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Main differences are usually the cam, more compression, and total lack of emissions equipment, in most marine apps, the 4.3 is fed by a Q-Jet...
 

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I built a 4.3 for a toyota, we used vortec heads and the biggest COMP cam they list in the online catalog with a 600 cfm holley vac sec. It made 272 hp and 300 ft lbs of torque. We used flat top 4 valve relief pistons and a edelbrock intake running the factory header type manifold. Only thing I would do differently is to run a 390 cfm Holley vac sec cause at 6000 its only pulling about 370 cfm.

I say go for it, its more then you need in a toyota.
 

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we used a couple of their 5.7Ls in one of our boats...very easy setup but I think I would rather pay almost the same price and get one of the advance adapters engines (or something similar)...we paid about $3500 each but we usually get a killer price break so I dont know what normal price would be...to give you an idea, we pay $9K-$12.5K for brand new merc 250 outboards and I believe they list for somewhere around $20K-$25K...

EDIT: The one thing that is nice about these merc engines is they are fully self contained...even the computer mounts on the engine. In a recent one of the HP mags (dont know which one for sure) they had a guy that built a 4.3L and got reliable 300HP for around $3K (that includes everything but the original block)
 

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Discussion Starter #6
I want to stick with my tbi unit I have on the 4.3 that is in the truck right now. I know I will have to get the ecm reprogramed but for rock crawing fi is the only way to go.

I would like to just get a strong reliable(200+hp) 4.3 that will still work with the stock tbi. If anyone can find any info on building one to get that kind of power from a tbi :eek: I would be happy. I have searched the net for about a week now and can't find any good info on what cam,heads, comp. ratio...ect to get a strong 200 hp.
 

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TOY 2 said:
I want to stick with my tbi unit I have on the 4.3 that is in the truck right now. I know I will have to get the ecm reprogramed but for rock crawing fi is the only way to go.

I would like to just get a strong reliable(200+hp) 4.3 that will still work with the stock tbi. If anyone can find any info on building one to get that kind of power from a tbi :eek: I would be happy. I have searched the net for about a week now and can't find any good info on what cam,heads, comp. ratio...ect to get a strong 200 hp.
The combo I used with about a 9:1 compression will work fine with your TBI and make at least 250 hp. Just get the PROM reprogrammed for the cam specs..
 

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those motors kick ass, they are the same as the volvo boats, which are just 4.3's with volvo badgeing, they sound like v-8's with duals and flows. and makes you think there is one under the hood. well worth the money.
 

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Discussion Starter #11
TPIJeep said:
The combo I used with about a 9:1 compression will work fine with your TBI and make at least 250 hp. Just get the PROM reprogrammed for the cam specs..

So use the Vortec heads a big cam and lower the compression to 9:1 :confused: Did you have your 4.3 dynoed?
 

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Yes I dynoed the 4.3 on my dyno. we used stock vortec heads, port matched the intake, and used cast flat top 4 valve relief pistons. I used a comp cam High Energy Series.. Part number 18-124-4 268 duration and .454 lift with roller rockers. The comp ratio came out to around 9:1-9.3:1. If you find a good PROM burner it will be all good. You need to flow about 375 cfm thru the Throttle body. We built this motor for under 1200 and that included the cores on the heads, the valve job, new valves, new pistons, rings, bearings boring the block .030 over, cam, lifters, roller rockers, and full gasket set.
 

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Discussion Starter #13
do you have a write up on this rebuild?What do you mean by "vortec heads"? are you talking about 96 and newer heads? I searched the part # you gave for the cam and could not find anything? Did the engine idle fine with that cam? or should I go with a milder cam for rock crawling? Do you know by chance what cfm the stock throttle body flows? I hope I'm not being a thorn in your side :D Thanks for all your help
 

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The cam is listed here http://www.compcams.com/Technical/CurrentCatalog/HTML/124-127.asp last one under the High Energy series.. I have no write up, we build to many motors to write about all of them..

The heads are vortec style, same combustion chamber shape as the v-8 vortec, I believe its the 96 and up, kidney shaped chamber. The motor will idle at 650 rpm and really has very little lope. Its in a Yota that we will soon link out for crawlin'
 

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I believe they started using Vortec 4.3s in 94.
 

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Actually the 4.3 was called, "Vortec" in 1985. But the "Vortec" heads you guys are referring to started in late 1992 or so on the vin code "W" engines.
 

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Discussion Starter #17
could I use a trottle body off of a 305 or 350 to get the cfm that I will need? If that won't work could I just buy an adjustable fuel regulator and turn up the fuel delivered to the engine? I'm assuming that my secound suggestion would not work because it still wouldn't get enough air :D
 

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TOY 2 said:
could I use a trottle body off of a 305 or 350 to get the cfm that I will need?
The only difference in the 4.3, 305, and 350 TBI units is the injectors (and of course the chip in the computer).

Pete
 

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who makes the intake that you are using to put the carb intake on vortec heads?

I would like to use vortec heads with on my tbi motor - I think I would just need a t-body adapter and a chip burned.

any inputs?
 
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