383 Stroker Help
Thread Starter
4th Gear
Joined: Jul 2012
Posts: 4
Likes: 0
383 Stroker Help
Gents,
I need some expert advice regarding a 383 stroker I had put in a little over two years ago.
Here’s what I know about the engine: The engine has a forged crank, forged pistons, and 6 inch I beam rods. The heads are World Products S/R Torquer Heads (aluminum) assembled with 2.02 valves, 76cc chambers. It has hydraulic flat tappet cam and lifters 230@.050 109LSA .480 lift. The engine has a Holley 750 80508S double pumper carburetor, Edelbrock aluminum intake, and HEI ignition.
Since I had the engine put in, it’s been running but I have a noticeable misfire. Specifically when I go full open throttle, it sounds like I’m running on 6 cylinders. I’ve tried several things to eliminate the issue including replacing the plugs (went to a hotter plug), plug wires, dist cap, rotor, and even the distributor (going to a HEI system) -- still no joy. Yesterday, I decided to do a compression test and here’s what I found:
8 – 180; 7 – 180
6 – 180; 5 – 175
4 – 172; 3 – 160
2 – 135; 1 – 155
I noticed that the sparkplugs in cylinders 4, 6, and 8 (Pictured) were heavy in oil and actually, the electrode was half black (oil I presume) and the other have was clean. Cylinders 1-3-5-7 looked like new plugs so I didn't include the pics but can if that would help. I will tell you this car is rarely driven; meaning it’s a weekend/sunny day driver only. With that in mind, I’m thinking the oil might be a result of the rings not seating yet.
In the interest of full disclosure, it did run hot on me one time last summer; didn’t realize it until it was the temp was 250 – once I noticed, I immediately shut her down. Turned out to be low coolant (but didn’t see any puddles in the garage).
The compression really has me baffled though; any divine guidance?
-Al
I need some expert advice regarding a 383 stroker I had put in a little over two years ago.
Here’s what I know about the engine: The engine has a forged crank, forged pistons, and 6 inch I beam rods. The heads are World Products S/R Torquer Heads (aluminum) assembled with 2.02 valves, 76cc chambers. It has hydraulic flat tappet cam and lifters 230@.050 109LSA .480 lift. The engine has a Holley 750 80508S double pumper carburetor, Edelbrock aluminum intake, and HEI ignition.
Since I had the engine put in, it’s been running but I have a noticeable misfire. Specifically when I go full open throttle, it sounds like I’m running on 6 cylinders. I’ve tried several things to eliminate the issue including replacing the plugs (went to a hotter plug), plug wires, dist cap, rotor, and even the distributor (going to a HEI system) -- still no joy. Yesterday, I decided to do a compression test and here’s what I found:
8 – 180; 7 – 180
6 – 180; 5 – 175
4 – 172; 3 – 160
2 – 135; 1 – 155
I noticed that the sparkplugs in cylinders 4, 6, and 8 (Pictured) were heavy in oil and actually, the electrode was half black (oil I presume) and the other have was clean. Cylinders 1-3-5-7 looked like new plugs so I didn't include the pics but can if that would help. I will tell you this car is rarely driven; meaning it’s a weekend/sunny day driver only. With that in mind, I’m thinking the oil might be a result of the rings not seating yet.
In the interest of full disclosure, it did run hot on me one time last summer; didn’t realize it until it was the temp was 250 – once I noticed, I immediately shut her down. Turned out to be low coolant (but didn’t see any puddles in the garage).
The compression really has me baffled though; any divine guidance?
-Al
Race Director
Joined: Jul 2004
Posts: 12,706
Likes: 329
From: Scottsdale Arizona
A leak down test would provide some further information, especially on cylinders 1 and 2 (and maybe 3). In lieu of that, you micght try adding some oil to cylnders 1 and 2 and repeating the compression test. If the numbers come up, it'll indicate an issue with the rings. If not, it'll indicate an issue either with the head gasket (unlikely) or with the valves. It seems unlikely that you have a leak in the head gaskets on both banks.
Thread Starter
4th Gear
Joined: Jul 2012
Posts: 4
Likes: 0
Thanks guys, I'll give those a go. Never thought about using oil to help isolate the problem. I'm also wondering about retorquing the aluminum heads. Saw conflicting articles that said you should retorque the heads and others that said you shouldn't. I guess I'm just having a hard time figuring out why the compression seems to drop when you get farther forward on the engine. what do you guys think?
