1966 Buick Riviera 425 Engine Info

**BluesBrothersBuicks** · 11-09-2008, 08:12 AM

I recently bought a 1966 Riviera with a nailhead. Can anyone decode the following number found on the top front of the block - right in front of the valley pan - on what I would call the valley "rail" - on the passenger's side - MW5I9. Despite the info I have found in other places on this website - these numbers are NOT upside down. Also, there is approximately 1/2" space between the M and the W - enough of a space to make them look like two different numbers - is this unusual? This number looks very different from the description given elsewhere on this website. I have confirmed that this engine is the original one through the six digit number also found on the same valley "rail" (although on the driver's side) - and the fact that it matches the VIN number of the car on the drivers door jamb. Also, this engine (Yes, it is a Nailhead.) has pollution control equipment on it. It has an A.I.R. pump along with all it's necessary plumbing - including an air cleaner with special connections to the pump. All pollution control equipment looks 100% original to the car and does NOT look "added on". A Motors Manual shows 1967 as the first year for a "California" car (pollution control equipment). Is this car a late, late 1966 model built in California? Thanks, BluesBrothersBuicks.

**norwegian66riv** · 11-09-2008, 01:03 PM

All i know about the 66 Riviera 425 A.I.R is that the carburetor number is 7036240. Hope it will help you.

**Dr. Frankenbuick** · 11-09-2008, 02:59 PM

MW = 1966 425 bbl engine. Exactly what the 66 Riv came with. They were stamped all kinds of ways and distances apart. The 519 is a date code tat will match the Protect-O-plate (MW519).

66 was the first year for the AIR system in CA. The 66 Cassis Service Manual has a chapter on it.

It should also have a Quadrajet carb.

**norwegian66riv** · 12-06-2008, 06:37 AM

Here is a pic of a 1966 Riviera with a A.I.R pump. Im not soure if this is original. Its from a car i found on Ebay.

**BluesBrothersBuicks** · 12-07-2008, 07:45 AM

Thanks for the help. Yes, this '66 Riviera has a Quadrajet. It has the number 7041305 stamped vertically on the drivers side of the main body - right above the throttle linkage (as is common with most Quadrajets). The carb looks like it belongs to this engine because all the linkages hook up like they are original. However, an Internet search for 7041305 reveals it belongs to a 1967 Buick which would mean it's for the new engine family (430 cu. in.). I found one post on a forum that stated the '67 carb was a perfect replacement on a '66. I find it hard to believe that a carb would be EXACTLY the same on two different engine series but, maybe so. Can anyone verify this????

**norwegian66riv** · 12-07-2008, 04:31 PM

Originally Posted by BluesBrothersBuicks

It has the number 7041305 stamped vertically on the drivers side of the main body

I have decoded your Quadrajet:

70 = Before 1976

41 = Year 1971

3 = ?.... 2 is for 49-state emissions, 5 is for California & high altitude.

0 = Chevy... Division. 0, 1 and 2 are Chevy, 3 is Cadillac, 4 is Buick, 5 is Oldsmobile, 6 and 7 are Pontiac. Rochester doesn't always follow this rule.

5 = Even numbers are automatic trans, odd numbers are manual trans. Rochester also doesn't always follow this rule.

Your Quadrejet is from a 1971 Chevy, i send one link so you can decode yourself to. 1966 Riviera 425 A.I.R carburetor number is 7036240.

Its a hard carb to find, it was only used on the 1966 Riviera, but other Quadrajet with same spec will do a great job

just remember this, the Quadrajet is the best carb to your stock Riviera. And if the carb you have has the right spec it will do a great job. God Luck. 66 Riviera is a wonderfull car

http://www.recarbco.com/technical/rochester/qjet.html

**wkillgs** · 12-07-2008, 08:42 PM

In this case the carb number does not follow the usual Rochester convention.
The 7041305 is a 'service replacement' carb, for a 1967 Buick. It was manufactured after 1967 (maybe even 1971) and may have some design changes from the original 67.

I recently bought a 7041305 off eBay. The bottom plate and linkage is the same as the 1966 carb, but the choke setup is different. I did post the info elsewhere, maybe that is the thread you saw.

Best way to ID a Rochester carb is to look it up in an old AC Delco catalog....those have the complete listings.

Smog equipment was available on 1966 Buicks. I have two Sky GS's that were build and sold in Calif with the A.I.R. system.

**55Spcl** · 12-08-2008, 07:18 AM

"M" stands for 1966. "MW" is the code for a 1966 425 cu. in. engine with a 4bbl carb.

I downloaded this Information a few months ago from:

http://buicks.net/shop/reference/eng...ent_63_75.html

**norwegian66riv** · 12-08-2008, 02:36 PM

Sometime you can find MT code on the 1966 425 cu. in. engine with a 4bbl carb to.

And some of the 1966 Riviera sold new in Europa have a 401 cu. in. engine.

**norwegian66riv** · 12-08-2008, 03:35 PM

Originally Posted by wkillgs

I recently bought a 7041305 off eBay. The bottom plate and linkage is the same as the 1966 carb, but the choke setup is different.

jepp, i know there is a replacement carb to the 1966 Riviera to with a new choke setup, and i think there is a new design on the pump assembly to. But i dont know the number on that carb.

Well, here is a PDF file you can download from Delco. You can find all Buick carb from 1955 - 1969 there.

http://www.newagemetal.com/pages/Buick/63-69/index.htm