I will start searching the forum for answers, but wanted to post an update on the 4165 swap.

I can see why the rebuild kit is so expensive. Lots of parts, a lot more than in your standard qjet kit. It was not any more complicated to work on than the qjet, just more parts. Since the linkages are simpler, it is easier to take apart than a qjet.

Unfortunately it was not a straight bolt on. The firewall side vacuum port for the power brakes is not threaded, so I had to use a T off the PCV port. No big deal.

Also have to use short studs to bolt it down, but I knew that from the Holley that the car came with.

The big stinger is the factory bracket that hold the throttle cable attaches to the back two carb hold-down bolts, but it will no longer work because of the secondary's accelerator pump. Any ideas, or even better a bolt on solution from O'Reilly's, would be appreciated. I may just rig a bar with holes off each stud, then attach to that, but it will be ugly.

Other than that it seems to run pretty well. The idle seems to vary rpm a little more that the qjet, and it appears that when I blip the throttle the gas come more as liquid than a vapor. Good response however.

I started to adjust the mixture screws to vacuum, but the passenger side screw is blocked by the choke vacuum pull-off. I assume I have to remove that to adjust the screw?

So Matt, it will be a few days before I can report on the road test, but I am really looking forward to it.

 

 

I will be interested to see your report. But my initial thoughts are that this is not a "bolt on and go". The lack of a threaded hole, firewall side for the brake booster is very odd....perhaps the lack of threads was a defect from the factory.

The pic shows a stock cast-iron 1974 intake (ignore the colour). Does the Holley run interference with that vacuum port adaptor at the back? Note the divorced choke as well. I would like to retain that.

 

Now that u mention it, i did have to buy a fitting for my PB. And once i drilled another hole as i didnt like the linkage ratio. And some studs were too long! Had to cut them
Also got some jam nuts! (thin)
Are you guys flustered this easily?
OK, i'm sorry, i should of said "bolt on and go to store for mis. parts to hook everything up"

 

Matt,

I have followed the thread with interest or else I would not have jumped in. The 4165 seemed like a reasonable alternative to a Q-Jet. I liked some of your thoughts.

My questions were well-intentioned as changing from a Q-Jet to the Holley will run me here in Canada about $600.00 with all the bells-and-whistles assuming I can find them on-line. I can't just go to a store or ask a machine shop to fab something up. I know some mods will be necessary: those are inevitable. It's a matter of cost and possible lack of function of some crucial systems (e.g. emissions). And the PB booster tied into a PCV line makes no sense to me; crankcase gases into the booster?? (not your suggestion). Back manifold vacuum picks up general vacuum services and the TH350/400 modulator with automatics; the back of the carb does the brake work. The PCV is at the front of the car. These are all separate systems.



Your reply implies some of us are mechanical twits. I am not a genius but I converted my 1967 327/300 from a fire hazard Holley to an Edelbrock #1406. I did all the tube bending work by hand complete with 37* -AN flares and fittings/adaptors. No rubber and it worked very fine and safely.

So you have chosen to poo-poo my comments. OK, this is a Forum and that fair ball but not reason for unnecessary ridicule as shown by the "rolleyes" pics. I have no further comment and will not contribute further to this thread.

I wish you well with your 4165 campaign. Your credibility would be enhanced by a shopping list of parts/prices for that conversion. No one at this point has done that.

 

Paul or Matt,
I am running an Edelbrock 1406 carb with a 2104 Intake manifold. I added a 5 speed with overdrive have been using my vette for a daily driver. Paul, What is gas mileage are you getting with your 1406 Edelbrock?

Matt,
You said in previous posts that a four hole spacer or gasket would improve mileage. I am getting around 13 mpg. Do you thing adding a 4 hole gasket/spacer would improve mileage?

Thanks,

 

I've got a 625 Carter which is very similar and my best out of that is 24mpg, it probably averages around 17-19mpg round town if that's any help.

Could you be getting fuel boiling?

 

Paul, that's a very nice conversion and super job on the hardlines. Very nice looking engine!

 

Yes, I put a lot of work into that Edelbrock conversion and many $$s. It did work very well. No regrets as the Holley was a nightmare in terms of power valve blowouts (I guess now protected) and bowl boil over onto the intake manifold (fire hazard). My Q-Jet has an off-idle stumble that all the Lars papers in the world (and I) cannot seem to resolve. So I thought of Matt's alternative but no more: no evidence of true costs of mods.

My last-last point is thus the true cost of conversion can be very expensive. Not only in terms of parts but my time. We have five months of Corvette driving in Canada. I want to be on the road, not in the garage.

As to mileage check the old magazines of the day. About 12-14 in the city was normal and about 16-18 on the highway. That is what I get and consider it normal.

 

[QUOTE=paul 74;1572415603]I will be interested to see your report. But my initial thoughts are that this is not a "bolt on and go". The lack of a threaded hole, firewall side for the brake booster is very odd....perhaps the lack of threads was a defect from the factory.

The pic shows a stock cast-iron 1974 intake (ignore the colour). Does the Holley run interference with that vacuum port adaptor at the back? Note the divorced choke as well. I would like to retain that.

[QUOTE]

Don't bail yet Paul, this thread can be of use.

My '74 is a BB, so the intake looks different, in particular the EGR is in the front. The "vacuum port adapter" could be a problem, as it looks kind of close. Maybe someone who has installed the carb on a small block can chime in, but the 4165 goes back about two inches from the back carb bolts.

