Anyone using a Crower 52242 Compu Pro camshaft ..

they dont make a spring for 3/8. do yourself a favor keep it simple, call ta-performance, there springs will work great. tell tim or mike if you can, you want about 125-135 seat and 295-315 open. he will tell you what installed height and keepers, might not need a shim with the right keepers. 93# seat wow, you will see a big difference.

 

About $250 kept me from ordering one sooner than I did. At $750-$800 its a no-brainer decision for me, I'd stick one in any BBB I'd build, but at $1,000-$1,100 I'd only do it on cars/engines I'm upgrading a bunch of other stuff on the engine or car.

 

There are several companies that will supply a Beehive spring/retainer setup for a 3/8 stem. The closest match is the BBC with a 370 lbs/in spring rate.
The installed heights are between 1.800 and 1.900.

Yes it is easier to use the TA springs but the Beehive can be done.

The TA 1125 is 125# @ 1.900, 295# @ 1.400"
An .015" shim will give you 130/300

Paul

 

Guys,

I skimmed this thread, and the only thing that caught my eye was the talk of having street cams ground on a 108LCS.

Don't do that. My testing years ago (cam changes on the dyno with identical lobe cams, just different lobe centers) told me that all your doing is making the motor peaky with a tight lobe center. Leave the tight lobe centers for the big race cams, that have to run them.

Take my advice, I have spent the money to figure this out, all theory aside.

I am also the one who first identified lifter failure (crash) on fast ramp cams, in the Buick community, about 12 years ago.

It is a common malady in about 60% of the hyd cam profiles, for all makes out there, the cam companies just won't admit it. Typical fix is solid lifters, I know several well known racers that run them, in a number of different makes. I have noticed in recent years several of the cam companies calling the most aggressive stuff "rpm limited".

This issue is worse in the BBB, due to the small core size of the camshaft.

Scotty Guadagno ran an extensive dyno test about 10 years ago, fast ramp vs conventional ramp cams, and found very little to no difference in actual performance between the two, when the fast ramp cam actually would allow the engine to reach it's peak rpm.. most of them would not.

JW

 

the ta- with .015 shim, that would be perfect, would like to see the difference the springs make. is coil bind all right.

 

Yes the TA 1125 looks good , my valve guide seals measure .530 O.D. I can't find specs of the inside dia. of the inner spring. @125# seat 295#open with .015 shim this ups the loads 5#, well then my queston is should I shim them higher to obtain the 10% that will be lost during the first few heat cycles ? My second question is there any reason to install the springs W/O the inners ? I woudn't think so ,the cam is broken in ...... but not with these pressures .

I have enjoyed this thread alot & it's great to read all the input & view points .... Jerry Stahls header boxs were printed with this saying , teamwork isn't who's right , rather what is right ... when it comes to Buicks, on this board theres plenty of teamwork.


Thanks

Mark

 

Mark

Instead of saying use an .015" shim with the TA 1125 spring, I should have said, use an installed height of 1.885" to get 130# on the seat.
At .500" lift or 1.385" height, the pressure will be 300#
Coil bind is 1.030.

The spring rate is 340 lbs/in so every .015" is 5.1 lbs
Shimming up another 10# would be ok if you knew for sure how much loss there is after the spring stabilizes.
You don't want more pressure than you need to keep the lifter on the lobe. Any extra contributes to lifter pump down or crash.

According to page 74 of the online catalog the spring OD is 1.385" and the ID is 0.745"

Keep the inner springs in place and use Joe Gibbs break-in oil.

Paul

---------- Post added at 11:39 PM ---------- Previous post was at 10:55 PM ----------

Jim

Thanks for your replies today on roller cams and cam profiles.
A while back I remember you saying for making good power for street/strip you found that LSAs between 110 and 112 work best.

Paul

 

listen to Paul dont go crazy with spring pressure, just compare it to what you have now.i would go no more then 135-315 before break in. you can always shim latter if this takes you in the right direction. you might still one day change to a crower or what ever. dont forget it still will be noisey with the cam you got now, but you will be happy with the performance. hopefully (cross fingers).

