[Steve C.]

Stan, the problem with some is the small block Chevy is not a Pontiac. Thus the testing to many is invalid.


PDC, thanks. Actually I'm a 70 year old crotchety trouble maker

.

[Stan Weiss]

If anyone wants to play around. This is close to what Chris will get for 0.050" intake duration

Estimate Cam Intake Duration Needed @ 0.050"
http://www.magneticlynx.com/carfor/calchpm.php

Stan

[Stan Weiss]

Originally Posted by Steve C.

Stan, the problem with some is the small block Chevy is not a Pontiac. Thus the testing to many is invalid.


PDC, thanks. Actually I'm a 70 year old crotchety trouble maker

.

Steve,
No question about it. For some it is much more complex then that.

Stan

PS - me to

[Formulajones]

Originally Posted by Steve C.

Stan, the problem with some is the small block Chevy is not a Pontiac. Thus the testing to many is invalid.


.

But Chris doesn't think so

[pmd400]

I feel as though I should justify my reasons for letting straub select this cam.
Iv done a lot of reading on cams in the last 8 years. Iv bought books and read cover to cover multiple times, read heaps of articles and spent hours on old forum posts across a number of brands of engines. This is my 3rd engine build, my 2nd v8 and 1st Pontiac. Iv got zero cam and dyno testing and never been to the track. Some things that become apparent are

1. Xe cams seem to have problems. People across all brands seem to have problems with them not making power. Tight lsa and short seat timing often get the blame, yet the tight lsa short seat timing voodoo cams work. Seems like xe cams can create valve train instability. I won't use 1.

2. The 2802 is sometimes critised for being to small in a 455. The 041 is reccomended with rhoads lifters instead to improve drivability. If the 2802 is to small and the 041 requires rhoads lifters it kind of implies that there isn't a cam for 455 that should be used with regular hyd flat lifters. I can't believe this to be the case. In fact the vast majority of professional engine builders would advise against rhoads.

3. With regular lifters and 1.65 rockers, Jim hands car was .1 sec quicker and 1mph faster with a 068 against the 041. With rhoads the 041 picked up 1.5 sec and 1.5mph. The 068 is 212/225 at .050 and the 041 is 231/240. Seems like a huge difference in cam size with performance difference someone like me wouldn't notice on the street.

4. Most cam manufacturers measure advertised duration at 0.006. I think crane measure at 0.004. Pontiac measure at a much lower lift point. Copies of factory cams also use a lower lift point, I'm guessing for advertising purposes. Crower 60919 is a good example. Crower will tell you the the seat timing is measured at 0.006 because all their other cams are. Put a degree wheel on it. It's nowhere near the seat timing they market at 0.006. Therefore some comparison made on seat timing between cams is not valid.

5. Say I have 2 455 engines with 9.5 comp. engine A has intake flow of 200cfm, exhaust flow ratio of 75% and uses factory exhaust manifolds. Engine B has intake flow of 230cfm, exhaust flow ratio of 85% and uses 4 tube headers. A lot of the time these 2 engines get recommended the same cam.

If the dual quads and/or straub cam don't work then I will discard them. Since I have no other 455 to use as a baseline I'll have to at least do a cam swap at some point to use as a comparison. I just so happen to have a 60919 on hand.

[Formulas]

In regards to XE. cams I think more weight should be given to seat to seat timing than .050 figures on sizing one for a engine and then don't under spring it.
I have a ( close to XE lobes ) small XTQ lobe with cool face solids in a 462 with 6X-8 heads 236/242 @.050 on a 112 L/C with a 2.73 gear Auto with a cheap 500 over stock stall..
At the time of choice it was my daily driver so I went conservative as one would expect.. Stupid torque just off idle not sure where it tops out at RPM wise because this car has no tach.
It still pulled a 13.6 1/4 @5800 DA. Which is real close to real low 13 at a decent track 60ft sucked due to traction..

I laugh inside every time I see a what cam thread

.

[Will]

Originally Posted by Formulas

...
I laugh inside every time I see a what cam thread

.

