Weber carb install

[Not Billy]

I've just gotten a new (to me at least) 87 mighty max that doesn't run and had been sitting for about five years, i bought it with the carb off and it's so corroded that i'm not going to attempt to rebuild it, to me it's not worth the hassle when i barely know what i'm doing in the first place. so while shopping around i came across this website and discovered it's really common to swap webers on to these old trucks and i decided that's what i want to go with. I know this topic has been done a million times but i'm lazy and after reading through 6 pages of discussion i decided i'd just ask for help. There's the basics of the carb and adapter itself and the electric fuel pump, and i've already ordered those so I've got a few questions about the install.

geezer101 said on a old thread "There are intake manifold modifications you will also need to factor in (sealing the coolant port under the carb seat gasket and the coolant barb that normally runs to the Mikuni water choke)." so i guess i'll finally get around to asking my questions, do i need to do anything aside from attach the electric fuel pump in terms of regulators or pickups in the tank, what do i seal the coolant port under the carb gasket and barb with? and with the deleting the mechanical fuel pump is there any items i'll need to add to my shopping list to do that?

Again, sorry for bringing up something again and that's been discussed a million times, and sorry for asking what i'm sure seems to you guys are dumb questions. i come from the world of Hondas and efi and have yet to work on a carbureted engine let alone modify one so it's a completely new world for me.

[camoit]

If you get the proper kit it will block off the water port. There is an adapter plate the sits under the carb that does that. Then it's just a simple water line block off.
As for PSI no more then 3 PSI

[SubGothius]

For good measure, that coolant port in the manifold's carb mounting flange can be blocked with a stainless M8 (or was it M6?) grub screw (set screw). I'd recommend tapping that port just deep enough for the screw to clear the carb mounting face when screwed in tight (i.e., not tapped all the way through), and be sure to use thread sealant (e.g. Permatex 59214).

There's a coolant tee towards the rear of the manifold you'll need to address, as you won't need the side branch of that to supply coolant to the carb anymore. Some folks just replace that with a straight barb, but mine would not budge one bit, so I just capped the extra barb with a short length of fuel hose plugged with a bolt, hose clamps on the barb and bolt ends.

To remove the stock fuel pump, removing the valve cover will make it much easier to see when the camshaft has rotated to a point where it can release the drive tang to the pump. To block off the hole where the pump mounts, get a fuel pump block-off plate for big-block Chevy/Ford/Mopar V8s or small-block Ford/Mopar V8s, the two-bolt diamond-shaped type (SBC uses a different 4-bolt plate style). You may need to shave down the two longer sides a bit to fit, so I'd advise avoiding the steel plates, as the cast/alloy/billet/aluminum ones will be much easier to grind/file down -- e.g., this (https://www.ebay.com/itm/264745374202) or this (https://www.ebay.com/itm/265085228389) should be fine.

Also, make sure you're getting a genuine Weber carb made in Spain, as the licensed clones made in China are poorly made and can never be tuned to run right in all conditions. All they licensed was the name/logo and general design blueprint, but they are not manufactured/finished to the exacting tolerances required for proper running and tuning. Clones will have a smooth/shiny finish with the Weber name/logo only on a decal or ink stamp, whereas the genuine article has a rough/dull finish with the Weber name/logo and "Made in Spain" cast right into the body. Clones also usually have a black plastic cover on the electric choke element, vs. a translucent/white cover on the genuine ones, but this isn't a dead giveaway either way, as choke elements can be swapped or upgraded from a water-operated choke.

If the fuel pump you got natively outputs 3-4psi or so, you shouldn't need a regulator. I really like the Carter P90091 pump for any Weber on any car, native PSI is perfect, and it outputs a smooth, continuous flow, whereas solenoid-piston pumps have a pulsing flow. Here's how I mounted it in front of the tank on my Gen2 '87 RWD longbed (not sure if other specs have similar structure here):

http://www.mightyram50.net/vbulletin/attachment.php?attachmentid=26414&stc=1 http://www.mightyram50.net/vbulletin/attachment.php?attachmentid=26415&stc=1

[Not Billy]

Thank you both so much for the help, I’ve ordered the block off plate and a better fuel pump, I originally ordered a cheap one but I figure it’s best to order one that I know from you guys works well with the set up instead of having to worry about it

[Not Billy]

Can either of you post a few pictures of the ignition coil and all the connections? The previous owner seemed to have replaced it with an after market unit, i knew about this buying the truck but looking deeper into i've seen the true extent of the jankiness of the swap. I don't know how similar our engines are but it'll at least give me a starting point.

