[dmac]

Originally Posted by Chris-Austria

Hi,

I'm wondering if I should change my cam.
The car is a 66 GTO with 462cui, E-heads, 10.25:1 CR, 4 speed Muncie, 3:55 gears performer intake with Sniper EFI.

The cam is a hydraulic roller with 224/230/110 degree.
The idea is to use a 236/245/112 (old faithful) and maybe another intake.

I think it's a rather small cam at the moment and I have too much low end torque for street tires.
What could I expect? Is it worth the money and time?

Thanks!!
Chris

I just saw this and thought that maybe a gear change might be easier like going to 3.23 or 3.08 if this is to be a street car you can afford to drive. If it is running great, I would hate to mess with it. It does not sound like you need MORE power but being a four speed does make just a gear change more of an issue that if it was an automatic. For street use, the factory cams were probably about as good as you can get, but you clearly have more than the factory intended. I don't know if RHOADS lifters would help, but would sure be simpler than a cam change. With the right adjustment, you might be able to bleed off a lot of the duration and lift at low RPM. I had Rhoads on a couple cars, and the ticking is not an issue for me, except when listening directly under the hood. Changing to Rhoads and experimenting with different weight oils might be worth trying if a gear change doesn't make sense for a 4 speed.

[Chris-Austria]

Originally Posted by Cliff R

The dyno chart I put up is a DIRECT comparison between two cams with NO OTHER CHANGES and it was done on the same dyno, same engine builder, same dyno operator.

I don't think we will ever get a better comparison between the XR276HR cam and the larger OF clone because there was only one change.

I'd also add here that the XR276HR cam made enough cylinder pressure that the 9.3 to 1 455 with professionally ported #96 heads pinged so hard it required rod bearing replacement before the dyno testing could continue. I only got involved because EVERYONE at the dyno facility including the guy who takes out the trash was blaming the Q-jet for ALL the issues.

Folks need to keep in mind here that a 455 is a huge engine and putting a relatively small cam in it not only leaves a lot of power on the table it can make them octane sensitive even with a relatively "low" static compression ratio.......FWIW....

Agreed, your dyno chart is what makes me want to change the cam more urgent than before I started this thread I just cannot leave that much power on the table. I don't have a detonation probem, car runs great for 5 years now with this combination. I only use 100 octane fuel as well.

Maybe it won't help with the traction problem, but if I use 3.23 gears and change the cam this would result in more power and traction.
On the wheels that I am allowed to use on the street (15x7) I cannot go wider than 255. On the track I use 15x8 with 275 MT S/S tires... still traction problems but much better.

I also think that there are no Rhoads lifters for a hydraulic roller.
But that leads me to another question... will I have to get new roller lifters for the new cam, or can I use the lifters from the 224/230/110 cam?

[TCSGTO]

I just realized you are running a Muncie trans. Most who have done that would agree they don’t usually do well behind big cube engines with good traction.
Just something to ponder.
If you want to hook up better I’d look to suspension work, especially if you’re spinning 275DR’s on the track now. Those tires are capable of holding much more power than you’re making now.

[Cliff R]

"Maybe it won't help with the traction problem"

Traction is NOT an engine problem. It's tires and suspension. Since you are tire limited that will continue to be an issue. The larger cam on a wider LSA will spread out the power (torque) but still make more of it everyplace. The smoother power will be more locomotive like so may not hit the tires quite as hard as the smaller cam but I still doubt if you will be able to hold it without slicks or DOT's and a well prepared track.

I am glad you were able to wade thru the BS put up after my first post. Every single time I show the direct comparison between the HR276HR cam and the OF out on a 114LSA we get to see some trolling around on Google hard enough to find some dyno runs with that cam and post after me. Instead of looking at the dyno chart and saying "man that is a NICE improvement in power and even better with smoother idle and no detonation" we get to look at other select examples which are meaningless as none of them were back to back on the same dyno and same engine with no other changes.

I have also been asked to custom tuned some troubled 455 engines that used the XR276HR cam and a few that used it's flat tappet cousin the XE268, something few if any on here have had the opportunity to do. If I'm wrong there put up the details where an extremely DISATISFIED customer who had dumped nearly $10,000 into a custom 455 engine build was horribly unhappy with that cam even with moderate compression and aluminum heads. So much so that after the engine builder, all his friends, beer drinking buddies, local "gurus" and even the wife's boyfriend couldn't make it run for chit he was ready to push the entire car down over the hill and buy a bass boat instead!. I can't say "turd" loud enough here. Those cams are poor choices for well thought out 455 builds with good flowing heads and moderate compression. They also make a LOT of cylinder pressure early in the RPM range and can be octane sensitive even if the static compression isn't all that high.

You will notice that Butler started offering that cam and quite a few others on wider LSA's, that did not happen by accident. It happened right after I had a talk with them and sent them the dyno chart comparison. Whether they used the info or were already on that path who knows, but for sure they started offering some much better custom ground HR camshafts which has been nothing but good for our hobby.......FWIW.......Cliff

[dmac]

Originally Posted by Chris-Austria

I also think that there are no Rhoads lifters for a hydraulic roller.
But that leads me to another question... will I have to get new roller lifters for the new cam, or can I use the lifters from the 224/230/110 cam?

Forgot all about the hr cam!. Now I am wondering if more lift would throw off your rocker geometry and mean you need new pushrods. .

A new cam could have a different base circle starting point along with different lift , I don't know if they are generally within a set standard. The experts here may know if you have any doubts on that point.

Back in the olden days, I was buying reground cams with smaller base diameters. But I was using factory rockers, which hide some of the issue. compared to roller tip rockers.

[Cliff R]

You can re-use the HR lifters without issue.

I suggested a smaller HR cam earlier in this thread with smaller lobes than the OF so no need to change the valve springs.

Here is a dyno chart from a 455 with unported #16 heads and dished pistons using the cam I suggested.......

[Stan Weiss]

Cliff,
You keep posting up the same dyno sheet and keep getting upset when someone posts results that are not the same as yours.

"Some trolling on Google" Really? Do you even know what that means?

What was posted up was real results from some of Tom S builds. Tom S has built a good number of Pontiacs and posted dyno results.

Stan

[ta man]

Your combo shouldn' t need 100 octane and should run quite well on far less octane.

[Chris-Austria]

Originally Posted by ta man

Your combo shouldn' t need 100 octane and should run quite well on far less octane.

we have 95, 98, 100 and 102 octane over here... even if I don't need 100, the difference in price is not worth risking anything.. even if the risk is minimal

[Chris-Austria]

Originally Posted by Cliff R

You can re-use the HR lifters without issue.

I suggested a smaller HR cam earlier in this thread with smaller lobes than the OF so no need to change the valve springs.

Here is a dyno chart from a 455 with unported #16 heads and dished pistons using the cam I suggested.......

If I can use the "old" HR lifters, keep the valve springs and pushrods I just need to decide if I want Butlers version of the OF with 100, 102 or 104 LSA and hope I have enough space to remove and install the cam with the engine in the car.

Would be perfect not have to mess with the springs or even remove the engine.

[TCSGTO]

Originally Posted by Chris-Austria

we have 95, 98, 100 and 102 octane over here... even if I don't need 100, the difference in price is not worth risking anything.. even if the risk is minimal

I think your octane rating is different than what we use in the states. Ours is the average of Research and Motor ratings and I believe yours is just Motor which will give a higher number for the same fuel grade.

[Steve C.]

How old are the springs ? often they will lose some pressure. You might consider removing some or all and check them. Take them to a shop that has a bench tester and have them checked at their varified installed height with their retainers.


.

[Cliff R]

"Cliff,
You keep posting up the same dyno sheet and keep getting upset when someone posts results that are not the same as yours."

Incorrect Stan, I keep posting that dyno sheet for two reasons. It takes a day or two off my "shadows" life, and it is the ONLY camshaft swap I've seen to date that was done by the same engine builder, same shop, same dyno operator and NO OTHER CHANGES.

You're a pretty smart guy, IF you were wanting to know what cam to go to, would you rather see DIRECT test results with the only change being the camshaft, or just random results Googled up and found from different sources and NONE of them have the exact same CID, compression ratio, heads, intake, exhaust, carburetor or distributor on them?...........

