4.3 "wake-up" time...questions

erin andeline · Sep 19, 2005

Hello everyone, I have enjoyed these postings for a long time, and finally decided to chime in with my own question(s). I own a 1986 Wellcraft American 190 bowrider with a 2-bbl 4.3 OMC Cobra (rated by OMC and Wellcraft at 175 HP). Well, as with most of you, I want to get a better hole-shot for skiing, better economy at cruising speed, and be fast as my buddy's 5.0 2-bbl when running WOT (~46-50 mph). Not too much to ask, right? Well I already have the L&S Shift Prop..SWEET!, except for the engine is at the lower edge (Power/Weight ratio)of being able to utilize the prop. Therefore I am using the 'ZZ' Cams (made for least amt of HP) and have to essentially trim high enough to cavitate the prop before it up-shifts. It does work, though, and is quite a feat in engineering! I recommend them. 11 Pitch is a CRAZY Hole-Shot!!!! Now then. I have been thinking about this upgrade for a while, and decided to stay with the 4.3 (rather than converting to a V8), and update with Vortec heads, intake, and a 4-bbl Edelbrock carb. I am going to stick with the stock CAM ($$ and not sure if other Cams will provide much impact). I wanted to convert to Electronic Ignition, but haven't seen any kits for the 4.3! I know in 1986 Mercruiser used the Thunderbolt EI on their 205 HP 4.3 engines (non-vortec 4-bbl) and points on the 2-bbl 175HP 4.3, so I assume it does have a performance impact. From what I can tell, I should be in the ballpark of 225 HP, using a stock Vortec Cast-Iron Intake Manifold, and Vortec Heads, with the E/B 600cfm Carb. Torque-wise, it should match the Non-Vortec, 2-bbl, 5.0 liter(GM 305ci) according to some literature, which would make me VERY happy! Questions: 1) Does anyone have an idea how to convert a marine 4.3 to Electronic Ignition, and if it is a noticable performance difference? 2) Does anyone know what improvement (if any) the Aluminum E/B Performer Intake Manifold (#2114) will have over the stock Cast Iron 4-bbl Vortec Intake? 3) I know some of you have done this exact upgrade, but I haven't seen much follow-up. I understand the Bondo has done this. I am interested in hearing successes or disasters, money well spent, or thrown away......? 4) I just want enough to make this prop sing as it is supposed to. Land & Sea indicated that they weren't sure it would even work on a boat my size (19') with only 175 HP, but that was the MAX offered in 1986 for the 190 American. Go figure! I appreciate the feedback!

Bondo · Sep 19, 2005

Re: 4.3 "wake-up" time...questions

1) You'll need a way to go Electronic,+ Still be compatible with the OMC shift cutout switch(which I know Nothing about)...... But,.. There's No Performance gain to be had,.... Nothing.... 2)Very Little,....... Again,.. I Don't Do OMCs,.. But Merc. uses a Mid-Rise 4bbl. manifold that' does a Fantastic Job..... Depending on What you find,... The Edlebrock might be the way to go for You.... The Iron Vortec Intakes are up to $170.00+ shipping,...Boating in the Salt could be an issue with the Aluminum 1s.... 3)Sort Of,..... I'm running a pre-vortec motor,... 4bbl...When I built it in 99,.. I started with the 4.3LX, 4bbl.Weber Carb.... Merc's Stated horsepower of 205hp....... I Only "massaged" it slightly,... so the HP is Maybe Just over the Merc. Stated 205hp.... I Have the Vortec Heads,+ Everything but the manifold in the garage Now,.. along with a New set of Exhaust Manifolds,(Ayuh,..Over 600hrs on Welded,+ Bubblegummed Frozen 1s, Still on there Now,.. Talk about being on "Borrowed Time",.?).... All this will happen Later this fall...... 4)Ayuh,............. I Love My Torque-Shift Too..................

There's No Difference the the Cam, between the 175hp,+ the 205hp motors,.... Just the Carb....... With the Carb.,+ the Vortec package you Should see an Honest 25/35hp Increase........... That's enough to FEEL the Difference....... Good Luck......... And,.. Welcome to the forums here at iboats.com......

Lou C · Sep 19, 2005

Re: 4.3 "wake-up" time...questions

That motor with the Rochester 4bbl was rated at 205 hp from OMC (I have one) so you could try locating an iron 4 bbl intake and marine Quadrajet and start with that. I don't know how much the Votec head design adds but if the top end of your engine needs rebuilding then it makes sense.If not I am not sure I'd change the heads. I have not tried this motor/boat combination with a 4.3 2bbl but I can tell you the 4.3 4bbl has a nice top end, really coming alive from 3000 rpm up to 4500. I would not bother changing the points to electronic, you need to put together a circuit to make the ESA work with it.

