I got a MC 2150 (not 2100) off of a 1985 (or so) Ford Van. It's a 1.08 (like the other 2 MC2100's I have) and I am going to put it on top of a 304. Distributor is stock except I have the Petronix electronic ignition on it.

Question is this: The only vacuum port coming out of it is on the rear for the PCV. What do I do for the vacuum advance for my distributor??????

On the 2100's, there is typically a port on the base of the carb in front to hook it up to. Not on this one.

Can I just advance the distributor to 7-8 deg. and go with that or ??? Not sure where I would get ported vacuum (versus the constant going thru PCV line).

I did a search and read Tim's writeup (awesome) but didn't address this.

TIA

I tried using manifold vacuum for the distributor advance, but found that (I had to back off the advance so much that when I stepped on the gas to pull away, and vacuum dropped,) I got a bog off the line. With a little experimenting you could set up the distributor for running off manifold rather than ported vacuum. Lots of hi performance motors run off manifold. You just have to set it up differently, and I was told the hei distributor works best off ported, so that's what I settled on and found it did work better. What was wrong with the mc2100's you found? Wrong size? Damn, we've got to start saving those carbs for ourselves any time we see one till we can all afford fuel injection for our old inline sixes.

Tim

the one I have was for a ford van with a 302...has multiple vac ports...and a PCV port.

Weird.

MJ

How would I set it up differently???

It seems I would have to back the timing off??:confused:

I would prefer to run it off of ported, but there is none.

The MC 2100 I have on my 258 is great. The one on the 304 is tweaked -- tried to rebuild it, didn't work, engine ran great temporarily with a holley on it.

I know summit and others sell adjustable vac advance kits..canister, and diaphraghm for HEI, and delco, and fords etc....

I f'd around with the Crane cams adjustable kit for a summer and never got it to my satisfaction. Went back to the hei's stock springs and vacuum pot. The crane kit was meant for using manifold vacuum. Manifold worked great for me at mid and top end, but as I mentioned, I never got around that drop in vacuum and loss of advance when you first pull away from a stop. I know the theory of using manifold vacuum is sound for drag racing, the engine at wide open throttle can't tolerate as much advance because the cylinders are fuller, and at part throttle you get better fuel economy and response because a partly filled cylinder can handle more compression and advance before detonation. But when you try to move the jeep from a stop with light throttle, you have low vacuum, very little advance, and subsequently a loss of low end power. Maybe keep looking in the boneyard for another 1.08 with the ported ports. Save the jets from that other carb, they might come in handy?

It is my understanding from looking at a few diagrams that your distributor vaccum is best supplied by the CTO switch located near the dist. It has 3 vacuum nipples on it and the Dist hooks up to the center nipple. The other two are either ported or manifold vacuum and the active source is selected based on current engine temp. The idea is that the valve applies different vacuum types - ported or raw- after a certain engine temp is reached. The dizzy needs manifold vacuum when cold, and ported once hot. Obviously it will work fine just off the carb base using ported all the time, but you will loose the CTO overide function of regulating the vacuum source if you do.