Question re: Head Casting Numbers, Valve Settings

[rcc]

I'm still familiarizing myself with my 70 Yenko. Pulled the valve covers off today to inspect the valve adjustment. The car is currently running a Howards 3972178 LT1 reground cam, and Comp Cam 7372 Push rods. The engine has less than 2000 miles since it was "rebuilt" by Bill Ulseth (I believe).

Q's: What is the correct valve settings/lashings? What are the correct casting numbers for the left and right heads? Is the correct carb a Holley 4551 with an "021" date code?

Many thanks [img]<<GRAEMLIN_URL>>/dunno.gif[/img] ,

Rick

[rcc]

I may need to correct myself. The notes with the car indicate a GM cam, part number 3972178. When I &quot;goggled&quot; that part number, a Howard cam came up (apparently virtually the same). Sorry for any confusion.

I still am looking for the answers to my questions--many thanks.

Rick

[YENKO DEUCE REGISTRY]

The 2178 cam is the correct cam, just google the Cam Card for that one and print it out for reference - I don't recall the valve lash off hand.

The correct carb would be a 4555, typically dated 05x since your car was built in 05D and most engines were assembled on 0520.

The heads are 186 castings, typically dated towards the end of April or early May of '70.

[earntaz]

Rick -- The lash should be .024&quot; intake and .030&quot; exhaust ... I'll drag out my Holley book and check what the carb came from ... TAZ

[earntaz]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: earntaz</div><div class="ubbcode-body">Rick -- The lash should be .024&quot; intake and .030&quot; exhaust ... I'll drag out my Holley book and check what the carb came from ... TAZ</div></div>

Marlin nailed it ... 4555 -- could not find a 4551.

[rcc]

Thanks for the assistance. Still working on the electrical issues.

Rick

[rcc]

Still working on the electrical.

On the valve lashing, I've read several &quot;opinions&quot; on the valve lashing anywhere from .020 to .024 for intakes and .023 to .030 for exhaust.

Any thoughts on the matter from the knowledgeable members of this forum? I appreciated the info from Taz, I just wanted to see if there are any other inputs before I undertake the adjustments.

Rick

[rcc]

Guess I will just set them at specs: .024 intake and .030 exhaust. YHX for the help.

Rick

[earntaz]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rcc</div><div class="ubbcode-body">Guess I will just set them at specs: .024 intake and .030 exhaust. YHX for the help.

Rick</div></div>

This will probably open a can of worms -- but you can slightly change the clearance (close up/open up) to change at what RPM (higher/lower) where power comes in ... but stock from Chevy is as indicated above. TAZ

[Lynn]

No can of worms here. TAZ is correct. You can play around with the lash a bit if you wish, but my LT-1 runs very well at .024 and .030. Shorten up the lash and it gives slightly more lift and duration.