I have 2.8l V6 from an 1983 s-10 in my 79 MGB. I have been looking at the recommended Holly 4 bbl 380cfm, but I have a Holley 4412 ( 2bbl 500cfm) that has been rebuilt and I have the adapter for it. Will I really see a big difference in power between one and other, or is a bird in hand... Currently, it still has the stock Rochester in it, and it has no guts what-so-ever.
Thank you,
Ron
Ron, I had the 350 Holley 2 barrel mounted sideways on the stock intakes on 2 different small V6's. It was perfect. One was a Jeep Cherokee 2.8 bored .040 and used the 3.1 crank. The other was a S10 with 3.4 crate. Both had cams and 1.6 roller rockers. The 500 would have to be jetted down a little and both 2.8's were gutless stock,but much improved after.
Thanks for the feedback, Jim. Any idea where to get the right adapter for the carb to the intake?
Ron, I used a Rochester to Holley adapter. drilled to fit the stock intake. You could also use a piece of aluminum plate and make your own.
Thanks. Any particular thickness on the aluminum?
Ron, here is a link with pictures toward the bottom http://www.mgexperience.net/phorum/read.php?40,1711520,1711520#msg-1711520 . I hogged out the intake to match gasket for the adapter and I would use 1/2" plate if making my own.
I have a Holley 390 on my ford 2.8. It's a good match.
Found the adapter at Speedway for $18. Can't wait to get it installed this weekend and then work with adjusting it. Thanks for the help and I will let you know how it goes.
Ron, Remember to hog out the intake to match gasket, I port matched my heads and intake when I rebuilt my motors also. You may want to upgrade your motor later on with a 3.1 or 3.4 crate. 86 and newer 2.8 can use the 3.1 crank and pistons also. Here is another picture I found:
s10_manifold.JPG
Jim: sorry for the stupid question, but what do you mean hog out the intake?
I took a dremel and made sure the hole matched the gasket like in my picture above. I also put some ideas in your water temp thread.
Jim: saw the post in water temp. Thanks. I will review the gasket kit and adapter when it arrives and make sure that it matches. Should get it tomorrow, so Saturday will be spent installing it and then get it tuned.
Ron, How'd the carb work for you?
Just finished it last night. I ended up going with a Weber Carb that was vacuum controlled, and a new distributor that was vacuum controlled since I do not have the computer installed. The difference is night and day. The car has a great deal of speed and torque (and I will be working on upgrading the brakes next). Really am surprised how well the engine responded to this new carb (and what a difference actually having the distributor advance working makes DUH!).
Need to road test it a bit more (Vegas) to make sure everything is tuned correctly, but I am very happy. BTW, I went with the Weber because the CFM flow seemed adequate for this engine, they had a bolt on for this car, and the air filter fits nicely in the hood with no modification.
Thanks to every one for your help and guidance.
Ron, post a picture if you can and where did you get the weber stuff from? thanks
Dave Craddock
Dave:
I will upload some photos on Monday, after I clean up under the bonnet (lots of old wires from the previous engine).
I got the carb from WeberCarbsDirect for around $320. It was made to bolt up to the S-10 60 degree V6 2.8L (replacing the E2S2 Rochester). Easy installation, and tuning it was straight-forward. It came with a bracket for the stock air filter, but I was able to remove that and find an air filter assembly that fit nicely for around $20 (http://cgi.ebay.com/ebaymotors/NEW-Chrome-Air-FIlter-DGV-DGEV-Weber-Carbs-2-50-Tall-/120774100552?pt=Motors_Car_Truck_Parts_Accessories&hash=item1c1eb28648). All and all, very happy.
The only issues I have left is that while the carb provides great mid-range torque and allow for passing even in 5th gear, it stutters a little while in first gear off a dead stop. It will shake the car (almost like it is flooding or conversely being starved for fuel) and then it picks up and runs fine. Need to investigate and find out why that is happening. It does not have a fuel regulator, so I might look there first. Any suggestions would be appreciated.
The car idles nicely at 650 rpm, and starts up on a dime. No stalling, even on a cold (well, California cold) morning.
Hey Ron,
Get a wide band air fuel ratio meter hooked up in there to see what you've got.
You could have a fuel problem or an ignition problem or even a driveline problem.
We need to narrow it down a little.
I have a nice Autometer guage that I just clamp into the tail pipe of whatever I'm tuning at the time.
A couple of alligator clips to the battery and it's good to go.
That way I only need one guage for many vehicles.
Cheers
Fred
I wonder if the off-idle stumbling is caused by having the vacuum advance hooked up to manifold vacuum instead of 'ported' vacuum.
Fred, I will try and get my hands on an air fuel meter and see what it reads. Never done that before, so t should be interesting.
Paul: the vacuum advance hose goes from the distributor bell straight to the carb, can you elaborate more on hat you mean?
Thanks,
Ron
What Paul means Ron is that if you use manifold vacuum at idle it increases the engine timing.
Then when you step on the throttle that vacuum goes away and the timing retards causing the car to stumble.
Many carbs have manifold vacuum ports on them and you should check to make sure your using the right one.
Use a vacuum guage and check the ports out.
The one you need will only have vacuum just off idle.
Hope that helps
Cheers
Fred
Fred, thanks for clarifying that for Ron.
Ron, 'ported vacuum' would be a vacuum signal connection that is between the throttle blade and the venturi. As the throttle is opened a pressure drop is created. At idle, when the throttle blade are almost closed, there would be nearly no pressure drop.
It might take a little work to get that signal conditioned properly. On a S10 (with the Isuzu engine) that I once drove, there were vacuum signal delay devices in the vacuum lines to improve the timing of the vacuum signal. It would be easy to see how an immediate change in spark timing might cause a stumble in off-idle operation, and a vacuum delay device might help that.
Ron,
I am a little late. I was going to recommend the CCE 4 barrel lower profile adapter.
It would be Great to see photos of your final results.
It sounds like the stumble is ignition or accelerator pump. Knowing enough about webers, I would check the accelerator pump first. Some of the webers even have an adjustable accelerator pump cam/rocker to allow for more fuel on depressing the throttle.
-BMC.