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Good afternoon gentlemen. I installed the f8-50 idles and set the mixture screws at 2 turns out. It behaves much better around the neighborhood, but still doesn't idle. I took it through town and back on the highway so I could take advantage of the on ramp. Now it seems to be running a bit lean on the main. It was hot when I parked it in the shop, so I swapped one of the mains up to a 145... I think... and I'll try again tomorrow. Stay safe my brothers

So I've resided myself to the idea that my engine may never idle below 12-1500 rpm. Between fuel falling out of suspension and an adapter that transitions from a 3" manifold to a 4" turbo inlet that provides a perfect shelf or ledge, for the fuel to get trapped on, it's just the nature of the beast.


And what a BEAST! My timing was purposely set retarded for tuning, to go easier on the engine. I set it back to 32 degrees BTDC, while still pulling 1 psi, per pound of boost. I have the f8-55 idles in it, a 135 AND a 140 main and it's completely happy to run through town like a big happy puppy and when you put your foot in it to get on the highway, it turns into a growling beast, spinning the tires through 2nd gear and accelerating HARD through 3rd and 4th onto the hiway. A quick glance at my overly optimistic speedometer says it's already pegged! Oh crap!

Can't remember whose tag line it is, but "Boost is addictive" claims another victim.

Alexander_Monday wrote: ↑Wed Sep 24, 2025 1:56 pm Can't remember whose tag line it is, but "Boost is addictive" claims another victim.

Ya! And this is at only 5 or 7 pounds of boost or some such silly thing. I haven't even started turning it up yet!

I took my wife out for her first ride in the blown buggy. I believe we ran out of fuel getting to 4th gear, even with the boost sensitive, fuel pressure regulator? Strangely enough, I couldn't get my lovely Mrs to climb into the back and hang her head out over the motor to watch the fuel pressure gauge while we did another full hit on the highway... sissy.


I'll probably have to just extend the gauge up to the driver's compartment with some ptfe tubing temporarily to prove the concept and maybe find a different check valve

What needle and seat do you have in there ? And was the AFR gauge leaning out? How is the boost sensitive reg plumbed? You could always find a way to record it......Go Pro ? Quad lock phone mount?

Hi panel. I have no hi tech goodies so I removed the fuel pressure gauge from the carburetor feed line and plumbed it (temporarily) up to the dash where I could see it and went for another test drive. It behaved just like it was supposed to. Off boost, the gauge showed 3 psi, and once under boost, fuel pressure went up to 5-6 psi. I was pretty happy with that. The regulator is (I'm pretty sure) a chinese copy of a holley that I drilled and tapped for the boost reference fitting on top of the diaphragm.

Yes. It did go lean on the top of 4th gear, even with 5-6 psi of fuel pressure. When I got back to the shop, I upped one of the main jets from 135 to 140

The needle and seat are 300 off the top of my head

Enjoy your Sunday

Are you also running a check valve in that line?

viewtopic.php?t=150032&start=45

Yes Sir. But I wasn't happy with the cheap ones suggested. I bought 2 of them and one broke in half as I was removing it from the package. I ended up with an all metal unit from an air compressor. I could blow through it with a good puff of breath, but thinking the spring might be little stiff, I cut a half a coil off of it and stretched it out to the original length. It was much easier to blow through one direction, and impossible to blow through in the other, so I was satisfied with the check valve modifications

The side draft float bowl is known to be on the small side and can run out of fuel on a larger engine demanding more fuel. It's possible the fuel bowl is not filling fast enough for the fuel draw at higher rpm and boost levels.
Check the float level to make sure it is at spec.

Thanks again for your input CB. I did set float levels in the past, but for sanity sake, I checked again this morning. Spec calls for 12.5mm at the top and im at 12.45mm. Pretty close i figure. The book also called for 25mm drop, but mine is closer to 27. I didn't think that 2mm more open would hurt in this application. Also I have verified that I do,in fact, have a 300 needle and seat. It's capable of flowing plenty of fuel

I just got off the phone with Ron Lummus. A respectable draw through tuner, and very helpful guy. I wanted to pick his brain about converting to one of his 4 barrel kits in hopes of getting a better idle. He suggests I might call Dave Kawell about tuning my side draft, but my problem lies in my turbo. The 4" inlet, and the lack of a carbon seal is the problem.......


Dammit. That's not what I wanted to hear

Aannd... my valve clearances continue to get tighter. FFS. Does it ever end?

My credit card is smoking hot and screaming for a break, but Ron Lummus is sending me a new carbon sealed Garrett turbo and Greg Tims has been confirmed to build a set of his stage II turbo heads and port matched manifolds. Looks like my winter projects have all been lined up.

Did you get 10% off?
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