I have a fairly stock 72 LS5. I have a Quadrajet on a stock manifold and a rv type cam. I have a set of headers so I don't have exhaust heat risers and I did put in the blocking plates on the intake manifold gaskets. The car run like crap when cold and it take 10 to 15 minutes to warm up and run right. I am running straight ported vacuum to the distributor with out the stock vacuum solenoid that is supposed to limit vacuum advance until the car is warm and in 4th speed. I also put a air/fuel gauge on the car with an o2 sensor. It doesn't read right until it gets good and hot. When it does get hot it shows the car is running pretty good. When I step on the gas it richens up but it does go into a real lean state if I just ease onto the gas gradually. I know the heat riser situation is not right and is not helping the cold running problem but I think the timing thing with the vacuum advance could be my main problem. Any ideas on how to set it up?

Without manifold heat and a correctly calibrated choke, your car is not going to run good when cold. It will waste gasoline, pollute the air, and be a pain to drive. Why headers with an RV cam? Restore it to stock and it will work fine.

My $0.02

My last car and my present ride did not have chokes but had headers. The previous car warmed up fairly well in a short period of time and performed admirably after only about 2 minutes.

I haven't been out cruising in my new ride yet but I do know it is definitely much more "finicky" and definitely takes a lot longer to warm up, just from the couple of times I have let it run checking a few things out. This engine is a little more radical than the last one which may be the reason or it could be the aluminum heads, don't really know for sure at this point.

Personally I think 15 minutes is a little long before it operates "as it should". Hopefully somebody will have an idea for you.

Good luck.



------------------
TC # 947
69 SS Sedan (http://www.angelfire.com/rock/69ss)

My car never likes to start in the cold either. My mechanics teacher got me a block warmer as a X-mas gift. Its a long rod that you replace the dip stick with during the cold night and plug it into a power outlet. It warms up the oild, so it's not thick and cold when you first crank over the engine. Starts nicely now. http://www.chevelles.com/forum/smile.gif

Well, you can always check the basic tune-up type things, but with your cross-over blocked and no hot air system I wouldn't get my hopes up as far as cold weather driveability. I take it that you don't have a choke hooked up either?

I think you may find that you are going to have to decide whether you want a car that has good driveability or one that is a little quicker, but doesn't like to get up in the morning.

Pull the intake and remove the block off plates-simple as that.I have no choke on either of my cars and I just pump the gas a few times,fire 'em up,and drive 'em.Those plates aren't worth the trouble,unless you have some kind of radical motor,an even then they're questionable.They shouldn't be used on a car that's street driven.

------------------
1970 Chevelle SS396/L78/M21/4.10 My 70 SS396 (http://www.chevelles.com/showroom/mr4speed70SS1)
1972 Olds 442 convertible(455,W25,M40) My 72 442 convertible (http://www.chevelles.com/showroom/mr4speeds442conv1)
1982 Oldsmobile Cutlass 350 Olds,TH350(daily driver)
"Be aware of the possible ramifications of the potential outcome"
Chris Corwel,the man from the too much taxes and over priced gas state of Connecticut
TC Member 785

Ditto on removing the crossover block off plates!

------------------
Steve Strasemeier (70SS 396, Fathom Blue/White Stripes)

You guys are lucky that you can remove the blockoff plates that easily!
I decided to block off the passages on my Buick intake. The only way to accomplish this was to set the manifold up in a mill, bore out the passages, and tap them for pipe plugs. I spent a couple of hours doing this--turned out great. Now my car runs like crap in the cold weather! D'oh! I never had this problem in Los Amgeles....
But isn't excessive fuel heating/boiling a concern with the exhaust crossover?

------------------
Tony Nausieda
1970 SS 396-350hp

I think that the GM engineers thought about that too. Can't imagine them designing a system that would boil the fuel. But, you never know...

My $0.02

Never blocked off the crossover ports in the 30 years I've driven the Chevelle, and have never had any cold weather driving problems either. Also, be super sure the choke is operating correctly, especially the choke "pull-off".

------------------
MalibuJerry350
Original owner '70 Chevelle.
540,000+ miles on car.
My Chevelle: http://hometown.aol.com/erie614/myhomepage/index.html

I guess I will pull the intake and get rid of the plates. One other thing. In the summer the car runs at 180 to 190 degrees when hot with a 180 stat. In the winter it won't go over 160 degrees max with the 180 stat in it. I will probably put a 190 stat in it for the winter.