I have a Crane HT-288-2-NC in my 396. this cam was installed 23 years ago when it was rebuilt. I have the info card but there does not show a listing for duration? I am hoping to rebuild and want to upgrade perf if possible without totally losing street manners. :D I have listed what the card says in hopes of an interpretation from someone.
Lift@cam 287 / 298 Ratio 1.7
Lift @ valve 488 / 508
valve timing
open 33 / 82
close 75 / 36 at .004
.050 lift timing
open 0 / 49
close 34 / (-5)
Right now I have The stock high rise / holley 650dp / headers / turbo 350 w/shift kit / posi 3.55 / mallory unilite
I would appreciate any input or suggestions.I am open to anything but really need to get it right the first time( kids , wife and $ dictate one chance for the next 23 years!) smile.gif Any of the above items can be changed! Thanks to all of you who log on , I have learned alot from reading other posts! Is this a great site or what! graemlins/thumbsup.gif

Originally posted by 70convt396:
I have a Crane HT-288-2-NC in my 396. this cam was installed 23 years ago when it was rebuilt. I have the info card but there does not show a listing for duration? I am hoping to rebuild and want to upgrade perf if possible without totally losing street manners. :D I have listed what the card says in hopes of an interpretation from someone.
Lift@cam 287 / 298 Ratio 1.7
Lift @ valve 488 / 508
valve timing
open 33 / 82
close 75 / 36 at .004
.050 lift timing
open 0 / 49
close 34 / (-5)
Right now I have The stock high rise / holley 650dp / headers / turbo 350 w/shift kit / posi 3.55 / mallory unilite
I would appreciate any input or suggestions.I am open to anything but really need to get it right the first time( kids , wife and $ dictate one chance for the next 23 years!) smile.gif Any of the above items can be changed! Thanks to all of you who log on , I have learned alot from reading other posts! Is this a great site or what! graemlins/thumbsup.gif =
Just add the opening & closing numbers +180.
Same for .050 numbers & you will have the duration ;)
IE: .050 intake; 0+34+180=214 @ .050
Ex; 49+(-5)+180=224 (you need to subtract the 5 as the -5 indicates the valve is closing before TDC.

The advertised duration would be 288° intake and 298° exhaust, .050" duration would be 214° intake and 224° exhaust, 107° intake lobe center, 112° LSA.

Wolfplace Thanks! I guess i am makin life hard cuz after your simple explanation i sure feel stupid! Well better to ask than continue in stupidity! Can you make any suggestions on my other questions please smile.gif

Originally posted by 70convt396:
Wolfplace Thanks! I guess i am makin life hard cuz after your simple explanation i sure feel stupid! Well better to ask than continue in stupidity! Can you make any suggestions on my other questions please smile.gif =
First, stupid is in my opinion one of a couple of things,,,,, not asking the question or worse yet already knowing everything :D

Sounds like a good home for something like an Isky 270/280 Mega Hyd or equivalent.
Numbers are 270/280, 221/232, .542/.565, 114sep

Ede RPM or RPM air gap, 3310 750 Holley, keep the compression about 9.0-9.5.
Headers 1 3/4",

Wolf- would I need a stall? How would you characterize the idle and perf of this cam vs what I have now? redface.gif Are special springs required with the lift on this cam. I have dual ones now but they are old.
thanks for your help graemlins/thumbsup.gif

Originally posted by 70convt396:
Wolf- would I need a stall? How would you characterize the idle and perf of this cam vs what I have now? redface.gif Are special springs required with the lift on this cam. I have dual ones now but they are old.
thanks for your help graemlins/thumbsup.gif =
You will not need a new stall although it would run better with a little.
Talk to Steve Oldani on here about the converter.

Idle will be pretty docile with the 114 sep.
You will know it ain't stock but it should have very good vacuum & low speed drivability.

Yes you need to change the springs even if yours would work.
Old springs are not a real good place to save money. ;)

You will also need to be sure you have enough retainer to seal clearance for the lift which is no big deal when the heads are being freshened.

