SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: TX TAHITI on January 04, 2011, 01:52:00 PM
-
Been long time reader but new to the site, I picked up a 76 Tahiti super tiger last year, the previous owner said it would run over 80 @ 6K on GPS.
I've taken it out a few times and have blown both bowl and nozzle gaskets out and have reversion problems with water in the exhaust when I try to run water thru the headers. (it runs great dry but cooks the sides of the boat and melted the carpet!)
The engine is a 514 (4.44 bore with 4.14 stroke) 10.5:1 compression with large valve 2.25 / 1.97 bowl blended & ported Dove "C" heads. the cam is a Erson JB300 but I don't know what the spec's.
I'm guessing it has a "B" impeller but will find out when I pull the pump apart.
Anybody have spec's for the cam and will the water restrictors that mount in the header -8 line help me with the reversion problem. I'm hoping to just allow enough water to get a LITTLE steam thru the headers until I can set it up with Lightning or other double wall versions. Look forward to your insight and help.
-
4.14 stroke Fords with ported D0VE heads make great jet boat engines. 8)
As far as the fogged headers, you can add a T-valve which stops water flow to the headers during idle, typically shuts water off to the headers below 2000 rpm when set up right. The water trees feeding the headers are usually 1/8-inch and the fittings that screw into the primary tubes should also have small orifices...I think 1/8-inch but I haven't looked at any for some time. Restricting the amount of water to the headers should help your excess exhaust water condtions.
Sig Erson Cams has changed hands a lot over the years, being owned by Super Shops in the 1990's and currently owned by PBM in Carson City, NV. You could check with them as I've contacted them in the past and received cam specs for out of production Erson cams. By the way, Erson cams typically have an LSA that is on the tight side relative to dur@0.050" (compared to OEM) and tight LSA cams generally work really well in the 460 engine platform...not surproised the boat hauls ass.
LO
-
Thanks LakesOnly
I'm also running an Offenhauser turbo thrust tunnel ram with two 6109 750 double pumpers. I did leave a inquiry with PBM a few day ago...I also found the '99 Erson catalog on line however it listed JB100 & JB200 with 108 LSA maybe the JB300 was a later grind or my reciepts are wrong? Erson#260281 JB300.
I have the basset headers although they're chevy headers mounted on aluminum adaptors and the exhaust ports had some type of insert with a "tongue" going up into the port.
The ports have been worked alot ~ I've run it with and without them and can't really tell if there's difference. I've only driven it about 1 hr so far.
In regards to the header plumbing I have a functional "t" valve and have cleaned / replaced the water lines. I'm running two 5/8" lines of the thermostat housing, one to header "t" fitting and the other to a dump line with a gate valve. The gate valve is wide open and I have the other gate valve off the jet pump set to maintain 160. degrees.
Last time out it would begin to mist the headers at 2400 rpm and when I stood on it I had pretty large streams of water pouring out between 5000 -6000 Rpm and then it started missing ~ stopped the boat and no water at idle. I'm thinking the restrictor jets for the -8 lines should really limit the volume and help me?
if I can get this water issue resolved I'd like to pick up some Ford headers and eliminate the adaptors. If not I'm thinking a larger solid roller something in the .255 /.265 @ 50 with .720 lift and ceramic coat the headers and forget the water!
Not real sure what rods are in this other than 6.8 length so I don't know if I should twist it anymore than 6K.