POVO gets a Holley conversion

[oscar]

A succesful one I might add. To be honest though it was a fairly simple conversion due to the Holley being taken off a previous conversion. So all parts were ready to go.

The only things I would've needed to purchase if i was starting from scratch is a square bore adapter plate, angled throttle linkage and some vacuum hose and maybe coolant hose and a few hose clips and screws and electrical wire and things ..... Check the photos to see what's needed.

We'll start with the main component, the carburettor. The Solex4A1 I'm replacing is actually fine. It works well and was recently raced. But since the application is an upcoming race car I wanted to try this spare Holley I've got which (fingers crossed), hopefully helps the M110 breathe better and give it some better acceleration.

The Holley replacement is an old squarebore 4bbl (4 equally sized barrels), 390CFM, 4160, p/n 0-8007. The Solex on the other hand is spreadbore (2 larger, 2 smaller barrels). The Holley pdf link says not to use a square bore to spread bore adapter. Stiff, I haven't got a hope of fashioning a square bore out of the stock manifold due to the way it's cast and machined. It's not one big flat surface that I can simply cut the middle from. Anyway, the adapter is thick and I reckon there's a bit of room for the fuel/air mix to get to where it's going without too much restriction. The adapter BTW has got "LYNX" cast into it and that's all I can tell you. No other numbers on there sorry

REMOVAL OF THE SOLEX.

A view of the naked manifold with spredbore configuration.

HOLLEY AND EXTRA BITS NEEDED

An underside comparison of the Solex and Holley. Not sure of the CFM of the Solex and after seeing the two together I wondered whether the conversion is actually worth it. Seems to rev harder when given full throttle but time will tell after a full test drive how effective the holley is in providing extra power. I wont know fuel economy as the car will be spending much of its time at wide open throttle anyway 8).

Extra bits needed-

Angled throttle linkage

A wire connected to the (+) terminal of the coil then goes to the spade terminal of the electric choke.

A self made bracket for the throttle return spring needs to be manufactured and placed where shown.

The coolant hoses need to bypass the carburettor all together. Either by way of a short piece of copper tubing as shown or replace both hoses with a much longer one.

One squarebore to spreadbore adapter plate. This one is LYNX branded. 4 allen bolts go into the manifold and four bolts poke up through from the bottom so the Holley can be bolted down.

Some vacuum hose and a "T" piece to tap the vacuum off the manifold. The black hose then goes off to the fuel purge valve that regualtes fuel pressure to the carby and allows fuel to flow through the return line under low load conditions. I think that's how it works :

INSTALLING THE HOLLEY

Install adapter plate to soft mount that was under the Solex.

Coolant hose bypasses carburettor

Install Holley on studs and screw nuts on. Attach fuel line. I was unable to remove the sealing collet so I just slid the fuel line as far as it would go, slightly over the collet, then screwed the clamp up. no leaks.

Vacuum lines to vacuum switch that provides retard at idle were plugged. Emissions aren't a concern for this car but you could add another "T" to that other vac line I spoke of earlier. When I find a cap I'll put it over the retard connection of the distributors retard connection. There's another large vacuum connection off the side of the carb facing the engine that was capped some time ago and wont be used.

Vacuum line that goes to the fuel purge valve is attached running from that "T"connection I put in earlier.

Throttle linkage and return spring

Attach vacuum line to the vacuum advance port on the distributor. (middle of pic)

Lastly, don't forget to attach the electrical wire from the coil to the choke. No pic sorry.



THE VIDEOS

The sound lags somewhat behind the footage for some reason but when it started it was really responsive.

First start attempt was a failure. The carb was empty and the fuel bowls needed to fill which I expected but the purge valve wasn't connected to a vacuum source either.


With the vacuum line to the purge valve connected. Eureka!!! But maybe the fuel bowls had filled by this time. I don't know. Time lapsed between first and second attempt was about 10mins. Flooding wasn't a cause of the non start first time round.


