hey everyone, hope this is the right forum. I'm Rebuilding my engine, 4-bolt main, .040 over, Stroker kit (eagle), and i have a 177 wieand supercharger with a Holly supercharger 750 double pumper. My first rebuild and i'm not sure what kinda cam i should get. Talking to guy from jegs and he gave me these specs Comp Cam - Grind 262, Lift 462/480, RPM 1.6 to 5.9 and Comp Cam - Grind 268, Lift 477/490, RPM 2.6 to 6.2 ...Basicly, This is going into my daily driver, BUT I'm not all that concerned with gas prices (or else i'd be driving a fuel injected vehicle)... I'm just worried about running correctly. I don't want a cam so large she tries to die every time she falls to idle. I just want something to put those damn fords in their place if i felt like i needed too. I'm also running a manual (T-5) tranny. But this guy was talking about using a 'stall converter' or something.... ....so i'm kinda lost... any suggestions would help. Thanks!!!!

OK first off, the stall converter, this is used on automatics only, with automatic trannys u have to get an aftermarket stall converter when u upgrade a motor like a 3000 stall, 3500 stall, 4000stall, etc. Say you have a cam with an rpm range of 3000-6000, when u mash the throttle you want the rpms to jump up into the cam rpm range, so u'd get a 3200-3500 stall converter, when u boot it the automatic tranny will jump to 3200 rpm and u'll be in the rpm range that you want to be. NOW with a manual tranny, u dont need any of that, all u do is a simple downshift and your in buisness much simpler than an auto.

As for cams, his cam choices are ok but i think they are alittle too small for my liking. First let me explain what you want, for a Supercharger you want a cam with a 113-114 lobe separation angle and a split duration (like 224/230, or 230/236) you DONT want a straigh duration like 224/224 or 230/230. Nitorus and blowers like the offset duration so they can get rid of the exahust gases quicker. NOW what the lobe separation angle does is moves your torque curve up, a supercharger produces alot of torque down low so you dont need a cam that will give you low end torque, u let the supercharger do the work.

Now i dont know how much money your dealing with but my recommendation to you would be to get a hydraulic roller camshaft, they are alittle bit more pricey but they have NO maintinance, DONT wear out, and NO break in. U put the cam in, get in the car and punch it! If you wanna keep the price down then get a hydraulic flat tappet, with this cam you will have to break it in which isnt so bad but if u mess up say goodbye to your lobes, i'm not a big fan of flat tappet cams but i have used them adn they do produce power.

OK now onto my recommenation:
I think the jegs guys recommendation is alitte small, maybe it'd be good for a mild 350 but not for a blown stroker, if it were my motor on a budget i'd most likely go with the 12-564-4 from comp cams (grind number nx274h), its a 230/244 duration .487/.501 lift on a 113 lobe sep., its not super aggresive but it'd be a really nice street cam for your setup.

Now if it were my motor i'd get a hydraulic roller camshaft:
something like 12-419-8 (grind number nx288hr) 236/248 duration .520/.540 lift (with 1.5 rockers) i always use 1.6 rockers so if u did your lift would be (.555/.576)



Hope this helps and shines some light on ur search, good luck man!
MJ

Wow, thanks.... you sound like you know more then anyone else i've talked to on the phone.

Allright, that cam you spec'ed, full kit should have all i need for 900.00 or so. ...i MIGHT be able to wing that (i've allready spent 3,500.00 and i'm about tapped out... and i still gotta get some parts for the tranny... but hey, thats what parents are for when your still young.. lmao.. j/j)

This cam, what kinda RPM range are we talking? I can't seem to find full specs on it.

Thanks again man!!!!

What power band are you looking for? What heads are you running? What compression? Exhaust?

SnkSknrZ28’s cams are OK, but I suspect from what you were describing they might be a little on the large side. Usually with a positive displacement blower you don’t really have to worry about lobe separation as much as with a centrifugal but the 113 LSA isn’t excessive anyway, but with decent heads those cams are going to want to rev to almost 7K rpm (well, maybe a little less depending on how big a stroker you’re building), which will require a more serious bottom end AND probably more then the 177 will feed on a well built stroker.

Without more info about your combination, taking a shot in the dark I’d lean towards something like the GMPP 12370846 (222/230/112LSA) the LT4 Hot cam (I’m not that excited about that cam but it should be a reasonable cam that you might find somewhere cheap, 218/228/112), or maybe a comp XE roller custom grind like a 218/230/113…

All of those should have your useful power band topping out in the 6000-6400rpm range with good heads and exhaust.

