Jayl13

Okay,
So now my tub floats and runs okay but I am encountering a few minor problems which I expected this early on.

While under load one of the engines randomly coughs and backfires out the carb about 1200-1400 rpm's
you get her moving above that she runs great, solid no problems and sounds mean as hell.

I have the stocker rochesters on there and a friend of mine was playing with the set screws for the fuel delivery
His method was turn all the way in, then back out one and a half turns.
both carbs were set to same so if one is okay Im not 100% sure but the other should be same or damn close to first one.
I ran the boat for a few hours yesterday and did not exceed 3800 rpm's and 90% of the trip was around 3100
she ran GREAT
No problems no issues no nothing
just all out had alot of fun and the wife had a GREAT time!!!! (big important thing there)
Now I have this tuning problem and Im at a loss.
It does not pop out of the carb when in neutral just under load.
I was thinking about changine out the rapid fire ac delco plugs with standard copper NGK plugs
Im not a fan of any weird v or rapid fire or platinum or anything whoptee like that
Gimme stock NGK's and or Champion's and im a happy camper
Reason I got these over priced pieces of crap is cause poop boys had 20 of them (oh yeah they break real freakin easy too for 5 bucks a plug they should last 15 years)
Toilets!!!
Im NOT getting a flame backfire just a woooshhh or a loud PUFF if you will
I have a new distributor cap, new wires, new rotor, plugs are as stated above
Engine rpm's between about 12-1300 to about 1500 or so is when it does this
when I was out of the sea wall from the marina and started pushing a little bit, bow came up and I heard it PUFF then ran for about 10 second or so and then PUFF PUFF then ran okay for about 10 seconds and puff again
then I laid into it a hair more to about 1900 -2000 and it was gone, fine??? Weird (oh as a side note, friend wire tied spark plug wires together and I dont like that.

Second problem
Same engine that puffs when you start it up oil PSI is about 55 or so
after running her for about 20-25 minutes it is down to about 20
Now I KNOW that is weird
other engine after oil is hot, turns about 40 psi
should I have anything to worry about or is a 12-13 year old gague just being a douche?
oh and Fuel gague decided to crap out on me yesterday too so Ill have to start messing with that now too
Any thoughts or advice to these issues (not problems now ISSUES)
thanks fella's

Jason

Audiofn

First off good deal getting the wife out on the baot. I am sure that was a big help in getting her to like all the effort some. This is what I would do. I would swap the carbs. Second if you did not modify your Q-jets to acomodate the new engine set ups you are asking for trouble. One thing that I know is that Q-jets are VERY good carbs however they are VERY engine specific. You can not just take one off a 330 and drop it on a 365 Mag motor. You said you guys are thinking that you are running in the high 400hp range!!! That is WAY to much for the carbs that are set up for a 330hp motor. Your pop I would guess is a lean out at that RPM. If you want you can swap carbs motor to motor and see if the problem swaps engines. I personally would go for a set of Holleys or Edelbrocks if you are running that much power or find some one REAL good at setting up the Q-jets.

Jon

Jayl13

Hey Jon,
Yeah she was smiling from ear to ear when going over some waves and she was yelling woohoo and all that
Then she saw the outerlimits fly by when eating lunch at a pull up restruant and she was like wow this is just cool.
Thats what I have been talking about baby face!!!
I think it is time to call the engine builder back and ask him about the carbs and what to do and or what he thinks?
Keep him involved and keep that warranty paper in my hands LOL
Oil pressure?
starts 55-60 psi and after hot drops to 20?
Is that like RED FLAG low or is that somewhat okay?
I know when my Trans Am gets super hot hot, oil psi drops to about 30 or so on those 100 degree days and your sittin on black asphalt in a black car stuck in traffic and fans have not shut off in 15-20 minutes and temp is spiked to 220
Oil is brand new castrol 10W40 and just put oil in saturday afternoon. Thermal breakdown does not happen in 30 minutes running at 140 degrees

Any ideas?

Jason

Audiofn

Personally I like straite 40 wt oil. Is your cooler plumbed correctly? You can swap senders and guages or just toss a mechanical guage in there if you want to test that way. You could be heating up the oil. Oil temp guages are a great idea. I assume that your 20 pounds is at idle? I have been told by lots fo people that anything over 10 pounds per 1000 RPM is ok.

Jon

Jayl13

No the 20 PSI is running about 3100 RPM's
at idle it is same after hot
when first fired up she has about 50-55 psi
then after it heats up, she drops to 20 while under way (slowly works its way down)
Cooler is plumed correctly, and got 2 new oil coolers when rebuilt so to prevent any future BS down the road.
so you like 40W
I thought about dumping in 20W50 but thought that might be too thick cause she runs about 145-160 temps all day long (so far is what I have seen) so I figured oil would be too thick if I used 20W50 but that will increase the oil PSI im pretty sure
Jason

ursus

20 is low at 3100. Sometimes after a hard run, 5-10 min wot, you will drop to 20-30 at idle and recover back to say 40 at idle after 5 min when the oil cools but even in this condition preasure will usually be 40 @ 2000rpm it will only drop to 30 or below at idle. at 3100 should be 40 like the other engine imo. 10w40 is maybe a little light, 20w50 or straight 40 probably a better choice but this is not likely the cause.

Jayl13

what are the possible causes?
Bad oil pump?
Water in the oil?
bad oil filter?
something clogging up somewhere maybe?
these things are brand new and last thing I need to do is pull a motor cause of a bad oil pump
Jason

audacity

get your engine builder dude involved...have him dial this thing in...or he WILL blame you for washing down the cylinders or something to that extent..as for "castrol 10W40 "...WOW cams hate this ****...get it out of there...if the syn's are too much then just use a 40w race valvaline oil....watch your plugs...it has a higher zinc content in it. VERY cool the wife is a happy camper!

audacity

ps...oil pressure and flow are not the same!

Jayl13

I thought all that 40W and 20W50 would be way too thick since this thing does not heat up that much
I have never had a problem with castrol before
I do run Mobil one in the trans am though religiously (hell aluminum block and everything)
but I figured castrol was good stuff.
I thought that the synthetics in these were not a great idea from mercury?
So bump to 40W straight?
That is thicker than 20W50
You sure a oil pump off a regular motor can handle that ?
Awful thick stuff
Jason