As the car warms up the electric choke is working, you can see it opening....slowly.


After the engine has fully warmed up I give it one more look over for fuel and coolant leaks then floor it a few times to check operation of the vacuum secondaries. You can see the gate of the secondarys' axle moving. The car needs to be under load to get them to be wide open, or I could possibly keep my foot on the pedal but not yet. I've got a rev limiting rotor in there and whilst it's brand new and still has it's counterwieght, I'm yet to hear it have an effect.

 

[SELfor50]

Great work dude, love the vids too!!

The documentation provided is a great source... very methodical and great scripting for anyone to follow. Interesting the different adapter plate etc... didn't realise they were different underneath. So does that mean the solex barrels? are 2 different sizes.. 2 of each etc and the HOlley theyre all equal??

Is 1 lot the secondaries etc?

Sorry if its a stupid question, dont know carbs..

 

[Michel]

Spreadbore carbies are known to be more fuel efficient in your are crusing gently yet have massive secondaries (look at the large bores in the secondaries) for when you put your foot down and open the carby up fully.

How big is the Holley?

 

[oscar]

Holley's 390cfm.
Not sure about the Solex. I'm just hoping there's going to be a noticeable difference for WOT and all 4 barrels open. Already I'm adamant initial acceleration and lower revs will have more power.

But the large secondaries, it's why you get people noticing a surprising boost when they open. I'm sure Martin will testify to that, I'm sure he's written something like that before.

Cam, you pretty much got it. Primaries are the smaller barrels, secondaries are larger in the Solex. That config is called a spread bore. The Holley's primary and secondary barrels are all of the same diameter and it's config is square bore. Pure race Holley's would have all that choke stuff removed and secondaries would be hooked up mechanically. But we're talking for much larger engines usually.

 

[B13]

Those large secondaries on the solex probably look more impressive then they actually are... although they are big, they would need large booster-venturis (which restrict how much they can breathe) in order to get fuel flowing thru them once they open.

Also when I set up a Holley I put the distributor advance vac line into the side of the primary metering block, and block off the vac line under the throttle plates which pokes out the front (of course I've only set them up on cars with electric fuel pumps), so if the distributor doesn't feel like its advancing try plugging it into the side of the holley.

After you test drive the car I'd be keen to hear what happens if you switch the vac hoses around.

I.

 

[SELfor50]

So...... are you gonna cut a hole in the bonnet and put a nice chrome ram air cleaner on??

 

[oscar]

I'd like to but not for POVO, maybe a v8 down the track. You know how there's older cars with just a single offset cold air intake on the bonnet. Can't remember what model now but I've seen em and thought of working something into the shape of the W116 bonnet but there's too much work to shape something tight enough to remain air tight and then fit over the carb. I'm going to instead fab a hat for the carb and run a tube and scoop to the front of the car. Maybe even remove the LHS upper bumper and bodywork and have a ram intake there. Same spot as b13's intake.

 

[B13]

Same spot as b13's intake.

Mine's on the RH side.

Yours would be sooo easy to set up since you don't have a battery in the way like I do (at the moment).

I.

 

[oscar]

Mine's on the RH side.

Really! Man I thought it was on the other side but I've just looked at the sandown pics and realised I was wrong. But yeah, looking back at those pics - man that was a great day Can't wait to try Sandown.

But you're right about the extra room. Not only because of there being no battery, there's just a whole lot of room on the left with the carb set up and I6 motor. But I'd happily trade some space in for some HP inprovement. Big ram intake and custom headers, that's next step. More info when if it get's off the ground but planning's underway . Turbo would be cool but looking at the layout of ancillaries there's so much to be re-routed for RHD. Turbo's on LHD M110s would be so much easier. Either way, coolant lines to the heater box have to be dispensed with.

 

[B13]

Have you have a chance to take Povo for a drive in anger and evaluate the difference between the solex and the holley?

 

[oscar]

Have you have a chance to take Povo for a drive in anger and evaluate the difference between the solex and the holley?

