[ponyakr]

WOW !

There have been more than 150 replies & over 3500 hits on this cam thread.

[silverbullet07]

Originally Posted by pastry_chef

Where did you read this?

The issue is where (angle) the pressure is and the time the engine spends there. Piston speed will change the time.

Jim hands book. I know nothing about this stuff so trying to crasp all this info with most suggesting cams for high rpm and track vs low rpm you see on the street and my needs of finding a cam work with my compression, exhaust and easy driving. What some suggest and then the cam builder says something else. Makes me just want to put a stock 068 cam in. Mil spc-7 or the 2801.

[Brent Flynn]

Originally Posted by "QUICK-SILVER"

OP's car is straight shift and you've got a 3200 converter. He would have to smoke the clutch to 3200 for his to feel like your's.

Stock 8.2:1 CR 400's feel strong off idle with 3000+ converters.

I think he wants to be able to get off the clutch at idle speed or close to it and the car feel good from there.

Clay

Oh, didn’t realize that...

Did he not say he had 3.42’s,?
I would think this setup would still work well with a 4spd, with 3.42 gear...
He could always go shorter duration. 60243 is 228/235 on 112Lsa if I recall...
but I’m at 9.6:1. If he’s in the 8.2:1 range , I’d go smaller...

[pastry_chef]

Fairly general info there and tighter LSA often does NOT narrow the powerband, from last years Engine Masters winner.. they dyno'd many cams to find the best.

Engine knock is more dominantly dictated by intake closing point, as is cranking compression.

More often "overlap" should be spoken about.

Originally Posted by CamKing post_id=440291 time=1372086789 user_id=5117

Overlap is extremely important.
It is controlled by the Intake opening and exhaust closing and is not directly related to LSA, or the difference in duration between the intake and exhaust.
After I calculate the Intake opening and closing points, I calculate the exhaust closing point based on desired overlap, then the exhaust opening point.
If the exhaust duration ends up being 12 degrees longer then the Intake, or 12 degrees shorter, it's irrelevant.

Was it Tim from Bullet that replied to you?
If so he has been selling and grinding cams for many decades!

[silverbullet07]

Originally Posted by pastry_chef

Fairly general info there and tighter LSA often does NOT narrow the powerband, from last years Engine Masters winner.. they dyno'd many cams to find the best.

Engine knock is more dominantly dictated by intake closing point, as is cranking compression.

More often "overlap" should be spoken about.

Was it Tim from Bullet that replied to you?
If so he has been selling and cams for many decades!

No it has been Kirk Millner. Once I told him about the pinging issue he wanted to change from from the initial suggested 105cl to 106cl. He said narrow LSA actually bleed cylinder pressure.

[silverbullet07]

Originally Posted by Brent Flynn

Oh, didn’t realize that...

Did he not say he had 3.42’s,?
I would think this setup would still work well with a 4spd, with 3.42 gear...
He could always go shorter duration. 60243 is 228/235 on 112Lsa if I recall...
but I’m at 9.6:1. If he’s in the 8.2:1 range , I’d go smaller...

I have 4 spd 3.36 and around 9.6 compression is what was calculated.

[pastry_chef]

Originally Posted by silverbullet07

Kirk Millner. .

Cool,
When I was very young I learned to qualify anyone I take advice from.

I have this CD. Don who is interviewing Kirk set 12 NHRA records.

http://speedtalk.com/shows/046_kirk_millner.html

This is old info
About the Guest: Kirk has been in the cam business since the mid-eighties. He started out grinding cams for Harold Brookshire at Ultadyne. He then left Ultradyne to help an unknown upstart cam company called Bullet Cams, there he made masters and did all the grinding. In 94' Kirk went to work for Joe Lunati. Currently he's heading up tech support for Comp Cams.

-------------------------------
Here is an article from Don
https://blog.raceology.com/2006/04/p...-camshaft.html

[silverbullet07]

Originally Posted by pastry_chef

Cool,
When I was very young I learned to qualify anyone I take advice from.

I have this CD. Don who is interviewing Kirk set 12 NHRA records.

http://speedtalk.com/shows/046_kirk_millner.html

This is old info
About the Guest: Kirk has been in the cam business since the mid-eighties. He started out grinding cams for Harold Brookshire at Ultadyne. He then left Ultradyne to help an unknown upstart cam company called Bullet Cams, there he made masters and did all the grinding. In 94' Kirk went to work for Joe Lunati. Currently he's heading up tech support for Comp Cams.

-------------------------------
Here is an article from Don
https://blog.raceology.com/2006/04/p...-camshaft.html

He should know his stuff then. However thought the builder that suggest mine knew but he build engines not cam.

