Posted By: 68CoronetRT
68 Fuel Vapor Separater for 440 - 12/21/11 05:05 PM
Does anyone have a recommended source for these?
Anything to watch for on the repos?
Anything to watch for on the repos?
68 Fuel Vapor Separater for 440
Posted By: lewtot184
Re: 68 Fuel Vapor Separater for 440 - 12/21/11 06:19 PM
the return hole is too large. it needs to be reduced to a maximun i.d. of .060.
Posted By: 68CoronetRT
Re: 68 Fuel Vapor Separater for 440 - 12/21/11 07:03 PM
Quote:
the return hole is too large. it needs to be reduced to a maximun i.d. of .060.
Is this true of all the repos?
If so what did you use to reduce the hole size?
Posted By: MR_P_BODY
Re: 68 Fuel Vapor Separater for 440 - 12/21/11 07:52 PM
Quote:Quote:
the return hole is too large. it needs to be reduced to a maximun i.d. of .060.
Is this true of all the repos?
If so what did you use to reduce the hole size?
Normally they have a .060 orifice in the return nipple...
if you want to make sure its .060 drill a .060 hole
in a piece of 1/4 round brass stock and push it in the
end of the rubber hose at the separator nipple then
clamp the hose on
Posted By: lewtot184
Re: 68 Fuel Vapor Separater for 440 - 12/21/11 08:48 PM
Quote:all of them that i've used have too large of a return hole. i've been soft soldering up the hole and redrilling with a .035-.040 drill bit. factory return orifice was .060 but they used special pumps that are no longer availiable. i use carter 6903 pumps with some minor modifications.Quote:
the return hole is too large. it needs to be reduced to a maximun i.d. of .060.
Is this true of all the repos?
If so what did you use to reduce the hole size?
Posted By: DaytonaTurbo
Re: 68 Fuel Vapor Separater for 440 - 12/21/11 09:19 PM
I had the same issue with the return orifice being too big. I threw a hose clamp on the return line and pinched it shut and she ran just fine after that. Solved the problem until I got around to looking at the orifice size.
Posted By: 68jim
Re: 68 Fuel Vapor Separater for 440 - 12/21/11 09:55 PM
In the process of chasing down fuel problems with my car last year I discovered that by pinching the return line my pressure would increase by 2 psi. Found out my opening was closer to .080"-.090". I soldered the end up using a small torch and drilled out to a recommended .030". My pressure drop now is much better at only .5 psi and I had no issues running the car in 95 degree heat this last Summer.
Jim
Jim
Posted By: 73rrak
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 12:20 AM
Get a Miller mig welder tip in whatever size you need cut the hose and use it as a splice. put some armor all on the welder tip and it will help you slide the hose all the way over the welder tip and you will never know it's there.
Posted By: Challenger 1
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 12:32 AM
Quote:
Get a Miller mig welder tip in whatever size you need cut the hose and use it as a splice. put some armor all on the welder tip and it will help you slide the hose all the way over the welder tip and you will never know it's there.
Won't you see the clamps?
Posted By: 68CoronetRT
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 12:50 AM
Quote:Quote:
Get a Miller mig welder tip in whatever size you need cut the hose and use it as a splice. put some armor all on the welder tip and it will help you slide the hose all the way over the welder tip and you will never know it's there.
Won't you see the clamps?
I think if you slide the tip in far enough so that the hose could fit over the nipple you wouldn't need an extra clamp.
Now do I need a .060 diameter hole or should I go with .035" or something else? Running a Holly 870 Street Avenger carburetor.
Posted By: MR_P_BODY
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 12:59 AM
Now do I need a .060 diameter hole or should I go with .035" or something else? Running a Holly 870 Street Avenger carburetor.
Time to T in a fuel gauge and find out what size
orifice you need... start small and watch the gauge...
run a hose with the gauge on it and tape it to your
windshield
Time to T in a fuel gauge and find out what size
orifice you need... start small and watch the gauge...
run a hose with the gauge on it and tape it to your
windshield
Posted By: lewtot184
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 01:09 AM
Quote:i've tested different sizes. the smaller the more stable fuel pressure is. consider .060 max and around .030 minimum. actually i got down to figuring the area of different orifice holes and compared them to each other to get an idea of what the reduction in size really meant. .035 is a nice place to be.Quote:Quote:
Get a Miller mig welder tip in whatever size you need cut the hose and use it as a splice. put some armor all on the welder tip and it will help you slide the hose all the way over the welder tip and you will never know it's there.
Won't you see the clamps?
I think if you slide the tip in far enough so that the hose could fit over the nipple you wouldn't need an extra clamp.
Now do I need a .060 diameter hole or should I go with .035" or something else? Running a Holly 870 Street Avenger carburetor.
Posted By: MR_P_BODY
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 01:43 AM
i've tested different sizes. the smaller the more stable fuel pressure is. consider .060 max and around .030 minimum. actually i got down to figuring the area of different orifice holes and compared them to each other to get an idea of what the reduction in size really meant. .035 is a nice place to be.
