Upgrade to Vortec Question

"Aside from a possible fit pro

"Aside from a possible fit problem with the vortec valve covers, will the original one piece OMC manifolds work with the Vortec 4.3. Didn't know if there was a flow problem or any other issues I should be aware of. The folks with the motors say that everything should bolt up with the exception of the shift linkage mount. The bolts on the Vortec intake go straight down instead of at an angle on the old motor, so the mount will take some fabing. Your thoughts?"

"As far as bolt pattern your m

"As far as bolt pattern your manifolds will "bolt up" to the Vortec head. But I can tell you first hand that the Vortec valve cover will interfere. When I did this upgrade and slid my "batwing" manifolds onto the Vortec head exhaust mounting studs they hit the valve covers long before the mating surfaces came together. When I was planning this upgrade a guy sent me a link to a picture where a guy had done it. I feel like he must have somehow shimmed them to make them clear. (bad idea in my opinion) You can see in the pic that they are probably still touching and maybe even bending the plastic valve covers somewhat.
http://www.michiganmotorz.com/article_info.php?articles_id=7
Also when I was shopping for replacement manifolds one seller told me there was a slight difference in the spark plug location on the vortec head that would interfere with some non-vortec manifolds. I cannot confirm this however. Apparently the guy that installed the pictured engine didn't have that problem or he came up with a "workaround".
As far as the intake manifold bolts, not only are they straight down but there are eight of them instead of twelve so the spacing of the bolts is wider."

are we talking upgrade to bala

are we talking upgrade to balance shaft 4.3? I thought all 4.3's were Vortec.

"I'm not sure when GM star

"I'm not sure when GM started the vortec thing, but yes this would be from a non balance shaft engine to a balance shaft one. Basically an 18 year upgrade. The easiest thing to do is to get the old model engine, but, you know how it is, I'm having trouble not wanting the new one."

The Vortec engine was first us

The Vortec engine was first used in autos in the late 80s but didn't hit the marine industry around 1996. I think the balance shaft started in 1993 to smooth out the vibration of the V6. Mines a 1990 and I don't really notice any vibration. I'd rather have the horsepower that the balance shaft robs.

"[b]"The Vortec engine was

""The Vortec engine was first used in autos in the late 80s but didn't hit the marine industry around 1996."

Ayuh,.....

While the Name Vortec was used on the valve covers for awhile,...

The actual Vortec combustion chambers,+ Vortec bolt patterns were Intro'ed in 1996 for All of the Chevies that use them....

Pre-1996 cylinder heads have the old standard D shaped combustion chambers....
In 1996, the Heart shaped combustion chamber,+ Vortec heads as we know them were intro'ed for the V6s,+ the V8s..."

"Thanks for the clarification

"Thanks for the clarification Bondo. I new the Vortec name appeared before the actual mods, but I thought the marinized version was a few years behind the autos. By the way, did you ever get yours done?"

"Nope,...

Too busy working,

"Nope,...

Too busy working,+ rebuilding a couple of houses,+ building a wood boiler,+ Way too many projects goin' on........

Winter is Fast approaching,+ I'm Hopeing the Boat projects materialize before Spring..."