Nah not yet. It's kind of the final test to check the conversion isn't it but I haven't had a chance yet. Might try and do it tomorrow. I did give it a start the other day and gave it a rev after warming up. She produced a bit too much blue smoke to my liking. Not thick and choking smoke but I don't know if it was there before or not. Perhaps I don't notice it when the car's moving. Anyway, check back tomorrow and we'll see if I can get a 0-100 vid up.

 

[Styria]

Hi Ossie, what a great write up and pics to boot. To be truthful, work like this is completely beyond my scope of understanding, although I am aware and familiar with some of the principles involved.

It will indeed be interesting to find out out if the work carried out will provide you with the expected improvements. I am looking forward to your test results. BTW, if indeed you're blowing an excessive amount of blue smoke, chances are.....no, wait, I was going to say that it's running rich...you know, excess fuel washing the bores etc. - not quite sure what to say. I do seem to remember , however, that on the day at Oran Park, Povo did not seem to exhibit any smoke from the exhaust. Regards Styria

 

[SELfor50]

Second that, there wasn't any smoke coming from Povo at OP. There was a red car and 2 107's that were puffing a fair bit though...

 

[oscar]

BTW, if indeed you're blowing an excessive amount of blue smoke, chances are.....no, wait, I was going to say that it's running rich...you know, excess fuel washing the bores etc. -

That's good news styria. Keeping in mind the Holley hasn't been reset. I simply put it straight on povo without adjusting anything. Last time I adjusted it it was after that rebuild last year and then reset it to try and get the red 280S going (which had compression and head gasket issues). I really need to tune the Holley by the book. A current rich condition is probably spot on.

Second that, there wasn't any smoke coming from Povo at OP. There was a red car and 2 107's that were puffing a fair bit though...

It's great to hear that you too saw no smoke from povo. You would have had a good view each time I over took you .... I mean, that should read the other way round I asked Nat but she slept most of the day so saw nothing and she knows a smokey w116 when she sees one. Too much first hand experience unfortunately.

I'll update after a test drive but the proper tune may be a little way off. Need to buy some more tools for the job.

 

[Michel]

Second that, there wasn't any smoke coming from Povo at OP. There was a red car and 2 107's that were puffing a fair bit though...

POVO wasn't being pushed hard enough..

That said RED car was being driven to the limit

What about the multi coloured 116 from Canberra...

 

[oscar]

Any smoke at OP was just tyre smoke wasn't it

Well, just been to the test track and back. I couldn't see any smoke from the rear view mirror so that's good. There's bound to be some but whatever's there isn't a problem. The 350's been much smokier in the past.

Anyhoo, the only prob with the holley under load is that at part throttle there's a slight hessitation, as there is from idle to WOT. Not really noticeable on the vids but it makes sensible driving annoying so far as the car will momentarily die then kick back in when on the move and accelerating from coasting speed. Not sure if it's occuring during the transition to secondaries (seems much earlier) or to do with the accelerator pump (which is what I suspect). I adjusted the pump and replaced the diaphragm last year but it's either coming on too soon and flooding or too late and is starving the engine for fuel at that moment where the throttle opens more. Not sure which.

Now for the vids. Nothing spectacular. Still around 10secs for 0-100. But I come back home to view these vids and think I should've pushed it harder. I need to rev out 2nd gear a bit more for starters. Sloppy changes really. But 2nd gear quickly loses acceleration once RPM is near 5500-6000. I need to improve engine breathing plus play with cam timing. Sorry about the reflection in the second vid. Didn't think it was going to be that bad.

 

[B13]

Where is the vac line, on the metering block, above one of the idle screws, connected to?

 

[oscar]

Oh ####! I see what you mean. I remember you saying something before and I forgot to respond to that question but I was going to say you were on the wrong track. Sorry man!

