Dart vs AFR heads on HP 500
08-21-2006, 02:42 PM
#41
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Re: Dart vs AFR heads on HP 500
Originally Posted by KAAMA
I cannot recall the the Crane 731 cam specs, but it might have too long of a intake/exhaust duration split for it to work well with the AFR heads. The head/cam combination have to work together for the engine to produce good results. I'm not saying a 731 cam wont still work, but you might as well retain the stock cast iron GM heads you now have and have some pocket port/bowl work done to them if you are going to keep that cam. With too much of an I/E split on the cam you'd still see some power increases with the AFR's, but without a properly selected cam you will be holding back their potential by not letting them do their job correctly.
Also, anything new would be good idea, although you can probably re-use the rocker arms you now have---just inspect them, but you may need a different length rocker arm stud for the AFR heads. I would highly suggest new springs, retainers, lifters, and pushrods. RMbuilder would be excellent to consult for your cam/valve train and will work with you & your engine builder.
Just make sure that whoever is doing the work does the job RIGHT and KNOWS what the heck he is doing...not by his sweet talking words---but by someone who has a lot of experience and a good reputation because there is a lot of $$$ involved and there won't be much room for error.
Also, anything new would be good idea, although you can probably re-use the rocker arms you now have---just inspect them, but you may need a different length rocker arm stud for the AFR heads. I would highly suggest new springs, retainers, lifters, and pushrods. RMbuilder would be excellent to consult for your cam/valve train and will work with you & your engine builder.
Just make sure that whoever is doing the work does the job RIGHT and KNOWS what the heck he is doing...not by his sweet talking words---but by someone who has a lot of experience and a good reputation because there is a lot of $$$ involved and there won't be much room for error.
08-21-2006, 03:22 PM
#42
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Re: Dart vs AFR heads on HP 500
Originally Posted by CONDOR24
...thanks for all your advise,what kind of realistic power difference is there between porting/milling my iron heads and switching to aluminum ones if i choose to keep this cam? whats the best cost effective approach?
I can tell you this....if you currently have the GM rectangle port heads you should be aware that they are prone to cracking inbetween the seats! So, why invest big money in porting the heads when they may end up cracking and have to throw away? Perhaps RMbuilder/Bob can help you with your choices based on how much you're willing to spend. He's very easy to talk to and very honest, and professional. The name of his company is called Marine Kinetics...(585) 654-8583.
08-21-2006, 06:01 PM
#43
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Re: Dart vs AFR heads on HP 500
basing your purchase on flow numbers is useless. Port length, cross section and many other variables is where you need to spend your time looking. I have yet to see a flow bench or a dyno with a prop on it and in the water. I could show you some antique iron heads that flow 330cfm at .600 that are from a small block ford engine, problem is they get very turbulent at around .500, but hey that 330cfm flow figure sure looks great.
08-22-2006, 01:22 PM
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Re: Dart vs AFR heads on HP 500
Kaama I see you are also from michigan, I have contacted Bob and he is cuurently working up an estimate and parts needed to do my upgrade with the AFR 315's and i was wondering if you can guide me to a reputable boat mechanic that can do the upgrape on my motors, as i ssume i will need to pull the motors to do the cams.
08-22-2006, 05:12 PM
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Re: Dart vs AFR heads on HP 500
Originally Posted by laszlo01
Kaama I see you are also from michigan, I have contacted Bob and he is cuurently working up an estimate and parts needed to do my upgrade with the AFR 315's and i was wondering if you can guide me to a reputable boat mechanic that can do the upgrape on my motors, as i ssume i will need to pull the motors to do the cams.
I don't know how soon Dave Wesseldyk would be able to get to you as he is trying to get two Skater's and a Hustler out the door, BUT there is a precision machine shop just down the street from him named Performance Engineering that has a very good reputation when it comes to marine hi-perf engines. The guy (Bill) who assembles the engines has been there for about 15 years and was trained by Dave Wesseldyk when Dave used to work there. They currently do all or most of Dave's block & head machine work there---so they know there stuff and are familiar with the clearances/tolerances it takes for a marine engine to survive.
