'77 and Cali smog battle / EMPI DFEV setup

[124Fan]

My '77 failed emissions today with the EMPI DFEV carb because the smog guy noticed the 2 14mm spacers under the carb. It was running good. Smooth idle at ~900 rpm, good throttle response and power. I did have a backfire on throttle "tip in" that was noticeable when cold, but pretty much gone when warm.

I tried to explain that these spacers were there to get the carb to the proper height (ie, studs are way too long to put it on without spacers), but he wasn't having it. He told me if I wanted to contest it, I'd have to see the smog referee. Sent me on my way. Argggh.

I went home, pulled the carb, removed the 2 14mm spacers and gaskets, put shorter studs into the manifold, and put it all back together with a single (new) gasket between the carb and manifold. The idle is really poor now. Driving around, it's ok above about 2500 rpm with some load, but idle is really rough and low. Below 2500, it sounds like my '72 did when I'd forget to open the choke after it was warmed up. Sprayed around the carb to verify that I don't have a vacuum leak. I tried increasing idle speed via the speed screw, but if I go too far with it, I start getting fuel dripping onto the primary throttle plate from another (main?) circuit. Besides, cranking up the idle speed is just a band-aid.

Will this carb just not run right without the spacers? The stock ADFA carb has a very thick spacer integrated into the base of the carb. I take this to mean that the '77 manifold needs some space between it and the carb. I know the spacers are often used for performance reasons, but in this case, aren't they giving the fuel a better chance to atomize before reaching the intake valves?

Thanks,
Sonny

[So Cal Mark]

we've put many on without spacers without an issue. Raising the carb generally provides more torque

[124Fan]

Hi Mark,

So you'd expect no change in idle/low speed operation with removal of the ~30mm stack of spacers?

I guess i could swap things back in (longer studs + spacers) and see if it goes back to running good (ie, maybe I bumped something when swapping).

I put a DFV on my '72 many years ago and it ran great with no spacers, but that setup was quite different than all of this garbage they've installed on the '77. With the '77, I need the two spacers just to get the DFEV to the same height as the ADFA or the studs are too long. Also, I assume I'm correct that if the idle speed screw is turned in too much, I start getting fuel from places other than the idle circuit?

I'm in NorCal or I'd have this thing on a trailer heading down to your shop.

Thanks.

Sonny

[So Cal Mark]

if you close the idle mixture screw you can't get fuel from other circuits unless you open the throttle plate.

[124Fan]

This is the behavior I noted when I had the idle speed screw turned in too far.

https://www.youtube.com/watch?v=Q_cyNe- ... e=youtu.be

A couple of friends insisted that the float level was wrong, but it doesn't do this unless I turn the idle speed screw in past a certain point. Plus, I've been trying to avoid having to break the gasket on a brand new carb. Mark, do you ever need to adjust the float on these things out of the box?

Thanks,
Sonny

[124Fan]

Yesterday morning, I hooked up a vacuum gauge to the intake manifold and saw that the engine was only pulling about 10" at idle. That made me suspicious that there was a leak I hadn't found yet. I unplugged all vacuum lines from the manifold and plugged the ports. 17" of vacuum and the engine is running better! Replaced the leaky hoses and got it running smooth.

Called the smog station to make an appointment and then started driving around to get the cat up to temp.

About 15 mins into my laps of the neighborhood, there was a change in engine note. I popped the hood and saw that the engine was running rough and that the air injection hose had gotten blown off and seemed to be dripping coolant. Pulled the plug wires one at a time and found that there was no change when I unplugged cylinder #4. Got it home, pulled the plugs and grounded them, and cranked it. Geyser of coolant out of cylinder #4.

The radiator on this car had been plugged and likely the engine ran too hot too many times.

So close yet so far away.

Sonny

[124Fan]

Well, pushing on I found the problem.

The coolant passage around the #4 combustion chamber is so badly corroded that it is allowing coolant to dump right into the cylinder. This head is toast, I'm afraid. Aside from this damage, 2 of the studs on the bottom of the intake manifold sheared off flush with the head when I attempted to (gently) remove them. Why did they put bolts here??? I know...to save 25 cents, but jeez, what a stupid decision.

Anyway, now what? It's a 1756cc head with air injection holes. I've got a good 1592 head in a box, but it has no air injection provision so that would be an automatic fail in California unless I got creative. This smog is such a pain in the a@@!




Sonny

[wizard124]

I have an 1800 head. PM me if you're interested in it.
Warren

[So Cal Mark]

the head can be welded, then resurfaced

[124Fan]

A local guy near work had a pair of 1800 heads, so I bought both. The cleaned up one is a 132AB head from a '74-'76 1756cc engine. The dirty one is a 134AS from a '78 1756cc. Same as my current one. Both heads are setup for air injection so I'm in the clear there.

I'm going to have a local machine shop (that has done engine work for me before) check them over. The 132AB head is nice and clean and is more appealing, but I'm not going to base my decision purely on looks. The 134AS head does have 2 broken off bolts in it which is potentially a big PITA. We'll see.






Sonny