Max fuel pressure for Carter 3705 carbs?

[Geoff 2]

Thanks for posting that, very interesting.
Hard to see in the #188 float in the pic, is it the smaller one?
Have you seen any conversion measurement for float level if switching between large & small floats.
9000 series definitely started as Carter, not FM. My catalog is pre - FM, these models for Chev: 9625, 9500, 9400.Ford: 9627. Chrys 9626, 9501

 

[Dragon Slayer]

Yes smaller smooth float. No I had not seen a conversion measurement.

 

[fmahannah]

The MSD RtoR junk does not have an adj vac adv unit, only non-adj. Vac adv HAS to be adjustable to work with your combo. Best bet is to buy one of these from Summit, both are in stock & cheap: SUM-851018 or PRO-6694. Both are mag trigger, will drive your 6AL, & come with adj VA units. I used the Summit one last year; it used the Mallory system for centri wt adjustment, an easy system to work with. WOT timing comes at the end, not the beginning. You do not need a fancy, expensive dist to drive the 6AL.
Because of the poor distribution that intake has, you are likely to have lean cylinders [ detonation ], so I think it will need high-er octane fuel.

I looked at both of these distributors with vac advance and can't find instructions for hooking them up to a 6AL? They both say you need to buy the kit with the electronic control box?
Any tips on what I need to buy and how to hook up to my existing 6AL, or can I just ditch the 6AL system and install the SUM-851018? I need the vac advance to get the idle where it needs to be and I suspect that there is something wrong with the current MSD system and new distributor.

Thanks!

 

[steve340]

The vacuum advance canister on the distributor is connected to a port on the carburettor - not the MSD unit.

 

[fmahannah]

The vacuum advance canister on the distributor is connected to a port on the carburettor - not the MSD unit.

I know where the vac advance hooks up, the question would be can the 6AL connect to that distributor? Sorry but never messed with MSD stuff before, more of a points and condenser guy LOL.

 

[33 IMP]

I know where the vac advance hooks up, the question would be can the 6AL connect to that distributor? Sorry but never messed with MSD stuff before, more of a points and condenser guy LOL.

Msd wiring diagrams are available on line. A 6AL can hook up to almost anything and everything. You do have the analog version, not the digital six, right?

 

[steve340]

Ah OK the way your post was written I got confused.
The 6AL can be triggered by just about any ignition points or electronic.
I think it is the white wire for points.

 

[fmahannah]

Actually its a 6BTM - boost part not being used

 

[Geoff 2]

Fma,
That dist will work perfectly. The large hex on the VA unit means it is adjustable. Most take a 3/32" Allen Key, so turn the AK fully CW. That is the lowest vacuum/softest spring setting. You need to hook it up to manifold vacuum, which is any source on the intake or below the t/blades on the carb.
Worry about the centri curve in the dist later, get it running & idling first.

 

[fmahannah]

Trying to hook up thise Summit distributor, old plug wires were for msd dist cap (male) and new dist cap is female.

Can anyone recommend a plug wire set that has 90 degree spark plug boots and 90 degree female distributor cap boots that will work with the MSD 6 BTM and the summit SUM-851018 distributor for a 413/426 engine? Thanks!

 

[Geoff 2]

SUM-860825 universal kit [ also in blue ], make yourself.
If you measure out the reqd lengths carefully, you will have at least one spare lead left over. Take no notice about the BS on 'lowest' resistance leads.

 

[fmahannah]

The MSD RtoR junk does not have an adj vac adv unit, only non-adj. Vac adv HAS to be adjustable to work with your combo. Best bet is to buy one of these from Summit, both are in stock & cheap: SUM-851018 or PRO-6694. Both are mag trigger, will drive your 6AL, & come with adj VA units. I used the Summit one last year; it used the Mallory system for centri wt adjustment, an easy system to work with. WOT timing comes at the end, not the beginning. You do not need a fancy, expensive dist to drive the 6AL.
Because of the poor distribution that intake has, you are likely to have lean cylinders [ detonation ], so I think it will need high-er octane fuel.

Ok I have installed the SUM-851018, new plug wires, adjusted the vac can to max. When idling at 1200 rpm it shows about 33 degrees of advance at idle. Idle is smooth, no longer way too rich.
Without the vac advance I am at about 9 degrees.

But now if I drop the automatic into gear it almost immediately stalls. I assume this is because when I put it into gear it is losing the vac adv from the canister because of the load change?
Can't be driven this way.

I don't want to have to idle at 1500 to get it to not stall in gear if possible. Any tips greatly appreciated. I am so close to being able to drive this Polara.

I wonder if the stall is because when put in gear the signal to the vac adv unit is lost if I might be better off advancing the initial timing without vac advance to 18 which is
as far as I can go since the mechanical probably adds 18? Not sure on this Summit dizzy what the mechanical advance actually adds?

It might not be reachable but my goal is smooth non-rich idle at 1200, being able to shift into reverse or drive without it stalling as it will be driven in traffic to shows etc.

