What needs to be adjusted when disabling EGR valve? (1 Viewer)

[IslandJ]

From reading various threads it seems as if one was to cap off the vacuum line between the EGR valve and modulator that recurving the distributor would be needed.
My 1985 runs like a new truck when I disable the EGR valve. Im thinking of running it disabled between smog appointments.
I'm in the middle of checking a bunch of components under the hood but getting to my wits end with the hesitation.
I read somewhere that some people don't recurve and haven't reported any ill effects. As long as they aren't experiencing pinging, what issues could be going unnoticed?
Thought it might be good if some of the more knowledgeable could chime in on the pros and cons of capping lines and recurving the distributor.

I've reached out to TLC Performance but haven't heard back. Are there any other sources to for a proper recurve?

 

[YooperCruiser]

Jim C of TLC Performance is the go to guy. Apparently you just send him your dizzy with info and he'll send it back when it's done. I've read turn around time is a couple months. He doesn't answer the phone or emails much since he is very busy.

I've desmogged my 88 and haven't had any pinging, yet I'm going to pull the distributor and go through it myself. I've got the springs and parts to recurve and refresh. There's some info on post #13 of this thread. I''ve copied the post below
'83 FJ60- Dizzy Recurve- Can anyone demystify this process?

I HAVE SUCCESSFULLY CRACKED THE DISTRIBUTOR RE-CURVE CODE!

I think it is common knowledge that desmogging an FJ60 and recurving the distributor go hand in hand. The distributor was set up to optimize performance based on a vehicle with the emissions equipment in place. Once all that stuff is removed the distributor provides too much advance and the advance comes in before you really need it and runs out when it is needed the most. Simply leaving the distributor and timing alone will, in most cases, cause pre-ignition or pinging when the truck is under load. There are a couple of band-aid fixes that will allow you to drive the truck but the results are far from optimal. One fix is to reduce the initial timing to the point that the pre-ignition goes away. This method can cause hard starts and stumbly idle and the truck will feel sluggish and under powered. The other band-aid fix is to leave the initial timing alone and run the truck with the primary advance from the carb connected to the secondary port on the distributor. The second method cured my pinging and allowed me to drive my truck for several months issue-free. It still felt sluggish though and I started to think hard about a dizzy recurve.

There is a vendor on this site who recurves dizzys, rebuilds carbs and sells de-smog components. He does excellent work. I've used him before and I always recommend him to others. I have a trip coming up and I wanted to get the Turdle ready. The vendor was not responding to my emails so I decided to go it alone using information gleaned from MUD. Here's what I did:

Remove the plug wires/vent hose from the distributor cap. Unclip the electrical connector on the side of the dizzy. Remove the cap. Take pics and mark the location of the rotor button in relationship to the engine (mine was pointing directly at the #1 wire position on the cap). Mark the position of the distributor housing. I used a dot of red paint on the distributor and marked a dot on the engine block directly behind. This is not super critical. You do want it close so that the truck will actually start once the distributor goes back in. You will tweak the timing later. Remove the hold-down bolt and pull the dizzy out. With the dizzy now on the work bench, gently remove the plastic cover over the electronic trigger. Remove the two screws that hold the trigger in place (consult the FSM when you re-install to set the gap properly). Remove the vacuum advance clip. Pop the advance rod off of the pin. Remove the vacuum advance hold-down screw from the side of the distributor. Gently wiggle and remove the vacuum advance canister from the distributor. Remove the two screws and the hold-down tabs that locate the advance mechanism. Pop out the vacuum advance mechanism to access the springs, weights and stop pin.

The first issue with the FJ60 distributor is the common problem of the advance stop pin bushing. Inside the dizzy is a pin that keeps the advance in check. Mr. T used a little plastic bushing on this pin. The bushings always crack and fall off leaving only the thin pin to limit the advance. The thickness of this little bushing equates to 3-4 degrees of advance so if your bushing is gone (it probably is) your distributor is advancing more than it should. To remedy this issue I found a replacement aluminum bushing at Lowes for 78 cents.
View attachment 1279395
The aluminum bushing just barely fits over the distributor pin. I drilled the bushing out just a hair and tapped it over the pin. It holds nice and tight and should provide years of service.