Here's the go - That metering block vac hose is actually cut off. It was cut off in the other 280 and I thought it was an overflow of some kind

Referring to the pic below there's 4 vac connections.
From the left,
- The first labelled "PCV Hose" is plugged on povo.
- Second, a bit of a revelation too here. There is an unmarked hose going over the top of the "Choke Thermostat". The hose is missing on mine. The connection down below is plugged but the top connection is simply not there. There's a hole you can see right through with no nipple or connection that should fill part of that hole. See 2nd pic.
- Third vac connection, the "Timed spark vacuum source" coming from the metering block has a hose dangling down the inlet manifold on povo. Open to the atmosphere. it should be going to the advance on the dizzy as I've just realised in the last 10mins.
- Lastly, below and to the right is the "Full Manifold Vacuum source" which I suppose should be plugged. Instead that's what I've wrongly got connected to the vacuum advance on the dizzy.

So, I've got to go to Wagga tomorrow for Rego. There's quite a few auto places down there so I might just try and get a part that fills that hole for the second vac connection. Not sure what it's for. It's unlabeled in the pic below and no comment is made in the literature. There's also no mention in the Holley exploded diagram vid (see youtube link at bottom). Any ideas?

Either way, I'll reroute hoses and plug what needs to be plugged. Wont be able to test drive again for not sure how long.

 

[B13]

That all sounds about right but don't worry too much about the plugged ones or missing ones just yet. Some of the smaller carbs in the series (of which yours is one) doesn't need as much air on choke so the omit that side aux air hose... it just brings some small amount of additional filtered air from around the seconary venturi's down to the carb base to make the car more drivable when cold (think of it as a bit like the D-jet Y-tube feeding the aux air valve and idle control block).

As for the PCV, its your call... since its a race car, leave him blocked and run the crankcase ventilation into an oel catch can... the scruitineers will love you for doing your homework.

Yes the Timed spark port needs to go to your dizzy, if you are still using vac advance (i know you are). Race engines like the 13B PP in my RX4 use no vac or mechanical advance, the advance weights in the distributor being welded permanently, and the timing set permanently to 30 degrees BTDC. It makes the thing a pig to do anything other than full throttle, but it does simpilify the engine bay even further.

The full manifold vac port has lots of uses... or just block it off... Its where I connect a vac gauge if you are putting one on your dash or if you are testing the engine in a dyno for the correct power valve. On a carby-turbo setup you use that port for a boost-referenced fuel pressure reg.... etc. lots of uses.

Ian.

 

[oscar]

Thanks very much for the advice Ian, and thanks again for bringing up the question of the metering block connection again. I would never have noticed I had it wrong. I'd love to take it for another spin now but it'll have to wait. I've plugged the Full Manifold Port for the time being and rerouted the advance line to the metering block.

I wonder if this was causing the lack of power towards the top end and not being able to reach the rev limiter cut off. Since the vac would be close to zero at WOT I'd be getting no advance at all. But I've also read a long time ago that for the V8's at least, vac advance only works to a certain point before mechanical advance takes over. In other words, at WOT and high revs the mechanical advance is doing all the advancing. Who knows. It's gotta be quicker off the line now surely. Never heard about permanently setting the mechanical advance weights in the dizzy to max position. Interesting stuff.

As for that bypass hose that's missing, I think I'll take your advice and leave it. Your theory of operation makes sense for that part and since i'm thinking about dispensing with the choke plate and choke it's going to take a few pumps and turns to get it started anyway. Warm or hot running is what we're interested in anyway.

A couple more things about today's run. Firstly, with enough speed, the airflow through the radiator keeps the coolant at just over 80deg. It was like that at OP too. Even without the rad fan, the electric fan only comes on when and if I park at idle for at least a few mins. once I start moving the thing cools down. Not really driving on hot days yet but I'm impressed.

Secondly, although I had the vac hoses around the wrong way, the difference between revving with and without air filter housing is amazing. There's so much lag with it on. The engine gets to high rpms much quicker with it off. Like I've said before, I have to make the engine breath better.