[77 TRASHCAN]

Cliff, Jim,
With the knowledge you have now, of using the 041 cam in a 10:1 455 street engine. Are there somethings you might experiment with to make the 041 cam even better? or is it at the edge of doing the best it can, for what it is???
Like
1. maybe a fuzz more compression to help w/ idle, maybe 10.5:1, yeah I know, then octane sensitivity gets even more potentially a problem. I don't know what some of the things you all have experienced in your experiments...
2.What cubic inch size do you believe the 041 is optimum for a 455-473??? maybe a 482??? Or is the 041 pretty much at home in a 455 (or in a 400 w/ std trans, as it was designed for) w/ Rhoads lifters and all the other perfect storm of parts and specs???
3. What cube size engine do you think the 041 might starting getting to small for???
4. I've read Jim's articles on cam experiments, and know the Wolverine 5059 performed well in the wagon. Are there any other directions you'd think about going for a streetable 455-474 engine???

I get a lot of crap from some folks when I tell them about engines over 9:1 compression running pump gas. Then you tell them it's a Pontiac w/ w quadrajet....

[Blued and Painted]

Then they get a confused look.

[rexs73gto]

I want to add a bit here . I've run a 455 +.30 over for about 5 years now & it has a RA IV cam Crane factory blueprint , & it idles fine , has a nice loop to it & it's or was in my 73 GTO with 4 spd. & 3:73 rear gears. I get about 16 mpg's & it was running high 11's . I was running the 1:65 rockers & the car ran great. Ido have E-heads on it right out of the box which gives it about 9.6 comp.???? I think. I do run it on 87 pump gas to. I know what the lift is but right off hand don't know what the dur. is but I usually get funny looks & comments when I say I'm running this cam because it's an old cam. But I've run this cam in several 455's & a few 400's over the years & it always seems to work good. & by all rights this is a 30+ year old cam design & works great for me.

[Cliff R]

"Cliff, Jim, With the knowledge you have now, of using the 041 cam in a 10:1 455 street engine. Are there somethings you might experiment with to make the 041 cam even better? or is it at the edge of doing the best it can, for what it is???"

For sure high ratio rockers really help that cam. I ran 1.73 Ford rockers on mine, pretty sure Jim ran Harland Sharp 1.65's (1.71 actual ratio) on his. It's also a huge cam, even in a 455, so if you want great idle quality Rhoads lifters are really going to help it. I would add here that I ran mine for quite a while with std Johnson HT-951R lifters, then swapped in the Rhoads lifters and immediately saw about 2" vacuum improvement at idle speed. The car ran no quicker with them, but my converter "flashes" well past 3000rpm's, so they are well pumped-up by then anyhow. They did improve idle and off idle smoothness, so I did see a benefit from them on the street and driving around in the pits. I would also add that an engine that idles smooth and strong against the converter also makes the car easier to stage without coming up against the brakes, so another side benefit for using them if you are a "foot-brake" drag racer.

The 041 cam is just a great cam for the 455 engine, maybe by coincidence or the fact that the engineers at GM really did know what they were doing WAY back in the 1960's. As good as the 041 cam is, it's not the best choice for the smaller 400 engines in most cases. Even in the big 455's, it really likes to be at least 9.5 to 1 compression, and 10 to 1 is even better. My old 455 with iron heads was right at 10 to 1, and it would manage any octane of pump fuel that I wanted to put in it. One of the first years I attended the Norwalk race with that engine in place I entered the street car race that required that we go off the track and run a 20 mile loop, then return to the track, fill up with pump gas right before we got back, and make 3 runs without shutting the engine down.

It just so happened we stopped at a station that only had 89 or 90 octane, no 92-93. It was one of the hottest days I can ever remember at Norwalk. LOTS of the other participants were dropping out with overheating issues, and one guy blew up his engine (high compression) making runs when we got back.

My 455 never even thought about running hot, overheating, and made three perfect runs back to back without shutting it off. After that experience I'm sure I could have ran closer to 10.5 or even a bit higher compression and still easily managed pump fuel with that engine.

Shortly after those runs we pulled the engine for the KRE head testing and HPP/Popular Hot Rodding articles that followed:

http://www.hotrod.com/how-to/engine/...-dyno-results/

http://www.hotrod.com/how-to/engine/...track-results/

With the new heads and higher compression ratio the engine still easily managed pump fuel, but I didn't play around much with anything less than 92 or 93 octane.

I still kept the original iron head testing in the back of my mind and decided to build the next 455 with smaller 76cc chamber heads, bigger cam, and 11 to 1 compression. Working directly with Dave at SD we got one of the first sets of his KRE ported heads and teamed them up with his "Old Faithful" camshaft. It turned out to be a great success, and the current 455 easily runs on 87 octane fuel at 11 to 1 compression. I even tried adding higher octane fuel to it at the track, and it slows it down a few hundreths, so it really likes and runs well on lower octane fuel.

