Ray, Thanks. Okay, that makes sense to me. I guess what I still don't understand is- if I have symmetrical lobes, and I measure everything out, what should I do with that info? Should I research published data on cams until I find one that matches, and then set the cam up per the card for that cam? David
If you measure the cam as described you will know the measurements. Symmetrical lobes have the opening and closing sides the same. If the intake and exhaust lobes the same but assymetrical using the method will get you very close. It's where different rate opening and closing lobes are used for the intake and ex like the "XE cams" it would be hard to get exact measurements for the LSA. Ray
If this is the case you will probably need custom pushrods as the cam's base circle has been changed.
Your cam install guy needs to find out the LSA between the two lobes. Then he can use the intake lobe and degree it correctly. You may have a 108* LSA to a 113*LSA. Who knows, your cam grinder didn't provide you any information. Usually a cam's intake lobe is degreed in at 4* advanced. If the cam has a 110* LSA degree it to 106*. With a 112* LSA 108. eg: If it was ground on a 112* LSA and the intake lobe is measured to be at 111* you would need to degree it 3* ahead (advanced) get the 108*. If for some reason it was at 106* you would back it up (retard it) 2* to get the 108. Ray
Ray thanks for all the info. I printed off Jim W post (All 50 pages) on degreeing cam. I just noticed the woodruff key is missing from my cam, I will drop by machine shop up the street and leave the cam and gear with them, hopefully they can resolve. If they have cam doctor software is will have them spec my cam. My guy is coming over tomorrow night to degree my cam. Hopefully I will have my engine running on the weekend. Fingers crossed.
That's good. If no Cam Doctor is available all your guy really needs to do is find the int. and ex. dur. #'s @.050" as Jim describes and use the formula he mentions. Here's part of the link (already has the .050" #s): Figure Lobe Center Separation. Here's the formula Intake duration@.050+Exhaust duration@.050 (233+240)= 473. Now divide that number by 4 (118.25)= A Intake open number @.050 + exhaust close number@.050 (10.5+7)= 17.5 Now divide that number by 2 (8.75)= B Now subtract B from A 118.25-8.75= 109.5 - that's the Lobe center separation of this cam. Advertised at 110 Then simply have the intake 4* advanced @.050" lifter rise. The way Jim explains it, it is pretty straight forward. As a side note the posted 110A cam card .050" specs are for a cam 4* advanced. This is why the intake is at 106* and the ex 114*. If it were straight up with no advance it would be 110*int. and 110*ex. @.050. Ray
Ok, That is nice and easy. I can work with that. I find out after that my cam guy is kinda friends with my ex-engine builder. Anyhow, nice enough fellow. But he took my builders word that my cam needed to be in at 110 degree. I watched and asked questions. So he did not do as you indicated above, which looks simple enough. He did determine that my pushrods need to be longer. He agreed that once snugged by hand that a half turn to bottom out on the rocker arm studs was not adequate and that probably was causing my lifters to leak down which is probably directly related to my cam grind. Remember that the cam guy started with a stock 300 cam and material was removed from the bottom of the lob to achieve desired lift. Dot to dot my came in at 106*, he told me to change the timing gear that is on the crank to -4* to obtain my 110* position. We took readings from intake valve which is not ideal but three times we took readings and were within a .5* of accuracy every time. Lifter kept leaking down, so we took it apart, removed spring and stacked it with 2 rubber washers for faucets and a couple of thin steel washers. Best we could do to create a solid lifter so we could take our readings. I think I could this on my own now that I have seen it done. And the instructions provided seem to make more sense to me now. My fuel pump eccentric needs to be changed and I am going to put a new thrust plate on my oil pump. How do I determine how much longer my pushrods need to be? I guess if I knew how much he took from the under side of my cam lobes that would answer my question.What is an extra full turn worth on a rocker stud? Oh, I also need a woodruff key. It is missing from my cam. Does anyone have a picture so I can see what it looks like. My cam guy stopped by my ex-builders place, he gave him one but it's not right. The upside to all this crap is that I am learning a lot.
Sounds like he used the old school intake centerline method. With this method you take your cam grinders word for the specs of the cam and just use the intake centerline (highest point of the lobe). You pick an amount around of at least .020" (you use the same amount for both sides, doesn't matter) from the top of the intake lobe on the way to max. lift and from max lift, add the two numbers on the degree wheel and divide by two (depending on the degree wheel). Your lucky to have someone come over and do this for you. Are you sure you don't have chevy lifters? The lifter plunger is much lower. If they are the proper Buick lifters and you require new longer pushrods I don't even think they are available and if they are they are likely as much as a new cam. I would then throw that cam out and contact either Mark http://v8buick.com/member.php?u=26517 and let him know your issue or call TA and let them know the situation, they don't list 300 cams on their website but they are in their catalog as per a recent past post. I would do it once with the specs you want and be done with it. Without wacking so much off the base of the lobes. I used a .484" lift cam and .040" gaskets and still had at least .020" lifter preload. Ray
Michel, D&D Fabrications will make custom pushrods for the 300, if you need them. Be careful measuring though- I do remember you saying that your valve heights were not equalized?
Ray, thanks the heads up on the lifters. I will try with my new lifters to see if I have the same issue. The lifter I used to degree was one of the old ones, i just tried the new ones, same issue, however, lifter not primed. The lifter I have are from valve train industries vl-73. .I know re him coming to help with this. He did not want any $$$, he was here from 5pm to 10 pm. Plus he drove in despite the long weeked traffic.I insisted on paying him. And yes he did use the method described above. VL-73 General Motors Conventional Hydraulic P, C, DLC, DLP 1.995"-1.975" 0.8425"-0.8420" 1.7700"-1.7500" link: http://www.valve-train.com/vti_techandquality.html BTW, what does LSA stand for? 64 skyconvert, thanks for input. EDIT: just did some research, funny that this company has one VL73 for all GM"s...crower and others all have a different number for Chevrolet and for Buick, ...So the replacement lifters and still wrong! At least I know.
I was looking at the duration and lift on the card and it is different than the poston book. Post book had 473 lift and 260 duration, identical in intake and exhaust for the 110A. I have been given a heads up that my current grind of 255 duration and 480 lift will cause clearance issues at the valve boss. Plus if you look at my lifter thread I am having issues with pushrod length. Anyone know who did the cams for Poston?
