Newbie w. New GN

[bryes]

Well if you guys haven't heard of it being a problem then I'm sure it's  safe to say its not a problem.

Side loading isn't an issue with rollers. If it was, flat tappets would be 100 times worse.

It doesn't seem like it though, with a round lifter (roller or not), unless the cam lobe contacts directly on top of of the lifter, there will always be a side force. With a flat lifter the force will always be in-line with the lifter bore. See the picture below.

Either way I just can't justify the extra $600 for the roller, so Steve, what I am thinking is to order the

Product ID: TA_V260H231H.440"-206'/.440"-206',112'
 
cam and

Product ID: TA_V1405V6 HYDRAULIC LIFTER

I really wish that there was something local because this will pretty much kill my efforts for this week, but then again knowing that these cams are a problem it is not worth getting a cheap cam. At least with this cam I will also know for sure that it will work without any other modifications and not break the bank.

Thanks to everyone once again!

[Steve Wood]

IF you can handle the money, I agree on the roller part

[bryes]

I can afford a roller, but I just can't see where it is worth the extra cash. 

In fact, right now I feel like there is  no real advantage for me over a new flat tappet. For my setup it seems like longevity is a real advantage to a roller, but then again I'll be driving the car so little (1k/ year maybe) that a flat lifter should hold up until I am in a nursing home anyway.

So I guess the only advantage would be in performance , so that's what I really need to know. Considering I  plan on running a stock engine and turbo, how much horsepower or et advantage ( potential for hp counts too) can I expect from the roller as apposed to the $200 cam that Steve suggested?

I would rather spend the cash other places if there is no real advantage for me.

Thanks

Bryes

[earlbrown]

You can get a 260H grind from Summit and they'll ship it tomorrow and not assrape you on shipping charges...

http://www.summitracing.com/search/department/engines-components/make/buick/engine-size/3-8l-231/engine-family/gm-v6/brand/comp-cams/part-type/camshaft-and-lifter-kits/grind-number/260h



If the flat tappet fails, takes out your entire motor, including the turbo and radiator, the extra money will look like a bargain.


On your cam drawing they omitted that the cam lobe is turning and the flat tappet lobe is dragging along the bottom of the lifter. That's actually the exact reason they like to go flat. On other engines when lift numbers start getting stupid big, they have to get bigger diameter lifters or install some mushroom lifters from the bottom.

[Steve Wood]

If for some reason the flat tappet fails due to a soft Chinese core, or more likely a soft Chinese lifter, then the real cost is that of a rebuilt engine as Earl stated.  For that reason, I offered a hardened U.S. made lifter such as offered by TA Performance.  Earl has a hard on for TAP because they charged him more for shipping than the oil pump cover gasket set  cost.  I tend to agree with him but offer than many companies do the same.  More than once, I have ordered a two buck part from Summit and have paid $9.95 for handling.  It's cheaper than the gas costs for a 100 mile round trip to town in hopes that they have what I want.

There is very little difference in performance between a roller and a flat tappet-particularly on a low performance engine.  On a high performance engine, it can be quite a difference because one can run a lobe profile on a roller that a flat tappet lifter has no chance of tracking.

On a stock engine, the factory claimed torque peaked at 2000 rpm and hp peaked at 4400 rpm.   They may have lied on the torque number and the hp number, but the rpm points seem about right to me based on my own experience with a new car back in '86.    The cars were programmed to hit 14 psi for two seconds and then fall back to 12 psi of boost for the duration of the run.  Certainly, the stock cam and turbo was all in by 4600-4800 rpm

The factory valve springs were perfectly adequate for these boost levels altho the quality of the spring was pretty sorry and they were usually tired within 50,000 miles.

Earl has given you the math already as to the reason to use a bit more spring pressure as the boost comes come.  Further, if we put a looser converter, bigger turbo on the car, then we not only chop some off the bottom of the curve, but we waste some at the top end if the cam will not rev further without some more pressure-both from a tracking the lobe matter as well as the valves bouncing around due to higher boost in the cylinder.

Most of the articles written about the oil and zddp amounts being too low happen to be talking about race cam with very high spring pressures, but this point is generally ignored by the hypsters selling zddp.  We do have a problem with flat tappet cams, however....if you look into the lifter bore on 3E, you will see that the cam lobe is almost dead center on the bore so that lifter is sitting almost in the middle of the lobe rather than being properly offset so that the convex base of the lifter is not readily swiped by the taper ground into the lobe front  to rear.  If you look at the engine while running, with the valve cover off, you will see that the push rod is rotating much slower on 3E because the lifter is rotating slowly.  This ain't good, but, if the engine is broken in properly and the springs are not 135 psi, it should be good to go.