Wolfplace =thanks again. Can I go any bigger on the cam and retain street manners or is this the best of both worlds? Are there certain springs/lifters you reccomend? Can you compare the idle of my exisiting cam to the isky you noted? THANK YOU !! :confused:

Originally posted by 70convt396:
Wolfplace =thanks again. Can I go any bigger on the cam and retain street manners or is this the best of both worlds? Are there certain springs/lifters you reccomend? Can you compare the idle of my exisiting cam to the isky you noted? THANK YOU !! :confused: =
Depends on what you call "street manners" :D
Yes you can go bigger on the cam. You can also use this general cam & close up the separation to 110 & it will build a little more torque & be a lot more noticeable as far as idle & I would then probably go with a small converter but again talk to Steve about this as it is what he does.
All depends on what you want to do,,, but from your first post it doesn't sound like you want to get crazy so I would limit the duration to about 280 adv & high 220's, low 230's @ .050.

Look at some of Harold's newer cams in the "VooDoo" line on the Lunati site & ask him about a cam recommendation as he appears to have a fairly good handle on cam design :D

(Just kidding Harold,,, I know you are out there somewhere keepin an eye on me,, really great talkin to you yesterday, you need to put me on speed dial so we can do it more often graemlins/waving.gif )

With stock heads I would want about 8-10 degrees more on the exhaust because stock Rat heads are not noted for having the worlds best exhaust ports.

I don't want to get crazy - but I do want to get right(whatever that is ) the first time! Will the hotter cam cause any vacuum trouble , and where do I contact Steve? Thanks again

Originally posted by 70convt396:
I don't want to get crazy - but I do want to get right(whatever that is ) the first time! Will the hotter cam cause any vacuum trouble , and where do I contact Steve? Thanks again =
Steve posts on here quite a bit & you can do a search for Oldani Motorsports ;)

Thanks again wolfplace! I checked out the isky site and put a yell out to UD Harold so hopefully he sees it! Now Oldani!
Merry Christmas to you Sir! smile.gif

Originally posted by 70convt396:
Thanks again wolfplace! I checked out the isky site and put a yell out to UD Harold so hopefully he sees it! Now Oldani!
Merry Christmas to you Sir! smile.gif =
You are welcome & thanks,, & may the big fat dude stop at your house too :D

Email me if you decide on the Isky stuff & I can probably save you a few dollars ;)

Cool can't beat that! :eek: graemlins/thumbsup.gif :D

70convt396,

If you're interested in my new VooDoo cams, you'll like the VooDoo 262. It is 262/268 at the seat, 219/227 at .050, .468/.489 valve lift, and 112 LSA, ground with 108 Int CL. It is part number 60102 from Lunati, and I've got about 50 at hand, although I don't know if they're for Jeg's or Summit, or what.... We are making cams in 50-cam lots right now. The SBCs and SBFs share the same lobes, the BBCs and the BBFs share the same lobes, and the 340C and 440C share the same lobes, which are TCT (True Chrysler Tappet) designs.
If Lunati won't release one yet, they should be at Jeg's and Summit by the middle of January.

UDHarold

Harold can you explain how that would compare to the
Isky 270/280 , 542/565 , 114 Lsa
Or the UD 280/290 221/231 525/550 112Lsa
I would really appreciate a answer that a novice can understand! Thank you !


;)

70convt396,

Wello, first, I must apolgize. I gave the specs for the SBC VooDoo 262, not the BBC. My only excuse must be that I'll be 64 tomorrow, and old age must be already settling in.....
The BBC VooDoo 262 is 262/268 at the seat, 219/227 at .050, .530"/.542" valve lift, and 112 LSA. It has a smaller exhaust than the UD 280/288, but the intake has more high-lift area above .200". We have not dynoed the VooDoo 262 against the UD 280/288, because we aren't competing against the old UD profiles. However the seat durations, and the valve opeining/closing rates, are different. The seat durations are a LOT shorter, because the opening and closing rates are a lot faster. However, the closing rates are still a lot lower than the XE stuff. I drove the car several days without hearing anything other than a nice exhaust note...
To explain how a shorter cam can make as much power or even more is fairly simple.
Start with the exhaust cam----
If 2 cams have the exact same air/gas volume in the cylinder, the one with the shorter seat timing --ie, the one that opens later-- has the longer power stroke, and puts more torque/HP into the engine. The 268 has a much longer power stroke than the 288.
Now for the intake----
The 262 opens its valve much later than the 280 does, and therefore puts less reversion into the intake port. However, even though the 262 is 4° shorter at .050 than the 280, by .200" it is EQUAL in duration, and has more high-lift area, and can put more charge into the cylinder because of this. Less reversion means higher intake port velocities, and increased high-lift area means more time/duration. More time to fill the cylinder and at a higher velocity means a lot more charge in the cylinder.
We also make the VooDoo 262 BBC on a 112 LSA, which tends to make it more streetable, with more vacuum.
The BBC VooDoos should be ready by mid-January.
I cannot comment on the Isky, other than Isky has previously stated that their cams are symmetrical.
Noe of mine have been symmetrical since 1976...

