Need some Holley 390 help

Hello, I am in the middle of installing some little upgrades to my 225. My ol Rochester 2g just flat wore out and I now I am going 4 barrell with an Offy dual port manifold and a Holley 390 carb. I did some searching here to see what people have done to get the 390 dialed in, but couldnt really find what I was looking for.
What parts do I need to get it dialed in? or to get me close? as far as jet sizes and spring colors.... stuff like that.
Any help before I mount the carb would be greatly appreciated.
My only other add ons are a new exhaust (2 inch) from the manifolds back, and an Hei. I am also running the 225 @ 1000 feet if that matters.
Thanks

 

Your best bet is to go to summitracing.com or any larger book store and have them order a book on Holley tuning.. read that and you will be a Holley god.. that way you will understand what you are doing and not relying on bunk info like I would give you.. haha..


BUBBA

 

Try http://www.amazon.com/exec/obidos/t...f=sr_1_1/002-3458275-2555245?v=glance&s=books

You can go to www.alibris.com and search for Mike Urich; isn't the 390 CFM a 4160? There's a book by Urich specifically for the 4150 and 4160.

 

Yup.

 

The 390 cfm carbs are 6299-1 or 8007 list numbers, avoid the 6299-1 it isnt designed for larger engines due to small circiutry. I had a 450 cfm on my after i did not like the performance of the 390 on my noy quite stock motor.

 

Thanks ... Ive got the book already, doesnt tell me how to set up for the 225 engine though. L ooking for someone that has done the "off-road" setup and could just tell me what stuff to get, and what jet sizes and the like to get me close so I can dial it in. Trying to cut down on the trial and error that I hear it takes to get these Hollys working good.

 

Ahh I got ya.. I am going the same route later but have not got to that point yet.. I'd like to build my own 390 "truck avenger" or actually I wish holley would build one for us!


BUBBA

 

You have a couple of questions 1) how to set up the jetting, pump squirt, metering block for the 225 and 2) what mods can be made to make the 4160 better on the trail.

This evening I'll try to post a condensed form of what I've learned, including some of the material from the Four Wheeler article that Greg Schardein sent me. Mostly this will address question 2, since I don't have any personal experience with the 225. I'd say install it with the jets and pump cam you have now, and drive it for a while. Note any stumbling or black smoke. Typically, for the jets, you'd pull the plugs and step up or down depending on how the plug color is. There are lots of articles on the web about reading plugs. Set the idle screws to "best lean idle" - adjust out 2 or 2.5 turns, then adjust in until the idle just deteriorate. Back both screws out 1/4 turn or so. Always move both screws the same amount together. The pump shot is adjusted by trial and error. Reduce the volume and duration using the cam kit until you get a slight stumble, then increase one step.

 

Tim hit it on the head. I could make a scanned version of that article (now that I have a flatbed scanner) and send it to you.
very briefly what worked for me for off road use was, set the float just a HAIR low, install a bowl vent "whistle" or "baffle" holley part in the front bowl. Take out the short bowl vent tubes on top of the carb and use a piece of copper tubing to make your own vent tube ala the truck avenger. Drill some small holes 4 or 5 along the bottom and carefullt tap it on. Done.
Some will say changing the vent tube will change the metering of the carb some. I am sure they are right but my real world experience is it works fine.
Can't for the life of me remember if I changed jets or not.
Did fiddle with the idle speed and mixture and accel pump setting till I thought it was right.
It was terrible off road before these mods. Now it is good to go. My only complaint is sometimes I get an off idle stumble, very minor, and it could be a timing thing (loose chain or maybe sticking dist advance weights) instead of a carb thing.

 

Sorry I didn't get this up last night - just didn't feel like it after my double root canal.

The article from Greg will give you the background that you need. It's a little dated, and some of the parts (off road bowl conversion kit) aren't available anymore AFAIK. There are other parts available - we'll get to them.

Your objective with the Holley mods is to keep the fuel in the float bowls under extreme attitude (side hills and up/down hill) and on rough terrain (bouncing the Jeep over rocks, etc). When I worked on my Holley, I had a 2300 so I'm not sure how these mods affect the secondary bowl... I expect you'll have to do some of the mods twice to apply the same fuel control to both bowls.

I think the best place to start is to look at Holley's design for the Truck Avenger: http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSC/f0-90670.html
Two aspects are seen here - the bowl vents and the bowl design. Greg mentioned the bowl vents - that's the irridescent Cad plated (shiny goldish) tube sticking up from the top of the carb. The bowl vents are the two holes it comes out of. This tube has a hole at the highest point to vent the bowls, and is bent sideways to clear the air cleaner mounting stud. Raising this vent keeps raw fuel from draining into the venturis on extreme attitude.

