Cam Timing?????

[DansBlown73Nordic]

Ok I bought this Cam thats from Herbert. The guy says the cam makes power from 3,000 to 7,500 rpm,s. He said I should retard the timing 4 deg. to change the power curve so that it makes power at about 2,000 to 6,000. Can anybody tell me if that sounds correct? Or should I just time it straight up?
Cam is 575 i.n. 600 E.x. 110 Lobe center Duration is 300 intake and 310 exhaust. @ 50 245 and 255.
Motor is a 454 with a B&M 250 blower and O/T Bassett headers. Square port heads. 7.5 to 1 compression...... :confused:

[Fiat48]

I think you got it backwards. Advancing the camshaft gives you low end and retarding moves the power curve up. Generally I put the cam straight up unless I know certain characteristics about the grind. But I would not put that camshaft in retarted 4 degrees for your application.

[DansBlown73Nordic]

I screwed up. It should be 4 advanced......:wink:

[BGMAN203]

I would run it straight up first, then see what it does.

[Moneypitt]

Be sure to check piston to valve clearance. SOME cams are actually ground 2-3 degrees up to compensate for chain strech. Are you using a 3 way lower sprocket, or a gear drive, and you ARE degreeing it, not just bumping with the lower sprocket, right??

[SJ Valley Dave]

Love that Cloyes hex adjust. You can degree cams in very accurate and is a very reliable chain. Doesn't cost the hp that a gear drive does

[cstraub]

On a 110, thats not a blower cam. I think you just got sold what was extra on the shelf. Blower cams are 112 to 116 Lobe sep with NO ADVANCE WHAT SO EVER!!!!!!!!
Chris

[Foggerjet]

I agree with chris, a blower motor "wants" a wider spread than 110. I think that a 114 would be much better. with 110 you will have too much overlap, a no-no with a pressurized intake. I'm no expert but this is pretty much the norm with blowers. Someone who builds lots of blower motors might elaborate more on this. But I would not put that in if it was mine. It's your stuff and do what you want but I see a cam change in the near future. just .02
fog

[LeE ss13]

What he said !!!!

[DansBlown73Nordic]

GREAT!!!!!!!!!!!!!!!!!!!!!!!:mad:

[waterslinger]

+ or - $ deg will not move the power 1000 RPM's 500 at best.

[cstraub]

With that Lobe sep, the intake valve is opening sooner. . .and the piston is still coming up on the exhaust stroke. By opening the valve early, the fresh charge is fighting the piston coming up the exhaust stroke.. So you get a scenerio that makes the boat very ineffiecent. You need a cam straight up no advance on a 112 or 114. Trust me, I have done custom camshafts, one off engine combo specific, I would not steer you wrong.
Chris

[Snowboat]

I'm waiting for Fiat, and George of Claysmith cams, to step in with their gas blower cam reccommendations. Here is the one Fiat had me use. Roller, 775 intake 723 exhaust. 110' lobe sep, straight up. 35 and 69 intakes and 79 amd 33 exhausts. Set the lash tight. I believe the wider lobe sep is primarily for alcohol. But, I admit that I have only used two different blower roller cams to date. George suggested a 110' also.

[Schiada76]

Originally posted by Snowboat
I'm waiting for Fiat, and George of Claysmith cams, to step in with their gas blower cam reccommendations. Here is the one Fiat had me use. Roller, 775 intake 723 exhaust. 110' lobe sep, straight up. 35 and 69 intakes and 79 amd 33 exhausts. Set the lash tight. I believe the wider lobe sep is primarily for alcohol. But, I admit that I have only used two different blower roller cams to date. George suggested a 110' also.
George is the MAN! Mines 110 also.:D

[Fiat48]

This started out on phasing a camshaft and changed to camshaft application.
Snowboat, you have a PM from me on your camshaft. I won't get into that here. Secret stuff. :)
cstraub69 "You need a cam straight up no advance on a 112 or 114. Trust me, I have done custom camshafts, one off engine combo specific, I would not steer you wrong."
He's right.
As far as cam recommendation for Dan, the cam you have (Flat Tappet?) looks small..but then it appears to me you want power from 2000 to 6000..a small blower and Ot exhaust with probably basic stock heads. And since everything I do is 5000 rpm out of the gate and up...and I don't know your boat...hard for me to call out a cam spec. And all I do is roller cams which have a whole different characteristics than flat tappets.