So should I trust him and go with his recommendation?

["QUICK-SILVER"]

Originally Posted by silverbullet07

I have 4 spd 3.36 and around 9.6 compression is what was calculated.

9.6 was based on the small piston dish correction.

Zero deck and what looks like a bunch shaved off the heads....True SCR could be higher.

Your cranking compression test was only 5 psi off the low factory pressure for one of these engines.

Warm engine, all eight plugs out, carburetor propped open...your cranking compression may be higher.
We just dont know
Clay

[pastry_chef]

Originally Posted by silverbullet07

the builder that suggest mine knew but he build engines not cam.

IF he built your full engine *maybe* he could have made that cam work for you.

I see Kirk's suggestion and Mike Jones suggestion are extremely close, what are the odds...

[silverbullet07]

Originally Posted by pastry_chef

IF he built your full engine *maybe* he could have made that cam work for you.

I see Kirk's suggestion and Mike Jones suggestion are extremely close, what are the odds...

He responded back with some very detailed information.
Lets look at the overlap numbers of each of these cams.
Now remember, the more overlap (or time that both valves are open at the same time) you have, the lower your cylinder pressure becomes.
First cam – comp 262 218/224-h10+4
1 degree of overlap
Second cam – bullet 223/233-h10+5
8 degrees of overlap
Third option – bullet 226/233-h12+4
5.5 degrees of overlap
Which one will bleed the most cylinder pressure, the second cam with 8 degrees
Last option – bullet 226/233-h10+5
9.5 degrees of overlap
A lot to think about but spending a little extra time understanding how it works will help with the final outcome.
If this thing doesn’t do what you expected then we both lost…
Kirk m

Sent from Mail for Windows 10

["QUICK-SILVER"]

Old post by screamingchief from 2007. About a 400 w/16 heads.

Originally Posted by screamingchief

Without knowing specific chamber CC's and deck heights and head gasket thickness,any compression ratio input given here amounts to educated guesses.

If you did'nt zero deck it expect the pistons to be appx. .020" in the hole as SOP for a 400 pontiac,possibly more with certain pistons.

And most "common" head gaskets are .039" compressed thickness.

And most heads are above the "nominal" listed specs,so figure 74 or so CC's for those heads with minimal milling and a basic valve-job and minimal valve recession.

With those assumptions,my educated guess would be 9.8:1 CR.

As for the XE284 cam,the XE cams use short seat events,and fast lobes,with a relatively tight LSA,and these are usually not the best choice for a borderline CR combo,as stated a slightly shorter duration cam on a wider LSA with the intake closing event later than the current XE284 cam you have chosen may give better overall performance and driveabillity while still avoiding detonation.

If you compare cams in the XE284 same approximate "size" range,to something like the Crower #60244,which would be comparable to the XE284,the Crower cam closes the intake @ 76.5° when installed on the recommended 108° intake centerline vs. the XE284 which closes the intake @ 68° when installed at 106° intake centerline per Comps recommendations.

If you compare the results on a dynamic compression ratio calculator like the one here,you'll get an idea the impact that can have.

But from the loks of things,the XE284 should still be "safe" enough cylinder pressure wise if that's the cam you wanna use.

But a smaller cam with a wider LSA would likely be a better choice in all around driveabillity and such,especially as this sorta cam will have much less total overlap.

For instance the Crane cam #283801,it has much shorter duration then the above cams,on a wider LSA then either of those above,yet it closes the intake @ 72° when installed per it's cam card.

See the result summaries from the linked website:
Your engine summary is as follows:XE284 cam
Bore - 4.15 inches
Stroke - 3.75 inches
Rod c-c length - 6.625 inches
With a static compression ratio of 9.8:1.
Your camshaft specifications call for an inlet valve closing of 68 degrees ABDC (after bottom dead center).
Your chamber volume is 94.46 cc's. With this camshaft your dynamic, or effective stroke is 2.81 inches.
Your dynamic compression ratio is 7.59 :1 corrected for cam timing, altitude, and rod length.
Your dynamic cranking pressure, corrected for cam timing, rod length and altitude is 148.46 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 7.59 :1.


Your engine summary is as follows:Crower #60244 cam
Bore - 4.15 inches
Stroke - 3.75 inches
Rod c-c length - 6.625 inches
With a static compression ratio of 9.8:1.
Your camshaft specifications call for an inlet valve closing of 76.5 degrees ABDC (after bottom dead center).
Your chamber volume is 94.46 cc's. With this camshaft your dynamic, or effective stroke is 2.57 inches.
Your dynamic compression ratio is 7.03 :1 corrected for cam timing, altitude, and rod length.
Your dynamic cranking pressure, corrected for cam timing, rod length and altitude is 134.26 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 7.03 :1.


Your engine summary is as follows:Crane #283801 cam
Bore - 4.150 inches
Stroke - 3.75 inches
Rod c-c length - 6.625 inches
With a static compression ratio of 9.8:1.
Your camshaft specifications call for an inlet valve closing of 72 degrees ABDC (after bottom dead center).
Your chamber volume is 94.46 cc's. With this camshaft your dynamic, or effective stroke is 2.70 inches.
Your dynamic compression ratio is 7.34 :1 corrected for cam timing, altitude, and rod length.
Your dynamic cranking pressure, corrected for cam timing, rod length and altitude is 142.09 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 7.34 :1.

So you can see how you can play around with the intake closing event and get to the same place with much different hardware being used.

But those calculators are'nt a "be all,end all",they're good to show the basic relationship that exists in these combos,but there is a lot more going on in all this.

Fast lobes with less seat timing will "mimic" smaller cams by taking away some portion of the total overlap compared to slower lobes with more seat timing.

Meanwhile wider LSA's "mimic" larger cams by delaying the intake closing event.

Overlap helps determine the power output and the RPM range,lots of overlap is helpful when the engine can breathe well enough at higher RPM's,enough so to have good exhaust scavenging helping boost the engines VE,but if the exhaust is restrictive,there can be serious issues with too much overlap.

Overlap (seat to seat/total) for these cams are:
XE284 = 70°
Crower #60244 = 78.5°
Crane #283801 = 56°

So if you choose to use the XE284,it will need a very good intake and exhaust tract,and will benefit greatly from ported heads and such,and a super efficient exhaust system with little to no back-pressure will be mandatory.

It would really help to know what sorta drivetrain is planned for this combo,,,things like trans,and gear ratio,tire size,intake and carb,head porting,exhaust system layout,that sorta stuff.

HTH.

Clay

[tom s]

Im a little confused I guess!I have been told like forever we put bigger cams in our engines to make more HP because of higher cyc pressures from more and better filling?Do they not make more cyc pressure as the RPMs increase?I understand more overlap bleeds off cranking comp at cranking RPMs.So I guess if we drive our cars around at cranking RPMs we wont have detonation?As the cyc gets better filling at increased RPMs can the detonation return?Inquiring minds need to know!Tom

[Will]

I find his focus on overlap as a determining factor for cylinder pressure somewhat odd.

Intake closing point also plays a huge role. In fact, I've always thought it played a bigger role than overlap.

With any normal cam, the exhaust valve closes well before the intake valve and significant pressure can't begin to build until the intake valve closes.

How does overlap affect this?

[Cliff R]

The XE262 cams doesn't work simply because it is too good at cylinder filling early in the RPM range (and far better suited to a 350 CID build with 7.5 to 8 to 1 compression not a 400 build pushing up near 10 to 1. The tight LSA/early intake closing doesn't help that scenario as it tends to narrow up the power curve and push peak torque higher and earlier. When you pull power down in the RPM range and spike it higher, the octane requires go up with it, pretty simple to figure that out.

The XE268 has a similar effect on 455 engine builds around 9 to 9.5 to 1 or so. HORRIBLE cam choice for those engines, and the XR276HR cam is even worse as it's more effective than the XE268 flat cam. See the attached dyno chart below next time Comp or anyone else recommends the XR276HR cam for your 455 build with 9.3 to 1 compression and professionally ported 250cfm #96's. Pinged so hard on the dyno it spun all the rod bearings AND didn't make chit for power for the combination of parts either.

I don't design camshafts I tune for a living, so will get to see all sorts of different engine combinations. We have cars brought here from great distances that folks are having troubles with, and rest assured they've used every local resource at their disposal BEFORE the long trip here.

General statement about camshafts from what I've seen actually doing it, tight LSA cams by far get the most complaints from the end user. Rough idle, stalling at lights, "soggy" power right off idle, RPMS fall off WAY too much when the auto trans is placed in gear, smells rich all the time, and the best one is that the wife woln't ride in the owners new restored pride and joy because it stinks her hair up!

By far and above the WORST cams out there for customer complaints are the Comp XE, but the Thumper and Thump your Mother 107LSA stuff is gaining ground on them rapidly. I've caused quite a few folks to yank out the their Thumper cams for much better choices, and every single time they absolutely LOVE the end results.

Far as the XE262 in a 400 build, as mentioned it's not overly impressive anyplace. Sounds a little "ratty" at idle, throws some power at you quick and early so "feels" pretty decent if you evaluate engine power by the "seat of your pants", then power flattens out and fades away up near the shift point. Even the next cam in the line-up (XE268) is no barn-burner in a 400 build, actually did one here with very well prepared #16's and it didn't make the grade.

