FAST, Holley v1, Holley v2 Dual-Sync Comparison
 

Here's a quick comparison of 3 different dual sync distributors, the FAST, Holley version 1, and Holley version 2.

The bodies of the FAST and the Holley v1 are the same, though there are differences. The Holley version 2 is a new body design, as mentioned in other threads, and appears to be a version of the MSD Pro Billet body.

Caps on the FAST and Holley v1 look interchangeable, but I would suspect they are indexed differently, and would have to recommend that you use the appropriate cap, to avoid having to at least check, if not correct, any rotor phasing issues.

The Holley v1 has a 5/16 threaded piece that screws down on the 'L' retainer, which is kind of cumbersome, since you would have to hold it in the groove in the body as you tighten it down.

The FAST cap retention is the common sprung 'L' bracket with a cross-flathead screw, and the Holley v2 is simply machine screws (with no positive retention to the cap).

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For triggering, the FAST uses flying magnets, similar to a crank trigger, in a 'casing' that's on the shaft. It appears to be a typical ford style mag pickup attached to the body.

The FAST shaft and rotor pad looks like a 'regular' dizzy, that's been welded. Both Holleys have a specific-built rotor pad, and is CNC cut.

Both Holleys appear to have very similar electronics, hall effect pickups and reluctors.

The FAST and Holley v1 has a vacuum can delete plate, and there is a hole that is not covered that passes into the body under the electronics plates. This could allow water/moisture to gain access to the inside of the dizzy, and could contribute to a 'crossfire cloud' or corrosion of cap terminals etc. If using one, I would recommend filling the gap(s) with RTV to prevent any potential moisture from entering.

You can see on the Holley v2, the 2 rollpins that are installed into the body to index the cap.

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I feel the Holley v2 has improved features over the v1 and FAST, the cap retention is more positive, the body and reluctor is black powder coated, and it is a smaller overall package.

The FAST, being a flying mag trigger, may have advantages over the hall effect triggers, due to the fact it would be more compatible with a number of systems. Holley EFI I believe, or at least used to, require a hall effect type trigger, though believe with the release of the HyperSpark dizzy, has made changes to the software to allow for flying mag trigger dizzys.

All state that no rotor phasing is required, due to the close tolerances during manufacturing. Both Holley and FAST EFI ECUs provide an IPU offset setting to help calibrate any variance, so not sure how much of a factor this is.

If purchasing one new, the Holley V2 would be my choice, if you're currently or have future plans to go sequential. If not, the HyperSpark (EDIT: Or an MSD Pro Billet) would suit your needs.

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Have to pull the cap off the Accel I have to compared.

The guys at Holley we’re very frank with me in a discussion I had with them about the sniper and the Dual Sync and support going forward for us guys who will actually drive our cars. I walked away from the Version 1 VS Version 2 question with the answer being that the v2 is now being manufactured by MSD and both are equal in performance

Would be nice to have it all in one thread, that's for sure! I honestly forget what they look like under the cap.

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Aside from the points I made, I would agree. But like I said, corrosion and tracking is going to be an issue with the 'open' housing of the V1 and FAST units.


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Now they did say the MSD unit was a nicer piece so I guess that’s what he was referring too

I looked in the garage must have taken it to the shop will snatch it this weekend for pictures.

No worries, would just be a close the loop thing, pretty sure they are not being made anymore.


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OK here is the ACCEL one. Under the circuit board to the right there is a black square hanging down. There are two different circular things under neath with a large single window in the inner one, the outer one has several hard to count maybe 8. Looks like the one on the middle one only under the circuit board.

Ah, now I remember! Yeah, those are still pretty nice, even if slightly older technology, but are hall effect. I know they worked well with the Accel EFI, from version 5 up. Would imagine they would work fine with any current EFI as long as it supports hall effect triggers (Know the Holley offerings do).

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I would have pulled the circuit board up for a look but figured it may mess with rotor phasing .

Pretty sure the board is 'keyed', and only goes in one way. No biggie though, I get the idea.

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Only goes one way but it is held in place by slot head screw in the slot and possibly could move a little. Since the senor is on the board I would screw something up!

Yeah, no sense taking a chance, I agree.


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And Murphy's Law always gets me!