The second obvious aspect is side-pivot floats. Most stock Holley carbs are set up for street driving, where lateral Gs are more problematic than hills. Here's a 2300 with center pivot floats: http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSC/f0-4412C.html
Note that the float adjustment port is at the center of the bowl, rather than at the side. The pictures of the 4160s on the Holley site show side pivot bowls, so this may not be an issue with the 390cfm 4160.The side pivot float certainly will work better on hills just because of the location of the plane of movement of the float. I believe it works better overall because the length of the float lever arm is much longer. This means that the carb can be tilted more (at least in one plane) before the needle&seat stop working.

There are some internal parts that might be worthwhile. First is Holley's off-road needle&seat (6-513). I assume that this is spring loaded; meant to damp out any float bounce over rough terrain. It's on Holley's parts page: http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSCA/Access.html
The side-hung float bowls (134-101 and 134-105) should be right, although there's a bowl conversion kit that may be right too (34-2), but not enough info. A couple other items that will help with fuel control are the vent whistle that Greg mentions (26-40 and 26-89) and bowl vent screen (26-39), both which help prevent slosh.

Another mod I was aware of are the jet extensions. These were said to be helpful, and are available with a notched float (116-10). It'd be interesting to open a Street Dominator and see if they are there.

Greg also mentioned lowering the fuel level in the bowl. Realize that a llower fuel level will lean out the mixture, though it's well known to be an effective mod for off-road.

hth Tim

 

Tim is right about the float level leaning the mix. Maybe my modified bowl vent counteracted that!
The 390/4160 is a side hung float (at least mine is).
The bowl vent whistle is for the for the front, and really mad a difference. The bowl screen is for the back and requires a metering block to be installed to replace the metering plate, effectively converting the 4160 to a 4150. I didn't do this, if you plan to I have the screen that I never used.
From what I can tell the off road conversion is no longer available as Tim said, but the main component was the spring loaded needle and seat. This is available, I have seen them listed in Summit racing catalog. Haven't done that one yet although I think it would help. Maybe someday.
Great write up Tim.

 

Great info Tim.

To add my $.02. Lowering the fuel level below the recommended "just below the site plugs" was a neccessity for me for any off road driving. The fuel would slosh and wash the carb out on any bumps. I had the vent whistle and was working on extending the vent tubes like the truck avenger before I gave up fighting the battle with the Holley. Mine also came with side hung floats.

My jeep never had more power then when running with the holley (as scientifically measured by the seat of my pants), but it also never ran right off road so I tossed in the towel. Pick your battles wisely.

 

Bob, what was your solution?

 

Motorcraft 2100. 2bbl. No slop, no hesitation, tune it once and be done. Seems to work fine no matter what angle I'm climbing or decending or how rough and washboarded the road I'm traveling is. I need to build an adapter for my 4bbl manifold - for now I'm running a stock 2bbl. I want to go back to the 4bbl manifold since it was port matched with the heads.

 

Well the Holley has worked out really well for me. This actually is my first holley, Most my fourwheeling time before Jeeps was Chevy= Quadrajet. I'll take a Qjet anyday. Thought of getting a factory qjet manifold (since I am running a 231) and going that route. This works good enough I am not messing with it.
On my 83 -7 I swapped in a FI 4.0 using some of the components of the MOPAR kit. FI is a beautiful thing. The only reason I don't go that route is I like the low tech of the old CJ-5 and don't want to ruin it with a computer and extra wires. If it was my primary offroader I would though. It is my daily driver, but with the ability to embarass "real" offroaders if they aren't careful!!

 

There 'ya go. Somebody ought to sort out the voodoo needed for TBI on an oddfire.

 

Thanks a ton for the info. Thats exactly what I was looking for. I had one question....
on the bowl vents, since it has the stubby ones on it now, do those just pull out? Want to make sure i'm not damaging anything.
Also is it worth getting the float windows or once its adjusted right I wont need them type or thing.

 

I believe the tubes are just pressed in... I think you can just grab it with thin pliers and twist it out. If you take the bowl and metering block off, you should be able to see the bottom of the tube to be sure. Greg's article may address this issue - can't find that page though.

 

mebbe if someone yells at holley enough they will build a 390 truck avenger??

BUBBA

 

I wasn't sure myself, don't really remember, think I just grabbed em with a needle nose and slowly started pulling... they came out easily enough. As for the sight plugs, if I could find one on a junk carb I would use it, but I ain't paying money for it.