Took a 66 Buick Riviera out for a test drive in the Idaho back country Saturday. The Riviera was last registered in 1993 and has like 145,000 miles on it. It started up ok with no excessive smoke but had a couple of problems: It had extremely poor throttle response. It was like I had to continuously feather the throttle. Also, I am not sure whether the secondaries in the Quadrajet carb ever opened up when I punched it. It also seemed to lack the power that it should have, but it had been sitting for 10 years and hadn't been tuned for who knows how long before that. The last problem was with the tranny (the owner's manual addressed a ST-400 transmission only). The trans was not making it final shift into 3rd gear without excessive RPMs, and even then it didn't always shift. By the way there was no decal on the aircleaner, but i think it is a 425 Nailhead engine because there were two W's on the front of the block next to the valley cover and also W342 stamped next to the W's. Is this a 425 engine? Any chance the problems just mentioned can be fixed without major expense? I understand that a complete rebuild on the transmission could be quite expensive, not to mention what an engine rebuild would cost. The body is decent with only one tiny spot of rust-through, but the interior is shot and a new windshield is needed. I can get the Riv for $1,100. Opinions, please, on the mechanical problems noted and on the engine displacement.
425 should be a 425. Trans sounds like a vacuum problem. Could be that you have several vac. leaks in various hoses, one of which goes to the vac. modulater on the trans. Sounds like a steal, but not if you plan to just put gas in it and go.
Re: 425 I'm with Skip on this one, plus the gas in there isn't helping her run any better. The points/condenser are probably shot, but they're quick and easy items to replace. If you don't pick that car up I'm sure several people here would love to have it!
The 425 was standard on the '66 Riviera. The letter code should be MW, followed by a three digit date code. The serial number is stamped on the other side....do those digits match up with the VIN? The '66 425 came standard with a Q-jet carb. '66 blocks also had a 'hook point' cast into the belhousing to make R&R of the engine easier. A matching hook is cast in the water manifold at the front. As Skip mentioned, check the vacuum line between the intake manifold and trans. If it's leaking, it'll shift late, if at all. Will it shift into third manually? $1100 sounds ok, will he take less? By the time you put $8000- 15k into the car to restore it, $300 difference in purchase price is pretty insignificant. If you really like the car, go for it!
What part of Idaho? I might want it if you don't. Ditto on the suggestions, and if you're an avid DIYer the TH400 can be rebuilt for around $150 with common hand tools.
Appreciate the input received thus far from you all. The numbers on the engine block match the VIN, so It's the original engine. I thought maybe the transmission was not the TH400, but rather the ST-400 because when i turned to the transmission page in the owner's manual, it mentioned ST-400. Aren't they different? Did the 66 Riviera usually come with the TH-400? Is there an easy way to tell which trans it has? If it's the ST-400, is that more expensive to repair than the TH-400? The car wouldn't take a lot of money to restore. When I said the interior was shot, I meant the seat covers mainly. The headliner was starting to come apart at a seam, but otherwise it's interior isn't bad. I will try seeing if the tranny will shift into 3rd next time i go look at it.
The ST400 is the Buick terminology for the turbo400 trans (aka TH400). Internal parts are the same as other turbo400's. It could be a switch pitch model, which has a dual stall speed. GM used these from like 65-67, not just Buicks. The switch pitch has an extra electrical connector on the side of the case and a slightly different pan.
It should have the switch pitch trans. There should be a micro switch on the throttle linkage that allows the trans. to go into hi-stall at traffic stops. You can find out more on the buickperformance.com web site.
That's cool info, BlownNailhead --- the dual stall on switchpitch versions, I mean. If I were to look at the tranny case, where would i look for the extra electrical connection? Any specifics on the pan to look for?
Here is a direct link to buickperformance.com switch pitch info: http://www.buickperformance.com/switchpitch.htm
You can join that group for only $2.00 a year. Many of the same folks are there and it gives you another source.