This sort of throws a monkey wrench into the proverbial "brick wall" theory of 9.5 to 1 compression for pump fuel, and I think the folks that make that remark are talking about 92-93 octane, not 87 or 89.

I certainly do NOT recommend for folks to do the "high compression pump gas deal", but we have shown that with careful engine building, and full control of timing/fuel curves that you can EASILY manage pretty high compression in one of these engines. It involves tight quench, and the right cam more than anything else. Of course you have to be able to keep the engine cool, so a small radiator and electric fans may not be in your future with that deal. I tried a big single electric fan for a while and it kept killing the battery trying to keep the engine cool on race days in really hot weather, so I went back to the stock set-up and all has been fine since.

The camshaft topic ALWAYS gets kicked all over the place on the Boards, so for the most part I sit back and watch the threads run. I have been paying close attention to folks who have came up WAY short in power with 455 builds, and they almost ALWAYS have chosen the smaller cams mentioned in this thread. I have also had a number of those engines brought here to tune, or set up carbs for them, and to date haven't been impressed in the least by any of them. I knew those cams weren't making the grade, so finally we had a professionally built engine by a well known shop try that deal, and we ended up getting dyno sheets on it, which prompted me to go public with the information. I certainly hope that it helps some folks out with cam choices for these engines......Cliff

[Steve C.]

When you see specific compression numbers touted in these cam discussions consider the cylinder head material, iron or aluminum, and consideration should be given to the chamber design involved.

"The design of the combustion chamber influences the performance of the engine and its anti-knock properties. The layout and shape of the combustion chamber has a bearing on the thermal efficiency and performance as well."

Typically a 'heart shaped' combustion chamber will tolerate a higher compression on some these aluminum heads. Iron heads and older style Edelbrock heads are a different ballgame. As an example, with the Edelbrock head and their 'regular' combustion chamber design some might suggest max of 10.25 with the 87cc chamber design and max 10.5 with the 72cc chamber design.

This for day-to-day type driving in all kinds of conditions for the average person, and as a precaution with unknown gas quality. And one doesn't always know how a customer would tune and drive the intended combo. Many will suggest for day-to-day type driving in all kinds of conditions, a potential for unknown gas quality and for the average person one still might suggest precaution.


.

[pmd400]

Iv read this whole thread, it's very interesting.
In a 9.5:1 iron headed 455, a cam with a 274 adv duration and 230 at .050 is considered to small. It doesn't make as much power as it should and is octane sensitive.

A crower 60919 has adv duration of 304 and .050 duration of 231. It makes great power but works best with 10:1 compression and rhoads lifters.

Is it possible that a cam with 230 at .050 and an adv duration of about 290 using standard lifter would be a good compromise? I understand that some companies also use a different lift point for advertised duration, so some cams seem to have a longer duration but in fact they are just measured at a lower lifter point.

Crower, comp, howards, lunati, melling all measure the advertised duration at 0.006 of tappet lift

[JLMounce]

I've been following this thread pretty diligently. As Cliff has suggested, that barrier at 9.5 SCR for pump gas isn't a hard and fast rule.

I didn't build the engine in my bird so I couldn't tell you exactly what cam is in it, however it runs on pump gas just fine. It's a 462 topped with #62's which should put it between 10.8-11.2 SCR depending on how it was built.

I suspect that the cam may be something along the lines of an 041, possibly with rhoads lifters. Though without taking the engine apart I just don't know.

This is great information for the future if/when I decide to do a rebuild.

[Will]

Originally Posted by pmd400

Iv read this whole thread, it's very interesting.
In a 9.5:1 iron headed 455, a cam with a 274 adv duration and 230 at .050 is considered to small. It doesn't make as much power as it should and is octane sensitive.,,,

I think this might be oversimplifying things a bit. Lobe centerlines play a very large role also as they determine valve opening and closing points in conjunction with the overall lobe profile. A fast-ramp cam like that might work just fine and have a broader powerband if modified to a 112 LSA and 108-110 ICL. Of course, the faster ramp cam will still have later opening and earlier closing points than a cam with similar .050" duration but longer seat duration ("slower" ramps) and the same lobe centers.

Isn't the point of a roller cam to minimize the seat-to-seat duration in relation to duration and lift off the seat? In that respect, a fast ramp flat tappet cam is an attempt to mimic the valve motion of a roller as much as possible. Of course it seems that running bigger rollers (as measured at .050" duration) than flat tappet cams is the way to go.

Which all comes back to valve opening and closing events and their relationship to other engine parameters being the key to whether an engine is a dog or a monster.

