4 barrel carb question???

What is the best 4 barrel to use on a 258 straight six??? I have a clifford 4 barrel intake, ported head, and headers. Is the Holley 390 my best bet???
Thanks
high5

 

Not a lot of choices. This topic has been discussed a lot here wrt the 225/231 V6 4V manifolds.

There's a 1.08" 4100 Autolite/Motorcraft that came with the early 289 (?). There's a 1.12" 4100 that came with the big block Fords (352, 390) too, and can be resized by Pony Carburetors to the smaller venturis. Unfortunately, I think the 1.08" 4100s are made of unobtainium today... Would be a fine sub for the Holley though, and should have the same off-road characteristics as the well-regarded 2100.

There's a new small Holley Truck Avenger that's supposed to coming out.

Hate to be a drag about this, but you could consider selling your manifold and running the stock aluminum 2V intake with a 38 DGES Weber.

 

Look at the Holley truck avenger.. It is designed for better off-road performance. They have 2 different sizes one is 700 CFM and the other is 470 cfm? I believe.

 

Is the 470cfm too big for this motor though??? I have had a motorcraft 500 cfm two barrel and a bigger 4 barrel on here and it has ran like crap. I wouldn't mind buying a new carb, if someone can assure me that it is the "right" one.
THanks
High5

 

You may be asking too much for someone to tell you the "right" 4V for a 258 with the Clifford manifold. Pretty much someone has to have used the same manifold that you have and made it work with a 258 to assure you it's the right carb. You could try calling Clifford and asking them what they recommend.

Some members here have made the 390CFM Holley work with the 225 V6, and if it works on the 225 it should work on the 258. There are some off-road performance issues with the Holley though. There was supposed to be a smaller Truck Avenger than the 470CFM in the works ... don't know the specifics.

The reason I mentioned the 38 DGES is because it's intended as a bolt-on performance upgrade for the 258; if it doesn't work like you expect it to, you can confer with Redline Performance and figure out what's wrong. Pretty good chance it'll work ok, since many of the kits have been sold. The AMC aluminum 2V manifold is ok, and works well with the Redline kits.

 

470 CFM is the same size as the most popular GM TBI that is swapped into the 258. Lots of guys running those. I would not think the 470 would be too big. Especially with a 4 barrel intake and exhaust to match.

I am actually running a TBI from a 350 or larger GM engine (dont know the exact size) on my 258 with stock 2b intake. It makes for a touchy throttle but other then that it runs good.

BTW I just looked. Holley Truck avenger comes in 770 CFM and 670 CFM.
write up from Rockcrawler.com
http://www.rockcrawler.com/techreports/holley_truck_avenger/index.asp

 

When posting threads like this there is always some block head that always suggests upgrades that you really don't want to do but let me be that block head this time...If you have the $$$ get on ebay and look for an EFI system for your Jeep. I'm running the Holley Projection on my 304 and my neighbor is running the Howell EFI kit on his 258. We both have had great luck with the EFI. I got mine for $500 and was amazed at how easy it was to install. It took a bit to get it tuned just right but it now runs like a new car and doesn't give me problems when its cold outside.

Just thought I'd throw that out there. Don't mean to get you off track but this is a great option that you won't regret.

Good luck...Casey

 

I'll sell you my 390 for $200 shipped. It has been rejetted for the 258. It will need a different power valve and vacuum secondary spring for your amount of engine vacuum. The rejetting was done correctly, using new gaskets.

It comes with the quick change vac secondary spring change housing. Also, I'll include an air filter and a Mr Gasket throttle cable mounting plate that sandwiches between the carb and the manifold.

I am going with a MC2100.

I can ship it in 2 weeks. Electronicmail me at "mjpavelko at yahoo dot comm" for a pic of my setup.

 

Boy, I would like to go with EFI. It is pretty expensive and I wouldn't know where to begin to install it. I can bolt stuff on, but I don't think my mechanic skills are that good. I hate to admit that
I will definitely think about buying your Holley 390 Mugzilla. Keep me post when you are ready to sell.
Thanks for your input guys
High5