cam advice

[kurt]

getting ready to order a new cam and lifters and thought i would check in with you folks for some friendly advice.454ci w/bassett raceing headers,single carb tunnelram,oval port(nothing fancy).compression is avarageing 127psi.the berk pump held the motor back to 4950rpms wot.i had a lifter collapse on the last outing a month ago.i was thinking a 282 duration .533 inch lift by CRANE would suit set up 8 degrees retarded.pumps comeing off tonight,just a little tweaking but no major mods.what do yah think?

[Jim Brock]

Is this going in the southwind tunnel in the picture, if it is it needs a lot of power to work, put in a (B) empeller add another carb (2) a clay smith 304-8 cam and it will haul ass, any questions give me a call (818)890-1867 Jim Brock

[Frosty_pop]

I asked this same question a while back and didn't get any advice. So I'll ask again. Stock 350 chevy, 750 DP Holley, turning a jacuzzi WJ. What cam would you think would give me more low end. WOT only gives me 4000 rpms.

[HotRod Sprint]

Hey Kurt, not trying to take away anything Jim Brock said, but if you haven't already, I would recommend taking this question over to the Gear Heads forum. There is a lot of great info over there, and someone if not several people will have already done what you're about to. Also, nice looking boat in the avatar.
Rod

[TopCat]

this quetion is like ass#$%^s everyone has one/ my advise is to go with less duration(around .272 or .276) and more lift(.580 or so) and if it is for the southwind they REALLY dont worrk well without lots of HP

[BrendellaJet]

Originally posted by HotRod Sprint
Hey Kurt, not trying to take away anything Jim Brock said, but if you haven't already, I would recommend taking this question over to the Gear Heads forum. There is a lot of great info over there, and someone if not several people will have already done what you're about to. Also, nice looking boat in the avatar.
Rod
Yeah, but Im pretty sure Jim is familiar with that hull-Id listen to what he says and not think twice about it.

[Duke]

Originally posted by BrendellaJet
Yeah, but Im pretty sure Jim is familiar with that hull-Id listen to what he says and not think twice about it.
amen, but its better to check twice and cut once..

[screamdreambrad]

listen to jim. lots of duration, lots of lift and a 112 lobe sep. for a jet buddy! brad

[bp]

Originally posted by screamdreambrad
listen to jim. lots of duration, lots of lift and a 112 lobe sep. for a jet buddy! brad
what's "lots"? i'm always interested in hearing about how to make a southwind run fast, n/a on pump gas :D
btw, that's an awesome looking hull in the avatar....

[Jet City]

Originally posted by Frosty_pop
I asked this same question a while back and didn't get any advice. So I'll ask again. Stock 350 chevy, 750 DP Holley, turning a jacuzzi WJ. What cam would you think would give me more low end. WOT only gives me 4000 rpms.
I just put together a mild 383 SBC that I wanted to make big torque and pull hard to around 5200, I ended up going with Cranes H272 cam (flat hydraulic), if I remember right it was around 218/228 @.050 on a 112 LSA, Comps XM262 is very similar, but the H272 seamed a tad better on DD2000. Not sure what CR you have, but these sticks will work well for the typical 9-9.5 CR SBC. The 383 with 9.3 CR, Pro Topline 200cc heads, Stealth intake, and headers shows 397 hp @ 5500, 425 ft lbs @ 4000 rpms, the 350 cube will probably reduce the peak torque number by 6% or so. BTW, if you give more info (heads, intake, impellor cut, CR and goals) you will get a better answer.
Kurt, I would also be inclined to follow Duane's recomendations, the only thing that concearns me is your ultra low compression, 127 psi? What does that work out to, 7:1 CR, why so low, did you have future plans for a blower? Nice looking Dragster you have there.

[Jet City]

Originally posted by bp
what's "lots"? i'm always interested in hearing about how to make a southwind run fast, n/a on pump gas :D
btw, that's an awesome looking hull in the avatar....
Lots is kinda like a "3/4 race" cam:D

[kurt]

first off im not sure where the pic came from next to my post.even though its a cool looking ride it aint mine.i have a 78 dimarco semi v.no blower for me with my hull.this thing dont need to go over 80mph for sure.im just going to putt in the river racer class this year and build a picklefork tunnel to get serious with.i do appreciate the advice though.im trying to not have to get into my valve springs with this new cam.(saveing money for the 110mph class).so i was thinking small so i dont have to change them.ill find a pic of my boat and edit my profile maybe that will help with the suggestions.thanks again folks.............

[Fiat48]

Originally posted by kurt
getting ready to order a new cam and lifters and thought i would check in with you folks for some friendly advice.454ci w/bassett raceing headers,single carb tunnelram,oval port(nothing fancy).compression is avarageing 127psi.the berk pump held the motor back to 4950rpms wot.i had a lifter collapse on the last outing a month ago.i was thinking a 282 duration .533 inch lift by CRANE would suit set up 8 degrees retarded.pumps comeing off tonight,just a little tweaking but no major mods.what do yah think?
Cranking compression is not a direct indication of your compression ratio. Camshaft overlap,camshaft phasing, valve lash,how fast your starter cranks and how accurate the compression gauge are some of the variables.
Phasing a camshaft 8 degrees from where it was designed is not a good move. You'll find that overall performance falls off.
I suggest a call to some of the cam grinders and tell them what you want to do. Compare with what several recommend and you'll find some answers to making a good choice.

