Question about using a Syncrometer for PMO
 

I'm getting ready for my first startup with PMO EFI and I will need to balance the throttle bodies.

My friend brought over his syncrometer that he has for his '71s with MFI. I was surprised that his syncrometer looked totally different than the one on the PMO instruction videos. The PMO version looks like it fits snuggly into the throttle body stacks and my friend's just sits on top.

Does anyone know if there is a difference and are they both just as good to use? And lastly, Pelican sells two that look identical but one is listed for PMO carbs and the other just says for carbs.

Here's my friend's type:
http://forums.pelicanparts.com/uploa...1412811810.jpg

Here's the one sold on Pelican and Clewett Engineering sites:
http://forums.pelicanparts.com/uploa...1412811850.jpg

Synchronometers
 

Can't speak to the one your friend loaned (Empi style), but I assume it works equally as as the STE type sync's that you posted the picture of.

The two listed on Pelican are the STE type (STE is the brand) and they come in 2 sizes: the BK which fits snug in 46-50mm PMO carb velocity stacks, and the STE-SK which fits snug in smaller diameter velocity stacks.

Here's a link to an instruction manual that shows both BK and SK models for comparison:
http://www.dellorto.co.uk/images/parts/Synchronometer%20instructions.pdf

Good luck,

Gordo

Don't buy 2 units to work both sides as they are not exactly the same when running.
Bruce

Thanks for the explanation & link!

I was worried that my friend's was too old and maybe worn - so, in my compulsion to have all my own tools, I bought one today from Pelican. I got the BK model and I hope that was the correct version. It looks like it is but I will measure the stacks tonight when I get home.

^^ I agree.

I machined my manifolds to accept vacuum ports and use the 4 channel sync gauge i use on motorcycles. I can test any 4 cylinders i want at the same time.

http://i1178.photobucket.com/albums/...ps111a9082.jpg

I tried to make them look nice when ports were not in use.

http://i1178.photobucket.com/albums/...pscc6706dc.jpg

Either works, but your friends version is adjustable and may be an easier fit on cylinder 3 (tall manifolds and stacks sometimes are too close to the firewall/sound pad).

Hi Vern,

Your friends syncrometer is identical to the one my mechanic used to setup my PMOs.


Cheers,

Harry.

That look good. How about a pic go the of the sync gauge?

the one with the tube will choke the cylinder. the newer style syncrometer will not.

Thanks all!

I bought the newer style and it will be delivered today. I tried the older style (my friends) and the tube that needs to be straight up will not fit over the rear stacks as it hits the sound pad on the cylinder's 3 & 6. It looks like there will be enough room for the newer style that fits into the stack (I'll know for sure tonight).

Based on my slow progress this week and a tough schedule at work, I probably won't be starting the engine until the following weekend. But that's ok with me as it gives me some extra time to check and double check everything.

I use a Morgan Carbtune.


http://www.moorespeedracing.co.uk/us...N-CARBTUNE.jpg


www.carbtune.com

A 6 channel version would be perfect :)

I've used both and have both.

I bought the one in your first picture first for tuning my MGB with SU carbs.
I bought the second one for tuning my 912 with Webers.

Both work well...but al the other advice here is good advice - use one, not both.

Unisyns aren't the best tool for the job, in this case. The synchrometer shown in the second picture doesn't, as others have said, interrupt the air flow to take a reading. BTW, the stack can be at any angle for the Unisyn to work, and they can be used on carbs where the configuration prevents the synchrometer from fitting the bore (i.e., Zenith carbs on a 356).

The Cap'n

My syncrometer was delivered last night. It fits but it's a tight squeeze. Actually, it fits all stacks pretty easily but #3 the top touches the pad, but it will work. I bought the BK version and it's possible that I should have bought the SX which is a little narrower. Regardless, it fits into the stacks snuggly.

BK Sync
 

In order to get a consistent reading - I need to hold mine in place, pressing them for a tight fit on the velocity stacks; otherwise they will fall over and leak (not so much at idle - but if I rev the motor they fall).

I assume this is normal - sounds like yours fit the same.

Gordo