. Works the same for both intake & exhaust, i,e, adjust #1 exhause when #6 exhaust is at full valve lift. You can work around in the normal firing order, just go to the opposite.
1 - 6
8 - 5
4 - 7
3 -2
Other methods get close, but not at full base of lobe
1 - 6
8 - 5
4 - 7
3 -2
Other methods get close, but not at full base of lobe
#14
Team Owner
TDC does not put the lobe on the base. Best method is the "opposite" from full lift. For example, to adjust #1 intake you bring #6 intake to full open position, then adjust #1. You match the opposite in firing. Use the following. Works the same for both intake & exhaust, i,e, adjust #1 exhause when #6 exhaust is at full valve lift. You can work around in the normal firing order, just go to the opposite.
1 - 6
8 - 5
4 - 7
3 -2
Other methods get close, but not at full base of lobe
1 - 6
8 - 5
4 - 7
3 -2
Other methods get close, but not at full base of lobe
I have done it this way and then went through the agony of measuring lash with the car running and hot and it was dead on.