Side by side photo of the 842 vs 074 head?

[MosportGreen66]

Hi All, looking to confirm - early L89 head use was the 842. The L88 as of March 69 used the 074 head. Are there physical differences in the exterior of the head?

Does anyone have a side by side photo or can you highlight the differences in pics?

Thanks,
Dan

[big gear head]

I may be wrong, but the L89 head is closed chamber and the '69 L88 head is open chamber. There is a huge difference in the shape of the chamber. Also, I believe the L89 head has square exhaust ports and the '69 L88 head has round exhaust ports.

[RALLY]

big gear head is right. I owned both heads at one time. 074 head like he stated was an open chamber head, which is better for flow, and round exhaust ports. Valve stud cast area was prone to cracking, but i used as long as a valve stud i could for better support in that area. 842 was a nice head, but as stated closed chamber with square exhaust ports. You are right by looking at these two with valves covers on and exhaust manifolds or headers, its hard to tell until they are off the motor. BB Chevy heads were notorious for bad exhaust port flow. I had my 074 head exhaust ports opened up under the valve.

[scuncio]

The 074 head might have been late enough that the large pipe plugs were already eliminated. For the 842 head there was a transition time somewhere in Feb-Mar 1969 where some were fitted with plugs and some were not. Otherwise there are no external differences until you pop the valve cover.

[1971ls6]

I have yet to see an 074 head with plugs,is there such a thing

[SuperNovaSS]

Yes Dan,

There are quite a few external differences. Mainly the lack of plugs on the end of the heads, contour of the tops of the exhaust ports and snowflake size. Once you know the exhaust port angle and snowflake difference they are very easy to distinguish mounted on an engine. I can snap a few side by side pics and post them for you if you like. I have the plugs if you want to add them to 074 heads to get a closer look.

Jason

[MosportGreen66]

Originally Posted by SuperNovaSS

Yes Dan,

There are quite a few external differences. Mainly the lack of plugs on the end of the heads, contour of the tops of the exhaust ports and snowflake size. Once you know the exhaust port angle and snowflake difference they are very easy to distinguish mounted on an engine. I can snap a few side by side pics and post them for you if you like. I have the plugs if you want to add them to 074 heads to get a closer look.

Jason

Hi Jason, side by side photos would be perfect. I'm more curious about the aesthetic...

Thanks,
Dan

[ssl78]

first set is 074 second set 842 looks like exhaust ports are lower on 842

[jerry455]

Thanks for the Education!
Jason is a first-class guy and amazing knack for finding parts-

[SuperNovaSS]

Sorry Dan,

I was swamped today and never got to snapping and posting pics. It looks like SSL78 got it done. I’ll try to snap a few shots after the kiddos are in bed. Thanks for the kind words Jerry.

Jason