If I were to use a flat tappet cam, I would use a special break in oil rather than an additive.  I used Joe Gibbs break in oil on the 440 in my challenger a year and a half ago.  I also would go a bit further than many do on a break in.  I typically go for 30 minutes and blip the throttle up to about 3200 from 2400 rpm every five minutes in order to throw more oil up top and keep it wet and cool.

More than one guy has run into the tens on the stock cam with stronger springs.  It's easier, however, if you add some duration to the cam (along with more lift) so the bigger turbo does not have to work so hard to make power at 5000-5400.

Earl's point stands however.  Cheap only counts if you don't have to do it twice 

[bryes]

Thanks Earl, I 'll check it out summit tomorrow thanks! Hopefully they'll have the good American made lifters. If not then I guess I'll get the TAs.


I just don't see the cam wearing out as an issue when all these cars are running around with 150k + miles on an unopened mill and stock cam. I am not building this thing to go 200k or run 10's, if I were then  I would buy the roller cam.  By the time the cam fails and takes out the radiator (you'll have to explain that one to me!) as far as I am concerned, my grandkids can worry about it! Plus who is going to want to drive this thing when gas is $120 / gal?

Besides do we really know that roller lifters are that reliable? Many flat lifters have run 300k miles and more. Who is to say that rollers won't give out, especially when companies start cutting corners, for all we know they already have. I can imagine steel needle bearing wreaking havoc in the bowls of my engine!


As far as the friction goes on the flat tappet cam, that dynamic friction forces you are talking about is a function of the coefficient of kinetic friction (mk) and is defined as:
                               
                                                     < P = atan(mk)

Friction can vary a lot for many different reasons, but for two polished hardened steel surfaces like a cam and lifter it will be very low (maybe as low as 0.1).

If its 0.1, then <P = 5 degrees
If its 0.2, then <P = 11 degrees

Even if the kinetic friction is 0.3, the pressure angel of  a flat tappet cam is 17deg which is still way lower than the 30 degree pressure angels seen in a round tappet cam, and the side loads will still be around 50% of round tappets. Those side loads create friction forces that work against the direction of the lifter, reduce power and efficiency, thus giving back some advantage of the roller mechanism.


Here is a source that talks about a similar side load advantage for flat tappets in a chevy engines
\
http://books.google.com/books?id=UlvzvjzQMsoC&pg=PA92&lpg=PA92&dq=%22pressure+angle%22+flat+tappet&source=bl&ots=DFI9EfSLu6&sig=L4Fb157U7QkknvXXYM1sbf3NyAc&hl=en&sa=X&ei=jcHbUJP3HI6I9QTRj4CoBg&ved=0CDwQ6AEwAw#v=onepage&q=%22pressure%20angle%22%20flat%20tappet&f=false

Also I think he covers it for more general purpose,
       
F.Y Chen, "Design of Cam Mechanisms"

Thanks again

Bryes

[larrym]

don't rollers have a faster ramp too?

[bryes]

Thanks Steve, I'm not going to buy anything but US lifters. Are the TA cams USA too.

I hear Earl on that shipping thing though. I went to TA a couple of weeks back to order a cam button for 12.95 or something and they wanted 15 bucks for shipping! Now I know that shipping prices have went up but that is highway robbery, and it cost them my business.

[earlbrown]

I was thinking I gave you the cam button part number to get one from a fast food parts house...
Sorry about that, you could have just picked one up locally for about $12 had it in your hand.

The shipping was only part of the problem with my test order at TA. They screwed up my order and when I called to try and get it straightened out, it turns out everybody at TA is new, nobody has any authority other than to take orders, none of them know each other and they'll say that discontinued items are in stock. Per TA, the shipping charges are always UPS's fault.
  There's a chance my experience was an anomaly, but they had one chance to get the order right, one chance to call me before sending it out and 2 or 3 chances to make it right after the fact. I always cut ties with people that give me that much greif right out of the gate.
 If I want piss poor customer service I order from whoever is cheapest. At least then you're not paying for something you're not getting.

I'm curious who makes their cam blanks. AFAIK there's only a couple companies actually making cam cores. That's out of my relm of expertise as the only current flat tappet knowledge is I have was accidentally absorbed.  Then again they also claim that the TA roller rockers made by T&D are better than the T&D rockers made by T&D. After reading that I tend to question their credibility concerning their parts.


Actually the off the seat ramp speed is faster on a flat tappet generically speaking. The actual lifter intensity is part of the cam grind, and what tappet is riding on it.