Ditto. Gotta keep the popcorn popper handy for these threads.

[Formulajones]

Originally Posted by pmd400

I feel as though I should justify my reasons for letting straub select this cam.
Iv done a lot of reading on cams in the last 8 years. Iv bought books and read cover to cover multiple times, read heaps of articles and spent hours on old forum posts across a number of brands of engines. This is my 3rd engine build, my 2nd v8 and 1st Pontiac. Iv got zero cam and dyno testing and never been to the track. Some things that become apparent are

1. Xe cams seem to have problems. People across all brands seem to have problems with them not making power. Tight lsa and short seat timing often get the blame, yet the tight lsa short seat timing voodoo cams work. Seems like xe cams can create valve train instability. I won't use 1.

2. The 2802 is sometimes critised for being to small in a 455. The 041 is reccomended with rhoads lifters instead to improve drivability. If the 2802 is to small and the 041 requires rhoads lifters it kind of implies that there isn't a cam for 455 that should be used with regular hyd flat lifters. I can't believe this to be the case. In fact the vast majority of professional engine builders would advise against rhoads.

3. With regular lifters and 1.65 rockers, Jim hands car was .1 sec quicker and 1mph faster with a 068 against the 041. With rhoads the 041 picked up 1.5 sec and 1.5mph. The 068 is 212/225 at .050 and the 041 is 231/240. Seems like a huge difference in cam size with performance difference someone like me wouldn't notice on the street.

4. Most cam manufacturers measure advertised duration at 0.006. I think crane measure at 0.004. Pontiac measure at a much lower lift point. Copies of factory cams also use a lower lift point, I'm guessing for advertising purposes. Crower 60919 is a good example. Crower will tell you the the seat timing is measured at 0.006 because all their other cams are. Put a degree wheel on it. It's nowhere near the seat timing they market at 0.006. Therefore some comparison made on seat timing between cams is not valid.

5. Say I have 2 455 engines with 9.5 comp. engine A has intake flow of 200cfm, exhaust flow ratio of 75% and uses factory exhaust manifolds. Engine B has intake flow of 230cfm, exhaust flow ratio of 85% and uses 4 tube headers. A lot of the time these 2 engines get recommended the same cam.

If the dual quads and/or straub cam don't work then I will discard them. Since I have no other 455 to use as a baseline I'll have to at least do a cam swap at some point to use as a comparison. I just so happen to have a 60919 on hand.

I agree with a lot of what you're saying. Read around here enough and I come to the same conclusions. Like I said, I'm interested in your cam choice and curious if it does what you're looking for. Hats off to ya for straying from the recommended norm.

[Will]

I just hope he reports back with his honest results once it's in and running.

[pmd400]

Originally Posted by Will

I just hope he reports back with his honest results once it's in and running.

Iv got no reason not to be honest. I'm not claiming 1 cam is better than another. I'm merely pointing out what I see as inconsistencies in cam recommendations. As such iv decided to leave the selection to a cam expert. I'm not going to keep the straub cam and dual quads if a 60919 and qjet is better. In could take a few years to give each cam a decent test as the car isn't daily driven.

[Formulajones]

Or maybe the Straub cam and a single carb setup worth a shot???

[Matt Meaney]

Originally Posted by Will

I just hope he reports back with his honest results once it's in and running.

I was thinking the same thing, but with no frame of reference (first 455 Pontiac), what does it mean? I'm sure he can pick out a ping and the like, but will it have the explosive mid range that feels like N20 or the boring broad flat torque curve of a lot of power, or is it just a turd all around.

imo, the big issue with all this debate, is everyone's personal opinion/frame of reference. one person's undriveable is another's just fine. one persons rocket ship is another's can't get out of it's own way.

on to that, you have to add in the variable of engine assembly and tuning. was the cam degreed or just put in, combustion chamber cc'd or just going by the published number, timing curved verified, fuel curve, etc., etc. the devil is really in the details on these things.

you could have all the "right" parts there, but it runs terrible/hot, with the exhaust burning you eyes out, because they were "all new parts" and just assembled assuming, everything would be right.

