Timing and Boost on a carbed turbo6

[techg8]

I am to the point where I will start messing with timing and boost to try to tune my 78 231 turbo

I have the basic timing specs from the 78 service manual and a general idea of what I am doing.

Within reason, it could be said that more timing equals more power, to a point.

At the same time it could be said more boost = more power, to a point.

and it could also be said that more timing AND more boost could lead to some problems.

SO
my basic question is this:

Am I better off starting with a constant boost level and tuning the timing to make the best power out of it without detonation, or is it advisable to set a constant timing (stock?) and then bump boost up for power?

The answer will probably be "a little of both"

What has worked for you? Any suggestions are appreciated. Lets start a discussion.

PS I know I need to get a knock gage/light. any recommendations appreciated. - Can a light be added to the 78 stock ESC system?

 

[gnpoweredrail]

best bet is to try and get a MSD Boost Timing Master box.It will retard the timing 1,2 or 3 degrees per pound of boost you want to run.

The stock HEI esc system leaves a lot to be desired but if it is working then use it.

 

[WarWagon]

More ignition timing is what will hurt the engine most vs more boost. MSD BTM works ok but I don't recommend it as it can take out too much ign timing. I'd use your second mentioned technique of leaving the ign timing as high and constant as you can run with your fuel you using and turn the boost up.

 

[techg8]

In my online researching I have seen that .5 to 1 degree of timing retard per pound of boost is commonly recommended.

I will probably set up my vacuum advance can as a poor mans boost retard.

I will add alcohol injection once I get a feel for the limitations without it.

 

[b4black]

I have a BTM. Stock boost is 9 psi. Even a ¼ degree per PSI is a lot of timing to pull. I wouldn't get a BTM again, but I typically run race gas and shoot for 15-20 psi.

 

[gnpoweredrail]

I ran pure Av Gas which averages 105-108 octane.

 

[techg8]

I realized my plug gap was set at .055 or so which I understand is not desireable for a boosted engine.

I am dropping it to like .032

Think this will help?

 

[WarWagon]

^-- yes that will for sure and especially if your on stock HEI ignition.

 

[techg8]

^-- yes that will for sure and especially if your on stock HEI ignition.

I am running stock HEI.

Regapped the plugs today and it was easier than I thought it would be to access them all. I had to disconnect the up and down pipes from the turbo for hand/arm clearance but thats it.

I should mention that I plan to run this on 93 premium pump gas. Nothing special.

I will take your advise WarWagon. I will set the boost to stock 9psi and tune for the most timing and best curve I can put into it. Then I will leave the timing and work on turning the boost up.

I appreciate your input.

 

[16mmsocket]

Not to hijack.......... very much. What is the best option for plugs? Best gap size?

 

[WarWagon]

I like NGK UR5 for these carb turbos around a .028-.030 gap. It's still a projecting tip plug But it may like more or less gap, a couple tests will see.

 

[techg8]

here is a little proof that the gap counts.....

I just got done fiddling with my timing etc after regapping to about .032"

Prior to the regap I was at .055" gap and my ESC system was pulling timing like crazy. So much that at part throttle I couldnt see the mechanical advance coming in with a timing light. It would start going up then dive like the bottom fell out.

After the re gap, The ESC no longer pulls timing when not under boost.. I can see the mechanical advance coming in all the way with a timing light. This helped me a LOT when trying for the lightest spring set I could manage.

I imagine that this alone will have a positive effect on my times with this engine.

After messing around a little bit to find the lightest spring I could use without being in the advance at 725rpm idle
I have set the timing (with vac advance plugged) to

16 initial
+20 mechanical in by 2700rpm

I need to do some driving tests and see how this total does under boost. See if the ESC triggers.

 

[16mmsocket]

Good info.

 

[WarWagon]

Ahh you guys and all your fancy distributers, I'm still using a computer locked timing one lol Even got a Unilite from Charlie and it's still in a box. Anyways yeah MSD BTM, meh lol. Tighter gap does help for sure, In my blowthru engine I use a non projecting tip NGK plug with a .025 gap with a lot of boost. Kind of tight gap even for the hotter ignition I used (Hyfire6 control) but the whole thing works great and a lot better rate of retard adjustment .1-3.0*
Coming to think of it now but it wasn't mentioned here. I think running the drawthru on alcohol or E85 is the way to go to get the most out of the system with that awful turbo foot.

 

[WarWagon]

Because everyone one knows they don't want to run boost in the single digits and want to turn it up or wire the wastegate shut.