[SubGothius]

My ignition was pretty janky when I got it as well, had an aftermarket canister-style coil just zip-tied to the stock solid-state coil, wound up replacing all of that with a stock-style solid-state Herko B108 coil off eBay for like $20. I wound up reassembling the brackets on that coil to put the resistor on the other side for better wire routing/management. As for the coil wiring, this post covers that pretty well (http://www.mightyram50.net/vbulletin/showthread.php/8541-Winning-the-battle-vs-the-ballast-resistor-88-g54b-ignition-coil-wiring).

[Not Billy]

hey thanks for the link, this helps a lot.

[geezer101]

You can also swap to a transformer type coil for some extra punch. They are an option in later trucks and are wired the same way. Added bonuses - cleaner burn, compact/space saving, more reliable/consistent spark @ higher rpm.

[SubGothius]

You can also swap to a transformer type coil for some extra punch. They are an option in later trucks and are wired the same way. Added bonuses - cleaner burn, compact/space saving, more reliable/consistent spark @ higher rpm.

Just to clarify/confirm, that would be what I called a solid-state coil, such as the Herko B108 coil I got. :)

[Not Billy]

How difficult would you say it is to wire in the electric fuel pump to go off the ignition? i was thinking i'll just wire it to a switch if it's a massive pain in the ass

[SubGothius]

You will at least want to wire in a relay, so the ignition switch triggers the relay, and the relay then connects power direct from the battery to the pump. I covered the relay wiring w/ diagrams here:

http://www.mightyram50.net/vbulletin/showthread.php/7609-Replacing-a-Mikuni-Carburetor-with-a-Weber-Carburetor?p=70182&viewfull=1#post70182

The oil-pressure safety switch there prevents hosing down the scene of a crash with raw fuel, by ensuring that power is cut to the fuel pump if the engine stops running with the ignition left on. That said, I haven't wired up that part yet, so for now I've just got ign. (+) power hooked directly from the coil resistor terminal (opposite the end connected to the coil) to terminal 86 on a SPST relay I had lying around. I plan to use some 2-wire lamp/speaker cord for the safety-switch circuit, to keep the wire routing tidy. A good place for the relay is on the inside driver's fender where the control box for the stock Mikuni carb used to mount, as removing that box leaves threaded bolt holes ready to use.

[Not Billy]

sorry for the dumb question, i'm horrible with this wiring stuff so i'll probably bring in someone else to help me either way but when i wire in the fuel pump with the relay would i be able to use the oil pressure switch as the trigger wire to send power from the battery to the fuel pump? at this point i'm kinda lost and trying to make sense of this, in other words i'm in over my head which sounds stupid but again, new platform, new everything for me but i sure as hell won't give up because i know there's a lot to learn with this project.

[Not Billy]

or trigger* not trigger wire sorry lol

[geezer101]

The preferred install method is using the live power to the fuel cut on the original factory carb set up as a trigger to a relay to run the fuel pump. It's the same wire you should be using for the electric choke swap on the Weber.

[SubGothius]

when i wire in the fuel pump with the relay would i be able to use the oil pressure switch as the trigger wire to send power from the battery to the fuel pump?

If you use an electrical relay, the trigger is turning the ignition key on, and w/ the oil pressure safety switch, that would interrupt the trigger circuit when there's no oil pressure -- i.e., there's two circuits going through the relay:


Trigger: Battery (+) > Ignition-on > Oil pressure safety switch > Relay trigger terminal 86 > Relay ground terminal 85 > Ground;
Power: Battery (+) > Relay power input terminal > Relay power output terminal > Fuel pump (+) terminal > [pump operates] > Fuel pump (-) terminal > Ground.

The stock oil pressure switch cannot be used as a relay or trigger by itself; all it does is complete a path to ground from the warning light -- i.e., oil pressure holds this switch open, so when there's no oil pressure the switch closes and completes the path from the single wire connected to it to the switch housing, which grounds to the engine block where it's screwed in.

