4.3L Vortec Marine Intake Conversion Helpfull Hints:

[UR50SLO]

Our Test Mule... 98 GMC 4dr Mega Moose Jimmy 4x4.


Hello 4.3L Fans....

If your looking for some information for deciding weather the Marine intake will work on your truck and if it's worth the work involved in doing the swap.

Let's start at the begining:

GM decided it'd be a cost saver to make a small compact injector with nylon lines with "poppet" valves for the 4.3L Vortec engines (and V8's)
They fit under the plastic upper plenum and click into the lower intake where they spray at the intake valve.
They generally have 23.1lb/hr injectors (v6/v8) Since they share the same bore and stroke. So there is no upgrades avalible for this system.

There is pages of GM Tech bullitens describing problems with this system.... Everything from hard starts to hesitations and mis-fires. The poppet valves tend to stick or leak.. Sometimes on a backfire the nylon fuel lines melt and it just sprays fuel in the plenum!

The two major reasons to change out for the Marine intake.

1) For a more dependable fuel delevery system that will be trouble free for many miles and should give better power and fuel mileage.
2) Your current system is not upgradable and there for will not work on a force induction application (turbo/SC) and you need a new way to be able to
add more fuel.

Let's start with the simple facts first.

The marine intake is a direct bolt on for any Vortec headed 4.3L.
Remove old intake,Clean,new gaskets,Install lower intake.
Uses stock application intake gaskets. Plastic/rubber.


From here there's several differences that your going to run into. I'll try and lay out the hurdles on each part one at a time so as you come across them you will be able to figure it out quickly.

Removal of old intake:

If your this far.. your commited.. Here we go.

Quicky removal stuff as usual:
Disconnect battery, De-pressure fuel,drain cooling system,remove fuel lines from top of injector pack, connectors,Throttlbody,distributer(label where it is or put on #1tdc)
*hint* remove a/c compressor... if you've got a carbide bit or dremel tool you can grind away some of the bracket to allow you to get at the intake bolt hidden under there. It won't hurt the bracket and it saves you from taking the entire bracket back or off to access that one darn bolt. GM should have made it accessable from the factory*.
Remove bolts and pull intake.
Clean and place new gaskets/new *HEAVY* lower plenum.. I wondered if they sent me a intake or a boat anchor.
*Mark exact position of distributer rotor position and make darn sure it go's exactly back
where it was* There is no adjustment like old ones.

Now the nitty gritty.

Brake Booster:
The upper alluminum plenum needs to be tapped at the back where the MAP sensor would go (for the marine application) 3/8 Pipe tap and fittings work good here to a barb where you can then plug your Brake booster line back into. *There are several other places up there you can do the same thing*
The Marine intake MAP sensor will not work with your system since it has the temp sender and the MAP all in one.

PCV:
Run the PCV line to the valve cover with 3/8 evap/fuel line. I used the Marine intake's metal line to do this.

MAP/Vaccume connections:
I used a few T-s to run the vaccume lines... One to the Fuel Pressure regulator on the Marine intake*Needs that*

EVAP:
You can hook your evap solonoid up to any vaccume connection if you desire.

EGR:
If your going to re install your EGR the Marine intake does have the brass plug up in the front that "can" feed EGR. You will have to get a bit creative here and make a flange coming off your stock feed tube. Then feed the port in the front of the marine intake the outlet of your EGR.
It's possible but this will take some fabrication. (I delted ours)
If your going to delete this... You can remove the fitting in the drivers manifold and put a plug in it or cut and weld that existing plug shut.

Injector wiring:
You will need to cut the injector harness off at the connector.
There are 12 wires total.
ALL Pinks are 12volts with Ignition on. (hot)
All the other wires are grounded by the ECM.
You will need injector connectors for your stye or choice of Injector.(6)
Wiring is as follows:
(Letters are on the stock injector connector)*see picture below*
#1 injector: (E) Pink and (F) Black
#2 injector: (H) Pink and (G) Green/Black
#3 injector: (D) Pink and (C) Pink/Black
#4 injector: (J) Pink and (K) Light blue/Black
#5 injector: (B) Pink and (A) Black/White
#6 injector: (L) Pink and (M) Yellow/Black
Please take the time to solder your connetions and shrink wrap. Make sure your wires are long enough to go to each injector.
This is the only wiring you'll have to do on the entire project. Cool !!!