[Jet City]

Originally posted by Fiat48
Cranking compression is not a direct indication of your compression ratio. Camshaft overlap,camshaft phasing, valve lash,how fast your starter cranks and how accurate the compression gauge are some of the variables.
Phasing a camshaft 8 degrees from where it was designed is not a good move. You'll find that overall performance falls off.
I suggest a call to some of the cam grinders and tell them what you want to do. Compare with what several recommend and you'll find some answers to making a good choice.
Agreed, you are refering to static CR VS. dynamic CR, but the 127 psi cranking indicates the DCR is low, and since he did not state the particulars about the current cam, cam phasing, etc. it kinda raised a flag for me, especially since he wants more cam than he currently has, which could further deplete his already low DCR in my estimation. While I'm not a big fan of running cams to far from their intended intake CL (more or less means you bought the wrong stick), Timminator has proved to me that it can be effective, he runs a 245 @ .05 stick in an 8:1 (static CR) engine (don't remember on what ICL), and makes really good power. I'm sure most cam mfgr's would recomend no more than 220-225 @ .05 for a 8:1 engine (if installed with the intended ICL). I'm certainly no cam guru, just sharing some thoughts.

[screamdreambrad]

Originally posted by bp
what's "lots"? i'm always interested in hearing about how to make a southwind run fast, n/a on pump gas :D
btw, that's an awesome looking hull in the avatar.... bp you got more (pump gas ) motor than i do. but i have a 284/295,748/725 112 nearly 13:1. sub par edlebrock heads are the killer on my combo. maybe someday i'll be able to get a pair of afr's! :) brad

[Fiat48]

Originally posted by screamdreambrad
bp you got more (pump gas ) motor than i do. but i have a 284/295,748/725 112 nearly 13:1. sub par edlebrock heads are the killer on my combo. maybe someday i'll be able to get a pair of afr's! :) brad
I'd like to ask what is your maximum RPM?

[screamdreambrad]

Originally posted by Fiat48
I'd like to ask what is your maximum RPM? i just cut the impeller, went to elsinore this morning, damn it was cold this morning! it ran 6500. motor made peak power at7000 on the dyno at westech. brad

[Fiat48]

Do you think that your wide lobe seperation of 112 is correct for that RPM range? Is the 284/295 cam specs @.050?

[screamdreambrad]

Originally posted by Fiat48
Do you think that your wide lobe seperation of 112 is correct for that RPM range? Is the 284/295 cam specs @.050? yes it's at .050, comp, and my engine builder like the wide angle for a jet. i was thinkin more like 106, but; that's what i got. i think dne uses a wide angle on his motors as well. bp can ya tell us, or would you have to kill us afterwards? i think the smaller angle works better in a flat and in a car, but not as good in a jet. brad

[screamdreambrad]

fiat, where do you race your flat? sparks is a long haul to anywhere usa. red bluff your closest? or chowchilla? probably a toss up huh?

[Fiat48]

Originally posted by screamdreambrad
fiat, where do you race your flat? sparks is a long haul to anywhere usa. red bluff your closest? or chowchilla? probably a toss up huh?
Just curious with the line of thinking on the camshaft. Thanks for the Info! Chowchilla is 275 miles, Red Bluff is 200. That's the closest. Flat has only been to 2 races since Blown Alcohol. Chowchilla and Dexter Reservour. Flat wasn't handling well but may be solved now. Hopefully will be back out on 2004. Just a bracket boat.
Your camshaft actually larger than my blown alcohol stuff except I run 114 L/S because of blown alcohol.

[screamdreambrad]

fiat hope to see ya in ihba next year. i'm only going to wrench on friends boat at njba next year. brad

[Fiat48]

NJBA and CDBA are the best places for me. I'm not a fan of IHBA. Should you ever get the chance, run with CDBA. Best group of guys you'll ever meet. Worth the tow.

[TIMINATOR]

IMO the lower the static compression is, the tighter the lobe separation should be for a mid RPM (4500-5200rpm) jet motor. On several occasions we have replaced 112-114 deg lobe separation cams with 106-110 lobe seps and have gone faster every time, (this is on pump-gas friendly 8-9.5 compression and A or AA impeller stuff). Think trapped compression, an earlier intake closing with a tight lobe separation allows a larger duration for more power."Circumstances alter cases",the more info we have the better the advice will be. P.S my cam is 278/282 at.050,with .714/.680 lift (roller),9.5 compression,AA impeller at 5800 RPM, on REGULAR PUMP GAS. Oh yea, also ONE CARBURATOR, and thru the transom exhaust. The locals don't like it. TIMINATOR :D

[Fiat48]

Just some food for thought. Below are screens (I know they are poor) of camshaft design for a typical BBC 470" with decent iron heads and 9.6 to 1 compression. Lobe seperation is found by adding Intake LC and exhaust LC and splitting it (divide by 2). 1st 2 screens are 6500 design. 2nd 2 are 7000 design. Pay no attention to deck height/rod length. Since there are a lot of these type engines in Jets, I thought it might help your desision making process. Enjoy.
6500
http://www.***boat.com/image_center/data/500/37465001-med.JPG
http://www.***boat.com/image_center/data/500/37465002-med.JPG
http://www.***boat.com/image_center/data/500/37465003-med.JPG
7000
http://www.***boat.com/image_center/data/500/37470001-med.JPG
http://www.***boat.com/image_center/data/500/37470002-med.JPG
http://www.***boat.com/image_center/data/500/37470003-med.JPG

[TIMINATOR]

Whoever P.M.d me please resend,I lost it before I could read it! TIMINATOR