The reason you lose the radiator is because the oil cooler gets cam lobe grit in it. If you don't replace it and use the cooler on the new engine you'll be metering fine abrasive into the new engine as it dislodges from the cooler.


When an engine experiences a lobe failure, the only plan to repair is to take the engine all the way down to the bare block and clean it. A very expensive proposition. Normally I don't mind chancing stuff but with this one the ROI just isn't worth it.


If you don't mine chancing it,  go over your stock cam with a fine tooth comb. If there is no pitting and you can clearly see the silver pathways the lifters have been riding on. (normally it's a silver line that goes around the base circle then gets the full width at the cam nose). Your lifters aren't beat all to hell so it looks like you might have caught them problem before the cam got damaged. Years ago the common rule was to never reuse lifters if you moved a cam to a different block. I used to hear about people running used cams with new lifters.

 If the cam looks runable put the stock springs back in without the cups, get a new set of lifters with hardned feet. (I think the part number is Johnson 969's or 969HT).  Take your thumb and apply the cam jizz like you're trying to force it between the molecules on the cam lobes. Put some Mobil1 in the pan with a can of ZDDP and pull the pin.


   After doing the break in procedure, Drain the oil, make a mental note of how much hair is on the magnetic drain plug, refill the crankcase and put a 100 or so easy miles on it.

If you can get both pieces to work harden without a failure, you should be good to go for quite a while.

  A dial indicator with a magnetic base can check the lobes just by pulling the valve cover and rocker shafts. If the lobes survive the bed-in process reinstall the new valve springs and run it.

I'd trust a factory cam more than I would a new blank. 

[bryes]

Oh that explains the radiator, I'd just get an external oil cooler though I think.

Earl, are you forgetting though that I have some lobes that  are worn by 0.030"?

I would absolutely love to go that route, that would be a cheap way out!

 

[earlbrown]

I thought you went back and remeasured and were within .002"?



EDIT: I went back and reread it...   Now I see where I retained the .002" number.  You might be OK with the difference since the published numbers you posted show a duel pattern cam. I've never measured a stock cam so I can't say what the actual lobe height is.

[Steve Wood]

I only know TA sells Johnson lifters...I am leaving this one with Earl as he has it covered

And, yes, Larry, they can have more abrupt profiles, but, on a small cam, it is seldom noticeable unless you get snookered by advertising claims

[bryes]

Thanks for all your help Steve!


Earl, you did save me that $$ because once I saw the $15 for shipping I immediately killed the order and eventually got it from NAPA! I owe you big time.

Back to the cam wear issue:

After you set me straight on the rocker ratio, I calculated the total lift for lobe 1 as,

(1.49 - 1.230) * 1.55 = 0.403"

This figure  is close to the factory spec of 0.408.

BUT, lobe 7 which corresponds to the #3 cyl intake valve measures 1.457" at the lobe maximum diameter, thus the lift is now,

(1.457 - 1.23)*1.55 = 0.352"

This is 0.032" short of the factory spec of 0.384".


I have done these similar calculations for all lobes, below is a summary for you reading entertainment:


I think I need to be in the market for a new cam as well, let me know what you think.

[bryes]

I just called TA and full throttle to find out about the flat and roller cams.

TA seems to be closed for business until Jan 7. 

I checked on rollers at full throttle who were very helpful. They said that the heads would need to have the guides machined to install any of their roller cams, which is another good reason for me not to go that route.

I am going to check with NAPA and the other fast food parts chains to see if I can get an American made cam and lifters; then again they will probably just say what I want to hear regardless of where it actually comes from. If not then unless anyone has other ideas, I guess I might just have to wait until after the break to do any further work.

Besides, there are a number of things that I have been putting off doing, like installing the chip, scanmaster, clean the engine bay, install the hotwire kit, that might keep me busy for awhile so it won't all be a waste. I wish I could turn the car around to at least check the fuel pump though, it was supposedly replaced but I think I'll put in a Walbro 340 (I'll take suggestions too) when I can. The shed that I am working out of is so small that my gut can hardly squeeze between the car and wall in order to get back there! I thought after I got the mill running that I'd take the car up to Ohio to get it on the lift and install that stuff.

[bryes]

I wound up ordering the cam from TA, they had a 208/208 grind that everyone seems to have good luck with so I installed it this weekend and degreed it in. I'm glad I did because I initially had the timing mark aligned with the key instead of the (really poorly etched) correct timing mark.

My goal for next weekend is to get the timing cover, oil pan and heads installed. It's nice to be in Savannah this time of year, the weather is perfect for working outside