Fuel Feed Fuel Return:
There's several ways to change the fuel line feed and return. They make fittings to convert the connetions at the back of the intake to AN. You can do it that way. More expensive but a very good way.
I ended up taking that fitting off the lines coming up from under the truck off. I removed the two small o-rings. I purchased from Autozone the "Goodyear" brand High Pressure Fuel Injection hose. 3/8 for the feed and 5 1/16 for the return. Also Fuel injection clamps. (worm clamp will work too) I did double clamp each end. The barb on the up coming fuel line helps keep the line on as does the barb on your Marine intake inlet fuel line.
We've had this on there for 15,000mi with no problems so far.

Coolant Lines:
I used a few fittings from the "Help" secion at advance/zone. To adapt a few differences in the heater hoses.

Throttle Body:
The stock marine intake throttle body will not work with our throttle linkage.
You will need to re-use the stock GM throttle body.(Or LS1) See below Post!

The problem is the marine throttle body has a o-ring seal on it.... where the stock GM has the seal on the plenum. So, when we go to use the stock throttle body on the Marine plenum.. we are left with no gasket!
Get some of the black gasket in a roll from auto parts store. It's like black cardboard.
Take some masking tape and lay it on the bottom of your stock throttlebody. Trace out with a marker where your holes are and pattern.
Cut out the places that need to be open, lay on your gasket material and then cut the gasket.
Make sure to trial fit it to the manifold and throttle body to make sure you have all the holes cut out and it fits with out haning out anywhere it shouldn't.
The cruze lever will hit the fuel rail. Carfully bend the cruze lever up till it does not hit the rail. Simple enough.


Making sure you've got all connections hooked up, wiring double checked, cooant filled,distributer clocked right it's time to see if your hard work payed off.

Notes from my experiences:

I had trouble sealing the 32lb/hr injectors to the lower manifold. I ended up using the o-rings off the marine intake and one thinner o-ring on top of that to get a good seal.

Stock Marine intake fuel pressure is higher than ours trucks was stock, The injectors are 24lb/hr also. So if your planning on not programming the ECM for the differences you will need to buy a Adjustable Fuel PRessure REgulator for the 98Corvette fuel rail. It is a direct fit for the Marine intake fuel rail and will allow you to adjust the fuel pressure down to where your (Short term/Long term Fuel trims) are low. 1-4%. Any Scan tool will show those perameters.
(link for AFPR)---http://www.ecklers.com/product.asp?p...LL-_-35855-_-X

Our 98 Jimmy is Turbo charged with stock Typhoon exhaust manifolds,turbo,downpipe. We have over 15,000mi on it being turbo and has 150+000mi on the stock engine. We run 10-11psi of boost every day. It get's better MPG than stock and is WAY more fun to drive.

With 9lbs of boost it went 14.40@93mph on 93oct in full 4wd

You Tube Video:
http://www.youtube.com/user/UR50SLO#.../2/Dqy_2X5uSmg

Overall the Marine intake has been fantastic. I've also done a 99 Blazer in the same fashon as ours that he plans on going turbo soon.

Any questions not covered here please feel free to e-mail me,
UR50SLO@aol.com

I will be updating this and adding complete pictures with details:
Cheers,
Scott

Information found by others while installing Marine intake!

1*Well, you should add in there "MARK THE DISTRIBUTOR/ROTOR/MANIFOLD"
DO NOT TRY TO EYEBALL IT AND REMEMBER WHERE IT GOES, MARK IT!!"


Seriously, it needs the boldness. lol

Here are some starter pictures. I hope it's ok if I put them all down here and label what they are instead of breaking up the above information.

Parts break down of the Marine intake manifold:


Page out of the manual for injector wiring:


Details of coolant and brake with 3/8 pipe tap.


Marine intake installed and wired, See how close that cruze lever is! Just bend it out toward the fender to miss the rail.


Close up of PCV location,Brake booster,Vaccume T-s for MAP and other vaccume related pcs.


Coolant bypass line with fittings from "help" and if yours is turbo like ours you'll want to drill/tap that place to feed the turbo coolant.
Also note the bend of the cruze lever from that angle.



I'll bring the truck over and pop off the A/C compressor and take a picture of how much material I took off the A/C bracket for access to that hidden bolt.

(Picture)

Here is what I did with our truck. Engine bay picture with turbo setup.

[04SilveradoMykk]

Thank you Scott, great information!

[UR50SLO]

Ok... so you've got your Marine intake all finished and it's running good... Now what?

If your this far your as nutty as Squirl $*** right?