The lack of a threaded hole is not a defect, as the tube has a lip around it, like it is supposed to have a rubber vacuum line over the top. That line would be way bigger than the 11/32 coming off the brake booster however. It does have a threaded plug inside, which I left in.

Using a T with the PCV vacuum port should not make a difference (I think?), as the line is always under vacuum, so no fumes from the PCV should ever enter the brake booster. Also, the front and rear vacuum lines of the carb open straight through the carb base to the intake manifold, so there should not be a pressure difference.

I also have a divorced choke, and the 4165 lined right up with that.

After looking at different threads, the throttle cable bracket for a '73 qjet shown in the Corvette Central website should work perfect for my application. Unfortunately it is about $40 w/ clamp and shipping, which keeps increasing the cost of my test. O'Reilly's has a generic bracket for $13, that also looks like it will work, so I am going to try that first.

This project does not have me flustered, Matt, or even discouraged. Flustered is when I have to make three runs to Home Depot for a plumbing project. Wrenching on the car is 99% fun.

I know it is all a learning curve, which is why I am listing what I had to get so the next guy does not have to make as many runs to the auto parts store. Matt we need you to stay positive on this as your guidance can make this easier.

Paul, I think you could do the swap for a lot less than $600, plus a few hours of jerking around. Assuming the bracket is the last of my surprises, I will in it for around $100.

 

Paul,
As well, nice mod, my conversion from 4 to 5 speed took much more time than I thought. I lost a summer, but I do like it better. That's why I'm driving now and will stick with the Edelbrock 1406 that I bought. It was supposed to go quicker.

I might try a spacer in case it is boiling over in the summer.

 

I got my spark restored <for about 5 min.> fired right up on fast idle cam and ran great, kicked right down to normal idle, engine sounded great, very responsive and smooth.. I was lovin it until spark went south again, back to diag on ignition system for little or no spark..

 

I got it in, and it really does run well. It cruises along nicely and the idle quality is about the same as the qjet. I did notice that the Holley seems to start faster, since I think the gas was syphoning back out of the qjet. So a nice side benefit.

What I really like is the mechanical secondaries. Much better response, and a whole lot easier to chirp the tires. It feels like it runs out of breath earlier, say around 4500rpm, but the response is worth it. Much quicker.

The only other downside is missing the qjet secondaries sound. I do like the sound when those kick in, and the Holley sounds different, though not bad.

The generic bracket from O'Reilly's worked fine. I had to bend up the tang on the front (see in front of the bolt) and the designed location for the cable was too close, so I flipped over one of the kick-down cable brackets. Works great and I now have an adjustable throttle cable (not that I need it).

Bottom line is I would recommend doing the swap for the mechanical secondaries.

 

Doesn't the 4165 have power valves and basically the same float bowl vent (see photo is post above) as the square bore Holleys?

 

Looks like you are using the stock steel line. What are you doing for a filter since the Holley does not have an internal filter?

Also, you have found the issue with having a 650cfm on a big block with running out of steam at 4500 rpm. To me, that would be an unacceptable compromise.

 

I'm running the stock. metal, inline filter on my 68 390 horse. Mine does not run out of steam at 4,500 RPM's and is good to 5500 very easily. Don't forget, back in 66 the factory 390 horse carb was only 580 CFM. They ran fine. I would suspect an electrical/ignition problem if the car won't rev past 4,500 RPM's.

 

There is a filter in the carb, just like in the qjet. Actually I used the same filter since I only put about 40 miles on it.

I understand the unacceptable compromise, and I am still not sure what I am going to do. I definately want mechanical secondaries, as it really is way more responsive. Using the forumla rpmXci/3456*.8 (from another thread), the carb should be good to 6000rpm, but it does not feel like it.

The real problem is I do not know what a '74 BB is supposed to feel like from the factory. The car ran terrible when I bought it, so I do not have a baseline for comparison. My old '68 427/390 was much quicker, but it had a built engine. I have made several changes to the car since I purchased it, and all have been a performance improvement. The car feels much quicker with the Holley, though I may have lost some top end speed (not a factor for me).

Since all this "tuning" started because the car ran terrible, and now it runs well, I will probably stop messing with the tuning and start focusing on other areas.......though what would happen if I pulled those top plates off the secondaries on a qjet? Wouldn't that now be straight mechanical secondaries?

 

It will definately rev past 4500, but in second gear, with the qjet, it felt like it really was coming on at 4500: like there was still a lot more room to go and it was really coming on. It could just be the sound difference, but with the Holley it is just progressive building of rpm. It gets louder at 4500, but more in a straight line vs. a steeper curve with the qjet.

I was so happy with the qjets performance over the Holley that the car came with that I did not do any quantitative testing. If we get a stretch of warm weather over the Holidays (70 yesterday, 45 today) and I get motivated, I will get some 0-60 and quarter mile numbers with both carbs. Just seat of the pants, though, the Holley is probably more than a second quicker to 60.

 

I have several 4165's with the vac secondaries that i bought with similar intentions as yours for a song at swapmeets. What i liked 'bout the vac sec Holley carb is simplicity in that no secondary jets (and i believe no power vlv either) - jet plate only. But now i wonder if the vac sec operation is more similar to a Qjet with an air valve.
Well the argument for the mechanical sec's is the second pump shot (as they say is for "come'n out'a the corners) gives a little burst response - rather than what your getting with yours now. Maybe a bigger sec pump shot would help. Holley sells cams and plungers for this.

Regardless its nice to see your clean looking conversion worked out - and on a real hotrodders budget.
cardo0

 

What is this intake, and where can I get it ??? (The one that says in favor of)