I too, applaud those who want to try/experiment with something that is outside of what is generally accepted. as long as they are happy with the results, then it's a success for them.

[Formulajones]

Yes I agree, we never really know the whole story on the internet and opinions are all over the scale, so results will vary, but I do like to see some experimentation though.

I've always thought what we really need is a well build 455 pump gas test mule, a dyno, and about a dozen Pontiac gurus out there send in their favorite version of a camshaft and start stabbing them in the engine and making pulls. Checking idle quality and vacuum readings, HP and TQ curve etc...pick your poison.

[gtofreek]

Man, what an idiot I was for putting a cam with a 108° LSA in my friends 6x headed 455 in his 73 Firebird. He only ran 10.90 @122 on 91 pump gas. Guess he would have gone 10.50's if we went with a 112° LSA.

[Matt Meaney]

Originally Posted by gtofreek

Man, what an idiot I was for putting a cam with a 108° LSA in my friends 6x headed 455 in his 73 Firebird. He only ran 10.90 @122 on 91 pump gas. Guess he would have gone 10.50's if we went with a 112° LSA.

and since you won't put one in, you'll never know, now will you.

the devil is in the details, and from your build post's, you are a V-E-R-Y detailed person. imo, this is what makes a great running engine. ( it's not exclusive to lsa) let someone else put that same cam in their build and you could have some very different results.

[pastry_chef]

pmd400. Fantastic job! You don't need to justify your choice to anyone.

Note that with 10:1 compression, a bit more head flow (say 255) and more gear a Straub custom would have different numbers.

Pontiac crowd needs a cam shootout BIG time! Actually 10 years ago.. LOL

Not flat vs (roller on 112 LSA)
Not flat vs (roller and CNC heads on 112 LSA)
Not a puny roller vs (larger roller on 112 LSA)

Hell I'll put up $100 to see the "Road Paver" VS Straub custom roller!
Paul Carter can dyno.

[tom s]

I dont think many people realize how much choke can be in our intake manifolds.Here is one of my street RA V engines.Notice what happens to the HP with just intake changes,NO cam change at all.You will also see how bad 2-4 intakes are compared to a dual plane single 4.Tom
http://forums.maxperformanceinc.com/...d.php?t=635335

[ta man]

Originally Posted by Formulajones

Yes I agree, we never really know the whole story on the internet and opinions are all over the scale, so results will vary, but I do like to see some experimentation though.

I've always thought what we really need is a well build 455 pump gas test mule, a dyno, and about a dozen Pontiac gurus out there send in their favorite version of a camshaft and start stabbing them in the engine and making pulls. Checking idle quality and vacuum readings, HP and TQ curve etc...pick your poison.

The problem with this test is there would only be with one test mule 455. Every cam choice depends on head flow,cast or aluminum,combustion chamber design,compression ratio,weight,gearing and intended use by the owner.

[Will]

Originally Posted by pmd400

Iv got no reason not to be honest. I'm not claiming 1 cam is better than another. I'm merely pointing out what I see as inconsistencies in cam recommendations. As such iv decided to leave the selection to a cam expert. I'm not going to keep the straub cam and dual quads if a 60919 and qjet is better. In could take a few years to give each cam a decent test as the car isn't daily driven.

Understood and I wasn't trying to accuse you of anything. It's just that a lot of times we never hear how these things work out.

Once you get it all together some feedback on how it idles, (vacuum and relative idle quality @ RPM), where the powerband is, etc. would be great.

[Formulabruce]

Originally Posted by tom s

As this is the street section performance to me is secondary to driveabilty with a high performance street engine.I have spent the last 20 plus years trying to find a balance of duration and LC with stick shift cars with engines from 366 CI to 455 CI and to me the tight centers are less friendly to wide.I could give a tinkers damn about 20-30 HP when I want to drive my cars as I will be doing in about 30 min to go to a pontiac car show.If HP numbers is the all important number than move it to the race section.Carry on.Tom

X2 !! Well said!!