Vortec Lives!! - Qjet questions

John_S

Rear Admiral
Joined
Jun 21, 2004
Messages
4,269
After some delay, finally fired the engine up this weekend. For those that might have missed my prior posts, I am upgrading my '97 Mercruiser 5.7L with vortec heads, performer intake, Qjet, and marine roller cam.

The two lessons learned, so far are:

- Exhaust elbows are not identicle, I had them swapped and only noticed during the torquing of the second. Scrap four graphite gaskets.

- Cam change in the boat is risky. Even though my engine access is relatively good, getting the oil pan/timing cover is tricky at best. I had an oil leak, and had to redo the oil pan torque/sealant again. No leaks as of yesterday, but keeping fingers crossed. My bilge has heard allot short verbs recently!


The engine is running well on muffs. Idles down nice, and sounds great revving it. While I've adjusted the initial base timing, I need to do the idle mixture. The Qjet is an electric choke rebuild from Carlos at I5 auto. The idle mixture screws apear to take a small square drive. They are recessed in the base, so my sockets would not fit. Is there a special tool or socket for these? Like to know before I get the ? look at the auto parts store. "Carb? what that?" :)

Secondly, even though it seems to be running well, I want to check the vacuum. Does anyone know if the Qjet choke pull-off is at engine vacuum? Otherwise, I will have to rig something from the intake port behind the carb. I can get a fitting for a large hose, such as power brake port, but didn't find one with a smaller barb for a vacuum gauge. Would have to neck it down, or build own fitting.

Hoping for a Fathers Day weekend splash. Installed the new 21" pitch prop, up from the 19". I have a 23" pitch ready to go, if I'm too much into rev limiter.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Vortec Lives!! - Qjet questions

Is that a marine carb you got from that Auto Parts Store?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Vortec Lives!! - Qjet questions

Volvo and Merc used the J tube quite often, but many didn't. As long as it's a marine carb you will be fine.......... well, hopefully.

Yes, there is a special socket for the mixture screws. I know napa sells them (at least ours does).

To check your vacuum, there should be a pipe plug on the manifold that you can remove and install a fitting for your gauge.
 

John_S

Rear Admiral
Joined
Jun 21, 2004
Messages
4,269
Re: Vortec Lives!! - Qjet questions

Thanks guys. I stopped at the auto store during lunch. I should have enough fittings to do vac guage off the intake port. I'll compare that to the choke pull-off. While there, I picked up a general carb adj tool. Basicly it is a flex shaft screwdriver with a selection of small bits. One of the bits looks like it may fit. While the counter guy didn't know if it would work on Q-jet carbs, he would refund if it didn't fit. :)
 

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
Re: Vortec Lives!! - Qjet questions

Hey John.............the title of your post sounds kinda familiar to me..........:)

Hope everything works out for you......

I played hooky from work today and went out fishing.........

The Vortec seems real strong between 3200 and 3800RPM's.......my Grady is cruising comfortably at ~32MPH and 3600RPM's...........sounds good too......I am running the exhaust tube instead of the bellows...........a little louder.......but I knda like it.

Mine is ideling real smooth at ~500RPM's in gear..........pulls about 19-20" of vaccum at idle in neutral.

What cam did you install............a stock mercruiser or something more aggressive?

Good luck.........am interested in you progress.,
 

John_S

Rear Admiral
Joined
Jun 21, 2004
Messages
4,269
Re: Vortec Lives!! - Qjet questions

Hi Tony,

Glad you are enjoying the boat. I hope to be out of the working on, and into that phase next week. I am using the stock Merc roller cam.
 

FreeBeeTony

Captain
Joined
May 15, 2002
Messages
3,991
Re: Vortec Lives!! - Qjet questions

Keep me posted..........waanna hear what you think of the Vortecs.........
 
Top