 

So how would you engineer the engines you built to be ran at 8000Ft + of Density Altitude, in terms of cam design, and keeping up the cylinder pressure so they arent a total turd at lower rpms ?
Thanks

 

Hey Nick,have you considered researching single engine airplane cam profiles? You think your Colorado air is thin @ 8,000 feet, 20,000ft has to be even worse.uzzled:

I have read before that a Buick aluminum 215 has been used in small airplanes before,can't remeber the details though.

Goodluck,I hope you figure it out!

 

8000DA?

You running at Denver on a bad air day?

I would not focus on camshaft for cylinder pressure correction, due to altitude.

I would do that work with static compression ratio. Not uncommon for motors in Denver to be a full point higher than sea level stuff, in fact I am building one right now.

JW

 

Jim
I believe you are buliding one engine for Phillip?
As for 8000 ft being a bad air day,thats more like a normal air day from June till end of September
Lasy year we had the race car in August,was 8900 ft of d/a Ive seen over 10000 d/a ft as well
At tmes it will dip into the mid 7000's but the norm on a hot summer day by noon/1 oclock is in the mid 7's-low 8's

As for the camshaft,ive found over the last 20 yrs of wasting my money lol,that up here unless you are running some sort of power adder,that the wide l/s stuff just wont make as much power
It will help to extend the rpm some,but you lose so much in the 1st 330-1/8 mile that is never recovers
In fact even on power adder stuff(esp nitrous)unless you are running a lot of jet,they still dont make power ith the lobecenters spread out
And on the street,esp with mild gear and , tight converters,they just dont run hard
You can hear em at the track.esp,where they sound like car with a hi 2/low 3 series gear and you can almost hera the motor struggling to 'come up into the power band " so to speak
Sound like an old 2 stroke motorcrossbike lol
ou:

 

Ya, that's correct ... STG 2 iron head 470 for Phillip.

What did you do with the static compression on those motors? I would figure that it's normal practice to run a race motor's static up around 15-1 on the mountain there.

JW

 

Paul, I would recommend break-in without the inners. I won't do break-in with anything above 275lbs over the nose no matter what oil/additives are used.

 

Hasn't this cam and lifter set already been run and broken in?
I thought that just the springs were being changed to put the pressure where it needed to be.

Paul

 

I thought we were talking street engines? lol
Although the old 380 sb in my car went 10.50's up here on pump at 11-1 and 9.30 on a 65 jet still on 93 octane

i guess im just asking about the cams,pertaining to what ive seen on a mid compression iron motor, that wont ping on 91 octane(all we get here) without pulling timing ,which ALL ENGINES want to run more ign lead up here than at sea level

And i understand the rise in static comp to help cylinder pressure,but once you get it, you still need to keep it lol

 

Paul, when I saw your post recommending that he use Joe Gibb's BR "Keep the inner springs in place and use Joe Gibbs break-in oil." I thought he was breaking in a new cam? Why would you use BR if it is just a spring swap? Chris

 

Chris

Just a precautionary measure
If the cam and lifters are being run at a higher pressure level that they have never seen before, the extra zinc content would help prevent a possible failure. it certainly can't hurt
After a few hundred miles I would change but continue to run a Joe Gibbs oil.

Paul

 

Joe Gibbs and Brad Penn BR oil by design is not recommend for anything other then Break-in, and some dyno pulls. It would be a waist of money using BR at this point, put a good high zinc oil in it to start with and drive it.

As far as that little bit of extra spring pressure needing further break in that won't change or help anything. Think about it this way, if that was the case then why dosen't the cam fail after installing the inner spring that is normally left out while breaking in the cam?

Before everyone started screwing with and changing the oil formulas I use to cap break-in spring pressure's @ 300 over the nose, since then I lowered it to 275.

 

Ok.. It was just a thought, just some thinking out loud.
With the increase in flat tappet cam failures I get a little worried.
We (Valley Machine) only use roller cams unless the customer is restricted to flat tappet by the rules.

Paul