[bigkatboat]

The 110 centers kill low end and a 'fast' flatbottom does not need 'monster power' under 2500RPMS. Straight up, that cam will start holding cylinder pressure at around 2800/3000 RPMS. ADVANCED 2/4 degrees will pull the power band down (aprox) 250/500RPMS. The 112/114 centers are for heavy/outdrive, lower RPM applications, that need 'pull' right off of idle. That 110 cam will make the POWER and really run from 4500 to 7000 RPMS. It really should have bigger carbs and a bigger blower. Many BGF boats running today, run Ultradyne Cams, and some run 108 centers. They also run a 'pinched' exhaust timing (something about holding heat), which I think is dangerous. Every Howards Cam (for blower) I have ever seen, had always run better (dyno and track) advanced. If you have the correct spring pressure, run the cam 2 degrees advanced and it will 'settle' at almost ZERO after a few 'laps'. Besure you are making boost at 2500 RPMS, WOT.

[Snowboat]

Two of the big guns have spoken---------------next????

[bigkatboat]

The motor and RPM range are 'small', vs. race 'junk', but the "blower" is the real problem. It will turn so fast that the two lobe rotors will almost "glow". Please buy a 'real' blower, like a 1071 for that motor. A 1071 will not need an intercooler if run under 8 LBS, 'cause you will only run about a 1/4 mile WOT. The 'mechanical heat' is the problem, we all know that pressure (boost) = heat, but those "wannabe" blowers (work too hard) run way too hot.

[396_Z]

Originally posted by bigkatboat
...Many BGF boats running today, run Ultradyne Cams, ...
...Every Howards Cam ....
Just to update you in the world of cam manufacturers. Ultradyne is out of buisness, and his name is Harold. He now works for Lunati. If your going to talk like you know him get your facts right.

[bigkatboat]

Just to get YOUR FACTS straight! Howards Cams is a brand name. Companies go in and out of business, and some people don't blow-up their motors every time out, so they still use the same cam. (the cam might be 5/10 years old) I gave examples because I have used/ or rebuilt, race motors with those name brand cams and specs. I'm just trying to give FACTUAL infomation, and not unproven "backyard BS". You can do whatever you like, but what it really takes to build a 'blower motor' that will last , and the 'trick BS' are not the same thing.

[bigkatboat]

P.S. I NEVER said I know anyone! I do know how to build winning and long lasting blower motors. Also, I DO NOT USE Ultradyne Cams, never did. You can rest easy now that you have got me up to speed on a subject that I have no interest in. The lobe center question and the 'cam timing' answers stay the same!

[Rexone]

before it even starts, this is a tech thread gentlemen. focus.

[DansBlown73Nordic]

Ut oh here we go.......:rolleyes:

[396_Z]

I wasn't even going to go there Mike. Just because someone get their panties in a wad doesn't mean that I feel the need to wad them up more.

[bigkatboat]

Mike! Did I not make "tech" answers? I am only speaking from the 'limited' knowledge I have. Mr. 396 Z, commented on something that he 'did not fully understand '. I do stand by my tech answers, and realize that some others here have not been where I have been. I also know that I have not been under the 'shade tree' that they have been. Someone here, please telephone a business that has a dyno, if they have done V-drive boat motors (all the better), and ask if my answers are wrong. Call Kenny Duttweiler, and ask if I'm wrong! Call Larry O'Friea, at Valley Head Service. Prove me wrong, I've had private E-mails on three boards to the contrary, I'm not looking for a fight. I'm looking for the TRUTH, just like those who ask the questions!

[Rexone]

Its not a problem bkb, I just saw the potential for escalation there and we're not having a jet boat forum type atmosphere develop in Gear Heads. I want tech info here not arguing and name calling (not that that had occurred "yet"). All is good carry on.