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Discussion Starter #1
please I need help on solving this one , I have a 1987 motorhome with a 460 and there are broken bolts on the intake manifold , should i remove the manifold and drill out the bolts or do i replace the intake if so what tpye would give me better performance thank you ps i have alot of raw fuel black smoke coming out my tail pipe, would reducing my jets help this? thank you.
 

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Intake

IF it is still available, I would recommend an intake similar to a Weiand SP series. These were designed for work from the basement up to about 5500 rpm, which is exactly where you need it. The alternative would be to just use a factory iron manifold, as for what you are going to get out of an aftermarket job, unless you plan other mods to the engine just isnt worth the expense, in my opinion. How long has it been since the engine was run, how old is the gas? How long since you did a tune up on the engine? How long since you went through the carburetor?
If you are going to replace the carburetor, I would recommend going with one not to exceed 600 cfm, the reason being is that you arent going to be racing this engine, and the smaller carb will give you higher fuel air flow velocities, insuring better mixture, which in turn will give you more power, and since you probably wont be turning this engine over 4500-5000 rpm at max, then a larger carb is totally unnecessary. Larger cfm carbs dont necessarily mean more power where you need it.

Were it my setup, I would probably run something in the neighborhood of a 500-550 cfm.
 

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Discussion Starter #4
intake on a 460

i tuned up my engine with new wires plugs cap and rotor, but my problem is that afew years ago i had the engine removed to repair exhaust manifold bolts, and the company doing the work removed and bypassed the air pumps and other smog and power robbing componants, the bolts that i broke off were holding down a makeshift plate over what may have been a port to the egr valve i dont have room to drill out these bolts and i'm thinking my 460 would run better with an after market manifold the carb is a factory ford holley i don't know the cfm, thank you guys for your input.
 

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Intake

An alternative is to check your local swap meets or look in the classifieds for a used intake. Otherwise I would go to the bone yard and yank an intake off another engine.

And run your stock carb.
 

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Discussion Starter #7
intake on a 460

hi again , i'm wondering what the spacer under my carb is for i'ts about 3/4 of an inch thick with a valve some what looking like an egr valve towards the back of the engine it's about 10lbs and has holes that line up with the intake , so i don't know if i should use a manifold with or with out an egr . talk to ya later.
 

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Intake

That adapter plate serves several purposes.
One is that is the EGR valve assembly and the extra ports do align to the intake heat crossover ports on the heads. Secondly, on a lot of Ford intakes, that spaced the ccarburetor high enough so the throttle linkage wouldnt hit on the intake manifold itself, causing limited carb operation. Thirdly, it helps increase the velocity of the fuel air mixture as it goes into the intake. On a lot of those spacer plates you will also find the fitting for the hose or tube going to the PCV valve. I dont recommend trying to run your engine with your stock manifold without it. That would have serious detrimental effects on its state of tune.
 

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Discussion Starter #9
intake on a 460

thank you Max . if i replaced my manifold with an after market one would i still need that spacer and when i get this thing running again what would be the fix for the black smoke out my tail pipe when i am pushing my heavy rv up a hill , with my secondaries about half way open and friends behind me say it smells strong of gas
 

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460 intake

I would run the spacer, unless your aftermarket intake doesnt have a port to supply the EGR. In that event, invest in a regular 4 port spacer plate available at most any auto parts place. Be sure to measure your venturis first, as those plates do come with a variety of port sizes. I would not recommend running one of the open one hole style spacers. I would also do a rebuild on that carburetor if I was you. Sounds like you could have a possible dead float (sprung a leak or got saturated inside), causing your secondaries to flood, or a variety of issues there that could cause you to be running rich.

Since you are going to have the intake off anyway, that would be a good time to go through the carb. Wondering if your engine misses or stumbles when you are pulling a load like that?
 

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Discussion Starter #11
intake on a 460

Hi Max thank you for you'r time, no my engine runs very smooth on idle and when pulling, but when i start it up after putting the petal to the floor to close the choke it will only run smooth for about1-2min then it starts to get very shakey and starts to smoke , at that point I kick the gas pettal the rpm comes down 200 or so and in another 5 min i can kick it to 800 and i have to stay in my seat and feather the gas till she is warm or it will stall. thank you
 

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460

I just happen to think of something, what about your choke? is it tight in its linkage? does it have a tendency to flop over and want to close under hard throttle? Try running your engine til it warms up, then with air cleaner off, watch your choke butter fly and rap up your engine with your hand on the carb linkage, or have someone give the throttle hard blips as you watch. It could be your choke is giving you problems, that the butterfly may be wanting to close partially under hard axceleration. When your engine is warmed up the choke should be full open and have not tendency to want to suck closed when you hit the go pedal. If it does, this can be adjusted by loosening the choke spring housing and turn it so the butterfly fully opens. Dont keep turning the housing as this will affect your choke not being able to work at all. If all else fails, install a manual choke kit on your carb.
 

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Discussion Starter #13
intake on a 460

thanx when i get my manifold trouble worked out and my carb reinstalled i'll give that a try.
 
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