no rpms

[jrau]

just got motor put together. went to lake it runs same as before. 455 olds, 10.1 compression, balanced. heads are k's but were warmed over by a reputable shop. pocket work, exhaust polished. edelbreck performer intake also worked by shop. cam is 474 lift, and 224@ 50 duration. carb is supposed to be the big rochester. this motor will not spin past 4000. It shoots the boat straight out of the water and imediatly my tach shoots to 4000. It sounds like its going to suck the carb through the intake. could a carb hold my rpms back that much. speed at 4000 is 57 gps

[Hotcrusader76]

jrau:
just got motor put together. went to lake it runs same as before. 455 olds, 10.1 compression, balanced. heads are k's but were warmed over by a reputable shop. pocket work, exhaust polished. edelbreck performer intake also worked by shop. cam is 474 lift, and 224@ 50 duration. carb is supposed to be the big rochester. this motor will not spin past 4000. It shoots the boat straight out of the water and imediatly my tach shoots to 4000. It sounds like its going to suck the carb through the intake. could a carb hold my rpms back that much. speed at 4000 is 57 gpsYes the carburetor is your limit on fuel metering. Your motor has changed the vacuum signal that is necessary to drawl fuel from that set-up. Sounds like you need to up-grade to something more respectable.
-Ty

[Liberator TJ1984]

Have a someone check to see if your getting full throttle at the carb when you mash the pedal down....what is the rpm range of the cam you got ??? don't know much about Olds power ..but lift seems small ???

[jrau]

what would someone suggest. motor is enclosed in boat. I run 2 blower fans sucking out of caompartment. could i run a auto carb? my fans come on below 2500 rpms

[Liberator TJ1984]

I think there is a law that you have to get a marine type carb.??? they have the "J" tubes for fuel flooding and sealed shafts .....try to find Boatcop on the boards and ask him...here in Tx. I have never been checked ....but there???

[jrau]

just lazy game wardens who know less than i do. if marine style is really that much more safe that would be better. any suggestions on what cfm, or brand? carb is opening up. cam sould run to 5500, springs should also had to go bigger valves and keep lift down for valvetrain geometry.
[ August 13, 2002, 02:46 PM: Message edited by: jrau ]

[Liberator TJ1984]

Marine carbs. are more $$$ but if there is a law there ..better safe than sorry..the extra $$$ will probably be spent on a fine if caught not using one..I've always had good luck with Holley 750 / 850s Double pumpers..Demon makes some fine carbs. too

[blowngas]

jrau:
just got motor put together. went to lake it runs same as before. 455 olds, 10.1 compression, balanced. heads are k's but were warmed over by a reputable shop. pocket work, exhaust polished. edelbreck performer intake also worked by shop. cam is 474 lift, and 224@ 50 duration. carb is supposed to be the big rochester. this motor will not spin past 4000. It shoots the boat straight out of the water and imediatly my tach shoots to 4000. It sounds like its going to suck the carb through the intake. could a carb hold my rpms back that much. speed at 4000 is 57 gpsthe old rochester (quad ra suck) always seemed to make more noise than other carbs---check the timing and make sure that its fully advance by around 3000 rpm---the other thing to look for is if the pump may have a double a impellar and is just more pump than the olds can pull---don't get carried away and put in a impellar that will allow the olds to rev to 65-6800---they are not a high sustained rpm engine---find someone who has a similar setup and see what he did to improve his performance---take it one step at a time, have fun and be safe

[blowngas]

[QUOTE]Originally posted by jrau:
cam is 474 lift, and 224@ 50 duration.
reread the post and got to thinking about the cam--if those are the specs, you have pretty much a stock type cam-- with the olds valve train as is, you might be able to go to a larger ratio rocker arms and adjustable push rods and get more performance with what you have with out pulling the motor down since just freshened---please check with someone who knows the limits of the olds valve train---this can usually be done on bbc with no problems---$.02 worth--good luck

[jrau]

motor is coming out tonight. the shop that did my heads think its the smaller carb. numbers are too worn to read. they want to put it on dyno in morning. motor idles with a lope. machinist thinks motor should have 550-575 lbs. torque and around 450-475 hp. he thinks a 800 dp is in order. will try it on the dyno since he has one before i buy a marine version. his numbers are referenced on the olds w-30 engine specs.
[ August 13, 2002, 03:59 PM: Message edited by: jrau ]

[blowngas]

jrau
will try it on the dyno since he has one before i buy a marine version. his numbers are referenced on the olds w-30 engine specs.[/QB]Now thats the right way to set a motor up---dyno's will let u see what's going on and where the problem can be---compare your cam specs against an aftermarket grind for a boat---pretty much stock cams will lope depending on carb setting, and timing---again, look for someone here on the boards that has an olds, and visit with them---best of luck---ps--let us know what you found, thanks

[jrau]

just finished about 10 pulls on the dyno. carb was a small 5-- somthing cfm. what a difference a carb can make. 432 hp @ 4200, 592lbs. torque @ 3000. that was with his 850 dp. the torque was great below 3000 with the small rochester but numbers fell off above 3500. cam is a dog also but with a olds,(below 5500 rpm motor), what gain would a big cam give me vrs. longetivity of my motor. motor now, on the dyno, to 5200. any guesses what it will do in the boat. am waiting for a rebuild kit for my pump. needs bearings and packing. I also need to find a 850 dp. marine carb any suggestions where to get one?

[jrau]

:D just got back from picking up my olds. The shop owner, retired old sprint car mechanic, played with the carb and dist. he got it to pull 483 hp@4750. thats amazing for a cam that small and only 10.1 compression. now if i could get my boat to use it. I would be happy with 65-70mph. is this possible. boat has no hook anymoore but is very heavy.

[CoastGuardSteve]

I am very happy with my BIGS carb. They are in Wisconsinand are very helpful. You can check out some of their stuff on eBay, just search for Bigs Holley. The number is 715.835.3726, ask for Jesse.
Good luck,
Steve

[Mohavekid]

Those are some pretty good numbers, lots of hp for the rpm. I'd check with your favorite pump guru for the proper impeller size. The wrong size will kill your performance.