After many attempts to get the 440/493 to run right on pump 91 fuel, I decided to pull the heads. I'm having them ported, getting the chambers opened up a bit and after that, a fresh valve job. To those members that are not familiar with this ongoing saga of mine, here is a summary:
440 block .030 over, 4.15 stroke, flat tops .017 in the hole. Fel Pro head gasket .039, Edelbrock 84 cc heads. Lunati Solid flat tappet 261*/271* @ .050 degreed in at 106. .556/.578 lift using 1.6 rocker arms. 160 thermostat. Performer RPM intake, BG 850 VS carb with 84/93 jets. MP electronic dist, with chrome box. Timing had to be limited to 30 degrees total or LESS to avoid knocking.
The engine always seemed to make decent power but never enough to really impress me. The engine ran fine in cool weather on 91 as long as I didn't keep it to the floor. I ran 104 octane fuel once as a test. The engine still knocked on it. I recurved the distributor using the stiffest springs in the tuning kit, but it didn't help. I could ease the car up to speed keeping at or below 1/2 throttle and it ran fine. Full throttle runs resulted in detonation every time....UNTIL I poured in some 110 leaded fuel. The car ran faster than ever and there wasn't a hint of detonation. This showed me that I had 2 choices: Dig into the engine and make some changes, OR run 110 fuel and leave the engine as is.
I wanted to run on the easily available pump premium fuel. I didn't want to limit myself to race gas. I like to drive the car out of town for shows and such and this means buying gas wherever I can find it.
There has been much discussion on quench and how if I just went with a THINNER .027 Cometic head gasket, I'd get into an optimal .044 quench distance. The problem there is that I'd then be at 11.25 to one! Quench or not, that is a ratio that would surely put me at the ragged edge. I decided to go the other route. I'm going to use either a .075 or .086 Cometic gasket. The .075 drops my ratio to 9.89 and the .86 lowers it to about 9.7 to one. This is assuming the heads have an 84 cc chamber. They have been lightly milled 3 times over the years and it is quite possible that they are less than 84 ccs.
The head porting guy has had the heads over a month. I'm pissed that it has taken this long, but apparantly his boss keeps pulling him away for other projects. I am quite anxious to get the engine back together. The lower compression will allow more spark timing which will certainly increase the power. The porting should allow the engine to make more power as well.
440 block .030 over, 4.15 stroke, flat tops .017 in the hole. Fel Pro head gasket .039, Edelbrock 84 cc heads. Lunati Solid flat tappet 261*/271* @ .050 degreed in at 106. .556/.578 lift using 1.6 rocker arms. 160 thermostat. Performer RPM intake, BG 850 VS carb with 84/93 jets. MP electronic dist, with chrome box. Timing had to be limited to 30 degrees total or LESS to avoid knocking.
The engine always seemed to make decent power but never enough to really impress me. The engine ran fine in cool weather on 91 as long as I didn't keep it to the floor. I ran 104 octane fuel once as a test. The engine still knocked on it. I recurved the distributor using the stiffest springs in the tuning kit, but it didn't help. I could ease the car up to speed keeping at or below 1/2 throttle and it ran fine. Full throttle runs resulted in detonation every time....UNTIL I poured in some 110 leaded fuel. The car ran faster than ever and there wasn't a hint of detonation. This showed me that I had 2 choices: Dig into the engine and make some changes, OR run 110 fuel and leave the engine as is.
I wanted to run on the easily available pump premium fuel. I didn't want to limit myself to race gas. I like to drive the car out of town for shows and such and this means buying gas wherever I can find it.
There has been much discussion on quench and how if I just went with a THINNER .027 Cometic head gasket, I'd get into an optimal .044 quench distance. The problem there is that I'd then be at 11.25 to one! Quench or not, that is a ratio that would surely put me at the ragged edge. I decided to go the other route. I'm going to use either a .075 or .086 Cometic gasket. The .075 drops my ratio to 9.89 and the .86 lowers it to about 9.7 to one. This is assuming the heads have an 84 cc chamber. They have been lightly milled 3 times over the years and it is quite possible that they are less than 84 ccs.
The head porting guy has had the heads over a month. I'm pissed that it has taken this long, but apparantly his boss keeps pulling him away for other projects. I am quite anxious to get the engine back together. The lower compression will allow more spark timing which will certainly increase the power. The porting should allow the engine to make more power as well.