Theoretically, you could use a DPST oil switch without a relay, so the two normally-open (N/O) terminals on the switch would perform the power-switching function instead of the relay, but this has some drawbacks:


No power to the pump while starting. This may be fine if you drive the truck daily, but if you let it sit long enough, you may need to reprime the fuel line by shorting the two leads at the oil switch together (or install a momentary switch to do this) to run the pump manually for a bit before starting;
A permanently-live wire running around the engine bay from the battery (+) terminal to the oil switch on the other side of the engine, so at least be sure to put a 10A fuse on this line right at the battery end, and route this wire well away from any moving or hot-exhaust parts (probably route it along the inner fenders and upper firewall). You'd also have some power drop to the pump due to the extra couple yards or so of wire this adds to the power circuit between the battery and pump.


The preferred install method is using the live power to the fuel cut on the original factory carb set up as a trigger to a relay to run the fuel pump. It's the same wire you should be using for the electric choke swap on the Weber.

That's one way of doing it, but IMO it's simpler and functionally-equivalent just wiring up the relay manually, since the ignition-on (+) terminal powering the coil is right there next to the battery anyway.

[Not Billy]

the way you just laid it out makes it so much simpler, thank you.

[Not Billy]

If you have a manual can you look up the torque specs and sequence for the bolts I scribbled on? I ordered one but it’s gonna be a few days

http://www.mightyram50.net/vbulletin/attachment.php?attachmentid=26443&stc=1

[Not Billy]

Tried to post a photo from my phone and it didn't work, here we go
https://imgur.com/w2R7o0p

[SubGothius]

Added that photo inline here for ya, Haynes manual says Camshaft Bearing Cap Bolts get 15 ft-lbs.

[Not Billy]

Thank you very much for the torque specs

[Not Billy]

do you know of any alignment dowels that will work? i had to helicoil a few of the bolt holes because the previous owner stripped them, I absolutely destroyed the dowels. I've looked all over automotive websites to look for replacements and haven't found any but i might just be searching the wrong terms, worst comes to worst i got one that's savable from a junk yard and i can use that to take measurements and make new ones

[Not Billy]

Trigger: Battery (+) > Ignition-on > Oil pressure safety switch > Relay trigger terminal 86 > Relay ground terminal 85 > Ground;
Power: Battery (+) > Relay power input terminal > Relay power output terminal > Fuel pump (+) terminal > [pump operates] > Fuel pump (-) terminal > Ground.

Most of this was simple enough for my smooth brain to understand but i'm a bit lost on the ignition-on part, what exactly do i connect to next to the battery?

If you're willing it'd be much easier (for me) if you post a few pics as it's much simpler for me to get the hang of stuff visually than otherwise. Again, thank you for all the help so far and i owe you tremendously.

[SubGothius]

Ignition-on just means the key is turned on -- i.e., you'd just run a wire from a terminal that has power when the key is on, to the oil-pressure safety switch. Then run another wire (or the other wire of the pair, if you use a paired lamp/speaker cord like I suggested) from the opposite terminal of the safety switch to terminal 86 on the relay. I only mentioned "Battery (+)" for the Trigger circuit to explain the entire circuit path; you won't manually connect anything to the battery for this circuit.

For that key-on terminal, I'd suggest using the one on the ignition coil resistor, opposite from the end that has a wire connected directly to the coil's (+) terminal. If you're not sure, one end of the resistor should have a black with red-stripe wire connected, and the other end should have a few black with white-stripe wires connected, and that last one is the terminal you'd use.

[Not Billy]

Well, there's good news and bad news, firstly, i got everything mounted, wired, and working correct thanks to you, but when I went to change the spark plugs one snapped in half, i was happy because no porcelain went into cylinder because of how it snapped, so i soaked it in PB plaster for a week, tried to get it off with a easy out and it wouldn't budge, came back later with a square easy out and more PB blaster and still wouldn't budge, so i heated the shit out of it, and even more PB blaster later i snapped the easy out. I've been looking and heads seem fairly inexpensive and i think that'd be the best option being the state the head is in already. is CIFIC a good brand to go with?

[xboxrox]

The busted spark plug still in the head? Get it out before buying a new head..!

