2bbl to 4bbl & intake worth the effort?

[mpalmer03]

Have a 69 w a 350 and 2bbl. Want to swap in a 650 edelbrock and performer intake. Unfortunately, the casting number on front of motor is absent so I don’t know which 350 I have i.e. cam, compression? I can’t pull motor apart to identify right now either. Does it make sense to do that swap for more performance without knowing that info? Thanks in advance

[demian5]

If the carb is in nice shape and the ignition is up to par, you will enjoy many benefits with the 4BBL setup (minus the decreased fuel mileage). Make sure to use a solid bead of RTV and NOT the end seal gaskets when swapping.

Now would be a great time to go HEI if you can. Just make sure you increase your spark plug gap to what a car with HEI requires (say gap for a 1980 pickup).

[Arnulfo]

Originally Posted by demian5

If the carb is in nice shape and the ignition is up to par, you will enjoy many benefits with the 4BBL setup (minus the decreased fuel mileage). Make sure to use a solid bead of RTV and NOT the end seal gaskets when swapping.

Now would be a great time to go HEI if you can. Just make sure you increase your spark plug gap to what a car with HEI requires (say gap for a 1980 pickup).

This man is 100% right. Just did that swap on my 1970 C20. I used a factory chevy manifold and carb so everything bolted right up. Very happy with results

[Ziegelsteinfaust]

It is worth it if your willling to tune it.

Typically you can eeak out a mile or two better if you play with it. 2 barrels rely on a cam to enrichen it based on throttle position more then holley 4 barrels vacuum secondaries do. Edelbrock, Carter's, and Q-jets use a similar vacuum plunger to enrichen the mixture as load + throttle position go up.

Don't tune it and mog can be in the toilet, and or you will have less power.

[HO455]

Originally Posted by Ziegelsteinfaust

It is worth it if your willling to tune it.

Typically you can eeak out a mile or two better if you play with it. 2 barrels rely on a cam to enrichen it based on throttle position more then holley 4 barrels vacuum secondaries do. Edelbrock, Carter's, and Q-jets use a similar vacuum plunger to enrichen the mixture as load + throttle position go up.

Don't tune it and mog can be in the toilet, and or you will have less power.

What he says times two. If your not prepared to spending hours on tuning an aftermarket carburetor then find a Q-jet you know came off a 350 truck and get it rebuilt by a knowledgeable Rochester rebuilder. If you are up to the challenge, and forgive me if you are experienced, it is a rewarding experience. Now days wide band O2 guages make this an easier task, but good ones aren't exactly cheap.
Do some more research as to what engine you have is. Unless you are one hundred percent sure it is factory and didn't get a swap back in 1977. It is possible you could have anything from a 283 to a 400. Look at the casting numbers and the date codes on the block, heads, and intake manifold. See if they all match close to what you expect to find. I found that the 350 in my Burban was a 305. Which helped explain it's anemic performance.

[CUDA8U]

edelbrock air gap and a 650 holley or quick fuel

eddy carbs are junk!


watch videos how to tune a holley, get a jetting kit and a vacuum guage.I had an eddy on my 440 and put an 850 holleyI watched multiple holley tuning vids,the first test drive I blew my cell phone off the dash and into the back seat,atleast 50hp gain over the 750 eddy

[muley]

Originally Posted by demian5

If the carb is in nice shape and the ignition is up to par, you will enjoy many benefits with the 4BBL setup (minus the decreased fuel mileage). Make sure to use a solid bead of RTV and NOT the end seal gaskets when swapping.

Now would be a great time to go HEI if you can. Just make sure you increase your spark plug gap to what a car with HEI requires (say gap for a 1980 pickup).

I am curious. It's been a while for me, 40 years, since I did a lot of engine building, tinkering. I always used all the gaskets on a intake swap and done carefully, never had a problem. What changed? Are the gaskets worse? Or are the sealants that much better. Granted the little rear gasket could easily be a pain. You really had to pay attention.

