Thread: Dumb questions...

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I'm new to the forums and new to the more technical aspects of car repair/upgrade. So please forgive me for my ignorance and if these questions have been asked on these boards before.

Okay, number one: my engine (see more info about it below) has an Edelbrock performer series intake manifold on it. On it resides a carb that does not fit the intake proberly nor is it set up properly. I have decided to replace it with an Edelbrock performer series carb. I have'nt ordered the new carb yet, because I'm not sure whether I need a a spread-bore or a square-bore carb. I have'nt removed the old carb yet, so my question is when I remove the carb, how do I know which bore type it is? What's the difference between square & spread bore?

Also, the engine in my Jag is supposedly from a '74 Chevy pickup. I wanna know though how do I tell if it's a big block or small block, what's the difference between big and small block?

Thanks in advance guys.

The only dumb question is the one you don't ask. Greetings. When you remove the carburetor, look at the mounting on the manifold. If it is square with four holes the same size, then it is a square bore. If the two rear holes are way bigger than the front ones, then it is a spread bore.

If the engine in your Jag is a 350, then it is a small block. You can tell by looking at the valve covers. A small block valve cover is held on at four mounting points--two on each side. Big blocks have more.

Greetings! And thanks alot. I thought your answer to the carb question was how it worked, but I wanted to be sure before I drop 300-400 bucks on a carb.

Another question on big/small block. Does engine size have anything to do with it? Meaning is there such a thing as a big block 350?

No. 350's are in the small block family. You can bore and stroke them to a much bigger size, but they are still referred to as a small block. It is designated that way because of external physical size, not internal cubic inches.

Don

Originally Posted by Itoldyouso

No. 350's are in the small block family. You can bore and stroke them to a much bigger size, but they are still referred to as a small block. It is designated that way because of external physical size, not internal cubic inches.

Don

Ah! Thank you!


That answers a very old question for me.

Some of the guys like Denny on here are very good at finding drawings and things like that. Maybe one of them will post some showing the difference between a small and big block for you and others who may need this info.


Don

That would be great!

Also if my edelbrock manifold has 8 bolt holes, that mean it will fit either kind of bore, correct?

Well, no. 8 bolt hole intakes were Vortec style, used from I think '87 up, and only on small blocks. Earlier (1955 up) used 12 hold down bolts on the intake.

If yours is truly a '74 engine, it should have 12 bolts. Looks like someone has put in a later engine.

Don

PS: Shoot us a picture or two of your engine.

Wait, 8 bolts on the Carb flange or intake to heads?

8 bolts on the Carb flange means it will probably fit a Holley or Edelbrock carb.

The intake to heads should have 6 bolts each side I think.

Kitz

Oh, you're right Kitz, he's talking about the carb mounting surface having 8 bolt holes, not the intake to heads. My mistake.

Don

The performer has accomidations for both Spread bore carbs, and Square bore ( holley ). You can mount either one. What do you currently have on there?

It's a quadrajet that does'nt fit right. It leaks around the bottom.

See, the guy that had the car before me was trying to do everything on the cheap and apparently had no clue what he was doing.

Makes me wonder. The performer should bolt up a Qjet just fine. The performer RPM on the other hand will not.

Hmm I'll do some more looking and take some pics. Maybe it just has a bad gasket on it. I'm going to replace it anyway I think, because the current one has setup issues, as well as the the fact that it's old and needs cleaning, etc.

Its probably just a bad gasket..............a Quadrajet is a direct bolt on a Performer manifold.