What was your running pressure with a .030 and at
what size did the pressure start to drop at
What was your running pressure with a .030 and at
what size did the pressure start to drop at
Posted By: 73rrak
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 01:59 AM
Quote:Quote:
Get a Miller mig welder tip in whatever size you need cut the hose and use it as a splice. put some armor all on the welder tip and it will help you slide the hose all the way over the welder tip and you will never know it's there.
Won't you see the clamps?
No .... Not if you slide the welder tip on the hose far enough. The armor all will help the tip slide all the way in the hose. If you do it near whatever you are connecting to it will hook up like normal with just a clamp on the connection a the fuel pump or carb or whatever.
Posted By: lewtot184
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 02:12 AM
Quote:
i've tested different sizes. the smaller the more stable fuel pressure is. consider .060 max and around .030 minimum. actually i got down to figuring the area of different orifice holes and compared them to each other to get an idea of what the reduction in size really meant. .035 is a nice place to be.
What was your running pressure with a .030 and at
what size did the pressure start to drop at
thats somewhat of a loaded question. i'm going on mental notes here. the real pressure fluctuations are below 2500rpm. with a .075 orifice and a rated 6lb pump. fluctations at idle where between 2-5.5lbs. a lot of needle flopping on the pressure gauge. reducing the orifice size to .035 would bring the pressure variance down to about a 1-1.5lbs at idle. the real killer with the big orifice was fuel pressure up around 4500-5000rpm. pressure would go down to 2lbs (street 440 6-pak engine). reducing orifice size down to .035 would bring the higher rpm pressure up to about 3-3.5lbs. since then i've done some pump work and fuel line changes (deleted the return) and have not recorded any higher rpm pressure checks but do have the engine idling at 7.5psi with no problems. i'd think 5000+rpm pressure is probably 4+lbs. i know the car sure ran a bunch better. if the engine is basically stock just changing the orifice is good. if modified go after the pump too.
Posted By: Challenger 1
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 02:56 AM
Quote:Quote:Quote:
Get a Miller mig welder tip in whatever size you need cut the hose and use it as a splice. put some armor all on the welder tip and it will help you slide the hose all the way over the welder tip and you will never know it's there.
Won't you see the clamps?
No .... Not if you slide the welder tip on the hose far enough. The armor all will help the tip slide all the way in the hose. If you do it near whatever you are connecting to it will hook up like normal with just a clamp on the connection a the fuel pump or carb or whatever.
Posted By: 68CoronetRT
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 04:15 PM
Quote:Quote:
i've tested different sizes. the smaller the more stable fuel pressure is. consider .060 max and around .030 minimum. actually i got down to figuring the area of different orifice holes and compared them to each other to get an idea of what the reduction in size really meant. .035 is a nice place to be.
. . . i'm going on mental notes here. the real pressure fluctuations are below 2500rpm. with a .075 orifice and a rated 6lb pump. fluctations at idle where between 2-5.5lbs. a lot of needle flopping on the pressure gauge. reducing the orifice size to .035 would bring the pressure variance down to about a 1-1.5lbs at idle. the real killer with the big orifice was fuel pressure up around 4500-5000rpm. pressure would go down to 2lbs (street 440 6-pak engine). reducing orifice size down to .035 would bring the higher rpm pressure up to about 3-3.5lbs. since then i've done some pump work and fuel line changes (deleted the return) and have not recorded any higher rpm pressure checks but do have the engine idling at 7.5psi with no problems. i'd think 5000+rpm pressure is probably 4+lbs. i know the car sure ran a bunch better. if the engine is basically stock just changing the orifice is good. if modified go after the pump too.
Thanks. That's some good information there. I'll start with .035 since I have some MIG tips that size on hand anyway.
You mentioned the fuel pump and I have an OEM replacement pump that was on the motor when I took it apart.
What kind (brand or type) of fuel pump should I be looking for.
Posted By: Moparlar
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 04:22 PM
Is the return hole size only on Repos or original chrysler ones also?
Larry
Larry
Posted By: MR_P_BODY
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 05:07 PM
Quote:
Is the return hole size only on Repos or original chrysler ones also?
Larry
If I recall correctly the orifice was .060 on the
factory ones... that was alot of years ago when I
worked on that stuff in the fuel lab
Posted By: lewtot184
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 06:45 PM
the single diaphragm 2 valve pumps won't cut it for performance usage. if the engine is pretty much stock a carter 6903 is a perfect fit. if the power level starts going above 400-425hp i'd tinker with the 6903 a little. i disassemble the pump. the bottom section, the bowl, has an inlet passage that goes from one side to the other. open that passage up to 5/16". deburr and radius the inlet and outlet of that passage. deburr and radius the inside of the outlet passage in the center section. i use some 320 paper and a smooth hard surface to correct any warps or distortions in the mating surfaces of the bowl and centersection (valve body). doing this will actually add a little pressure. i don't mess with the valves. to get the pressure above 7psi i had a .060 rubber washer between the diaphragm seal and lever body (lever will need to be taken out to do this and probably isn't necessary to do unless you want to push the envelope a little). i played with an edelbrock 6lb pump a little and these pumps already have the bowl modifications but pressure was excessive, 9-11lbs, and they didn't pump anymore fuel than the 6903. ironically, the edelbrock pump is made by carter.