[HO455]

As long as the heads haven't been milled a bunch, the gaskets still work. But as you said you have to pay attention and glue one side down before dropping the intake on. Lots of folks find it faster to lay a 3/8" bead of sealant on the block and drop the intake down on the sealant and be done with it. Just different ways of doing the same thing. Now if the heads have been cut on there may be no room for a gasket and you're forced to use sealant instead of a gasket. There is also a case to be made for the new generation of sealants making a gasket free seal virtually leak free. Permatex's Right Stuff is an excellent product as are anaerobic style sealants. But these are more expensive than the old school RTV silicone products. But sometimes good old #1 or #2 Permatex is still best. Over the years I have tried lots of products and found some that work for me and some that didn't.

[SeanB242]

This will definitely wake up the engine. I did it when I got my first 68. I’ve installed intake both ways. With gasket and without. If you use the end gaskets use a little glue to hold them in place on the block and put a small dab of sealer on the four corners. Now, I know everyone has their opinion on what works, with that being said, have you already bought the carb? If not I would say get a Holley. When I put my Edelbrock carb on the first time I had nothing but problems. Tried all the metering rods and springs and still couldn’t get it to run right. Dropped a Holley on and ran great. But like I said that’s just my opinion.

[TinnMann]

I never use the end gaskets, just permatex gasket maker (heavy oil application) for the ends and permatex gasket sealent around the water jackets only, not the intake ports. The gasket sealent is tacky and helps hold the gasket in place as you drop the intake on.

I like my holley 600 carb with eddy performer intake. If you think its fun tuning and enjoy the little bit of work that goes along with it, get a holley. If not, there is nothing wrong with a q-jet! Just make sure you make a decision before you buy the carb and intake because you have to match up the spread bore or sqaure bore intake with the carb. A lot of people bolt on square bore carbs on spread bore intakes and vise versa and are not getting the full benififs of either.
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[Overdriven]

Originally Posted by muley

I am curious. It's been a while for me, 40 years, since I did a lot of engine building, tinkering. I always used all the gaskets on a intake swap and done carefully, never had a problem. What changed? Are the gaskets worse? Or are the sealants that much better. Granted the little rear gasket could easily be a pain. You really had to pay attention.

I wish I had a picture of the engine in my dad’s 72. The front intake gasket is hanging out the front, about half the width. There aren’t any leaks but it obviously shifted during installation and the person doing the install didn’t notice or care. I’ve never used the front and rear gaskets just to make installation easier as it’s one less thing (well 2 gaskets actually) to worry about.

[Ziegelsteinfaust]

That is common, and be caused by crank case pressure too. Which is why most guys will use permatex on the ends or equivalent. It is not under compression like the cork so it doesn't have a tendency to just push it own self outm

On my 64 G10 project I pulled the motor from a 73 C20 I bought for the title. The reason I got it so cheap besides the rust was the end seals blew out. This causing a oil S storm the appt manager hated where he lived.

[mpalmer03]

That's all valuable input, especially the part about the carbs. Was going edelbrock as I have a Performer intake but will look at Holleys now...just need to check the bore style on intake. Initially, was concerned that I needed to change cam to realize the potential gains from 2bbl to 4 bbl but sounds like I should be good to go as long as I tune properly. Cam and heads are in the works but this is good start. Welcome any more feedback as well. Thanks!

[SeanB242]

The performer intake will work with either carb.

[panhead59]

Not all sbc v-8 s use the same intake. Most do but make sure your valve covers aren't the center bolt type or the intake u have won't work. Post some/any/all numbers u can find on block, front and rear by dizzy, and off heads. We most likely can id that motor or get real close. Never mind cuzz that would be a throttle body intake and u say it's got a 2 bbl on it now. I don't even know if u can buy a 2 bbl intake for a center bolt/throttle body engine. If the #'s are missing off the front of block, it's probably been decked.

[SeanB242]

Originally Posted by panhead59

Not all sbc v-8 s use the same intake. Most do but make sure your valve covers aren't the center bolt type or the intake u have won't work. Post some/any/all numbers u can find on block, front and rear by dizzy, and off heads. We most likely can id that motor or get real close. Never mind cuzz that would be a throttle body intake and u say it's got a 2 bbl on it now. I don't even know if u can buy a 2 bbl intake for a center bolt/throttle body engine. If the #'s are missing off the front of block, it's probably been decked.

All true. But he said he already has the intake.

[garyd1961]

What heads do you have on it?

[mpalmer03]

Heads are: 3932454. Block:3956618