Mk IV's don't have the bypass in the bloack and in any case your engines are previously running marine 330's that didn't have oil P problems in there previous life so don't have incorrect bypass valves in them.

Jay,

I'm not sure if the q-jet works anything like the holley, but with the Holley, it has 4 different jets....One of each corner. These control the fuel flow above idle speed, and into the secondaries.

The screws on the sides are for the "idle circut", from which i have been told has nothing to do with mass fuel flow when throttle is applied.

So whether or not the q-jet has primary metering rods...i don't know...but i would make sence that it does if it works like a holley. Unless the metering rods supply both sides?

Any q-jeters out there?

http://www.geocities.com/gtopercy/Pi...rajetTech.html

a decent description of how quads work there altho its for auto's so the metering size info is not applicable

What about an intake valve sticking open at those rpms? Jay, did you try swaping carbs? It was just one engine doing it right? Swap the carbs and you will find out in a hurry if it is the carb or not.

Man o man and I am glad you guys said it Ursus, Birdog and Form31.... I was about ready to jump out my frikin skin. The proper method for problem solving goes.

You have a "fussy" situation... You fact find..... you establish problem definition... you generate solution, then and only then... you take action. Talk about jumping from a fuzzy situation to solution... with minimal facts. Maybe if Jay could list all the facts as known to him, relevant or not, then maybe we could move towards problem definition. Right now the guy definately needs to do more fact finding. Don't spend penny one on a carb until you at least have problem definition!!!!

One additional fact I am curious about is if your spark plugs were loose after your last run? Of course I am still waiting on my windage tray question, but I guess that fact will never be known.

Infrared guns work great. I use one almost every day. The trick is having a proper baseline and knowing what affects its accuracy. Reading the directions that come with the unit with usually suffice. Surface temps are greatly affected by airflow over the surface, so you need to account for that accordingly. There are other variables as well. Any facts are good facts.

BT

Jay,


Certainly your #1 problem is oil pressure. As was mentioned before I would let the engine builder know about this and ask for some recommendations from him. As far as the popping at low RPM's are both engines popping? If so it's possible they are both lean on the bottom end as well as the top. If only one engines popping it's got to be another problem. If you want to richen up the engine at lower RPM's start here. The primary circuit on these carbs has removable jets & metering rods. Don't replace the jets unless you can't fine tune any further with the metering rods. The stock primary metering rod is a .042. I would start with a .038 part # 7034838. Again this may not be the exact one you need but it should get you in the ball park. These are a little more difficult to change than the secondaries. You will have to remove the top of the carb, not a big deal and it can be done with the carb still on the boat. Take a good look at it and you will see all the screws & linkages that have to come off. You also may need a new upper gasket as sometimes they get stuck & tear when taking the top of the carb off. I like to coat the new gasket with never seize so it comes apart easy the next time & doesn't have to be replaced. Once you get the top of the carb off you'll see the primary metering rods in the front and how easy the are to be changed. Don't be intimidated by carb work. If you can remove & install the engines you are mechanically inclined enough to do carb work !! Once you've done one your an expert !! Good luck & let me know if I can help any more.

Bo

Hay Jay put Bo's telephone number in #1 speed dial on your cell phone he is good (god) Charlie

Oil pressure-
I would definitely change the filter, and pour the contents out into a pan and sweep a magnet through it to check for cam glitter.

I always change the oil and filter after the cam break-in period. I use the moly cam lube that Isky recommends, and the moly particles will plug up a filter.

Temperature-
The overall engine temp in an engine running lean may be 5 or 10 degrees hotter, but the piston top may be 100 or 200 degrees hotter.

The leaner a mixture is, the hotter it burns, also faster. Always start off fat/rich, and work your way down- eliminates concerns about melted pistons. Also, I would be very careful about running year-old gas.

"Infrared guns work great. I use one almost every day"....what brand is it????

....like i stated and supplied data for in my previous post.....they only work good in a past/fail...yes i'll use them too shoot all the headers to find a dead hole...but i will not use them for accurate temp readings...i will account for the down time and have a tech put a TC in it...or do it myself!....they are used a lot more in an electrical diagnostic situations.

J, i wish i knew the Q-J stuff...i would help ya....funny all this talk about carbs....and last night i spent 5 hours on a mill making chips form a holly(s) ....then i had to do another set of props ....i'm tired!....KAMMA....do you want a set of 32's after the race season????

Okay if you want to know all the data that I do have here we go

First general engine data
9.5:1 compression
Large oval heads
edelbrock performer manifolds spread bore dual plane intakes
No choke on Rochester carb
Gen 4 blocks (stock 1990 blocks that came with boat new)
Oil pan DOES have a tray inside it yes
Cam is as follows
Comp grind # xe-268H12 PN 11-242-3 Intake Dur 224 Exhaust Dur 230 Intake lift 515 Exhaust lift 521 LSA 110
Put in 10W 40 and had engine trouble starting and leaked a little water in engine
took all oil and oil filter off, changed, dumped a few quarts of oil in engine while pumping it all out to clean out water
put in more oil 10W40 ran it one time in driveway and developed a snap out of the carb on port side engine
bent pushrods
took to engine builder
changed all springs and seat shims ect.
Put back together, Changed oil again after both engines ran at engine builders for about 10 minutes a piece and oil filters were changed again
Took it out on the river for about 15 minutes on a quickie test drive to see how she was
brought back, changed oil and filter again
I took boat out for about hour and a half and oil psi on this run dropped to 20 on port engine stayed around 40 or so on Starboard engine
I am NOW going to change the oil AGAIN (not filters this time) to straight 40 weight
none of this car **** anymore
I have 16 qts of HD 40 straight syrup from aunt Jemimah!!!!
I ordered the secondary metering rods for the carb as a JUST IN CASE type of thing

When on start up engine produces just under 60 psi on BOTH ENGINES
After running 10- minutes or there abouts a glance at the gauges tells the tale
The starboard engine runs fine, No oil pressure problems, I dont think that is the engine that is POOFING out of the carb (that one has run solid since before I took engines out to begin with that one never had any problems but if your going to do one engine you better do both!!!)
the port, that is the one with the bent pushrods, had problems when I first pulled the engines out to begin with it had ingested water, and the oil pan tray broke and was slamming into the crank shaft under load. (weld broke in oil pan and the tray would lift up some how and hit crank dont ask I have never heard of that one before)
I set both engines timing to 8 Degrees on the MONEY!
both idle in and around 700 ish when warmed up
little high but cams chug a little too much any lower than that.
Friend of mine (RCM255 here on OSO) he turned in the set screws on both of the carbs and turned them back out one and a half turns for the fuel on the left and the air on the right
He said that was a good place to start and should be close to what you need

NOW as far as volumetric efficiency NO CLUE joe my friend, I have no damn idea.
I AM running 2.19- 1.90 vavles I THINK
I WILL have to check with engine builder on that
they are Large Oval heads
one is off a 1970 something and other is a 1969 set
there were new guides seals (big deal seals whoopeee doo) springs, retainers ect all installed
the douche bag that put the seats too high
(4 shims and the rotater on top of 4 shims) was FIRED
he was a junkie and an old douche bag
If I go messing around with all of this and get a mechanical oil pressure gauge and slap it on there and an oil temp gauge and it reads high, I THINK im going to yank out this engine and take it back to engine builder and say well here is your warranty case, pull it apart again and FIX it!!!
So Ill be in the dog house with the wife so if any of you are truly friends you can put me up for a few days?????
She is going to flip if I yank this back out but if I cant get it to stop poofing and low oil pressure ect what else can I do?
Jason