Here's most of the parts you'll need to get TurboCharged with some garage know how and pure drive to be different and re-design somthing with a bunch of parts GM already made ! It's a slap in their face for sure... given that they've already designed all the parts we'll be useing for the most part and they don't have the smarts to know that they can use stuff they've already got to make a truck more power,better economy and blow away other brands trucks away... heck most of the other brands muscle cars away for that matter!

Here we go:
It's fairly labor intensive.. but the parts shouln't cost that much.

Never Ever buy a FMU to fuel one of these engines. I'm not going to rant on about that but a FMU should never be used to fuel a engine PERIOD. I'd put a piggy back system on before I'd use one of those steaming piles. Ok.. rant finished.

You'll need:
Sy/Ty stock exhaust Manifolds (300ish used)
Stock Sy/Ty style turbo/downpipe (75ish) Will weld to stock exhaust! Wow.
Marine Intake Manifold (e-bay) 400.00 ish. *cheaper now..*
30lb/hr injectors or larger.
HPTuners. I have a file setup for 10psi
Some 2.5" mandrel bends (steel) 13-15.00 each bend
E-bay Intercooler (Under 100.00)
Moroso 2-part epoxy to affix a bonnet to the Throttle body. Or have a flange welded on ... A guy on another site said that a LS1 throttle body is the same size but has a nice long snout on it that you could attatch a bonnet to with out welding! You'd need to transfer the shaft from the 4.3L to keep the same throttle apendages.
Cut/weld pipes so it's arranged in a flowing fashon.. like mine or not..up to you.
You'll need to plumb the oil feed off the drivers side oil pressure feed line (above oil filter housing) You'll need 5feet of -4 AN hose and fittings.
There's a fitting you can put where your oil level sensor is for the oil return.
(Guy's with 3.8L F-bodys do it with no problems) I've not tried it yet. I put mine in the hard way... took off pan.. ect.
Coolant feed to-turbo/from turbo.
Relocate MAF Pre-turbo.
Put IAT sensor into incoming pipe (after turbo/IC)

Tuning.... Tuning... That's what is going to make or break these setups.
If it's not tuned right or skimp on fueling it correctly/timing/settings you'll be looking at a yard orniment with a blown engine. 4.3L don't take detonation well. It wipes the mains right out of them.
3.8L buicks are more forgiving and just blow head gaskets. We've got too much clamping force on our 4.3L head to blow them out.

Finished picture of engine bay with Intercooler pipes.



Power steering stud/bracket that will need removed/cut all the way down so exhaust manifold will fit on (Typhoon exhaust mfld.)



How the Typhoon turbo coolant/oil feeds are routed.



Where to put the 3/8 pipe to -4AN fitting into block above oil filter housing



Where to install the return line from turbo to bottom pass. side of block.



More to come.

OK.. New update: The below pictures shows the stock Thorttlebody with a hat I made... I epoxy'd that together to see how long it would hold.
It lasted till today. Approx 25,000mi. Not bad for steel to allum. with only epoxy holding it.

Well you all wondered if a LS1 throttlebody was a direct swap. I can tell you now that it is almost a direct swap. Below are the pictures and details of how to intergrate a LS1 Throttlebody to your Marine intake.

This includes swapping over sensors.. (easy)
ANd then grinding off the shaft ends off both throttle bodys so you can transfer your stock linkage to the LS1. (They are clocked different)
I made another gasket for this.
If enough people are interested I'll make a bunch of the gaskets.

The reason for the change in throttle body is that the stock Throttlebody does not have enough of a "Lip" to hold a clamp or anything when going to a boosted application.
With the LS1 there is plenty of a lip to grab onto. Plus it's a tad bit bigger

Below are pictures of a LS1 Throttlebody:





Below you must grind that tab off and remove the linkage till the "Stop" is left. Then install
your stock linkage so the clocking is correct for your stock throttle cable/cruse!



Below shows the clocking differences in the two throttlebodys


Below is the stock throttle linkage installed and welded at the end



Below here it is intalled .. and open into the Marine plenum/intake.




Here it is after a hour of figuring out what to do.. taking pictures for you guys and re-installing it back on the truck.. started right up. The blue coupler will get replaced with a red one. And I need to paint the pipes again.. but it's a daily driver.. not a Typhoon.
It's just intended to make Trailblazer SS's scratch their heads and most mustangs LOL!




