# 1970 455 questions



## goatseateverything (Mar 22, 2017)

Hey yall, I am a newbie on here and I have acquired my sister's 1969 GTO. It has a '70 455 with 4 spd hurst. The car is stock and I am in the process of getting things together to get it running again. It sat for a few years before she let me have it. I do have a couple of questions in regards to the '70 455. 

1. I have read that there is a standard 455 and HO 455. How do I tell which one I have?

2. It has an 4 barrel Edelbrock carb on it. Not sure on rebuilding so I will be buying new with electric choke. What size CFM is recommended for these cars?

and last 

3. What type of oil should I be using in this and how much? Again, this is a stock car and will be mostly a weekender with no track time/racing.

Thanks for all the help and I look forward to sharing my progress with the rebuild!


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## Pinion head (Jan 3, 2015)

the most common Pontiac 455 for '70 models was the YH engine with 15 casting heads. This was the standard equipt engine for '70 Bonnevilles. Pontiac built a TON of '70 Bonnevilles, & only a few received the optional big valve 64 casting headed XF engine. Most of those were XF's & went in '70 GP's.

the WA, YA/YC 455 big valve engines are what the engine emission call out label on the top of several '70 Pontiac body style will call a "455 HO" . This engine was also avail as an XF or WG coded 455 big valve engine in '70 GrandPrix's & was optional, but extremely rare install, in '70 B series (Catalina's, Executives, Bonnevilles). "64" casting 2.11/1.77 valve heads, screw in studs are the main difference in the heads. As this engine only used standard log type manifolds, not HO (RamAir) Dport exhaust manifolds, & only the manual trans engines (WA, & WG) even came with the S grind "HO" cam, many of us that are longtime in the Pontiac muscle car hobby do not consider the '70 455 big valve engine as a true "455 HO". 

Internally, the factory coded WA, WG, YA/YC, XF '70 model blocks should have factory 4bolt main caps. The '70 YH coded 455's, Ive found about 20% of them, give or take, were factory machined & asm with 4 bolt main caps. Have been pulling '70 455's since the mid 80's & out of several dozen '70 YH engines have had half a dozen '70 455 blocks that had 4 bolt caps factory installed. In the early '90's in the pick-n-pulls & friendly yards, I always pulled the heads, then short block, usually pitching the '70 casting 15 heads, & grabbing a pair of 6x-4 or 6X-8 heads, the latter were very common in yards @ the time. Eventually I began hanging onto the '70 model 15's as their high 80 cc chamber size is an optimal size for many pump gas street/strip iron head 406's & 462's. Bought right, under $200 a pair, the '70 model 15's can be ported, upgraded to hardened ex seats, one piece 2.11/1.77 stainless valves/ screw in studs.

carburetion...the YH '70 455's received a 7040262 or 7040562 (California) Qjet. The XF, YA/YC 455 big valve engines typically received a 7040268 Qjet. manual trans '70 big valve 455's received the 7040267. A very few '70 GTO's were built with the 455 big valve engine & factory RamAir. this includes a very small amt of '70 Judges. When this engine made it into '70 GTO's with factory RamAir, the Qjet was same as used on '70 RAIII & RAIV engines, yet the factory installed exhaust manifolds were still the standard log manifolds, just like on a base 350 2bl Tempest.


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## bigD (Jul 21, 2016)

"...It has an 4 barrel Edelbrock carb on it. Not sure on rebuilding so I will be buying new with electric choke. What size CFM is recommended for these cars?..."



They came with 750cfm Q-jets. But a 1976-79 properly rebuilt 800cfm Q-jet would be my choice. SMI has a good rep for Q-jets. You can tell 'em what you got, and they can fix you up.

SMI Carburetor Street Performance Rochester Quadrajet 800CFM Buick, Oldsmobile and Pontiac Quadrajet 4BBL SMI- Sean Murphy Induction


"... What type of oil should I be using in this and how much? Again, this is a stock car and will be mostly a weekender with no track time/racing..."

The answer to that question depends on who you ask. Opinions vary WIDELY. I use 15w-40 Delo 400 diesel grade oil.

Some recommend 10w-30 or 10w-40. Some will nothing but synthetics. MOST agree that you need to use oil which has a high ZDDP content, or add a ZDDP additive to regular oil. The high ZDDP content oil is quite expensive. I always added 6 quarts total. I like to fill the filter, then pour the rest into the engine. 

Also a good idea to use a good filter, definitely NOT a Fram brand, and change it after no more than 3000 miles, probably less, if you don't drive it much. I've used mostly NAPA Gold 1258 filters. They're made by Wix. The Wix # is 51258. 

https://www.napaonline.com/en/p/FIL1258

http://www.oreillyauto.com/site/c/detail/WIX0/51258.oap?pt=C0289&ppt=C0023

I used a K&N filter, on my latest 455 bracket engine, because it is supposed to filter down to 10 micron size particles. They're said to be good quality filters, and they have a nut attached to the bottom, to help remove 'em. But, they're twice the price of the Wix/NAPA. If a few bucks don't matter to you, then you might like the K&N. 

https://www.summitracing.com/parts/knn-hp-2003

http://www.autozone.com/external-engine/oil-filter/k-n-high-performance-oil-filter/161006_427815_0/


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