300 six with a 6=8 intake

-so i had origionaly grabed the intake from my brother who was at school , put it on my truck with a gasket which at the time i did not realize was missing the intake gasket, anyways we could never get the engine tuned right, or carbotator (rebiult edelbrok 4bl 650cfm) and then after a while it started having vacum leeks, when removed it was obviously the gasket, well that was the thought, now my brother puts it on his 250 aiming to show me up, puts the carb on it and it runs like crap, he puts an identical working carb off of a 75 ford of my dads that has a biult 390, this carb runs great but my brother can never tune it to the truck and it seems to load up all the time, the engine has no ***** and loads up and backfires when running the manual trany down hill with out touching the gas pedal, after many days of tweeking engine timeing and idle mixture, my brother gave up and removed the manifold to put his stalk manifold and 1 bl back on,

now, my question is, what causes this problem, is there somthing we should do, we have a cap we biult for the top of the stalk manifolds that boltd on with factory gasket, but it is thought the heat from the mainfold is needed in the four barrle but there no way to do this like the factory manifolds do, theres gotta be a trick cause i know these manifolds are used all over the country to biuld the 300 sixes

any answers are welcomed, thank you

 

i have a F-150, his is a f-250 to clarify that 250 number both have 300ci inlines in them

 

are you trying to use a 4 barrel carb on top of a 1 barrel manifold ? if that is so it will never work as you will be pouring gas down the engine ! that 650cfm carb would be way to big for that 6 cyl even if it was built up ! Clifford and Offy make a 4 barrel manifold that they recommend a HOLLY 390 cfm 4 barrel carb !

 

Without a very high level of tuning expertise, a 650 cfm carb probably won't work. Back off to something like a 500 cfm 1403 Edelbrock or as suggested, a 390 cfm Holley. And since the Clifford and Offy C are of the open plenum designs it might be productive of better results to use a 4-hole spacer between the carb and manifold.

 

He said he's using Clifford's intake, which is a 4bbl intake.



Dillon, unless I missed it somewhere, did you ever replace the gasket that was missing? No matter the amount of tuning you do, there's not a lot you can do to overcome vacuum leaks.



Also, have you adjusted your timing? It could be that your engine timing is out of tune with the carburetor. In the sticky on the main page, there's some good advice on how to properly adjust the idle mixture and engine timing using a vacuum gauge. I'd start there.

 

[quote=AbandonedBronco;10040337]He said he's using Clifford's intake, which is a 4bbl intake.


well i see that now , just slap me

 

Use Mr. Gasket #260.

From what I have seen from owners, a lot of time I would say that, "Clifford 6=8=trouble".

 

Sorry, rereading what I wrote, it kinda sounded snappy.

But if you insist...

 

Dillon, unless I missed it somewhere, did you ever replace the gasket that was missing? No matter the amount of tuning you do, there's not a lot you can do to overcome vacuum leaks.



Also, have you adjusted your timing? It could be that your engine timing is out of tune with the carburetor. In the sticky on the main page, there's some good advice on how to properly adjust the idle mixture and engine timing using a vacuum gauge. I'd start there.[/quote]


-yeah i never had the intake back on my truck, my brother put it on his, with a new gasket, he has adjusted timeing and idle, everything we can think of, and nothing seems to get it running good, it would idle at one adjustment good, but load up or have no *****, at the same time, im not sure which but my brother tried alot of things, i just gave up and took it off of mine, he finally has too, but id like to give it another shot on my truck, i just want to know what the problems have been

 

First, I would check for v.leaks with some quick start spray. Very methodically.

It sounds like it is running rich. Did you ck the plugs? What did they look like?

The paperwork in a rebuild kit will tell you what jet sizes that carb should have for particular engines, as well as where to set the float level, etc. I would guess the settings for a 289 would be good starting point.

IIRC on the Pony carburetors site there is a guide to help you choose cfm carb for your engine.

Good luck.