I wouldn’t stretch your budget to the limit here since it seems like you always need a few more parts once you think you have everything…

With more details and if you really want to go roller or flat tappet we could probably narrow it down more.

i guess the cams i chose may be on teh large side but he said he didnt care about gas milage or nething, ha, i work at Jan-Cen motorsports so commign from a racign background i like bigger cams

Anyhow 83 crossfire may be right, maybe they are alittle on the large side, i'd say go the next one down with a 224/230 duration and split the difference but i still say 113-114 lobe separation, 224/230 is always the PERFECT all around cam anyway u look at it. A roots type blower like the weiand is a torque monster, any roots blower are huge torque down low.. A centrifugal blower like a procharger or vortech are RPM blowers so then maybe a 112 would work ok but personally i wouldnt go under 113 ls, and honestly i think would get a custom grind and get a 114lsa made in the same 224/230 specs. Just my personal experiece about the lobe separation so take it with a grain of salt and do alittle more homework, lots of info and lots to learn out there.

Like 83 crossfire said more info might be a benifit, how much boost are you wanting to run, compression, heads? And good point on watchign the budget, there is always them little things you always forget when doign a build and it adds up very fast

Ok, catch me up here, I think i'm understanding this... but...

224/230 = Intake/Exhuast duration angles
113 LSA = Seperation between centerline intake/exhaust.
Grind# = ????

What kind of lift should i be looking at? I'm not 100% on the size of my heads, but i know there one of the larger CC's. (i'll get part #'s the machine shop guy)

Also, I guess for now, i'm going to go with the Flat tappet hydrolic (like i had) and just upgrade down the road some time.

Thanks guys, you've been a MAJOR help to at least get me on the right foot. I've been googling this crap all day and just seem to be comming up with the same simplton crap (animtions showing what a cam does, not the specifics exactly)

ok ok.. 64cc heads... Cast# 3947041

it looks like Rotating assembly has to be returned. I'm going to be having around 10.9 compression... which with the supercharger is going to be way too much (i'm told)... supposedly for non-racing engines, 8.5 is good. so mabey between that and 9.0... but i dunno)

go 8:0 to 8:5 to 1
compcams#s
xe262h-14/218-224-114
xe268h-14/224-230-114
268ah-14/222-226-114
what size will the motor be

it's a 4-bolt 350. 40 over. Was going to use a stroker crank, but cant.

And thanks!

Those are roller cams, he has a flat tappet block. Try comp part #12-268-4, XE268H. 224/230 .477/.480 114 LSA. Up the lift with 1.6 roller rockers a bit if you can, that cam should be very streetable and make good power.

Use Crane cam #113801 for your supercharged street motor.
The Cam and lifter set pn is 113802

This cam is very street friendly and supercharger friendly.
Yet powerfull . Works very well with the small blowers like the 177.
Works fine with a stock torque converter or a mild stall if you wish.
use a mid 3.XX gear. Over all and nicer cam then the Comp cams mentioned.
CraneCams

The right piston to build a supercharged motor for the street using 64cc heads is Speed pro # L-2441F-30 forged 21cc dished only available in a .030" size. if you must go .040" oversized an alternative is Federal mogul #H620CP40 21cc dished hyper piston. Either will give you a blower friendly 8.37:1 cr with 64cc heads.
Either will work fine on a street blown motor with moderate boost (7psi) on pump gas. Use cooler spark plugs and limit the ignition advance to 28-30deg while onder boost at WOT. (boost timing retard)

If you want to get adventurestic (and build a better motor) go with a mild street solid flat cam. Crane # 113841 is the way to go for a solid blower cam. its a beaut... easy street manors and will out power and out rev any of the hyd cams mentioned.
Yet easy to live with on a daily basis.

http://www.cranecams.com/index.php?s...41&lvl=2&prt=5

Getting proper valve spring seat pressure is critical on a supercharged motor as the blower boost pressure acts against the intake valve as it is trying to seat (close).
Follow Crane cams spring pressure recomendations to the letter. you can even shim the intake valve springs for 10 extra lbs installed seat pressure to ensure adquate seat pressure. Yes , it does make a difference.

This is a little off topic but what would be a good cutoff on the duration of the cam....@ .50 and advertised ....for a supercharged application, and a turbocharged application?.....with some reliability and gas milage as no concern at all.

Pick a supercharger motor cam's duration just like you would a N/A cam. Select the duration based on the rpm range you want to enhance ( torque range) . But select the LSA a little wider on a SC motor than a N/A motor. Extra exhaust duration helps too.

Selecting a good cam grind for a turbo motor is a little (actually a lot) more involved.
Generally, the intake duration is shorter than a N/A motor cam. The LSA and exhaust duration must be carefully choosen based on the turbo's exhaust/intake pressure ratio . As a general statement a typical street turbo cam has exhaust duration that is less than intake duration and LSA is even wider.

Race turbo cams are very "engine design speciific" The timing points used enhance airflow (cylinder filling), turbo response etc , and must be specific to the combination to avoid power robbing induction/ exhaust cross flow during overlap. Air always moves for high pressure to low pressure reguardless of piston movement or direction. Pressure in the exhaust tract and intake tract of a turbo motor is all different than a N/A motor or supercharged motor.
No two turbo motor setups are the same. So it would be misleading to state rules in selecting the "right cam" for a particular motor build.