[Chris-Austria]

Originally Posted by Steve C.

How old are the springs ? often they will lose some pressure. You might consider removing some or all and check them. Take them to a shop that has a bench tester and have them checked at their varified installed height with their retainers.


.

4-5 years and maybe 4000miles... there are not much shops that do such things near me... it would be easier to just buy new ones and install them if there is a doubt

max rpm is 6000 for me, I also set my Sniper EFI to this

[Chris-Austria]

Originally Posted by TCSGTO

I think your octane rating is different than what we use in the states. Ours is the average of Research and Motor ratings and I believe yours is just Motor which will give a higher number for the same fuel grade.

thats possible... I once was told that our 100 octane is about the same as your 95 octane.... so translated to US readings I use only 95 octane but that should be fine and I also don't run too much timing (34 degree)... I custom build a table on the Sniper EFI which runs really fine.. thats one thing I really prefer over a distributor with springs and so on

[Chris-Austria]

Originally Posted by Cliff R

"Cliff,
You keep posting up the same dyno sheet and keep getting upset when someone posts results that are not the same as yours."

Incorrect Stan, I keep posting that dyno sheet for two reasons. It takes a day or two off my "shadows" life, and it is the ONLY camshaft swap I've seen to date that was done by the same engine builder, same shop, same dyno operator and NO OTHER CHANGES.

You're a pretty smart guy, IF you were wanting to know what cam to go to, would you rather see DIRECT test results with the only change being the camshaft, or just random results Googled up and found from different sources and NONE of them have the exact same CID, compression ratio, heads, intake, exhaust, carburetor or distributor on them?...........

Cliff... if you search the same thing you will get 100 different results since every engine is different, thats also what I had and didn't like... I found many posts about what the OF is about and also different results, but an engine with the same cam I have now and nothing else changed but the OF cam is perfect (for me)

I also bolted on the MT SS tires today and went for a short test... they hook so much better... I'm now searching some 255 60 15 that are street legal over here and will grip better... but the cam change is something I really want to do now besides getting more grip
I also read some article about how to improve my suspension

[PunchT37]

Tires will go a long way.


Intake, with FI ? Go with T2.


I might try those 2 changes 1`st.


That cam change will make the whole thing better after the 1`st 2 changes. Should be good to 5800-6000 after that.

[Chris-Austria]

Most important there seem to be almost no complains about the OF cam in a 455 or bigger and most people I ask think that my actual cam is rather small, so it cannot hurt and will surely give more power.
Not sure if there is much to gain from the T2 over the RPM... I guess I should at least port match either of them.

How is traction with the Mickey Thompson Sportsman S/T Radial Tires compared to the BFGs?
The Street SS is also available in 255 60 15 and will fit my wheel, but I'd surely prefer white letter tires for the street
(plus the drag radials could get me into trouble at the inspectations)

[Steve C.]

I've mentioned this before regarding a loss, personally I've seen as much as 14 pounds on the seat after a dyno session. I know of one build where the valve springs were set up for a hyd flat tappet application with an initial setting of 130 lbs on the seat, knowing they would lose pressure with run in. The actual pressure after a day on the dyno was 122 pounds.


.


.

[TCSGTO]

Originally Posted by Chris-Austria

Most important there seem to be almost no complains about the OF cam in a 455 or bigger and most people I ask think that my actual cam is rather small, so it cannot hurt and will surely give more power.
Not sure if there is much to gain from the T2 over the RPM... I guess I should at least port match either of them.

How is traction with the Mickey Thompson Sportsman S/T Radial Tires compared to the BFGs?
The Street SS is also available in 255 60 15 and will fit my wheel, but I'd surely prefer white letter tires for the street
(plus the drag radials could get me into trouble at the inspectations)

The Sportman ST wouldn’t be much different than the TA radials for bite. The SS radials would be a big step in the right direction. I hear their not too bad in the rain either. They have a decent amount of tread so unless you’re inspections are super strict you should be ok.
Must be pretty cool tooling around the Austrian countryside in old American iron.