 

[MNcarbturbo]

I run my BTM at 1.2ish on 87 when im DDing it. It will audibly detonate at .5 deg/psi from 3-4 PSI and stop when the alky kicks in at 5PSI. It wont audibly detonate at 1 deg without alky so i set it at 1.2 to be safe incase the alky quits. The extra 50 cents a gallon for 91 isnt worth it for putting miles on it. (we dont have 93 here). On 91 and alky I can run virtually nothing on the BTM. Its the best way for me to DD the car affordably and still have power to pass somebody or accelerate at a fun rate.

Ive been hunting down a holley spreadbore to do an E85 conversion on, I think it would work awesome. But between getting my rainier ready for the winter and getting a 200r4 in the car it wont happen this summer. Im going to get back into trying to get the 87 inducer in my 80 housing now that the CNC lathe at the shop is fixed so hopefully a year from now ill have something ready.

 

[techg8]

I run my BTM at 1.2ish on 87 when im DDing it. It will audibly detonate at .5 deg/psi from 3-4 PSI and stop when the alky kicks in at 5PSI. It wont audibly detonate at 1 deg without alky so i set it at 1.2 to be safe incase the alky quits. The extra 50 cents a gallon for 91 isnt worth it for putting miles on it. (we dont have 93 here). On 91 and alky I can run virtually nothing on the BTM. Its the best way for me to DD the car affordably and still have power to pass somebody or accelerate at a fun rate.

Ive been hunting down a holley spreadbore to do an E85 conversion on, I think it would work awesome. But between getting my rainier ready for the winter and getting a 200r4 in the car it wont happen this summer. Im going to get back into trying to get the 87 inducer in my 80 housing now that the CNC lathe at the shop is fixed so hopefully a year from now ill have something ready.

SO are you running locked timing like Warwagon or are you running stock initial and mechanical and then using the BTM for boost retard?

Running 87 would be nice. Its much cheaper than the 93 in CT.

 

[MNcarbturbo]

Using a stock NA 3.8 distributor with mech and vacuum advance functional and the BTM for final retard.

 

[techg8]

I have tinkered a bit with the timing.

I can get about 34 degrees into the advance at 8-9lbs boost without audible pinging.

When I go as high as 36 degrees (stock 16 initial 20 mechanical), I get audible pinging on WOT runs when the transmission shifts into 3rd (TH350)

I used the lightest springs I could find that would keep me out of the mechanical advance curve at ~750rpm idle.

The 78 Service manual specifies the 9.5-11.5 degrees of the mechanical advance should come in by 2000 rpm and these springs do accomplish that as well. They just open from there to full mechanical advance much quicker than the stock springs.

It really makes a difference in how the turbo spools up. You can hear and feel the response. Dont get me wrong, its still kinda laggy, but in a "relative" sense it definitely spools up more quickly.

SO I am thinking there are two ways to proceed from this baseline timing-
1) add lbs of boost and retard timing to make it work
or
2) add an alcohol spray above the carb and see what boost I can cram into the engine before detonation.

Any votes on the way to go? I favor the alcohol spray.

PS I have been running without an air cleaner lately. I havent modified the hood for cold air yet but that is coming soon.

 

[techg8]

Here is what I came up with for an Alcohol spray. This is a preliminary system so dont rag on it too much. I plan on improving it as I work on my air intake stuff. Constructive suggestions are appreciated.

I used a generic washer pump from CarQuest with a 12V feed from the HEI lead, grounded through a stock boost switch (not sure the boost level - its the white one). For fluid, I teed into the washer reservoir and added check valves - before the wiperwasher pump and after the alky spray pump. I teed into my boost gage line (from the compressor "foot") to provide signal to the boost switch

I got a spray nozzle from McMaster Carr, a 3 way 1/8NPT brass manifold and a plug (the kind with the square nub on the end) from the hardware store, and a 1/8 NPT / hose barb fitting from Carquest. The Spray nozzle and hose barb went on opposite sides of the Manifold, and the solid plug went in the bottom. I drilled a screw hole in the bottom of the plug and fabbed up a mounting arm (might be 6 in long - long enough to center the spray cloud over the carb) off the front carb bolt.

SO for now, the system will trigger anytime the boost switch grounds the pump. It will likely make a big mess under the hood but I will make some improvements as I go.

Future plans:
A master cutoof switch, preferably a style that can light up when the system triggers.
Additional reservoir capacity, preferably with a low level indicator light of some sort - maybe thru the switch?
Some sort of cold ait intake scoop through the hood.
repositioning the spray nozzle to spray into some sort of air intake box or into the intake scoop I plan to add to the hood.

I am not taking credit for all the ideas. This site sent me in the right direction (even gave part numbers) and all credit goes there.
https://sites.google.com/site/beforeblackracing/alky

Filled the reservoir with 50%water, 50% washer fluid. And added a full turn to the wastegate arm.Not sure what boost that will create but I will see.
I havent driven the car yet but I will post results as I get them
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