cam choice?
 

I know the crane 731 and 741 get great press for a Hydr. roller but what about a hydr. flat tappet thats close? anyone.......

Re: cam choice?
 

Dyno,
You can only get so close due to the limitation of the ramp angles on a flat vs a roller. If you are sold on a hyd flat you do have the option of increasing the lifter diameter, but it's hard to justify the expense, or you can have a flat custom ground to your combination.
Bob

Re: cam choice?
 

sounds like I'm going to need to switch to a roller....is it worth the cost?How much more hp can you make with a 741????

Re: cam choice?
 

Dyno,
A rule of thumb is a [email protected]" roller is equal to a [email protected]" flat. Roller should be worth around 7 to 10% increase in power. Cam's don't make power, cams allow power to be made. They are the brain of the engine. The key is that the brain must let the right amount of air and fuel in at the right time to make max power under the curve.

Chris

Re: cam choice?
 

Thanks Chris! I'm leaning twards building some stroker 454's this winter and wondering if the upgrade to a roller cam was worth the cost? Power is the third goal...reliability is everything! cost is second the best power is third....

Re: cam choice?
 

Dyno,
If reliability and performance is your focus, roller lifters are the clear choice and well worth the cost.. There are some new lifters available(are they ready yet?) that Chris has done some R&D on that have passed and exceed some stringent durability testing. They are very nice pieces. They aren't cheap, but they are cheaper than buying them twice.
Bob

Re: cam choice?
 

For Mark 4 engines ? And then if so, do the lifter bores have to be trued and bushed?

Re: cam choice?
 

Mine are gen 5 but have been told that the lifter bores can be a problem....

Re: cam choice?
 

Bob,
Lifters have been shipping. . .new LS1 stuff has really taken off. The lifter will fit Gen 4, 5, and 6 without machine work.

Truing lifter bores is a good deal for a competition racer. Is it worth power. . .yes. BBC are notorious for lifter bores being out a few degrees. This throws of cam timing and can lead to lifter failure in flat tappet applications. Is it a good idea for a boater. . .if you can justify the $500 to $600 to have it done for a gain of around 20 to 30HP then yes do it, but for a pleasure boat I would not.

Dyno, what heads do you have?


Chris

Re: cam choice?
 

merlin ovals...

Re: cam choice?
 

RMBUILDER, I have heard of the GM "taxi-cab" lifters that are hard to get. Do you have any advice on them?

On another note, my machinest has had 3 engines go bad due to a bad batch of comp cams. Anyone hear about?

Re: cam choice?
 

Back in the late 60’s an early 70’s we ran the Trans-Am series. At that time many of the team mechanics would work on both the Can-Am and Indy cars as well as the Trans-Am. Because the T/A cars were production based platforms rather than “pure” racecars they were often referred to as “taxi cabs”. I know that doesn’t answer the question but it did jog my memory. Thanks.
As to any particular company having a run of bad cams, I have not heard of that. I know that with flat tappet applications in particular many of the current failures are lifter related rather than core problems. As critical as break-in, spring pressures, and lifters are in flat applications the cam companies often take the rap for failures that are unrelated to their product.
Bob

Re: cam choice?
 

Dyno,
Then you have good heads. Those would be my choice for a "500" incher or less.
Cam failures are rampent these days in the flat tappet arena. Due to the loss of some lifter MFG, the problem was real bad 2 years ago. It has gotten better but with EPA laws, overseas production, and poor QC, you have to be very careful before you put a flat tappet in. I would highly recommend a run in stand before putting an engine in a boat to "1st time fire it".

Chris

Re: cam choice?
 

Chris we always run on the floor before install...break in the cam and change the oil. The next mills will go on the dyno just for peace of mind...I'm thinking 496 ci, would you use the Crane 741 in it???Whos lifters would you use? I've been told to use Luinati springs and I'll have no issues....

Re: cam choice?
 

Dyno,
Due to polical correctness, e-mail me and I'll give you my opinion:
[email protected]
We mfg so many items for this company and that I can't really post I would use this cam mfg over this cam mfg. Hope you understand.

Chris

Re: cam choice?
 

Dyno,
Due to political correctness, please e-mail me [email protected]
We do so much work for other companies I don't wish to publish my oppinion as to not offend anyone.

Chris