# 1970 YC 455 with #16 heads?



## nraven68 (Mar 9, 2013)

Hey guys. I have a question I was hoping someone could possibly give there opinion on. I have a YC 455 (Block and Crank only). I talked with a mechanic that has drag raced Pontiacs for years. He made the suggestion of running the #16 heads, which were used for the 400 block. Anyone have experience or thoughts on this combo. I'm a little nervous about the compression.


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## BearGFR (Aug 25, 2008)

nraven68 said:


> Hey guys. I have a question I was hoping someone could possibly give there opinion on. I have a YC 455 (Block and Crank only). I talked with a mechanic that has drag raced Pontiacs for years. He made the suggestion of running the #16 heads, which were used for the 400 block. Anyone have experience or thoughts on this combo. I'm a little nervous about the compression.


As well you should be. #16's would be a disaster on a street 455 unless you were running pistons with _at least_ 25 cc's of dish in them. Also be aware that #16's had smaller valves than the other performance D-port heads. They can be refitted with the larger 2.11/1.94 valves, but of course that costs money for the machining.

What are you wanting to do with the engine?

Bear


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## PontiacJim (Dec 29, 2012)

Bear is correct in that there is a small valve/low performance head using cast#16. Smaller valves and press in rocker studs for quick ID. However, Pontiac used in 1968-1969 GTO/Firebird/428 CI performance heads cast #16 and I think this is what you are looking for. The #16 was also used for the 1973-74 Super Duty 455, but you probably won't trip over a set of these any time soon. 

Bear is correct on compression for street applications. Racing is a different ball game. The #16 heads are 72 cc's. Play around with one of the many online compression ratio calculators to see what size combustion chambers yield different compression ratio's. Many factors such as head choice, cam, gearing, etc. all come into play. I think you will find most on the board agree with 9.0-9.5 the max limits for street with iron heads (unless using racing gas). A little more with aluminum. You can get your compression by head choice or piston choice, or a combo of both to get the cc's needed for the 455 CI. Many thoughts on head choices here on the forum, from reasonable to exotic. Its all about budget and what power level you want.

FYI. Personal experiences. Don't use or buy a set of iron heads unless they have been magnafluxed for cracks and guaranteed/money back or the seller allows you a money back guarantee in writing that he will take them back if any cracks. If he does, send them to your local machine shop ASAP and get them checked. Will save you a lot of grief. To easy to buy a bad set at a swap meet, Ebay, local, etc. and get stuck with junk.

Good luck.


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