86 C-10 305 with new Edelbrock 1406

[ebgwd]

Just got this truck a few months ago. It does run but bucks and jumps when underload or even going up a steep hill. It has a new eddy1406 carb and I checked the fuel pressure and it jumps around while at idle and goes to about 5 psig when I rev it up. It has electric choke.

If I floor the gas while at idle the engine bucks and chokes completely.

I pulled the carb fuel inlet line and checked the screen, it is clean.

Is 5 psi enough for the 1406 carb?

I am new to fixin trucks and eager to learn so that I can get this baby up and running like it should.
Thx

[benoit454]

you checked the plugs? could be running lean, we had a quadrajet do that.

[gchemist]

Yea, the problem is the air filter. Your are choking the engine! I had a 305 with the same carb. I used a 4.5" K&N filter. It would scream all the way to floating valves.

I see the fusible link is bypassed. Does it have a fuse somewhere else? You are also running ported vaccum on it.

[nbpro]

These carbs trys to flood at more than 5.5 psi. I use an adjustable reg and keep mine at 5.25 psi

check your pump shot, for your 305 you may need to put the linkage in the bottom hole or middle hole

These carbs DO NOThave "fixed" jets . They have removeable and changeble jets

They do use metering rods and step up springs and you do use those for most mild tuning though.

The vac ports on carb front
pass side little = timed or ported vac (no vac at idle)
center large = full intake vac (common PCV valve hook up)
driver side little = full intake vac


EPS Carburetor Owner's Manual
http://www.edelbrock.com/automotive_...406_manual.pdf


EPS Carburetors Installation Instructions

http://www.edelbrock.com/automotive_.../1000/1406.pdf

[C-10 simplex]

i continue to be perplexed as to why EVERYONE (and his brother) insist on switching carbs(usually holley or edlebrock) on a stock engine with stock manifold?

[Warrens69GMC]

Originally Posted by C-10 simplex

i continue to be perplexed as to why EVERYONE (and his brother) insist on switching carbs(usually holley or edlebrock) on a stock engine with stock manifold?

The cost for a rebuilt "Stock" quadrajet with the electronic feedback solenoid is ~$500. Grab a adapter plate and a NEW Edelbrock 1406 for ~$300

[von guido]

1406 is too big of a carb for that motor. anyway, have you had a carb backfire recently?

[spudz]

Originally Posted by von guido

1406 is too big of a carb for that motor. anyway, have you had a carb backfire recently?

It doesnt have a power valve that blows out like a holley when it backfires. truck will run just fine with this carb.. Adjust and ride. his truck prolly just needs a tune up and timming adjustment/dist. rebuild.

[von guido]

Originally Posted by spudz

It doesnt have a power valve that blows out like a holley when it backfires. truck will run just fine with this carb.. Adjust and ride. his truck prolly just needs a tune up and timming adjustment/dist. rebuild.

lol.. i had a brain fart.

[nbpro]

1406 is what a 600 CFM Carb thats to big for a 305 ?

[ebgwd]

Pulled the ported Vac line off and plugged the hose and capped the fitting on the carb. It runs LOTS better now. Will check timing and read the install/operation pages from eddy. Thx

[benoit454]

a 600cfm is definately small enough for a 305, I got the sae one but manual choke on the 84 305 that dad had in his truck. I got a smaller air cleaner then that on it and it doesn't choke out at all. but ported vac plugged? where did it go? if it went to the dist. that aint too good of an idea to plug, but for me, running the dist. vac. adv. on ported worked best.

[gchemist]

My old 305 would smoke a stock 350 with that carb. I would easily flood it going from idle to WOT. Mechanical secondaries are the downside. Tune it for ported vacuum. It will run great.

[benoit454]

ok I gotcha and yea ours is the same way the 85 monte carlo with that 305 from the 84 c10 and that 600cfm man. choke vac. sec. carb will smoke the tires off of it but the 350 I had in it not so much lol and I had a stall convertor behind the 305 that was mildly built lol.

[nbpro]

My 500 CFM Carb is actually a old remanufactured Carter.
with the Edelbrock logo tag over the Carter tag But it's actually bigger than what Edelbrock rates it.500 CFM its more like 625cfm Weber is called Magneti Marelli. They have a plant down south where they make the Edelbrock carbs

[oldblue1968chevy]

so is a 500 eddy enough for a 355 vtec headed motor? or should i step upto 600cfm?

dude you need to find out where all those vacum lines go to! you have tees etc everywhere

[nbpro]

Originally Posted by oldblue1968chevy

so is a 500 eddy enough for a 355 vtec headed motor? or should i step upto 600cfm?

dude you need to find out where all those vacum lines go to! you have tees etc everywhere

step upto 600cfm i would say but I may be wrong. A lot of it has to do with cam, emissions systems. In some states you have to leave that on to pass emission standards. But that carb should run fine on your motor in my opinion, but I'm no expert, and I haven't stayed at a Holiday Inn recently either. i would ask in the engine and drivetrain forums for a better answer.

[68 TT]

Have you checked the vacuum level? That stock 305 should be pulling close to 24 inches of vacuum at idle unless it has a larger cam.

I have seen many engines with carb adapter plates that did not fit right and leaked a bunch of vacuum.

Check for vacuum leaks around the base of the carburetor.

My 1406 came with a thin metal spacer that fixed some of the vacuum loss problems as it covered more area than the adapter plates did. Did yours have one?

[nbpro]

Ported vacuum with-holds vacuum advance at idle, no vacuum will be applied till the throttle blade moves past the port thus exposing it to the pressure inside the manifold. As the throttle moves toward WOT at some point the manifold pressure and atmospheric pressure become nearly the same, thus no vacuum is present with a normally aspirated engine. So the vacuum advance amount becomes less and less as the throttle is opened.

Un-ported vacuum shows the advance mechanism manifold pressure from the moment the engine fires. To that end vacuum advance is present at idle This can help a low compression engine or a long cammed engine to idle and transition to mid throttle more smoothly.

There really isn't a right or wrong here, it's more studying what the engine as it's installed in the vehicle likes best.

[benoit454]

yea all of his vac. lines are smog junk, our 84 c10 w/ 305 had it all and I threw it away.

[Malo83]

Originally Posted by C-10 simplex

i continue to be perplexed as to why EVERYONE (and his brother) insist on switching carbs(usually holley or edlebrock) on a stock engine with stock manifold?

Agree!!!

[nbpro]

Originally Posted by Malo83

Agree!!!

This may be true, but if you look, he Just got this truck . Also, just the fact of the cost involved of a Quadrajet, which has already been mentioned.

[benoit454]

agreed not to mention how user friendly the edelbrock is and how easy/cheap it is to rebuild, like $40 for a kit and even somebody like myself who has/had never built one before can do so very easy. I did it and it was my first carb rebuild ever. Turned out great.

[nbpro]

yes that to

[Malo83]

I know he bought it that way but in the long run he'll have a better running truck with a properly set up Qjet, wonder if the people he bought the truck from have the old Qjet?