Dyno shows Air Fuel Ratio rich

Blu427 · #1 (**permalink**) 09-09-2011, 01:45 AM

elmariachi,

I think smaller jets in the main as jhv48 says so I need to be going down in size from present 66 mains not larger so might try 62's .

Gaz64, I am not sure if the Offenhauser 360 Degree is a dual plane .Engine was built in 1994 by Racing heads .

Cheers

Blu427 · #2 (**permalink**) 09-10-2011, 04:00 PM

Hi,

Done some checks today ,

Checked both float levels whiche were found to be low no fuel dribble out of bowl screws and so adjusted . I dont think this will cause a rich issue. Checked power valve and found this to be on at no throttle so adjusted .
Fitted in -line fuel pressure gauage and found pressure at 2lbs so not over pressure .
Few more checks tomorrow.

Cheers

blykins · #3 (**permalink**) 09-10-2011, 04:14 PM

You need to go down in jet size.....a lot.

Also, if your fuel pressure is indeed 2psi, you need to raise that up to about 5-6.

Blu427 · #4 (**permalink**) 09-11-2011, 09:56 AM

Cheers blykins,

I thought the fuel pressure was low at 2 psi .

Cheers

elmariachi · #5 (**permalink**) 09-12-2011, 11:47 AM

Quote:

Originally Posted by Blu427

elmariachi,

I think smaller jets in the main as jhv48 says so I need to be going down in size from present 66 mains not larger so might try 62's .Cheers

Correct, it was a typo. Smaller jets make it leaner, larger make it richer.

EDIT....One item thing worth mentioning, in the absence of a chassis dyno, Innovate Motorsports makes a nice O2 sensor setup you can connect to a laptop that's let's you log A/F readings. Made a huge difference for me dialing in my carbs.

Blu427 · #6 (**permalink**) 09-18-2011, 05:22 AM

Hi,

Back at the rolling road today . Following adjusted fuel levels on both bowls which were low and adjusted fuel pressure to 5psi. I took the choke plate and stem from the horn out as this got struck on when I went on a drive .I think this could have been my problem . New figures show AFR show 13,s . Following timing settings I got 288 bhp up from 267 bhp and torque up to 360 ft pounds .The distributor was well struck . Had to use a co2 fire extinguisher to cool the alum and then it moved with mole grips .I see this as acome problem on the Cleveland blocks .
I think the under exhaust is way to small as its only 1 7/8 pipe from front to back box which is robbing me of more BHP .

What primary headers size and main under pipe size for the exhaust ? Might post this in engines section now