For lower compression 400's the XE274 starts to show us something. We've had customers send us some decent dyno sheets with later model 400 builds using 6X heads on them and compression around 9 to 1 or so do pretty well with that cam. Even so I know the Crower 60243 is a better choice, and the "softer" ramps don't require battleship valve springs to keep things in check and for sure no "clattering" from the super-quick opening/closing ramps the XE lobes use.

Your contact from Bullet is only partially correct about the tight LSA comments when he mentions increasing overlap and lowering cylinder pressure. However that is only looking at a small part of the big plan from a "static" perspective. Tight LSA and early closing intake is why the current cam isn't making the grade.....and you want to go that route again?.........Cliff

PS: forgot to mention that not only did my cam recommendation make a little more power than the one from the Tech at Comp, it idled better, smoother off idle, and fine on the same grade of pump gas they blew it up with on the dyno when they tried running optimum timing to it to get better power numbers......

[pastry_chef]

Originally Posted by Will

Intake closing point also plays a huge role.

Yes, and the Ultradyne cam will have a VERY different intake valve close!

LSA is NOT the problem, any such suggestion is confusion. We can also look to Vizard for that proof, THOUSANDS of dyno tests.

Originally Posted by Cliff R

it idled better, smoother off idle, ..

BS.. A cam with 40% more overlap area will NOT idle better. Unless the original engine had a BIG problem, and it probably had a cam degree issue (retarded). Others have used that cam in a mid 9 CR 455 without any detonation. Paul K, Tom S etc

Tom put many miles on the car with California gas.

Originally Posted by tom s

455 pump gas engine for my Judge.455,9.5C,completely stock 48 heads except springs and 1 pc valves.I used a XE276HR on a 110 as I had it in my drawer.We ran a stock AL SD intake with Joe Shermans dyno carb and custom 2in Tyree 4 tube headers.The engine made 432 HP at 5200.That cam was 224-230@50.We ran 1.65 H&S rockers.I put Daves new Stump Puller II in the engine with exact same intake and carb put replaced the 1.65s with 1.50s to keep the lift virtually the same.Because I wanted to know the performance as it will be in the car I used long branch 2 1/4 exhaust to about 2 ft of 2 1/2 pipe into Joes dyno mufflers.The engine made virtually the same HP 234 but at 5400.Joe figures we gave up about 15-20 HP with exhaust from the 4 tubes.We also ran no spacers as I cant run one with the 69 T/A RA pans.This cam was on a 112 put in at 107.He is going to pump it.FWIW,Tom

Another 455 with the 276 HR - Peak hp was 484 at 5,000 rpm. made almost 70 dyno pulls
https://www.hotrod.com/articles/hppp...e-stuska-dyno/

Oh yes, and the dyno numbers in post 175? Is what happens when you compare a cam with 145 duration at .200 to another cam with 160 @ .200 !!! LMAO One with nearly a 140 IQ understands these things..

[shaker455]

Originally Posted by silverbullet07

I have been having problems with WOT pinging with the Comp CAM XE262H on straight 93 Oct gas with out severely retarding the timing. It runs great on 96 Octane by mixing 12 gals 93 to 3 gals of 110 octane.

I currently have the distributor set up to max degrees cent. at 16° and initial at 6° with 22° total with vacuum advance disconnected.

I still have some very light pinging at WOT but good power and could be driven like this.

My build is 9.2 compression, 0 deck, 16 iron heads 30 over. Many people say it is the Cam giving me the problem. I could keep adding 110 octane but thought I was building a motor to run off 93 octane.

The XE262H is 218\224 @.050. What should I be looking at to not cause so much cylinder pressure.

Would the summit 2801 be closer to my needs. it is 214\224 @.050

Would like to get the pinging to stop and run a little more timing,

Yes these XE series cams are not favorable and have been covered here countless times over the past 20 years...
Consider moving onto something better suited for your combo
I've had great success with Lunati VooDoo series.
Have you tested cylinder pressure?
how is your carb jetted and @ what RPM does all your timing come in?

[72LuxuryLeMansLa.]

"When I was very young I learned to qualify anyone I take advice from."

[silverbullet07]

This is why it is to confusing to pick one out. The grinders say one thing the tuners say something else. Many of the Voodoo cams are on 110 LSA and larger duration and they seem to be liked.
Seems I would be safer to just go with the 2801. Lots of people like it and no one has said it would not be good for me.

[shaker455]

I had a car here recently here with one and I did get it running nice so it is possible.
I'm sure proper cam degree will play in but also dialing in the tune.