engine misfire (to high of compression?)

steve68 · Post by **steve68** » Sun Mar 06, 2005 9:33 am

i fixed that valves (regrounded them) ran fine for about 30 seconds then started misfiring agian. we think the compression is to high from the cut head. It is still thicker than what the min req. is. So why can't i get it to run fine with the higher compression? we messed with the timing didn't help. any ideas? any thicker head gaskets?

thanks
steve

steve68 · Post by **steve68** » Sun Mar 06, 2005 9:42 am

well we believe that the ratio is close to 11 now so im just going to pull the pistons out and mill the dome off, that should lower it down a point.
so im going to start gathering parts to do the efi and turbo but thats going to be a bit.

can i take the pistons out with the motor in the car?

thanks
steve

steve68 · Post by **steve68** » Sun Mar 06, 2005 9:43 am

and o..is there a way that i can use the u20 crank with out having the snout milled off?

steve

nomadtrash · Post by **nomadtrash** » Sun Mar 06, 2005 2:52 pm

chris@cin-cityperformance.com <chris@cin-cityperformance.com>

Try Chris Luers for thicker head gaskets.

You might want to try higher octane gas (race gas) to see if your problem really is related to compression. You could also try colder plugs. You could be having problems with fuel mixture or ignition.

Can you describe the conditions during the misfire? Is it under load or just revving in the driveway? Are you getting popping and backfiring or just a ping or knock from the block?

Thanks,

steve68 · Post by **steve68** » Mon Mar 07, 2005 8:53 am

its bubbling sounding..and theres some knock under rev. it gets worse when it heats up and under load..so much that its not even drivable.
i can get unleaded 100 octane from the sunoco down the street..should i mix that in with the 93? i can get 110 from the track (me and my dad drag race) and just add a quart every full tank?

either this or mill the heads.but i think im going to get some 100 and mix it in and see if it helps

thanks
steve

nomadtrash · Post by **nomadtrash** » Mon Mar 07, 2005 5:24 pm

I would run it on straight 110 octane and not mix it with anything. Drain the tank and put in two gallons of 110 octane. Make sure the fuel lines and float bowls are purged of the old gas. Run it with the 110 and see if you are still getting the funny sound you describe. My race motor was 12.5 to 1 and didn't knock with Sunoco 105. If yours is still making the funny sound with 110 then I would think it has to be something else. I would check the plugs to see if it is running lean or if the tips are hitting the piston tops. Check the compression and points. I would try everything possible before opening up the motor.

steve68 · Post by **steve68** » Mon Mar 07, 2005 7:12 pm

well they were out of 100, its at 4.5 a gallon..and 110 is 5 something..*shrugs

im going to put it together tonight and try to get some fuel this week and see

thanks
steve