Need help w/ 455 & Holley DP

Yesterday I picked up a 69 Skylark with the 455 from a 70 Riviera swapped in. This is my first real forte into the carburetor world. My previous vehicles have all been LS motors or turbo 4's.

On to my problem....when I picked the car up, the guy who sold it to me said the carb was an 850dp, and that he thought it was too big for the motor. His reasoning behind this, was that when accelerating from a stop with light pedal pressure, the motor would bog and buck till it going going a little bit. Dead spots are what he called it. Giving it more gas would also help. I should probably also mention that the car fired right up and idles very smoothly. I drove the car about 2 miles from my house to a gas station and when I went to pull into the space the RPMs didn't want to go down and I was fighting it trying to drive through the brakes. After I got it stopped and turned it off the car "dieseled" a bit. After coming back out to the car it once again fired right back up and I decided to take a longer route home. Every time I came to a stop it would do the hesitation/bucking thing but once moving it ran pretty smooth, although it definitely didn't feel like it had big block power. As I was cruising home at a constant RPM it started bucking a little so I gave it some gas to get the RPMs up which smoothed it out, but as soon as I let the gas back out it started to sputter until the engine shut off. I coasted to a stop and tried to restart it and was not having any luck. Thinking I may have flooded it I let it sit for a few minutes and it still wouldn't start. At that point I popped the hood, pulled the air cleaner and (once again not having much knowledge about carbs) tried moving the throttle by hand to see if that would help. As I was moving it to WOT fuel started spraying from the back of the carb at high pressure onto the firewall. Not wanting to die in a horrendous fire I decided it was time to call a truck and get a tow home. As of this morning, it will still not fire (no pun intended) up.

Hopefully some of you with considerably more knowledge than I can give me some advice. As of right now, the motor is bone stock. My current plans for the car are a nice fast weekend warrior that I will occasionally take down the strip. I was planning on doing headers and intake and possibly a cam. Should I ditch the 850 double pumper for something smaller, or is it worth sorting out? If I keep it, can you you give me some ideas as to what might be causing these issues?

Thank you, and sorry for such a long post.

 

No apologies required.
Although I am not a fan of Holley carbs. on street driven cars the carb. is not too big. Assuming the carb. itself is in good shape and somebody hasn't messed it up beyond repair you need to sort out what you have. Holley's are relatively simple, there are books devoted to them that explain in plain english how they work and how to fix/modify them. Don't give up on it. Mike D.

 

The 850 is not too much like Mike said. You should probably rebuild it or replace it, it should not be squirting fuel anywhere but down into the intake.

Could you take some pictures of it so that we can get a better idea of what you have?

 

Thanks for the replies guys. I looked up the number on the carb (6210-3) and it looks like the guy is full of it....its actually a 650cfm. The fuel appears to be spraying out of the accelerator pump. I will take some pics shortly.

 

Ah if it is a 650 that is not enough CFM. Usually you should run at least an 800cfm for a 455. Although I think the 70's may have come with a 750 I am not 100% sure. Those are relatively simple to work with if you are wanting to rebuild it. But if it is just leaking from the accelerator pump and nowhere else you can take that rear bowl off the carb and just replace the accelerator pump.

 

when in park does it idle high? i would suspect that they might have a square bore on a spread bore intake. causing massive vacuum leak. and high idle causing runon.what intake is it? tyler has good information. i would go qjet or 850 holley. if you want a qjet. tylers dad mark. aka carmantx does a good job. he built mine

 

Well, I decided that since it was just a 650 I would put something new on and not mess with rebuilding it. Per 462 Chevelle's question...it was on the stock intake with no adapter or anything. I got a really good deal on an Edelbrock Performer intake and a Holley Street Avenger 870, so that will be going on this weekend hopefully.

 

Remove the small 650 carb from your engine. Double check your manifold to make sure a square bore carb is compatible. Assuming it would be, get a 850 holley DP and install it. In my opinion a larger carb like an 850 is good because it gives you some room to make changes if you want to make power. Thank you for going with Buick power. I don't want to offend our LS-kylark friends out there. John. :laugh:

 

go qjet if its a street car. never seen a holley that fits on the stock intake i bet if you spray ether around carb base it goes crazy.

 

Have a 455 & Holley on my '69. Need at least 750 cfm or 800 cfm for a stock motor. Sounds like at a minimum you will need to add in an adapter plate to cure a massive vaccuum leak (no plate, bolted to stock intake). Next up, be sure to use some liquid gasket glue (Permatech Indian head works great) to seal the adapter to the intake when it is bolted down.

Next up, install the new Holley, this time with out the glue. You should have cured your leak at this point.

As for the 650, take it to a swap meet.... Sounds like time for a rebuild as it is dried out. Bet it's full of _rap as well.

BTW - 750 cfm was stock on '70's, '71 and later went to the 800 cfm Q-jets. Caddy had even a bigger Q-jet on the 502's, Carb Shop can set one of those up for your Buick!

Jim

 

Lonnie, Holley makes a spreadbore Carb that fit on stock jet intake. Most were 650 cfm. I have a couple of them on the shelf.

 

As mentioned...the carb is coming off. I don't know anyone local that is good with Qjets, and I got a deal so a Holley Street Avenger 870 is going on. Along with this an Edelbrock Performer manifold is going on too.

 

Cool. Now you just need to post some pictures. :TU: