Dual Exhaust Idea

[Machspeed]

Haven't forgotten,

Quick update:

Headers have arrived no dents looks like a great start.

I doubt i'll have any action for a few weeks at least

I have shorty headers going to Flowmasters and exiting out in the factory manner behind the passenger rear wheel. Frankly, I don't like the sound of them. Gary described them exactly as I would, "flatulent".

[Rusty_S85]

I have shorty headers going to Flowmasters and exiting out in the factory manner behind the passenger rear wheel. Frankly, I don't like the sound of them. Gary described them exactly as I would, "flatulent".

Yep flowmasters sound like glasspacks they are loud obnoxious and they love to pop on decell.

Big reason why I went with Thrust Glasspack on my truck as it was more of a mellow sound but now with my new engine build and EFI I have a single stainless steel round Magnaflow XL 3 chamber muffler. Im looking forward to how it sounds and hopeful it sounds more like a late model setup where its nice and mellow at idle but will become very aggressive on the throttle.

Id like to be able to come into and out of a neighborhood in the middle of the night not causing a bunch of noise.

[Bulletproof250]

The thermactor port at the back of each head will take a 5/8-11 bolt when you remove the air injection crossover pipe.

This bolt should be really short (like 1/2") so you're going to cut down a bolt that has threads to the head.

I'm pretty sure Gary has recommended using a metal crush washer to seal them.

Those you can find in the HELP! section, for drain plugs.

5/8 is about = to 16mm

Thanks ArkWrkin

I know it's been a while, I thought that I had read that if I were to remove these tubes that it might effect the ignition timing. Is this true? if so could someone recommend a updated ignition timing setting?

 

[ArdWrknTrk]

Thanks ArkWrkin

I know it's been a while, I thought that I had read that if I were to remove these tubes that it might effect the ignition timing. Is this true? if so could someone recommend a updated ignition timing setting?

The thermactor pipes inject air directly into the exhaust ports to help burn any carbon monoxide leaving the heads.

They also provide some air to quickly heat the catalytic converter. (if you have one)

They should have no effect on combustion.

You may be thinking about the EGR.

Without adding inert exhaust gas to the intake charge you often need to retard your vacuum advance or you'll get detonation under cruise or tip in.

[Bulletproof250]

The thermactor pipes inject air directly into the exhaust ports to help burn any carbon monoxide leaving the heads.

They also provide some air to quickly heat the catalytic converter. (if you have one)

They should have no effect on combustion.

You may be thinking about the EGR.

Without adding inert exhaust gas to the intake charge you often need to retard your vacuum advance or you'll get detonation under cruise or tip in.

ArdWrknTrk,

Thanks for the quick reply. I'm pulling the EGR stuff too. What do I have to do about the timing there? ...."retard the Vacuum advance".... is there a preferred number of °?

 

[ArdWrknTrk]

ArdWrknTrk,

Thanks for the quick reply. I'm pulling the EGR stuff too. What do I have to do about the timing there? ...."retard the Vacuum advance".... is there a preferred number of °?

I don't think there is any hard and fast rule.

Back then you could often get around it by going a little richer on the transition jetting.

Ideally you would set up the whole distributor curve when making major changes like a free flow exhaust, cam, new carb & intake or deleting EGR.

But that's complicated by having to remove and disassemble a DSII distributor, repeatedly...

If I were you I would make sure my vacuum advance is adjustable with a ** 3/32" allen wrench and then go drive the truck while trying to get it to ping under slight acceleration.

You can see if Gary has the Crane Cams distributor adjustment instructions somewhere with the DSII swap tutorial.

They might give you an idea of how much advance each turn will take out (or add)

[Gary Lewis]

I don't think there is any hard and fast rule.

Back then you could often get around it by going a little richer on the transition jetting.

Ideally you would set up the whole distributor curve when making major changes like a free flow exhaust, cam, new carb & intake or deleting EGR.

But that's complicated by having to remove and disassemble a DSII distributor, repeatedly...

