Holley 390

[73Vegaguy]

Does anyone have experience using a Holley 390 on a Vega 140 engine? I've been considering adding an Offenhouser 4-bbl manifold, 390 c.f.m. Holley and a header to my stock 140. I'm wondering how the Holley would work "out of the box." Does anyone know if this would be suitable, or would there be significant drivability issues requiring rejetting, additional tuning, etc? Thanks!

[hammerdown7]

What are you trying to accomplish with the change?

Dick

[spencerforhire]

Performance AND driveability were both great with a similar setup that I had on my 76 GT. After the V8 swap, I sold everything(Holley 390, Spearco intake and 2 different headers) to another board member(orangeastre). He ran it on his 74(?) Astre, and had good luck with it as well. I believe he has it up for sale, but has only gotten insulting low-ball offers so far.

[73Vegaguy]

I'd like driveability about like a stock 140 with maybe a bit more power. My concern is that it may be running too lean without my knowledge and may lead to burned valves or pistons. (Running too rich should be fairly obvious.) I'm also concerned about this combo causing hard starting, flooding, flat spots, etc. The March, 1971 Rod & Custom featured an article using this set-up. They said that out of the box the primary jetting was ok but the secondary needed richening to a size .059 jet. I don't know how the jets and metering plates in the current 390's compare to the 1971-era carbs. I really want to install these parts for the "wow" factor, but if it's going to damage the engine or make the car difficult to drive, I'll pass.

[spencerforhire]

The 390 Holley is a vacuum secondary carb with a non-adjustable secondary metering plate(no jets or power valves). It is designed for small V8's and 6's; the chances of it being too lean and damaging your 140 cube engine are pretty remote.

[73Vegaguy]

Spencer, my gut feeling also would have been that the Holley 390 was jetted rich enough for a 4-cylinder, but as i previously wrote, Rod & Custom found that not to be the case. They said the stock secondary jetting on the (1971-vintage) 390 was "pretty lean" at higher rpm's. They increased the secondary jet to .059 and got good results with it. One problem is that I don't know what size jet that the metering plate in the current 390 would correspond to. I could upgrade the metering plate to one with a larger orifice if needed, but I don't know where I would be starting from. I guess a call to Holley's tech support people is in order.

[hammerdown7]

I had great success with the two barrel version of the Offy Dual-Port and the Holley-Weber 5200. At the same time I used a Clifford Research true dual header and exhaust system. This was in '74-'75 during the first gas crunch. I also changed the R&P from a 3.36 to a 2.53. I felt I had the same performance as the stock car even with the R&P change and my mileage never dipped below 30mpg around town and over 40mpg on the highway. This was a 4-speed car and I put over 100K miles on it.

I think the 390 mounts sideways and needs some special linkage if I remember correctly.

Dick

[lincolnolli]

The Holley 5200/Weber 32/36 is an extremly good carb in my book.
Ford Germany had them on all of their 4 bangers with grat success.
The german based mustang 2.3L "pinto engine" had it too.Fantastic mileage!

When it comes to the Holley 390 i would prefer the Edelbrock 500cfm for simplicity and
the bolt on and go factor.No powervalves and gaskets below fuel level too.
Carter/Edelbrock dry flow there carbs,while Holley does that wet.
The 500 is actually way smaller and has nice small primaries.The secondaries are "vacuum" so size doesnt matter that much..

Ollie

[Sirshredalot]

Depends on which 390 holley you have...some had jets...some didnt...some are better than others. What numbers do you have?

Ive got a pair of 390 carbs for a tunnel ram and Theyre the good ones. they work well with anything...and have dual metering blocks and must be mounted sideways on a tunnel ram.

God bless
-Shred

[73Vegaguy]

I haven't bought the carb yet. I'm trying to decide whether I should buy a new one or look for an older one that has specific features that a new carb doesn't have. Any suggestions?