Bob Madara has worked with a customer who took his supercharged engines there last fall for a rebuild and provided cams for his project as Performance Engineering built the engines. They have a nice labor/price sheet (plus directions, phone number, etc) on their website so you know how much it will cost for a specific machining operation, assembly, etc. They're usually pretty slow this time of year...so, I am sure they can probably get to you pretty quickly if you want.
Here's their website: www.Pereng.com
08-22-2006, 05:54 PM
#46
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Re: Dart vs AFR heads on HP 500
Originally Posted by KAAMA
(plus directions, phone number, etc) on their website
08-22-2006, 06:01 PM
#47
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Re: Dart vs AFR heads on HP 500
Originally Posted by woody1
basing your purchase on flow numbers is useless. Port length, cross section and many other variables is where you need to spend your time looking. I have yet to see a flow bench or a dyno with a prop on it and in the water.
This is where your Profeesional head porters come into play. They can give you more information then your brain can digest for a while.
The AFR heads are very modern and top of the line for 'out of the box' stuff. Just keep the sizes in check - again talking to a Pro head porter, AFR themselves, or a WD/retailer that knows/breathes/lives what they are doing.
Speaking of cross section - I, for one, cannot wait until the AFR Oval port and Oval Port CNC heads come out and people start to use them on our normal 454-509 (or so)cid marine motors. Hopefully soon, real soon. Let's cross our fingers.
Drool, drool.
08-22-2006, 07:30 PM
#48
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Re: Dart vs AFR heads on HP 500
Sorry to keep replying (in a row) but I truly love this medium pocket $$$ stuff. It is what get's me up in the morning.
These don't get advertised much so I like to mention them.
http://www.bmfracing.com/bbc_flow_310.htm
Yes, flow #'s are big. Okay, huge. No, we shouldn't think this is marketing and the heads are being sold off of flow #'s only. These heads have huge air speed (velocity) thru a relatively small port and make killer + responsive power. Then again, this is Carl Foltz we are talking about, so we know it's good stuff.
These don't get advertised much so I like to mention them.
http://www.bmfracing.com/bbc_flow_310.htm
Yes, flow #'s are big. Okay, huge. No, we shouldn't think this is marketing and the heads are being sold off of flow #'s only. These heads have huge air speed (velocity) thru a relatively small port and make killer + responsive power. Then again, this is Carl Foltz we are talking about, so we know it's good stuff.
08-22-2006, 10:06 PM
#49
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Re: Dart vs AFR heads on HP 500
Originally Posted by woody1
basing your purchase on flow numbers is useless. Port length, cross section and many other variables is where you need to spend your time looking. I have yet to see a flow bench or a dyno with a prop on it and in the water.
Also, I DID mention the experience I had a few weeks ago in my first post...Post #3 on Page #1 about running into a friend of mine with the same boat/hull/length. Now, weather his 556cid engines actually made the 810hp on the dyno sheets I saw is/could be speculation. Do they really make 810hp??? Are they tired and in need of new rings, etc??? Would different props work better for him (he's already tried several)? I can't truly answer these questions accurately....BUT I guess I just didn't expected him to "spank" me.....truthfully, I expected him to RIP MY LUNGS OUT!!!
Hey....it's just a hobby and I am just a weekend warrior with my boat....so, I guess I should be at least pleased with my set-up and my "tiny AFR 315's that are way too small for my 565cid inchers that don't/won't make any power"......and that would also include the little cams I have in them.
Anyway, I still think you brought up a valid point.
08-22-2006, 10:14 PM
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Re: Dart vs AFR heads on HP 500
Not directed at anyone in particular, people just get caught up in flow numbers really easily. I cant comment on your buddy and your boats as Im a total hack when it comes to marine, we run 600-800 inch IHRA pro stock motors and dabble heavily in small block ford racing. I just see numbers get thrown around far too often. Come and play with some ford hemi head cylinder numbers from an 815 inch kaase motor, then I get excited Both the dart and afr head have been proven to be great quality, on the flipside, couple them with the wrong cam and valvetrain and they will end up looking like dogs. Lot more to it then heads. Carry on
Both the dart and afr head have been proven to be great quality, on the flipside, couple them with the wrong cam and valvetrain and they will end up looking like dogs. Lot more to it then heads. Carry on