I don't under stand what you're after as far as a duration "cut off" rule.
But a supercharger cam does not need to be such an extreme profile as to valve rate of lift, as the supercharger "Makes the power" So an "extreme" cam that takes the valvetrain to the limit to get that last bit of power is not nessessary. If you want more power, simply run more boost.
You want a cam with a stable yet powerfull lobe design that will get the job done but, be easy on the valve train. Thats why I like these Crane hyd and solid "Powermax" street cams for blower/NOS applications.

UMMM Can u explain the difference between a roller block and a tappet block? Becuase there is NO such thing.. You can put whatever cam you want in there, hydraulic roller, solid roller, hydraulic flat tappet, they make cams for every application. I have a GenI 4bolt main block '010' that i built my 383 out of and i put a 254/260 .627/.630 lift solid roller cam in it making 550hp on pump gas, this block originally cam with a flat tappet cam, which is the same block that he is using, now why i cant do this??

The later L98, LT1 blocks used hydraulic roller cams from teh factory so thats why you see 87-98 305-350 engines in the cam description, but they do make retro-fit hydraulic roller cams for the good GenI blocks late 60s early 70s SBC.

MJ

He has a flat tappet block, and said he is sticking with flat tappet cam instead of buying a "retro fit" roller cam kit.

I’ll bite, what the hell makes this any better then any of the comp cams selected?

Looks like it has slightly milder lobes and similar timings, it’ll run about the same times and idle slightly rougher, get slightly less mileage…

Not to be a pain about this, but yes, solid cams can be nice if you’re willing to put the maintenance in, but why bother in this range, and if you make it big enough to actually make sense you’ll out rev that little blower anyway.

Boost pressure is the same on either side of the valve as long as the valve is open and once it closes the pressure in the cylinder starts building on the compression stroke and boost pressure on the other side stays the same., you shouldn’t need any more spring with or without it.

Over the years people have made up all sorts of rules for spring pressure to “deal” with boost, like 10 extra lbs, increase it by x for every lb boost… and I don’t think I’ve ever seen any documented improvement over the spring that works correctly in the same application/rpm without boost.

Yep, but there’s a few things to consider… as your LSA gets wider to limit overlap it moves the top of your RPM range up, as does boost in general, so usually you’ll get about the same rpm range as you would in a similar NA setup by picking an intake lobe a step or so smaller then you would for the same rpm range NA.

Extra exhaust duration help if you’re limited in exhaust breathing. It also hurts overall efficiency, mileage… If you size the exhaust ports, headers, exhaust… for the amount of power you’re making under boost you don’t need the extra exhaust duration and you’ll end up more efficient all the way around.

Also, as you increase exhaust duration you usually want to increase LSA to keep overlap roughly the same since if you increase exhaust duration and let it add to the overlap you end up just blowing your exhaust into the intake rather then giving it more time to get out.

Yes, and those later “roller blocks” got bosses in the lifter valleys to bolt down a spider that keeps the roller lifters aligned taller lifter bosses, the front of the bock is machined for a cam retaining plate and it uses a different timing chain sprocket to accommodate that plate. They used a stepped nose cam to match the retaining assembly and don’t need a retrofit kit to run a roller cam.

With an older, non roller block you use the retrofit parts which usually use something like linked lifters that are attached to their partner to prevent them from spinning and usually a button/thrust washer/Torrington bearing assembly to retain the cam (flat tappet cams are ground with their lobes tapered so that when the lifters push against them the force the cam to the back of the block, you can’t do that with a roller cam).

Crane cams advertized numbers are not directly comparable to comps. They are measured differently. If you were to measure a crane at comps .006" seat spec you'd see that they are just as "extreme" But usually more stable designs. Most stock heads especially sbc heads are short on exhaust flow and need the extra duration in a supercharged application to get the exhaust out. The extra duration is added to the opening side of the exhaust event to increase "blowdown" A super charged motor does not need to depend heavily on exhaust overlap scaveging like a N/A motor as the blower dampens the pulsing you'd see in a N/A motor anyways. requires a differnent exhaust event. requires less overlap cause the pressures seen in the exhaust and intake tract at overplap are differnt than N/A. You end up with a cam with more exhaust duration, wider LSA and slightly more advanced intake C/L. These cams fit the bill well.

The lil solid is a great street cam and is very blower friendly. It works. Its not a race cam. it does not need 400lbs spring pressure or a stud girdle.
it needs periotic valve train adjustment but is not a pain to do. if you were to try some of these milder street type solid cams you'd get to apreciate their increased performance over a hyd cam. A hyd cam has to be quiet at idle or its just not a "hyd cam" this limits the design. A solid cam has just a little more lobe rate to it. and is more stable at high rpm. can recover and pass thru mild spring harmonic surge where a hyd will pump up and limit further rpm.

makes for a nice snappy blower motor for the street, yet easy to live with.
The soid cam sound and superior top end is worth the effort. try it. Ultradyne/now part of Lunati's line and Isky and Engle have nice lil street solid cams too. you need to widen your horizons a bit. there is a big difference between a race cam that runs for a few seconds on a dyno or in a race, and a "street type performance cam"