Got a few questions:
1. I have a set of 1973 heat exchangers I want to install. The flanges are about .250", but the stock exhaust flanges from the '77 exhaust are about 1.0" thick. Is there a trick to install the older heat exchangers? I used a bunch of washers under the nuts against the flanges, and they didn't seal against the head very well.

2. The idle (stock CIS induction) is at about 1200 rpm. Is that normal? Should I adjust it down? How do I do that?

Thanks,

Nathan

 

My '77 has SSI headers that bolted up properly. My first guess is that you will want to use different studs with those heat exchangers.

As for CIS, everyone's first guess seems to be vacuum leaks. I would not adjust anything until you rule that out. There are some good books on CIS worth reading.

Now we can hope the experts will jump in and give you better answers.

Glad to see another 2.7 in TN! You may want to join us for future runs to the dragon, etc.

 

Sure, I'm in. You know anyone that needs some work done? 356s, 911s, ...

 

Damn i wish you lived closer ... I have a set of thick flange in my garage and I need a set of thin flange .. ( i have a 78 sc and I have the exchangers off a later thick flange.

anyway Normal idle is at about 950 - 1050 but that is when the car is fully warmed up . On mine there is a large round knurled **** on the throttle body with a slot in it for a slotted screwdriver.

you may see it in this pic

 

Thanks for the pic. I'll check it tomorrow. All of the boots and hoses were replaced last year. I only have 1500 miles on it, so I don't think I have a vacuum leak. I do think I'm running a little lean at a constant rpm. I had the heat exchangers cerimic coated black, so they look good and hopefully should last a while.

 

Well if the boots and hoses were replaced I sure hope they would have done a CO% check. if they did and it is just adling a litle high it could be an idle issue which this will resolve. If you know anyone near you with an air/fuel meter throw it on and you can recheck the CO% , this will effect idle more anyway

 

Unfortunately I don't...

 

The first thing that should be checked when dealing with any CIS issues is the CO% (fuel mixture). Everything else is just shooting in the dark...

 

Words of wisdom from PZ.

PJC

 

Thanks guys. I appreciate the direction. What percentage should I see with the CO analyzer.

 

on a 2.7 I am not sure Pete would know for sure. On mY 3.0 SC I ham set at about 2% and it runs flawlessley.

 

I just checked my tech spec booklet, and it says 1.0-2.0%. So I guess I ought to flip through it sometimes. Thanks guys. I lowered my idle to 1000rpm. I'll drive it a while a see what happens. In the meantime, I'll look for someone with an air/fuel meter.

-Nathan

 

I ran 3.5% mix.

I disconnected distributor vacuum retard hose permanently. I ran 35 degrees max. That may give you a 5 deg advance.

I had a high idle issue with the CIS that turned out to be a faulty deceleration valve. Sometimes they can just be reset by the deceleration valve adjuster screw. I just disconnected the hose and plugged it. No deceleration valve, no issue.

After I rebuilt my 77 2.7 I confirmed my head studs were ok by setting torque wrench to spec and only turning clockwise. Do not turn counter-clockwise as per retorqung procedure.

I checked valve adjustment after 1,000 miles

New distributor points break-in. They should be checked after 500 miles and should stop wearing? If they were greased it may take 1,000 mi or more.

party hearty

 

You can change the studs I just got some pipe and cut spacers to fit and torqued from there never had an issue. As for co I ran 2.5% for years and the car ran great. Lots of rubber to leak and a pesky AAR that could be stuck to keep the idle up.

 

Yeah to me I would go with the pipe spacers if i had to do this. not pretty but it will work . Replacing the studs to me is just to high in the risk/ rewards ratio. Bust some of thos studs and you will wish you had used the spacer.