1978 231 turbo 6 build

[techg8]

did bypassing your PECV help?

I was thinking of capping the pecv port just as a full-rich test to see if it would cover a lean spot, if one were there.

but in my case, the timing is definitely being pulled

Its possible I have the "best" of both world.....

 

[MNcarbturbo]

The best way the cars ever run is to bypass the PECV and run the power valve port on the carb to atmosphere.

 

[techg8]

I swapped in a Monte SS 3.73 rear yesterday becuase I had it laying around.

WOW what a difference. I mean I expected a sportier feel, but the 3.73 gets the engine into rpms faster so it spools quickly.

With the little stock tires I have it really rpms in 3rd with the TH350 though. Really would prefer an OD trans with these gears.

But the car has a lot more pep now. Good for an around town bomber...

still need to work on timing etc. Its getting better

 

[techg8]

I got to the 1/4 mile track yesterday and made a few runs.

The first was a 17.1 ET

I played with the timing for the next two runs and made it worse, eventually going 18.1

I went back to the original timing curve and pulled the air cleaner off. Ran the best of the trip - 16.5ET

60ft in all cases was around 2.7s without stalling the converter up. green = mash pedal.

Clearly there is some room for improvement but I learned a few things.

Especially that the stock air cleaner hat is a nice looking chromey restriction. gonna put that on the garage wall with the rest of the swag

As always, the biggest obstacle to overcome is the detonation that kicks in the timing knock retard. Its definitely slowing me down.

 

[b4black]

My first time down the track was also a 17 sec pass. But it's the best way to figure out was is going on. Building boost against the foot brake will certainly lower those 60'. Low 2.Xs should be possible with decent tires.

I'm going to try ditching the chrome carb elbow too. Hopefully I can make it to the track soon and do some back-to-back comparisions.

Thanks for sharing. Track data is always good informaton.

 

[mikemcvaney]

I

I went back to the original timing curve and pulled the air cleaner off. Ran the best of the trip - 16.5ET

60ft in all cases was around 2.7s without stalling the converter up. green = mash pedal.

Clearly there is some room for improvement but I learned a few things.

Especially that the stock air cleaner hat is a nice looking chromey restriction. gonna put that on the garage wall with the rest of the swag

As always, the biggest obstacle to overcome is the detonation that kicks in the timing knock retard. Its definitely slowing me down.

 

[mikemcvaney]

have said the factory hat was to restrictive for years my car has the back of the scoop cut open so it looks cool and works.my car falls flat on its face with the stock hat.

 

[techg8]

Ive ran into the same issue. Motor is good at cruise and not in boost and screems when in boost but that 4" to 3 PSI zone rolling into it seems like a dead spot. I cant get my power valve system to work. At one point I bypassed the PECV since mine was bad. Its good under 8" but real lean anything less until the secondaries open. My power valve isnt releasing even with a good PECV.

I never thought that timing was causing the mid throttle dead spot. Ive got an NA v6 distributor and MSD BTM with no ESC.

Well I was wrong, not about the carb hat but about the cause of the ESC system triggering early.

it was not the timing that caused the knocking and got the ESC to trigger and pull advance.

It was my plug gap. I had been gapped at .055". When I regapped to .032" the timing drop issue disappeared.

I will do some driving tests and report back.

Here is my timing thread: I am now at 36 total without Vacuum
http://www.turbobuick.com/forums/threads/timing-and-boost-on-a-carbed-turbo6.411746/

ALSO
I had been having some low oil pressure lights when the car got good and hot - typical stock buick system in my experience. Reminds me of my SBB350.

I went to 20W50 oil to tighten things up a little and
I added a spacer to the regulator spring to preload it a little. (Since I seem to have lost my spare red "60lb" regulator spring.)

Well somehow I lost the pump prime - and after trying a host of things to prime it again, I had to take the pump apart and pack it with vaseline to get it to prime.

I did change the pump shim from .008" to .005" to try to tighten things up a little too.

It was a pain - more than it should have been - but the effort was worth it. No more oil light when hot.

 

[WarWagon]

Pretty consistent ET's for the drawthru Buicks, You made great improvement while you were getting it dialed in. My stock drawthru without a working ESC or feedback carb did several 18.0sec 1/4 passes too and never improved.
Pour some HEET in the gas tank cheaper than octane booster and same thing, Methanol help reduce any knocking and ESC wanting to pull timing. Good attention to the oiling lol.