erin andeline · Sep 20, 2005

Re: 4.3 "wake-up" time...questions

Bondo (or anyone else with experience with this), Was it a noticable improvement going from a 2-bbl to a 4-bbl, without going vortec? Obviously it would be cheaper. There is a Holley Intake (non-vortec) floating around on Ebay that always catches my eye, but I have been dreaming of vortec, so I haven't bought it. I am not sure how much to trust the mfgr HP ratings, which imply a 20 HP increase just for using Vortec stuff (not sure of the torque improvement). In the scheme of things, a local parts yard has a low mileage set of vortec heads for $100. Add typical head work for $85/set, and I'm basically $185 more for a vortec system, using a stock 4-bbl cast iron intake. Sounds like you think the vortec is "better", based on the fact that you have the stuff in your garage........ I am suprised to see the postings where people with 4.3's are easily going over 50 MPH! I can run 40 all-day, but 43 is another story! Of course my rig is 2400 lbs dry, maybe I'm asking a lot of the V6. When I was growing up, my family had a 1984 19' IMP bowrider with a 5.0 (305 OMC), rated at 200 HP. I loved it! I want mine to run just like it. Thanks, Erin

Bondo · Sep 20, 2005

Re: 4.3 "wake-up" time...questions

Well,.......... Basically,......... The 4bbl. will get you a Noticeable 15/20hp improvement......... The Vortec package will get you a Noticeable 15/20hp improvement......... The Vortec/ 4bbl. package will get you a Noticeable 30hpPlus improvement......... In the end,.... Tuning the New Package will determine the Final HP#s.......... All with the Stock Cam,+ a Stock Cast Iron manifold.............. BTW,..... The Stuff in the garage Will be on the boat by Spring.................

The Full Dressed Fishing Machine(Ayuh,.. a Tin Boat),.. That you see in My avatar will pull 43/44mphgps in Freshwater,.... 52/53mphgps the Saltwater..... And,...... As You Know,..... 0 to Flat Out happens Really Fast with a Torque Shift Prop.............

4.3sunbird · Sep 20, 2005

Re: 4.3 "wake-up" time...questions

quick rundown of mine ... more later if needed but short on time right now non vortech shortblock (roller cammed) .030 over flattop pistons vortech heads with only bowl blend done and valve spring upgrade cast vortech intake with #3 cylinder runner opened up to match the others (you'll see what I mean if you buy one) eldelbrock roller cam under factory roller lifters rochester q-jet carb electronic delco ignition intake and ignition set-up came from http://www.michiganmotorz.com/ gotta run, RED

Lou C · Sep 20, 2005

Re: 4.3 "wake-up" time...questions

OK guys, one last question. I recall hearing that some inboards with the newer Vortecs were known for sucking water up the ex because of different cam timing. Now was this just BS because they were installed too low in the boat, or a real difference?

4.3sunbird · Sep 21, 2005

Re: 4.3 "wake-up" time...questions

Originally posted by Lou C: OK guys, one last question. I recall hearing that some inboards with the newer Vortecs were known for sucking water up the ex because of different cam timing. Now was this just BS because they were installed too low in the boat, or a real difference?

Im too new to boats to know anything about that but I dought it was cam timing

erin andeline · Sep 22, 2005

Re: 4.3 "wake-up" time...questions

Guys, Based on your thoughts, and my research, I am convinced that the conversion to a 4-barrel Vortec is the way to go. However, I have two more EASY questions: 1. On Ebay, you can purchase an "I5" rebuilt Rochester 4-barrel Quadrajet (some say "quadrajunk") for $245 that is jetted correctly and has the correct linkage for a 4.3 OMC. Is it worth the extra $100 (or so) to get a 600 CFM Edelbrock over the Rochester? 2. I plan to continue using the stock CAM and shortblock. I am concerned, though that the valvetrain might be different. Does anyone know if my Non-Roller lifters/pushrods/rocker arms will bolt up and fit just fine? Or do I need to also invest in some roller stuff? I'd prefer not to spend the extra $$ on roller stuff, if I don't have to.. Thanks Again!

erin andeline · Sep 22, 2005

Re: 4.3 "wake-up" time...questions

One more question....(this time) Are there other details that I am overlooking when making this change? I don't like suprises when they cost me $$..... RED (4.3sunbird) listed the components for his rig, which included a roller cam, flat top pistons, roller rockers, "bowl blend", etc. Are all of these just tricks of the trade; or will I have to do some of them to make it work?? Thanks, Erin

4.3sunbird · Sep 22, 2005

Re: 4.3 "wake-up" time...questions

no you dont need all that stuff to make it work .. them are just for more power

you had mentioned wanting to run like a 2brl 5.0 combo I mentioned runs more like a 4brl 5.7

erin andeline · Sep 22, 2005

Re: 4.3 "wake-up" time...questions

RED, So the current (non-vortec) cam/lifters/pushrods/will work with the vortec heads with no additional mods? If so, maybe I'll run somewhere between a 305 2bbl and a worn out 350...

