Thread: Dumb questions...

Tweet

For anyone still folowing this thread, I went ahead and took some pictures of the carb/engine on my car, in case that helps things at all.
The images are at this link. WARNING! The images are 1600x1200 res and as such are quite large.


Also, for the new carb I'm thinking of going with an Edelbrock Performer Series 750 cfm carb. Jeg's has a factory remanufactured one for $209. Seems like a good deal to me. Any thoughts guys?

Yep, a picture is worth a 1000 words...........

What you have is a small block Chevy, non Vortec, prior to 1987 (I think 87 is the start of Vortec. The carb is a Rochester Quadrajet.

No, the 750 is way too big for a 350 Chevy (assuming this engine is a 350 and not a 305) You want no more than a 600 CFM or you will be overcarbed.

Evidently your intake is set up for spreadbore and squarebore (from what others have said, but to be sure pull the carb and look at the base pattern).


Don

Okay, thanks. And quick question, what do you mean by 'overcarbed' what happens then? Also I would guess that what I was told about the engine is atleast possible if not indeed correct. Also, what size/type of carb would folks recommend for a 350?

The deal is that I bought the car from a small dealership, and everything I know about the car comes from the guy that worked at the dealership and most of what's been done to the car so far was done by the guy that had it before the dealer. So, most of what I know about it is second hand.

Thanks for the help guys. All the answers in this thread have saved me many hours of trial and error and research. Thanks!

Edit; Just wanted to correct my semi drunken grammar/spelling. Haha.

A couple of things..............

I see that you live in the cooler part of the country...falling leaves. The fact that your choke is not hooked up will greatly affect the way it runs. That carb requires the choke spring type of choke. That mainfold has the heat riser system. I would put a manual choke on it.

You said that the carb is leaking...It may be from the throttle plate rod shafts. Quads are known for this. Have a good look for this.

If going with a new carb...600 cfm should be about the max, as it appears to be a stock engine other than the intake.

Overcarbed is just what the name implies.........the carb has too much airflow and fuel being metered into the engine for it to all burn/be used. As an extreme example, if you put a four barrel carb on your lawn mower it would be overcarbed. The engine can only use so much, and will run very rich and badly if overcarbed.

Ideal for your engine is about 600 cfms. There is some mathmatical formula that I think Richard (techinspector1) has posted, but I forget what that is exactly. I just know the typical small block runs well on about 600 cfms.

Just for sake of asking, why do you want to lose the Rochester that is on there. Although they generally don't have the performance image of Holleys or Edelbrocks, they are actually very good carbs for a street engine. Mercruiser and all the other boat engine manufacturers have used this carb for years and years, and the nice thing about them is that they are very economical to operate due to the small primaries. You could have it rebuilt and probably be fine. The Jag isn't a drag car, so for smooth street performance the Rochester would not be a bad choice IMO.

Just a thought.

Don

Nice car.... and ditto about the "600 cfm"...
If you do decide to use a new carb, you may want to consider one with an electric choke.... they are easy to hook up and work great....
Also the local parts store should have "studs" to replace those bolts holding the carb down!

I would also recommend doing something about the spark plug wires...
A set of custom length wires and some wire looms would go a long way in improving the look and reliability of the ignition system...
As they are, (lots of extra length and no real order)... something will eventually burn or arc or crossfire or......

Okay, quick update. I went ahead and ordered a 600 cfm performance series carb and an edelbrock fuel pump from Jeg's. As for the studs I'm gonna wait until I get the carb, because I noticed as I was taking the carb off today that that two of the mounting holes on the manifold are parcially stripped. I'm crossing my fingers hoping I won't have to re-thread them and if I do I'll need studs that fit the newly threaded holes, obviously.

As for custom spark plug wires, that sounds good. I'll get around to that soon I think. But it's gonna stay low on the list because I have to replace the steering column and do some cooling hose work, and make a decent air intake system... Etc. Etc.

Needless to say, she's a bit rough right now

You can pick up a heli-coil kit at the auto parts store that will restore the threads to the original sized stud. Cheap and easy to use.

Don

Since you obviously have hood clearance problems I suggest you look into a drop base air cleaner from K&N. The initial price is rather high, but you'll never have to replace the element. For spark plug wires I'd check Taylor Spiral core. Summit sells a good set for under $60 and Jeg's probably does too.

Update. Looks like I don't have to worry about the mounting holes in the manifold, the outer set will work nicely.


Okay, so the carb is a spread bore, and the manifold is compatible with spread and square bore, but the gasket that came with the carb is for a square bore. Is that gonna cause me problems?

I had other questions, but I forgot them. Maybe I'll remember later :P

Are you sure the new carb is a spread bore? I can't see a regular gasket coming in the box with it if it is.

Snap a picture of the base of the new carb and also of your intake with the carb off so we can see what you've got.

Don

Okay, I'll take some pics but, according to another thread on here "Square bores have the same size throttle plates for primaries and secondaries. Spread bores have bigger throttle plates for the secondaries." the secondaries are the holes toward the rear of the carb on the bottom, right?
My holes on the rear are bigger.

Edit: Okay, I just ran out and snapped a couple quick pics. The pics are at this link. The two on the bottom are the pertinent pics. (IMG_1500.JPG and IMG_1502.JPG) They were both taken with the front of the car to the left of the frame.

Ok, so you are saying your gasket holes are smaller than the holes in the carb??

Don

Sorry to confuse. The gasket has one big square open area in the center. Should I take a pic?

Edit: In my almost-drunken state, I just realizd the gasket and camera were within arm's reach so I snapped a quick picture. Hope that answers the question.


And thanks for putting up with me

No, you are ok with this gasket.

Don