SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: osbo68 on May 31, 2010, 07:52:49 PM
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When I step on the gas the motor will rev up then hesitate for a second then continue to rev up..It's a holley 4150 with stock size jets and powervalve.. Fresh rebuild... bought boat in Vegas and live in ogden, ut.. 4500 ft.. Where am i off in the jetting... Primary??? Secondary??? Powervalve??? Help :screwy: Other than that it runs on a dime.. Plugs are a nice chocolate color...
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Living in Vegas myself, I know that we would always rejet the quads when we would go up to Coral Pink, UT to ride and reverse it when we came back to Vegas.
Its been a while since I have had to do it, just dont remember how many sizes we went over stock. Good thing is there are alot of guys on here who should be able to help give you a starting point.
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What size acc pump is on the back? 50cc's front and rear would probably knock that
right out of it.
It sounds like your plugs show good mixture being chocolate.
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your accelerator pump have too much lash ? no up and down only side to side ...
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I ran in the SS nationals in Odgen in 1970. Couldn't start the motor (427) BBC. One of the Mang boy's came by and handed me some jets, I was running 80 they gave me 60 and ran. Never gave a thought of the sea level change.
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The altitude thing kills me... I'll have to check my pumps for the sizes.. I forgot and she is already covered for the week. :screwy:
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I ran in the SS nationals in Odgen in 1970. Couldn't start the motor (427) BBC. One of the Mang boy's came by and handed me some jets, I was running 80 they gave me 60 and ran. Never gave a thought of the sea level change.
20 numbers is a huge jump :o
I wouldn't hesitate to make a 10 number change to what you have and use that as a starting point.
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So your saying 2 sizes won't do much..
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2 numbers is a fine tuning change, if it won't run you need to be make a big change to get in the range.
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If the plugs porcelain are chocolate color it's a little rich. you read plugs down in the center of the fire ring. Reading the porcelain can be fuzzy because of the additives they put in the fuel.