[nytrainer]

I happen to own a practically new (thumbs down in a friend's 455) Comp cam XE 262 cam (specs below).
To the gurus who can decipher the specs. would this cam work nicely in a 9:1 cr 350 with dual ex, iron manifold and q jet or is there no place for it in any Pontiac engine? I read all the posts in this thread but still can't answer that question myself.
Also, plans are/were for my 455 to get the 041 cam (9.8:1 cr 6x-4 with push rod holes enlarged) or should I be looking at the Crower offerings (619...). Car is a 4 speed with 3.23's. I'd rather do regular lifters and would be OK with a rumpity idle (but I do have power brakes). Are Rhoads a must? I think the ticking would send me over the edge. It's a once in a while cruiser car during nice weather.

[ponyakr]

"... is there no place for it in any Pontiac engine?..."


I've read that those cams were made to increase cylinder pressure in low compression engines. There were plenty of low comp(7.6-8.5:1) 350 and 400 Pontiac engines in the 70's. So, for those just wanting to increase performance a bit, without switching to high comp heads, these steep ramps are supposed to fill the bill.

But, since you don't want the noise of Rhoads lifters, you may wanna go with a Lunati Voodoo 262, instead of that XE 262. I've read that the XE cams make noise, because of slapping the valves shut. I've even read of several guys who pulled their XE for this very reason.

And for the 455 cam question, if you can't stand the Rhoads, but want lots of idle vac, you'll just have to settle for less cam, or go with a high dollar roller set-up. But, since I said that, I'm sure somebody will come up with some cam that is bigger than the 041 and has more vac, without Rhoads. That seems to be the way this thread has gone. What don't work for some, seems to work great for others. So, I reckin it all depends on who you believe. Or you'll just have to try 'em in your engine and see how they do.

But, then I'm no expert. Some of them will be along shortly.

[nytrainer]

Thanks Ponyacker. I have the XE262 and regular lifters. Both like new and lifters matched to the lobes when removed. Just looking for a place to use it. Thinking it might be a better performer than the orig. cam (pn 254?). '68 350 rated at 9.2:1 cr but reality probably 8.5:1 I'm guessing.
I had the springs setup for the 041 (ported, 10 degree locks, new guides, clean up mill, cut for Viton? seals, pushrod holes enlarged, new valves, etc) to use on the 455 block but after reading the thread it's as clear as mud as to what hyd. cam I should use. I think roller setup would need different springs too so I'd like to keep the heads as prepped. Just need to have the gurus direct me to which cam.

[Steve C.]

Running a big cam and getting less than adequate vacuum for your power brakes?

Solve those problems with a electric vacuum pump kit. Easy to hide if desired.

One of many companies: http://www.mpbrakes.com/accessories/vacuum-pump-kits


.

[neill]

Originally Posted by nytrainer

Thanks Ponyacker. I have the XE262 and regular lifters. Both like new and lifters matched to the lobes when removed. Just looking for a place to use it. Thinking it might be a better performer than the orig. cam (pn 254?). '68 350 rated at 9.2:1 cr but reality probably 8.5:1 I'm guessing.
I had the springs setup for the 041 (ported, 10 degree locks, new guides, clean up mill, cut for Viton? seals, pushrod holes enlarged, new valves, etc) to use on the 455 block but after reading the thread it's as clear as mud as to what hyd. cam I should use. I think roller setup would need different springs too so I'd like to keep the heads as prepped. Just need to have the gurus direct me to which cam.

I believe the stock cam for that motor had either 269 degrees or 273 degrees duration. my 455 with 275 duration often pings with 91 octane and 8.96 to 1 compression. I would be very hesitant to try it in the 350. But I am no expert

[Nicks67GTO]

I just saw a dyno video on facebook from a very well known Pontiac builder. 4.25" stroke 400 with aluminum D ports, RPM and FAST 2.0 EFI. I asked for details but he didnt disclose. It made 488hp@5000 RPM and 580 lb/ft @ 3900. Not bad but not overly impressive imo. I was curious about the cam selection and port work as it seems compared to others with similar combos like the KRE290/RPM/OF combo, that this one its leaving a lot of HP and probably 5-700 RPM on the table for minimal costs. Ive also seen people mention that these guys like to run the modern lobe, tighter lsa profiles, I guess thats why its maybe worth mentioning here.

[Will]

I'm no expert but I'd think that XE262 would probably work decently in a medium compression 350 with a mild stall (or manual) and mid 3-series gearing behind it. Good flowing exhaust will really help.

I ran a Comp 270 Magnum with Crane Hi-Intensity lifters (similar to Rhoads but slightly less effective at improving low speed characteristics by all accounts) in an 8.5:1 400 with stock log manifolds backed up by an M-20 and 3.73 gears. It was a bit soft on the bottom end but came on strong at 2500 and pulled well to 5000 where it ran into a wall. The XE 262 should produce similar results in a 350, maybe even be a bit better on the bottom end. That 400 would likely have pulled better on the top end with headers and something better than a 2" compression bent exhaust system.

The tighter the lobe separation the more the engine needs good flowing exhaust to make upper RPM power, in general.

[Squidward]

Originally Posted by nytrainer

I happen to own a practically new (thumbs down in a friend's 455) Comp cam XE 262 cam (specs below).
To the gurus who can decipher the specs. would this cam work nicely in a 9:1 cr 350 with dual ex, iron manifold and q jet or is there no place for it in any Pontiac engine? I read all the posts in this thread but still can't answer that question myself.
Also, plans are/were for my 455 to get the 041 cam (9.8:1 cr 6x-4 with push rod holes enlarged) or should I be looking at the Crower offerings (619...). Car is a 4 speed with 3.23's. I'd rather do regular lifters and would be OK with a rumpity idle (but I do have power brakes). Are Rhoads a must? I think the ticking would send me over the edge. It's a once in a while cruiser car during nice weather.

Satan cam. I gave one away to a friend after my low compression 400 failed with it installed. His first run out to the dragstrip with that cam wasted his rod bearings in a 70 350. I think the devil was inside...

I went with the Lunati 10510702. Couldn't be happier, on a 112 LSA. But I digress. Back to 455's...

[neill]

Originally Posted by Will

I'm no expert but I'd think that XE262 would probably work decently in a medium compression 350 with a mild stall (or manual) and mid 3-series gearing behind it. Good flowing exhaust will really help.

I ran a Comp 270 Magnum with Crane Hi-Intensity lifters (similar to Rhoads but slightly less effective at improving low speed characteristics by all accounts) in an 8.5:1 400 with stock log manifolds backed up by an M-20 and 3.73 gears. It was a bit soft on the bottom end but came on strong at 2500 and pulled well to 5000 where it ran into a wall. The XE 262 should produce similar results in a 350, maybe even be a bit better on the bottom end. That 400 would likely have pulled better on the top end with headers and something better than a 2" compression bent exhaust system.

The tighter the lobe separation the more the engine needs good flowing exhaust to make upper RPM power, in general.

So Will, would you install it @106 or retard it to 110 to match the intake closing angle of the 270 magnum? How octane sensitive was your 400?

[Cliff R]

I've had a couple of 400's in here to build carbs for and tune that used the XE262 camshaft, and it's not very impressive anyplace. The last one had 7K3 heads on it, so 8 something to 1 compression. One would think that a tiny cam like the XE262 would fair good there, but it was a complete "turd" everyplace, IMHO. It didn't even act like it had a "big" cam in it, idled with a "deep/heavy" sound, not the first hint of "lope" anyplace, power curve was flat and done early in the rpm range.

Of course I had no idea what else was done to the engine, it could have had .100" quench in it for all I know?

I have been around "low" compression 400's before, and they can be STRONG runners with correct rebuilding and cam selection. The 400 that used to power my Ventura had 6X heads on it and ran into the high 13's with a stock converter and 2.73 gears......Cliff

[Skip Fix]

"I didn't build the engine in my bird so I couldn't tell you exactly what cam is in it, "however it runs on pump gas just fine. It's a 462 topped with #62's which should put it between 10.8-11.2 SCR depending on how it was built."

Just because you cant hear detonation does not mean it is not happening. Go put it on a chassis dyno and load it make a pass, then drain the gas run it on 104 race gas and see what it does. Bet it picks up a bunch because it needs more octane

Cliff you got many 455s running 11.2:1 iron heads on pump gas for a street car?

Those 11.5 NHRA stockers using low compression 78 motors sure got it figured out! But the chassis and cam are definitely not too street friendly

[77 TRASHCAN]

The answer to post 270 is post 279,,,still no, I've read it here several times. Just because a company makes a product, doesn't mean it'll work, even though most of us have trusted them for years,

You're getting this experienced info. from someone that does this work EVERYDAY!!!
The biggest things a lot of folks can't wrap their mind around, is not knowing how their engine performs in comparison (lets say a low comp 400 w/ an XE cam) to an engine that has a perfect storm of parts, and modifications performed by an experienced pro doing the job, all the way from the build to tuning your engine.

You let somebodies grandpa, (that's done machine work for 40 years, and maybe the machine work is... even very good!!!) select your cam, and he has no part in your engine tolerances, induction selection, or especially tuning the thing. You MIGHT have a car that you THINK runs pretty good. BUT you have nothing to compare your performance to.

I read these forums to learn! So that I don't make engine building mistakes that have been performed over and over for decades, because of lack of knowledge...

That XE262 cam would make a great boundry marker for your property.