4.3L V6 Mods Question
July 10th, 2023, 11:00 AM
#1
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4.3L V6 Mods Question
Hi All,
I bought a car that had been modified to take a small block V6 (which only had about 5,000 miles since the rebuild). The engine was modified by a guy that used to work for the Hendricks racing team. Needless to say, he made some mods to it which included: 4.030 bore, 4 valve flat top pistons, 337/350hp copy camshaft, new lifters and a 3 angle valve job. It also had a custom Quadrajet on it which I replaced with a stock Edelbrock (probably a mistake, but I didn't know it was custom). Anyway, been trying to tune everything, but struggling a bit getting a nice clean, smooth idle at around 800-850 RPMs. I'm also concerned that I'm only pulling about 13 to 13.5 inches of mercury at idle speed (which I measured directly from the manifold). The engine seems to run great at speed and acceleration fine. I am obviously not an engine expert, but normal specs say 10 to 12 degrees of timing advance and normal vacuum should be 16 to 20 HgV. My question is really whether the mods I detailed above can impact manifold vacuum and smooth idle? I understand possibly yes, but not sure I can/should make adjustments to compensate. With this setup, should I just expect these characteristics and consider them normal for my engine?
I bought a car that had been modified to take a small block V6 (which only had about 5,000 miles since the rebuild). The engine was modified by a guy that used to work for the Hendricks racing team. Needless to say, he made some mods to it which included: 4.030 bore, 4 valve flat top pistons, 337/350hp copy camshaft, new lifters and a 3 angle valve job. It also had a custom Quadrajet on it which I replaced with a stock Edelbrock (probably a mistake, but I didn't know it was custom). Anyway, been trying to tune everything, but struggling a bit getting a nice clean, smooth idle at around 800-850 RPMs. I'm also concerned that I'm only pulling about 13 to 13.5 inches of mercury at idle speed (which I measured directly from the manifold). The engine seems to run great at speed and acceleration fine. I am obviously not an engine expert, but normal specs say 10 to 12 degrees of timing advance and normal vacuum should be 16 to 20 HgV. My question is really whether the mods I detailed above can impact manifold vacuum and smooth idle? I understand possibly yes, but not sure I can/should make adjustments to compensate. With this setup, should I just expect these characteristics and consider them normal for my engine?
July 15th, 2023, 3:04 AM
#2
CF Monarch
Hi All,
I bought a car that had been modified to take a small block V6 (which only had about 5,000 miles since the rebuild). The engine was modified by a guy that used to work for the Hendricks racing team. Needless to say, he made some mods to it which included: 4.030 bore, 4 valve flat top pistons, 337/350hp copy camshaft, new lifters and a 3 angle valve job. It also had a custom Quadrajet on it which I replaced with a stock Edelbrock (probably a mistake, but I didn't know it was custom). Anyway, been trying to tune everything, but struggling a bit getting a nice clean, smooth idle at around 800-850 RPMs. I'm also concerned that I'm only pulling about 13 to 13.5 inches of mercury at idle speed (which I measured directly from the manifold). The engine seems to run great at speed and acceleration fine. I am obviously not an engine expert, but normal specs say 10 to 12 degrees of timing advance and normal vacuum should be 16 to 20 HgV. My question is really whether the mods I detailed above can impact manifold vacuum and smooth idle? I understand possibly yes, but not sure I can/should make adjustments to compensate. With this setup, should I just expect these characteristics and consider them normal for my engine?
I bought a car that had been modified to take a small block V6 (which only had about 5,000 miles since the rebuild). The engine was modified by a guy that used to work for the Hendricks racing team. Needless to say, he made some mods to it which included: 4.030 bore, 4 valve flat top pistons, 337/350hp copy camshaft, new lifters and a 3 angle valve job. It also had a custom Quadrajet on it which I replaced with a stock Edelbrock (probably a mistake, but I didn't know it was custom). Anyway, been trying to tune everything, but struggling a bit getting a nice clean, smooth idle at around 800-850 RPMs. I'm also concerned that I'm only pulling about 13 to 13.5 inches of mercury at idle speed (which I measured directly from the manifold). The engine seems to run great at speed and acceleration fine. I am obviously not an engine expert, but normal specs say 10 to 12 degrees of timing advance and normal vacuum should be 16 to 20 HgV. My question is really whether the mods I detailed above can impact manifold vacuum and smooth idle? I understand possibly yes, but not sure I can/should make adjustments to compensate. With this setup, should I just expect these characteristics and consider them normal for my engine?
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