You have the right idea to loosen stuck threads but at this point you need a way to apply a LOT more heat in a LOT faster manner !!

Take steps to protect the ECM computer from welding Google it before drawing an arc on your truck !!

One last resort is to use a stick welder 'n welding rod (1/8 ") with machine turned up high enuff to melt it not weld it ~ cut the rod length in half for better arc control ~ you can use heat tape to cover the areas you don't want touched with a HOT ARC ~ all the aluminum head area & around the spark plug's wrench flats 'n just arc in the center ~ try to maintain an arc long enuff to make the steel spark plug metal cherry red orange or even yellow ~ THEN COOL DOWN ALL THE METAL by giving the spark plug a garden hose shot of cold water, the colder the better ~ wrench only on COOL COLD METAL ~ wrenching it in both directions tighter & looser DO TIGHTER 1st ~ wrench on it like you're tapping threads with a tap ~ after you remove the spark plug you can use a 14mm thread restorer with anti seize compound to fix & restore the aluminum threads NO PROBLEM

ANOTHER METHOD: Chisle off the spark plug insulator & weld a hex head bolt onto the steel portion of the plug ~ taper the end of the bolt a little to help make a good strong bond ~ favor more taper in areas easiest to reach with the welding rod (use 3/32" size rod) shorten the welding rods for better control

ANOTHER METHOD: Remove the stuck spark plug by melting it out ~ I AM NOT SURE which is best for fire safety ?? Have that cylinder @ compression intake or exhaust stroke ?? I THINK COMPRESSION STROKE @ TDC WOULD BE MY CHOICE (that would present the least amount of cylinder 'n valve to possibly get crapped up)

ANOTHER METHOD: Done with cylinder head either ON or REMOVED from the engine ~ use a 1/4" die grinder with a bulb headed or end cutting cylinder shaped tungsten carbide BURR

LAST RESORT: Buy & install a new cylinder head ~ I think you can remove the stuck spark plug & hope you do

Stuck spark plugs might be caused by galled threads which can happen when dissimilar hard & soft metals are threaded together ~ I BEEN PREACHING NEVER INSTALL OR REMOVE SPARK PLUGS ON A WARM OR HOT ENGINE

NOTE: The 3M Heat Tape is pricey but needed ~ if the local welding supply stores don't have it then try government & military repair shops ~ you'll get it out even if you need to melt it out ~ everything after that is a piece of cake ~ any folks with decent stick welding skills can do it ~ good luck & have a way to extinguish any fires just in case
:thumbup:

[geezer101]

It is really risky to go chopping or melting a plug while the head is mounted (you could leave a nasty surprise inside the cylinder bore - game over if you don't remove it) So you actually snapped the body of the plug where the plug socket would normally grab it?

[SubGothius]

The steel plug may have galled (cold-welded) to the aluminum head. To avoid this in the future, use one of those anti-sieze crayons on the threads, and torque to spec (14-22 ft-lb -- I'd stick with 14 due to the lubricant effect of the anti-sieze).

[Not Billy]

Only thing that's left is the threads and the ground electrode

[Not Billy]

I really like this truck but man this is a massive kick in the nuts, guess it's the risk you take when you buy a truck that's been sitting forever. https://imgur.com/mFfW96g

Anyone know who makes the best rebuild kit?

[Not Billy]

I bit the bullet and brought my motor to a machine shop to have them redo the block, aside from that i've taken the opportunity to go through and clean up my wiring further and find a better mounting spot for my fuel pump. All new parts all around and everything seems to lined up so I'll leave it at that, I'm mostly writing this post to thank all who have contributed and answered all my dumb questions. Especially you SubGotheus. After this project is wrapped up I think I'm gonna stick to the engines I know well, This has been a huge learning curve and one I quite honestly don't want to experience again.

[geezer101]

The 4G54 isn't the simplest engine to work on even though it's 'only' a single cam 4 cylinder. To do anything on it requires tearing almost 1/3 of the engine apart, the stock carb is the stuff of nightmares and there is always some confusion over timing and starter motor compatibility etc. Most shops don't have a clue about them and invariably mess something up. That being said, the steep learning curve is worth it. When you get it glued back together with the new carb, it'll be a whole new beast to drive.