SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: fixxzilla on April 23, 2008, 10:04:43 AM
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hi guys love the site i think ill stay lol im bulding a 460 scj with ar scj alum heads stainles valves stuk with stok compression on the pistons its getting an isky duek intake (not a high rise) i need some roler cam sugestions for it if you need valve sises i can mesure them i basicly want a realy cool sounding idle and good crusin hp for pulling skiers id like to go with duel 800 hollys and jet them down but im not a carb guy i just heard it was a good idea for the airflow thanks for any imput ;D
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please clarify what heads you have, ar, to me means allen root
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ar means air research from my information i think its a brand name though like blue thunder
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Sounds like you're going to be sticking on alot of flow, on a motor without much compression and a dual plane
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ar means air research from my information i think its a brand name though like blue thunder
not to be as ass, but, if you dont know what you have its hard for me/us to help you
do you have flow #s for the heads, how many cc's are the combustion chambers. all info you will need to know when picking the correct cam
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hi guys love the site i think ill stay lol im bulding a 460 scj with ar scj alum heads stainles valves stuk with stok compression on the pistons its getting an isky duek intake (not a high rise) i need some roler cam sugestions for it if you need valve sises i can mesure them i basicly want a realy cool sounding idle and good crusin hp for pulling skiers id like to go with duel 800 hollys and jet them down but im not a carb guy i just heard it was a good idea for the airflow thanks for any imput ;D
Dual 800's? Too much. Isky does make a dual carb dual plane, so if that is what you want to run, you need to get a couple of 390's, 450's (mech) , or the 600 vac secondary models. If you are running a single carb on a dual plane, then anywhere from 650-900 is fine.
Compression works with the cam, if you are running stock compression, which I will assume is around 9:1 then you need to keep the duration @ .050 to 225-235. Higher the lift in that duration range, the more power it will make. The more duration, the more compression you need.
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I have not been able to locate any information on any Isky manifolds.
I have a low/mid rise Offy dual quad intake on the Hondo that I'm playing with. I'm running two 600 vacuum secondary carbs on a mild 454, with stock jetting it runs very rich. I jetted it down a lot before my last time out and now have a mid-range stumble that I need to correct for.
Two 800 carbs (even vacuum) would be way to much for most engines you'll find on the water. Unless this is a very limited use race boat there is no reason to even try to run so much carburation.
not to be as ass, but, if you dont know what you have its hard for me/us to help you
do you have flow #s for the heads, how many cc's are the combustion chambers. all info you will need to know when picking the correct cam
There is some very smart people on this site that are willing to help when possible but as Ralph noted, we need more information to be able to give real information.
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I have not been able to locate any information on any Isky manifolds.
I have a low/mid rise Offy dual quad intake on the Hondo that I'm playing with. I'm running two 600 vacuum secondary carbs on a mild 454, with stock jetting it runs very rich. I jetted it down a lot before my last time out and now have a mid-range stumble that I need to correct for.
Two 800 carbs (even vacuum) would be way to much for most engines you'll find on the water. Unless this is a very limited use race boat there is no reason to even try to run so much carburation.
There is some very smart people on this site that are willing to help when possible but as Ralph noted, we need more information to be able to give real information.
On my pops boat, it's a Hondo as well with a mild BBC ;). We went from dual 650's to dual 450 DP's, gained ALOT of throttle response, didn't have a GPS so not sure if it gained mph. But you can definetely feel the crisper throttle. 900Cfm of carb can take a motor a pretty decent way ;D
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i posted another post instead of hittin the reply button lol :banghead:http://www.socaljetboats.com/index.php?topic=3568.0 im definatly aperitiative to read all the info and expirience on here i wish id gone into machining instead of remodeling lol :screwy:
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hi guys love the site i think ill stay lol im bulding a 460 scj with ar scj alum heads stainles valves stuk with stok compression on the pistons its getting an isky duek intake (not a high rise) i need some roler cam sugestions for it if you need valve sises i can mesure them i basicly want a realy cool sounding idle and good crusin hp for pulling skiers id like to go with duel 800 hollys and jet them down but im not a carb guy i just heard it was a good idea for the airflow thanks for any imput ;D
You will certainly have a "really cool souding idle and good cruising hp," but the combo you are assembling will be a dog of an engine and have a high dollar-to-horsepower ratio.
Where you go from here depends on a LOT of things, inclduding the boat, the pump, the changes to the engine combo that you might be willing to make. Frankly, for pulling skiers and having good cruising power, you most certainly do not need aluminum heads, two carbs, and a roller cam. Fact is you can make a much better, much more suitable, much more reliable, much better matched combo (read: more power) than the build you are envisoning.
LO
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please clarify what heads you have, ar, to me means allen root
Ralph, he means the new AFR head.
LO
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ok im goin with the 550s thanks for that input i definatly want the throtlle responce i also read that if i go 10.1 id do better the isky intake only has about a 3 inch rise to it i did that to keep it low in the boat i have a 21 ft daycruser 76 tahiti with rebuilt stok berkley jet and full rear trim tabs semi v hull if i can get of this dial up ill post some pics :banghead: