94 4.3 blazer bad miss after installing new head
#1
04-19-2010, 01:20 PM
94 4.3 blazer bad miss after installing new head
I have a 94 blazer that i recently installed a new head on. A buddy overheated it and cracked the drivers side head. My old man had another head off an 89, which i believe has mechanical lifters on it. When I was installing the intake gaskets, I had to trim them a little because the ports on the head were a little different. Now that it is finished, It runs like crap. No codes, good fuel pressure, no vacuum leaks, good compression. I have removed the the head 3 times thinking it didnt get a good seal, but nothing has worked. Is the head the problem because it is from an 89 and mechanical? Oh yea, the dead cylinder is the drivers rear. I replaced the fpr because it was leaking, which made it run a little better. Im tired of this thing and cant figure it out. Any help would be great!
Thanks, Nick
Thanks, Nick
#2
04-19-2010, 01:29 PM
It is not a good idea to build an engine with two completely different heads. Enough changed between '89 and '94 that you should not have used that old head. By using the '89 head, you have created a rather problematic disruption in the flow on that side and have shrouded the injector nozzle.
ORIGINAL: Rebuilding the New Chevy 262 by Doug Anderson
1992-’93 TRUCK WITH CFI, BALANCE SHAFT:
When the high output VIN "W" engine with central fuel injection was introduced in ’92, the heads were redesigned for the application. They had "eyebrows" added to the top of the intake ports to make room for the injector nozzles, so the intake surface above the ports was increased by 0.250˝ for improved sealing, and the cast ledge above it was narrowed down to 0.350˝ to provide more room for the intake manifold.
The 10077626, 14099064, 10240209 or 10238181 castings were used, but be sure to check them over carefully because there are two versions of the 10238181 and 10240209 castings with an important difference. In ’92 and ’93, they came with an 8° top angle on the intake seat and a 75° throat, but that was changed to a 30° top angle with an 80° throat in ’94. Separate the 8° heads from the 30° heads and use them only on the ’92 and ’93 engines.
Tonawanda switched to "net lash" rockers in ’92, so some of these are adjustable and some aren’t.
1993 TRUCK WITH TBI, EXCEPT HEAVY DUTY:
The intake manifold on the TBI motor was modified in ’93 to take advantage of the wider intake surface that was machined on the ’92 and up heads, so these engines must have the heads with the wide intake and should use the castings with the 8° top angle on the intake seat.
1994-’95 TRUCK WITH TBI OR CFI, EXCEPT HEAVY DUTY:
The top angle for the intake seat was changed from 8° to 30° and the throat was opened up from 75° to 80° to give a 10% increase in intake airflow for better performance in ’94. The same heads were used on both the TBI and CFI engines through ’95.
Both the 10238181 and 10240209 castings were used, but they have to be visually sorted because the early ones with the 8° seat probably shouldn’t be used on the ’94s and ’95s. If you do decide to stretch the rules and use the ’93 heads on a ’94-’95 engine, be sure to use them in pairs. Some of the ’94s still had adjustable rockers because Romulus didn’t switch over to "net lash" until ’95.
1992-’93 TRUCK WITH CFI, BALANCE SHAFT:
When the high output VIN "W" engine with central fuel injection was introduced in ’92, the heads were redesigned for the application. They had "eyebrows" added to the top of the intake ports to make room for the injector nozzles, so the intake surface above the ports was increased by 0.250˝ for improved sealing, and the cast ledge above it was narrowed down to 0.350˝ to provide more room for the intake manifold.
The 10077626, 14099064, 10240209 or 10238181 castings were used, but be sure to check them over carefully because there are two versions of the 10238181 and 10240209 castings with an important difference. In ’92 and ’93, they came with an 8° top angle on the intake seat and a 75° throat, but that was changed to a 30° top angle with an 80° throat in ’94. Separate the 8° heads from the 30° heads and use them only on the ’92 and ’93 engines.
Tonawanda switched to "net lash" rockers in ’92, so some of these are adjustable and some aren’t.
1993 TRUCK WITH TBI, EXCEPT HEAVY DUTY:
The intake manifold on the TBI motor was modified in ’93 to take advantage of the wider intake surface that was machined on the ’92 and up heads, so these engines must have the heads with the wide intake and should use the castings with the 8° top angle on the intake seat.
1994-’95 TRUCK WITH TBI OR CFI, EXCEPT HEAVY DUTY:
The top angle for the intake seat was changed from 8° to 30° and the throat was opened up from 75° to 80° to give a 10% increase in intake airflow for better performance in ’94. The same heads were used on both the TBI and CFI engines through ’95.
Both the 10238181 and 10240209 castings were used, but they have to be visually sorted because the early ones with the 8° seat probably shouldn’t be used on the ’94s and ’95s. If you do decide to stretch the rules and use the ’93 heads on a ’94-’95 engine, be sure to use them in pairs. Some of the ’94s still had adjustable rockers because Romulus didn’t switch over to "net lash" until ’95.
#3
04-19-2010, 01:56 PM
Thank you very much. I kinda figured that was what was going on. I guess i got some bad advice.
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