Thanks again for all the help

 

[Dragon Slayer]

What distributor do you have? You should be able to inspect it to see slot length to determine amount of mechanical adv applied. 18 and 18 is not out of reach for a big block.

 

[Geoff 2]

Did you turn the Allen Key fully CW in the VA unit?
After doing this, check with the timing light when placing in gear that timing is not dropping off. You may need an assistant for this. Another way of checking this is if you have an old dist cap. Cut the side out so that you can watch the VA actuator.
If the timing drops off, it might not be the VA causing it. At 1500 rpm, you might be activating the centri curve in the dist, & this is dropping off slightly with the rpm drop going into gear.
It also may not be ign related. Going into gear loads the engine more & rpm drops. The carb now has to be rich enough at this lower rpm to carry the load. So you could try richening the idle mixtures screws.

 

[fmahannah]

SUM-851018 as recommended here to get vac adv. Instructions are pretty skimpy and don't say anything about the curve or the amount of mechanical advance given at any RPM.

Right now I have it at 18 initial, 25 with vac adv, and it idles good but only at 1100-1200 rpms and stalls immediately when dropped into gear. If I bump the inital more to get it to idle in gear (since vac adv goes away when put into gear) then I risk having too much total timing (inital plus mechanical) since I don't know how much mechanical advance is in this distributor or when it all comes in either. Not sure what springs to buy to recurve this dizzy. I have springs for MSD but not sure they would work. Main thing is I am not sure how I can limit total advance with this dizzy other than one of those plates I see available. Not sure which one to buy for the Summit dizzy but it appears to just be a replacement for factory Chysler dizzy?

 

[fmahannah]

Did you turn the Allen Key fully CW in the VA unit?
After doing this, check with the timing light when placing in gear that timing is not dropping off. You may need an assistant for this. Another way of checking this is if you have an old dist cap. Cut the side out so that you can watch the VA actuator.
If the timing drops off, it might not be the VA causing it. At 1500 rpm, you might be activating the centri curve in the dist, & this is dropping off slightly with the rpm drop going into gear.
It also may not be ign related. Going into gear loads the engine more & rpm drops. The carb now has to be rich enough at this lower rpm to carry the load. So you could try richening the idle mixtures screws.

Actually I had my wife watch vacuum when I dropped it into gear, and she said it dropped all the way? Not sure why it might lose all the vacuum advance other than because it stalls so fast?

Before I changed to this distributor and replacing the carter carbs I only had 6 inches of vac at idle around 1000. Now with new carbs and initial at 18 and vac advance bumping that to 25 or so I am at around 10 inches of vac idling at 1200.

Yes I did try turning the vac adv unit all the way and backed off a little. With it set that way and initial at 9 it was adding 24 degrees of timing for a total at idle of 33

I will try richening the mix screws tomorrow to see if it will keep idling in gear.

 

[Geoff 2]

You are on the right track. Forget about the centri curve for now & concentrate on the idle.
With that low vacuum, you must have the AK adjusted fully CW [ softest spring setting ]. Can you PM me an email address, I want to draw a diagram for you on the best set up for the VA.

 

[Dragon Slayer]

You can check your total by making sure you have a mark on balancer that is 30 or 35deg BTDC. After warming up engine you can rev it up and see what total you get. Personally, I would do this with vac disconnected and port plugged. This at least lets you know what total this distributor gives based on your intitial.

 

[fmahannah]

Update .... I hate to admit it but I had the mixture screws set at 1 1/2 turns out and had forgotten about them since on the old carbs they had no effect at all (blown out seats). I turned them out another half turn and now it stays running in gear.
Apparently idling at 1100-1200 I am into the transfer slot so that is where fuel was coming from, but the rpm drop in gear made it try to run off the normal idle circuit which needed more fuel?

For now I set the initial at 12* to prevent going too far with mechanical until I test what it adds, and vac adv bumps it up to around 30. Seems to like it there.

BUT because of the cams low vacuum the vac adv won't kick in until I get the idle up to around 1100 rpms.

Does the adjustment on the vac adv affect how much vac advance is added OR does it also affect when the vac adv kicks in (at what vacuum level)? Or is there any way to make the vac adv kick in at a lower vaccum level?

Thanks to all the help here I might actually take this beast down the road this afternoon

 

[Dragon Slayer]

It controls when the Vacuum can come in based on a preload of the spring. How far it advances is based on the arm. Should have a number stamped on it. There is a minimum Vacuum before it starts to add advance. By lightening the preload fully you have set it towards a minimum. You could put a vacuum pump with gauge on it and see what vacuum it starts moving. The only way to limit how much it adds is to get one with the amount you want, or modify the arm with a stop to limit how far in it can be pulled. Or add more preload, but that also can effect when it comes in. Your low vacuum probably doesn't allow a full stroke, unless that can be adjusted to really remove the preload, and has a light spring to start with.