UDHarold

Harold - Thanks so much for taking time for us average Joes!
Thanks and Merry Christmas and Happy Birthday!
I am sorry for asking you to comment on someone elses cam, I was trying to understand the differences between the cams had based on their particulars! What/how does a symmetrical cam differ from a non?

Harold,Merry Christmas and Happy Birthday!

70convt396,

Back in the old days, before there were PCs, cams were designed by calculators, and I don't mean the pocket kind. Numbers had to be entered, and the lever pulled, for each degree of duration, and sometimes 5 or 6 times, depending upon the calculator. It might take a week, or more, to design ONE side of a cam. Therefore, most cams got only one side designed. Besides, airflow benches were just coming into use in the late 60s, and there was not a lot of discussion in the hot rod industry on the effects of airflow on cam design, and vice versa.
Designers designed symmetrical cams(opening and closing sides identical) because everyone thought that was all that was needed.
However, when you start looking at airflow requirements vs dynamic requirements, a different picture emerges.
There are 4 major events in a good cam design, and the order is:
1st---The exhaust valve opens. The longer you can keep it shut, and still develop the proper exhaust gas velocity by BDC, the more torque is put into the crank. If you are going to keep the valve shut to maximize torque production, you have to open the exhaust valve fast in order to have the necessary gas velocity by BDC. If you do not have the right gas velocity, other cylinders must produce torque to PUMP OUT the remaining exhaust gas, which is more than would have been with the right gas velocity. This is called PUMPING LOSS, and is BHP subtracted from what the engine actually produced.
2nd---The intake valve opens. It opens BEFORE TDC, and the piston is going up, approaching TDC, and pumping out the exhaust gases. They have both a volume and pressure in the top of the cylinder. The opening intake valve has a slight vacuum behind it, and the pressure differential-- high exhaust pressure, lower intake pressure-- causes exhaust gas to flow into the intake port. This is called REVERSION, and the amount of reversion determines when the intake port starts flowing clean air and gas into the cyclinder. You want the good air/gas mixture to start flowing as soon as possible.
3rd---The exhaust valve closes. This is the least important of the 4 valve timing events. Its' major effect is at low RPM, where the actual time, in milliseconds, that the valve is open after TDC allows pressure waves in the exhaust to re-pollute the combustion chamber.
4th---The intake valve closes. Many people think this is the most important part, I put it as number 3, with exhaust opening and intake opening being tied for number 1. If you have a good high velocity built up in the intake runner, it will continue to fill the cylinder well after BDC. It is important that you still have charge trying to get into the cylinder when you shut the intake valve.
I design my cams to maximize these events, with different opening and closing rates, and different opening and closing durations. Those who design symmetrical cams say there is no need to design seperate opening and closing rates or durations.
I starting designing unsymmetrical cams when I became Competition Cams' cam designer in January 1977. It was my gift to them, which gave them tremendous growth in the late 70s, because the cam designs just flat worked. Some of my orignal designs are still being sold by them today.....

UDHarold

Harold - it sounds like the brain is still workin' fine!
I hope you had a merry christmas/birthday!
I am very interested in your 262 voodoo.It sounds awesome! Do you need a special strength spring or retainers to help with the quick closing rates perhaps causing more strain? Are the standard stamped steel rockers up to the task? Is there more stress on the valve train or is that not an issue?
Thanks for your lengthy and informative responses. :D
I am actually starting to understand some of this stuff!
Thanks again! graemlins/thumbsup.gif