The second issue with the FJ60 distributor is the advance springs. The primary advance spring is soft and thin and the secondary advance spring is thick and quite rigid. They work fine on a truck with the emissions intact but being de-smogged, I knew I needed something different. I picked up an MSD recurve kit (PN 8464) and used the springs in that kit. The kit was $16 at Pep Boys.

View attachment 1279400 The kit comes with a pair of hard, medium and soft springs. I replaced Mr. T's primary spring with the blue (medium) spring from the MSD kit and Mr. T's secondary spring was replaced with the silver (light) spring from the MSD kit. Here is a pic of the factory springs next to the springs that replaced them.
View attachment 1279399

Once the MSD springs were installed I reassembled the dizzy and re-installed it. I re-installed the vacuum lines with primary to primary and secondary to secondary as they were intended. I played around with the timing and I found that this set-up likes more initial advance than the original set-up. The timing light I have is a cheapo so I don't know my exact setting but it has to be around 15-17 degrees advanced. The BB is down below the sight window about 1/4". It seems like a lot of advance but the truck starts right up and runs great. I drove the truck hard with several pulls all the way up to redline. The truck pulls much stronger throughout the RPM range. Overall the truck just feels peppy. There was no pinging whatsoever and the advance curve seems very linear. My butt meter tells me I have a new truck now! I know I don't but the drivability is night and day compared to before. I will continue to drive the truck and tweak things as needed but for now I am very happy with my set-up.

I am sure that a professional recurve would improve even more on what I have done here but for $17 and a couple hours of time this set-up is hard to beat!

 

[OSS]

A very old engine with low compression running hi octane fuel won't ping audibly if just the EGR valve is disconnected- but it will still pre-ignite a bit which you won't hear.

Swapping the vaccum advancer hose on the distributor to the outer diaphragm will knock back the vacuum advance about 10 degrees but only at lighter throttle.

My experience doing that (distributor vacuum hose swap) resulted in the engine running noticeably hotter and I could hear the fan clutch engage more often - and two years later, all of my exhaust valves were leaking (burnt) because of incorrect timing --- SO DONT DO IT.

 

[Skniper]

Jim C of TLC Performance is the go to guy. Apparently you just send him your dizzy with info and he'll send it back when it's done. I've read turn around time is a couple months. He doesn't answer the phone or emails much since he is very busy.

I've desmogged my 88 and haven't had any pinging, yet I'm going to pull the distributor and go through it myself. I've got the springs and parts to recurve and refresh. There's some info on post #13 of this thread. I''ve copied the post below
'83 FJ60- Dizzy Recurve- Can anyone demystify this process?

‘88 with a distributor?

 

[IslandJ]

A very old engine with low compression running hi octane fuel won't ping audibly if just the EGR valve is disconnected- but it will still pre-ignite a bit which you won't hear.

Swapping the vaccum advancer hose on the distributor to the outer diaphragm will knock back the vacuum advance about 10 degrees but only at lighter throttle.

My experience doing that (distributor vacuum hose swap) resulted in the engine running noticeably hotter and I could hear the fan clutch engage more often - and two years later, all of my exhaust valves were leaking (burnt) because of incorrect timing --- SO DONT DO IT.

So if one was to cap the EGR valve between smog tests, as well as recurve the dizzy and adjust timing, would the engine stay in good health?
Would there be any adverse effect to running the engine with the recurved dizzy and egr plumbed properly?

 

[OSS]

If the distributor is recurved for non EGR use by a pro, then EGR valve can be disconnected and the engine will run great. Also the engine will still pass a smog test when the ERG valve is made operable again (mine did).
Recurving the distributor will pull back the spark advance, which actually reduces emissions (to a point). That's why there's a Check Timing procedure on smog test forms to make sure people don't cheat the test by retarding the timing

 

[YooperCruiser]

‘88 with a distributor?

Um yeah, what else would it have? No distributorless ignition back then.

 

[Skniper]

Um yeah, what else would it have? No distributorless ignition back then.

LOL, misfire on my part. Sorry I was thinking distributor, carburetor, desmog, recurve, 60/62 all in one thought.