PDA

View Full Version : motor



555cid
08-07-2001, 07:54 PM
I have a 555cid 10.25 compression gil manifolds 1050 holley carb best pull on dyno was 756hp at 5600rpm. When I foor the boat the motor is pinging. Like bad gas but I have 92 unleaded in it Ive pulled the timing to 32 and jetted the carb up did not help that much motor temp is 115 tops. My old motor was a 540cid 600hp 9.1 compression cast iorn head ran fine just not as fast as the new 555 at 3/4 gas can any body help my next step is race gas or maybe bigger headers. Can you run 10.25 on pump gas Im also at 3200 feet.

skijake
08-08-2001, 07:43 AM
Try a mixture of 50% 92 or 91 octane and 50% av gas. This will give you a chance to see if it is octane related.
Don't know where or when you fueled up but starting the first of this month the gasoline in california was dropped from 92 octane to 91 octane thanks to Unocal (try to bocote Unocal, they are driving up prices and made them lower the octane)
Also are your new heads steel or alum?

TX19
08-08-2001, 06:29 PM
555... I have run 10.5 to 1 compression on 92 octane with no problems.....with aluminum heads - I think you are on the edge at 10.25 with iron heads.
Have you looked at the plugs to see if the pinging you hear is detonation? Also, I run a little more heat - minimum of 150, more horsepower for me at 180. Good luck!

555cid
08-08-2001, 06:57 PM
I just put 108 staight gas in the boat and the same thing. It must be in the lifters or springs the motor ran fine on the dyno the cam 256 260 lift 620 630 on 112. Maybe when the oil gets hot the lifters can't keep up can any body help. I do have a big oil cooler and 10qt gil pan.

555cid
08-08-2001, 06:59 PM
The heads are 355 alum dart.

555cid
08-08-2001, 07:40 PM
The noise starts at 5000rpm maybe 5200. My old 540 was a soild roller cam I did not like running the rack so we when to a hdy roller I only ran the 540 5500 so I thought I could run a hyd cam in the 555 just bigger prop. The power is a lot better than the 540 past 3500 but the motor does not run right at high rpm 5000 plus its a big cam but is it too big for hdy roller.

GEOO
08-09-2001, 06:02 AM
Check your fuel presure when the engine pings. Maybe you have a fuel restriction and it causing the engine to lean out? Did you try changing your fuel filter? How hot does your engine compartment get? Some times after idling the air in the engine compartment gets real hot? GEOO

555cid
08-09-2001, 09:46 AM
Fuel pressure 8-9 lb I have hatch off the motor

555cid
08-11-2001, 03:56 PM
Thanks four the replys skijake,tx19 and geoo the vaules needed to be ran one more time or turn 1/2 insteed of a 1/4 I could not be any more pleased with the new motor. The motor man said the loser we can run the rack the more power the motor will make so he thought he could get away with 1/4 but we could not I sat the msd rev limiter at 5600rpm and the motor pull to it. My old 540 would not turn 5600 at 800ft the 555 turn 5600 at 3200ft from sea leavel.