Hope that helps,
Scott~
UR50SLO@aol.com

[UR50SLO]

Hope this helps someone who wants to do a cheaper better fuel pump for the sending units like this one. The Warbro 255lr/hr pump is 99.00 through www.fullthrottlespeed.com
Here's the process.
Dis-assemble with screwdriver. Push in the two tabs on each side of the slide in plastic center section.. it comes apart. Remove all old parts from inside.. including the black plastic line/rubber gromits ect. Gut everything.
I put the pump back in the black rubber jacket that was on the old pump. It sets the right depth for the new one. It's snug.. .but it'll go on. Light oil might help slid it on.
The pump comes with all hose/clamps/wire harness adaptor. Plug and play.
I cut approx 1/4 to 1/2" off the hose it comes with since the pump is on "springs" and you have to push it down some in the tank.. By cutting that small peice off it pre-loads the springs and it shouldn't kink the hose when you put it in the tank. If you leave it too long there's a chance when you push it down into the tank it could fold too far and kink the rubber feed line......
That's really it. I filed the top of the sending unit by where the wires plug in so I could get the screwdiver/clamp on a little deeper....
Hope that helps,Scott~
All apart and gutted



This is all the stuff you won't need


All parts... tools old/new and kit.


This is almost together. Need to cut that much off the hose (excess to load the springs)
Then slide it all back down into the housing and make sure the fuel sock(Strainer) is at the bottom. Click the wires together and it should look like this.(below)

After doing this I had a issue with 25,000mi on the fuel pump where the hose pictued below "Grew" maby with the local stations having some ethanol in the fuel. It was kinked a bit after it grew and causing some feed issues. I decided to use two small sections of hose and a peice of 3/8 steel fuel line between the pump and pipe... then pipe to top of sending unit so there was no chance of it growing and pinching off over time. I know the turbo buick's use just a small section of this hose with no failures.
I thought i'd give you a update of what happend to mine. I installed a new Warbro just in case it got damaged with the kinked hose.

Here it is all together and with the box part number for you. That is how much hose I cut off the end to pre-load the springs.
Shouldn't take much longer than 15-20min to do this.


~Scott

[CoreyDTesta]

do the injectors & fuel rail come with the marine intake? i noticed u mentioned u get this intake set up from gm, do u have a part number?
and thanks again for this info,u jus brought my faith back to the 4.3 i cant wait to do this

[UR50SLO]

You'll have to get this from E-bay. It comes complete with fuel rails/injectors/lower/upper plenum and FPR. I paid 400.00 for mine but they've been going for about 200.00 now... Guess I should have waited.

The intake is for the 4.3L but Mercruser is who is in charge of it. These were never put on a production vehicle.
Hope that helps,
Scott~

[CoreyDTesta]

Originally Posted by UR50SLO

You'll have to get this from E-bay. It comes complete with fuel rails/injectors/lower/upper plenum and FPR. I paid 400.00 for mine but they've been going for about 200.00 now... Guess I should have waited.

The intake is for the 4.3L but Mercruser is who is in charge of it. These were never put on a production vehicle.
Hope that helps,
Scott~

thanks again that should get me there

[CoreyDTesta]

http://cgi.ebay.ca/Mercruiser-Volvo-...|39:1|240:1318shoot is a 4.3 mercruiser-volvo it? this is the link

[UR50SLO]

That's the one!

Great price... dang!
~Scott

[bobfig]

nice write up but one question what injectors dose this take? and what numbers?

[CoreyDTesta]

thank u very much im tryin to get m y sis to put it thro her account
are they pften around cuz its the only one on right now.. shes tryin to put me off a bit cuz of the christmas shit, i really should jus link my card to paypal and do it

[UR50SLO]

nice write up but one question what injectors dose this take? and what numbers?

You can install any top feed/GM injector in it. The manifold comes with 24lb/hr injectors. If you plan on using them you'll need a AFPR to dial down the Fuel Pressure till your LTFT/STFT's are with in 5%. (long/short fuel trims)
I listed the AFPR application above.
hope that helps,
Scott~
(Turbo Pic's are above)

[F4tal]

I cant believe i just found out about this forum!!!
IM IN HEAVEN!!!
Great write up... im thinking of doing this same setup on my 4.3 silverado

[UR50SLO]

Welcome to the board!!

It's a very reliable setup. It's definatly got my wife "by" since I've been working on her 92 Typhoon. If I had not taken the time to turbo the 98Jimmy I'd hear about it every day.
She's got the boost bug as bad as I do....
Let me know if you run into any trouble with the swap,
Scott!

[F4tal]

Id rather just pay to have it put in. I could do the swap... I just wouldnt feel comfortable drill tappin holes and rerouting lines...