Chine Walker UK

Hi everyone, just bought 1990 311 running - 502 chevys with 8.71 blowers 4 barrel hollies etc. ssm v drives, w/17" 29 4 blade props.

What HP should they turn out? Does that set up sound right? Guy recon'd that they are chief SC800 motors but chief don't do a 502 sc 800. They have Chief rocker covers on i recon thats about as chief as they get. Do chief do blown top ends for regular big block 502 motors.

Its very slow out the hole, like 5000rpm for 40 seconds, flat out i think 70ish was about it.

Does that whole set up sound right sound right? what can i do to get it moving quicker so i can wake board behind it.

The drives seem too high out the water.

I've never heard of a machine that uses soo much fuel, jesus, i recon it burns or leaks 60 gallon per hour at full chat. Is that normal?

Asking anyone in the UK is like asking someone who fixes Johnson 60 HP out boards how to fix an 747 engine.

I wish i had kept my 1997 BAJA Hammer great fun boat reliable 7.4 merc. and good on fuel.

Needless to say all the sailing boats which are a majority at my marina hate me already (noise etc), which is great cos i kick everyone ass in a 100 mile radius, until it runs out of fuel and we have to call the coast guard!

C_Spray

iTrader: (2)

Hmmmm.... Lots of questions (and issues) in your posts, but you're pretty much in the right place. I'm not familiar with 311's, having just become a Formula owner in 2000. Anyway:

1) For God's sake, stop using the boat until you get rid of all the loose fuel AND fix the tank. You're just a bomb looking for a detonator, and you've acknowledged your problem in a public forum, so all liability is now yours. I'm not being harsh here - I'm doing you a favor.

2) Sounds like you got a boat that was set up expressly for top end speed at the expense of all other factors. As to how fast it should go with that power, I will defer to the "311 experts" on the board.

3) Your problems getting up on plane are related to #2 above and your high drive setup. You just have to baby the throttles as the boat breaks on to plane and give the props a chance to hook up. There are drive spacers and larger props out there...

4) Formulaboats.com will put you in touch with the factory as far as any recprds or technical assistance they might be able to give you. Ask for the TAG (Technical Assistance Group) office. They're fantastic people, and very helpful.

No offense, but you might want to get a marine survey done on the next boat you consider before you buy it.

CMG

Cspray's right lot of q's. lets see, 70mph is wrong. out of the box with 454mags that was the advertised speed. with the big blower you should be closer to 80mph (Jaybird where are you?) you mentioned 5000 revs for 40 sec out of hole, sounds like cavitation. what is your flat out revs at wot? i'd guess somewhere around 4500. post your revs, I bet your over propped. btw -with the boat and power, 60 gph sounds pretty good!

jaybird

My 311 w/ 454 420's and 174 blowers can hit somewhere in the low 80's. Your boat when setup correctly should be pushing into the 90's. Something(s) don't sound right. The only way to be sure is to go through EVERYTHING, which is a big pain in the arse, but really ought to be done. You've got alot going on there, and you need to baseline things as you seem to be going much slower that it should.

Is that 70 mph speed GPS or the dash gauge? The spedo pickup tube on those don't work worth a squat (mine actually kicks out right around 70 quite a bit), especially at high speeds so a GPS is a must.

I can tell you the 311 is a solid hull that handles great, so no worries about the boat (well after you fix the gas tank anyways). But to be honest you should probably post this in the tech Q&A forum as there are alot of people there who have run or built themselves a similiar engine/ drive package just on a different boat. I'd ask about tuning specs for that setup (plugs, timing, fuel pressure, as you can blow a motor up if any of those are wrong).

Good luck - that boat should be really fast when setup.

jaybird

BTW - since you have that setup, there are a lot of places that fuel could be leaking in the engine room instead of a bad fuel tank. Those engines have had to had upgraded fuel pumps that can develop a lot of pressure, so you could just have a fuel line or fitting leaking somewhere. The fumes will travel all the way to the cabin through the bilge area. Just start at the fittings on the fuel tank and work your way up to the carbs.

Got any mechanics around that like to work on Chevy street rods? You may be better off looking for someone like that as far as the engines are concerned.

EDIT - never mind you said in the other post that you actually have fuel under the step in the cabin. First things first, fix the tank.

Dano

ssm v drives?really...got a little bow lift? Definitely fix the leak first dude not much happening after a sparker...might blow ya' all the way to France...and that's just not right What's the ticket on a liter of high test petrol in the UK now?

Seriously...check the fuel lines first and get that fixed BEFORE you put that in the water.

Chine Walker UK

Fuel in Uk is £0.90 per litre $1.50 crazy!!. Diesel is only £0.35. If only diesel boats were a bit faster.

Jaybird - it accelerates fast to 10 knots then starts cavitates at 5000 rpm even if you baby it and eventually grips after 30 - 40 seconds then goes pretty quickly and settles at 3500.

I had GPS reading of 59 knots with drives at 0, this was before i put the drives down to 2-3 on the gauge the revs went up by 1000 rpm'ish but i did not have the GPS on this time to check speed.

I have only used it 3 times so its all new.

Would really like to have smooth acceleration. I'm afraid that i will blow a motor rev'ing them that much. The last merc. 7.4 in the Hammer red lined at 4500.

Do all fast boat take this long to get goin?

When the boat was out the water the whole prop did not look like it was below the keel line to catch all passing water is that normal? can you get spacers to make the drive ride lower?

Dano - would like to go to main land europe that was why i bought it!..pipe dream. It is 89 nautical miles to Amsterdam from Great Yarn-mouth 50 miles down south from Hull - East Coast where i live.

Two main problems A. running out of fuel and B. having too much fun in the Dam and not bothering to come home! Theres always channel 16 VHF (emergency coast guard).

The guy who i bought says it had a range of 110 miles but i have so far manged around 20 off 2/3 of a main tank. The front water tank has been converted to gas with a syphon function. I really need to do some more tests but every time i go for a 10 mile test ride it costs around $150!

Calling all American Off Shore boat makers - please make a fast diesel boat - which sounds as good as twin v8's but costs 2/3 less in fuel to run.

C_Spray

iTrader: (2)

Now THERE's a likely candidate for your fuel leakage problems!

CMG

5,000 rpm is not only safe, its where you need to be (at least) for speed. Marine motors are made to run at these revs all day. I am not familiar with your drives but it sounds like your not trimming out enough, you want to get the bow, almost all of the boat, out of the water for speed, less drag. I get highest speed by almost hitting the highest setting. coming out of the hole, bury your drives along with the trim tabs, should come up on plane pretty quick (BTW, hard hole shots not the best treatment of the drives)

converting the water tank to fuel is friggin insane . drain it and disconnect the line.

After that, get out there, go WOT and trim it out as far as you can without props slipping,believe it or not, your mileage will go up without the whole boat being wet. More speed will translate into more distance.






EDIT: I am not a mechanic - but I do play one on tv!

Dano

I'd definitely start with the water/gas tank dude....

Amsterdam ahhhh what a place to get stuck, if they had palm trees it would be heaven on earth.

Measure the x-dim. If it's high a set of spacers will definitely help. With blowers you have to feather the puppy up on plane. Sounds like it is set-up for top end hence the low range problems.