Blew engine...was it lean?

bcarter

bcarter

New member
I lost my street ported 12A last race up here in Canada, the frozen North, and we aren't sure if we went lean. Toasted some bearings, lost power, lots of metal crap in the oil... I'm trying to figure it all out, with a new motor, by looking at the plugs. It was a new carb on the toasted engine, and I have run the same carb on the new engine for about 500 miles below 5000 rpm, to break it in. Plugs are now sort of tan coloured... I'm using the NGK 8's right now, as we're testing, 9's in race. I just don't know what they should look like. Don't want to fry another motor once I get back up to rpm in 10 days... Thoughts?
 
We blew one this year also. Did the seals in and we think it was because the engine leaned out.

All of a sudden the oil and water got very hot, caught a quick glance at the EGT's and they were off the scale (1600).

We thought our problem might have been the fuel pump as it was making more noise then normal. We replaced it, but also moved our fuel pressure gauge inside. Here is what happens. At speed in 4th or 5th under load, the fuel pressure comes down from 2 1/2 down to under 1. It is OK in 3rd up to 8500 where I shift. The guy that sells the tri-link had the same problem with the holly FP Reg and his solution was to put two of them in and do a step down. We are in the process of doing the same thing and will test it next week to see if we can hold fuel pressure above 6000 rpm on 4th.

That may be your problem, we think it was ours. Be curious to know if other 1st gens are experiencing the same problem.

R E Plank
 
Interesting... My side seals went as well..Well, we run the stock fuel pump, and I am sure it isn't strong enough at 7500+. We can't run bigger pumps or regulators by the rules. I am going to put it on a chassis dyno this week, and check the air/fuel at high rpm. I don't think timing is a factor... and the new carb should be OK, so I guess I'll see what the dyno says. We haven't lost any other motors due to lean conditions in the series, so I'm just not sure.
 
If you would use a Carter, you wouldn't need two. Most of us have had real good and consistant fuel pressure from the Carters, and I have heard nothing good about the Holleys. Save your money for other things, and invest in one Carter.

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Corey L. Clough
ITS RX7 Soon-To-Be
[email protected]
 
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