Posted By: 68CoronetRT
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 09:00 PM
Quote:
the single diaphragm 2 valve pumps won't cut it for performance usage. if the engine is pretty much stock a carter 6903 is a perfect fit. if the power level starts going above 400-425hp i'd tinker with the 6903 a little. i disassemble the pump. the bottom section, the bowl, has an inlet passage that goes from one side to the other. open that passage up to 5/16". deburr and radius the inlet and outlet of that passage. deburr and radius the inside of the outlet passage in the center section. i use some 320 paper and a smooth hard surface to correct any warps or distortions in the mating surfaces of the bowl and centersection (valve body). doing this will actually add a little pressure. i don't mess with the valves. to get the pressure above 7psi i had a .060 rubber washer between the diaphragm seal and lever body (lever will need to be taken out to do this and probably isn't necessary to do unless you want to push the envelope a little). i played with an edelbrock 6lb pump a little and these pumps already have the bowl modifications but pressure was excessive, 9-11lbs, and they didn't pump anymore fuel than the 6903. ironically, the edelbrock pump is made by carter.
I am shooting for 500+ hp on this build for a street car. 4.360 bore, 915s with oversize valves, stock 3.75 stroke steel crank, zero deck, .039" Felpro HG, Hyd. Comp Cam 241/247 @ .050 with .582 lift using 1.6 roller rockers. 4 speed with 3.54 Dana 60.
Will the modified 6903 handle this?
Thanks for your help.
Posted By: lewtot184
Re: 68 Fuel Vapor Separater for 440 - 12/22/11 10:53 PM
i think a modified 6903 at 500+hp might be close to the limit. you'll need about 3/4 gallon per minute at the carb. you don't state an intake/carb combo or if the heads were professionally ported with big valves (professionally done preferred). i tested a carter 4862 high pressure pump and it would do almost a gallon in 30 seconds (!), but would need a regulator (9lb psi). my combo is a pump gas 440, 9.3:1 comp, stage 5 heads done by dwayne porter, 6-pak, engle k65 cam (238@.050-.510 lift), tti 2" headers and 3" exhaust. personally, i don't get caught up in the big hp numbers. most of it is magazine garbage. i'd think my combo is about 475hp net real world hp. maybe more if the air is real good. anyhow what i've done does seem to be good enough what ive got. more will probably need more.
Posted By: 68CoronetRT
Re: 68 Fuel Vapor Separater for 440 - 12/23/11 12:40 AM
Quote:
. . . you don't state an intake/carb combo or if the heads were professionally ported with big valves (professionally done preferred).
Sorry, I knew I forgot something. Holly 870 Street Avenger carb and Edelbrock Performer 440 dual plane manifold.
I am planning on 1 3/4" headers with 2 1/2" exhaust out the back.
The heads have 2.14/1.81 valves with hardened seats and the bowls were blended but no other porting was done.
The 500 hp is a guestimate based on the previous build (8:1 CR with a MP purple cam 284/484, Holly 750, 906 stock heads) that put out over 400 hp on a chassis dyno. Been a while and I can't remember the exact numbers.
Posted By: gtx6970
Re: 68 Fuel Vapor Separater for 440 - 12/23/11 04:46 PM
I've sold dozens of these and never heard a single complaint yet.
I will go on record, the return orfice is slightly larger than a factory original.
There are/were 2 companies making seperators.
And as far as I know only 1 has the stamped writing inlet/outlet stamped on the can represents the good one ( the one I carry )
ps- I have one of the junk ones on hand( long story) if anyone wants to see a side by side comparison picture
I do not know if the bad one is still being made. But they are out there so beware. Any questions , my advise would be,,, ask.
I know myself and Jamie at Megaparts both carry the good one, anyone else your on your own.
I will go on record, the return orfice is slightly larger than a factory original.
There are/were 2 companies making seperators.
And as far as I know only 1 has the stamped writing inlet/outlet stamped on the can represents the good one ( the one I carry )
ps- I have one of the junk ones on hand( long story) if anyone wants to see a side by side comparison picture
I do not know if the bad one is still being made. But they are out there so beware. Any questions , my advise would be,,, ask.
I know myself and Jamie at Megaparts both carry the good one, anyone else your on your own.
Posted By: THESHAKERPROJECT
Re: 68 Fuel Vapor Separater for 440 - 12/23/11 06:10 PM
I can tell by your pic that I have 2 bad ones . 
Posted By: badblack68
Re: 68 Fuel Vapor Separater for 440 - 12/23/11 08:41 PM
That the same vapor seperator we stock as well.
http://pepsparts.com/proddetail.asp?prod=v3
http://pepsparts.com/proddetail.asp?prod=v3