If I were you I would make sure my vacuum advance is adjustable with a ** 3/32" allen wrench and then go drive the truck while trying to get it to ping under slight acceleration.

You can see if Gary has the Crane Cams distributor adjustment instructions somewhere with the DSII swap tutorial.

They might give you an idea of how much advance each turn will take out (or add)

Yes, the Crane instructions are on the page at Documentation/Electrical/Ignition and then the Instructions tab and then the Crane tab.

And the vacuum advance is the place to adjust because exhaust gas was admitted when the vacuum was high and they had to dial in quite a bit of advance because the flame front is slow with the inert gas added. Take it out and you have dial back the vacuum advance.

[ArdWrknTrk]

Yes, the Crane instructions are on the page at Documentation/Electrical/Ignition and then the Instructions tab and then the Crane tab.

And the vacuum advance is the place to adjust because exhaust gas was admitted when the vacuum was high and they had to dial in quite a bit of advance because the flame front is slow with the inert gas added. Take it out and you have dial back the vacuum advance.

Thank you, Gary!

Evidently there is no exact value given for turns = X degrees.

Yes, high gear at high enough rpm that all the centrifugal advance is in.

Typically a long grade on the highway.

Tip into the throttle slowly while listening for engine rattle.

Back off the adjuster until it doesn't do it any more.

[Bulletproof250]

Thank you, Gary!

Evidently there is no exact value given for turns = X degrees.

Yes, high gear at high enough rpm that all the centrifugal advance is in.

Typically a long grade on the highway.

Tip into the throttle slowly while listening for engine rattle.

Back off the adjuster until it doesn't do it any more.

Thanks Gary!

Thanks Jim!

I'll start the adjustment once I get the waterpump and radiator back in....

https://lh3.googleusercontent.com/_B3BTY3BONVzdZoq0DgV91Bt4dyZQz-NBg2s4X6UzYsPIMkx3CmuYSY4NF8024Z82ATgILAYHT_5wYcUrn6RHqkVqubhdaa6y0CjmSqv-f4NDcBthntIlwbuNvmLdGsfdKH34JXFhwA=w1200-h1500-p-k

....any tips on fixing broken bolts? weld on washer and nut?

Left handed Drill bits (prob not with this amount of age?)

EZ-Out?

Etc, Etc

 

[Gary Lewis]

Thanks Gary!

Thanks Jim!

I'll start the adjustment once I get the waterpump and radiator back in....

https://lh3.googleusercontent.com/_B3BTY3BONVzdZoq0DgV91Bt4dyZQz-NBg2s4X6UzYsPIMkx3CmuYSY4NF8024Z82ATgILAYHT_5wYcUrn6RHqkVqubhdaa6y0CjmSqv-f4NDcBthntIlwbuNvmLdGsfdKH34JXFhwA=w1200-h1500-p-k

....any tips on fixing broken bolts? weld on washer and nut?

Left handed Drill bits (prob not with this amount of age?)

EZ-Out?

Etc, Etc

Ouch! Those are going to be a serious problem.

There are two approaches. My approach on my vehicle would be to clean the area where the bolt meets the timing cover and then try to get the timing cover off. But that requires removing the fuel pump, and it means you need the timing cover gasket and pan repair gasket.

It is more work and if the bolts are really corroded to the timing cover you may not be able to get it off without a LOT of struggle. But if you do you can then properly get the bolts out of the block. On the other hand you may not get it off w/o destroying the timing cover as sometimes the bolts are REALLY married to the cover, and in that case you have created a lot of work.

The other approach is to get the ones out you can and drill/tap the ones you can't. On the ones that protrude I'd weld a nut on them. But the others you'll have to drill and then tap, and do your best to get the drill bit centered in the bolt.

Whichever way you go, slather the new bolts with some preventative! Some use anti-seize, but Jim has me using Loctite 56747 PST High Temperature Thread Sealant. It isn't cheap, but it will sure prevent things like this in the future.