Spending minimal $$. I found a set of vortec heads locally for $100, and head rework for $85. Slap those on with a vortec 4bbl intake and the carb of my choice, and I'm ready to play. Any thoughts on my carb question? I see you run a quadrajet.... Thanks, Erin

4.3sunbird · Sep 22, 2005

Re: 4.3 "wake-up" time...questions

most people dont like quads but I know my way around them pretty good and they are great carbs if you can get them right the small primaries on the quad help out alot on fuel usage during normal use you wont see a big difference performance wise in whichever you choose most the vortech heads are non adjustable valvetrain .. the easiest thing to do is get a set of arp rocker studs for them .. they sell them for that reason then youd be able to adjust the valves correctly you should have no problem with your pushrod lenth if you do make them adjustable they do require self aligning rocker arms so see if you can get them with the heads you need the valve covers for them also .. the plastic ones that say vortech on them I also had to do a minor tweak to the throttle bracket to be able to bolt it to the vortech intake but nothing major there I can post pics when you get to that point I'll be around

erin andeline · Sep 23, 2005

Re: 4.3 "wake-up" time...questions

RED, Thanks for all of your help! I think this budget project will be getting a quadrajet... After all, my 'real' goal is to make my shift-prop work correctly by adding needed HP. Maybe in the process I'll blow my buddy's away with my "little V6"!

Please send the pics... I may begin immediately. BTW, my valve covers are currently held on using studs in the center of the head. I thought this was the same as vortec?? Doesn't really matter. If a set of valve covers makes a difference, I have bigger problems..

Bondo · Sep 23, 2005

Re: 4.3 "wake-up" time...questions

Just My Opinion,............ I Love the Merc./Weber/ Edlebrock/ Carter Clones,........ Way Ahead of the Rottenchester for Simplicity,......... And,.... Even though it's a Square-Bore mounting carb.,..... The 600/650cfm carb. has the same Smaller primaries,.. Just like the Rochester......... Much Simpler,... Much Cheaper to work on,.... Much Cheaper to Buy,.....Usually............

AdamB · Sep 26, 2005

Re: 4.3 "wake-up" time...questions

Just to add my own thoughts to your torque shift prop. I have a Chevy 350/ alpha one combo and I use the ZZ cams. I believe the ZZ cams are for the most HP. Any other cam will allow major over reving during initial WOT puch. I think you should try to drop down in cam selection (starting with "Z" cam). What is your initial WOT RPM when punching it with the ZZ cams installed and how does that compare to what your WOT RPMs should be? If it doesn't reach the expected rpms, change prop cams.

eja · Oct 11, 2005

Re: 4.3 "wake-up" time...questions

AdamB, Now you have me thinking... L&S told me to use the ZZ Cams and light springs due to my Power/Weight ratio... I think the ZZ cams should shift sooner than the Z (for instance), but in my case, I have to trim the lower unit up to a point where I am basically cavitating before the shift will occur. It is a pain in the a**, because everyone in the boat gets slammed from the porpoising when trimmed up that high... A little more power should get me out of that predicament, I think.. If the prop is all the way down-shifted, then I can easily over-rev the motor, therfore I am very careful not to exceed 4000-4200 RPM. As I recall, the boat will speed up to about 25mph in a heartbeat, but that's as fast as you want to wind up the 4.3, so if you are slalom skiing, you have to shift up, which means trimming up and porpoising the boat, and so on... According to an article I just read, the cams only change the shift RPM, so increasing the CAM profile would make it worse, right?? Thanks!

Bondo · Oct 11, 2005

Re: 4.3 "wake-up" time...questions

eja,.... We need to talk about your L&S prop,....... Please start a New Thread with a C&P of this last post here,....... This thread is about "4.3 "wake-up" time...questions",........ Start another about the Problems you've got with the prop.............. As for your Plans for the motor,........ Reguardless of whether you go with or without the Vortec Heads,..... You'll Feel the difference with the 4bbl. Carb. in the seat of your pants,...... Your Cam,+ Lifters will work Just Fine,....... If you Do Use the Vortec Package,..... The Pushrods, I'm not sure on,..... The Rocker Arms Are Different,.....Like I said,.Cam,+ Lifters are Just Fine..... Good Luck,+ I'll see ya over at your L&S Prop thread,......................

burtonrider11 · Oct 13, 2005

Re: 4.3 "wake-up" time...questions

Hey Eja, It looks like you and I are looking to do pretty much the same thing. I wondered if you have proceeded with any of your plans and if so, what are the results. I am in Michigan, so it will be springtime before I am able to wake up mine. Let me know anything you find... Bondo, Thanks again for all the information. I have one question, Edelbrock has two Perfmormer 600 CFM carbs, one regular and one for "marine". Is there any advantage to going with the marine one? Or is this just built to accept a flame arrestor?

Bondo · Oct 13, 2005

Re: 4.3 "wake-up" time...questions

Bondo, Thanks again for all the information. I have one question, Edelbrock has two Perfmormer 600 CFM carbs, one regular and one for "marine". Is there any advantage to going with the marine one? Or is this just built to accept a flame arrestor?

You Need the Marine version,...... The float bowls are vented into the venturis,... Rather than onto the Hot Motor......... The air horn flanges are the Same......

4.3 "wake-up" time...questions

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