My 1970 CST 402 BB has the stock Roch. carb beyond help

[bookemz9]

I really like what this site and everyone involved has done sharing their knowledge and experiences with likewise vintage truck lovers. Please bear with me as this is my first attempt at writing a post. Please let me know if I am not doing things as to protocol. I own a 1970 CST with the 402 big block and turbo 400 my dad ordered this truck new to haul his 5th wheel around the country the glove box door was almost not big enough to hold all the options decals so from an early age I knew this truck was going to be mine. After my dad raqcked up 327000 miles he parked it when he heatd the first hints of a rod knock to keep any damage minimal it sat almost 2 years before funds were available to fix it.all this time I'm doing anything I can to try and buy it from him the truck was still as new and meticulously maintained. He didn't cut any corners in the rtebuild either he spent 2800.00 for a professional rebuild by a well known local who did an excellent job.after break in and the local station rebuilt the stock rochester 4bbl carb things just worked my way I have ten other siblings with at least half of them showing an interest in the truck . I ended up with the truck because he knew it would never be sold or in need of repair and would always be reliable when he needed to borrow it so for the sum of 3000.00 I was a happy new owner. I am a painter by trade and have now owned the truck for 10 years and I've put on almost 6000 miles since they were costly miles due to the fact the carb was worn out prior to rebuild I wqs lucky if I got 6 miles per gallon it was dunping the gas as fast as it could in fact at one point I had a fire under the hood luckily I caught it befure any damage occured biut it scared me enough to know I need to fix it also I have never been able to enjoy the power of the fresh big block.This is where I Am reaching out for experienced information on the best way to obtain the extra horsepower I know Ive been missing. I have had all kinds of motors but this is my first experience with the 302 I have acquired an almost new holley 650 cfm and would like to know if this carb would be suitable for this motor and what manifold should I pair it up with I dont know for sure if ihe heads are square or oval port I gfelieve they are oval but I would rather take the word from someone with experience I am on a budget so I was hoping that I could get away with a used manifold and if so what are the negatives I should look for if any that could be problematic down the line. I also have access to a new in box edelbrock 600 performer carb if I could mate that with a cetain manifold I am open for suggestions I know with the right combination I'll get power I should have had long ago. Thanx Bookemz9:

[2tons of fun]

your typing is horrible.


the 650 should be ok for mild driving but ultimately they are both too small.

a basic rule is 1.8 cfm x the ci, ie a 402 should run a 700 cfm carb.

[LockDoc]

Originally Posted by 2tons of fun

your typing is horrible.

We try not to criticize people for typing, punctuation, and spelling errors on this board. We have people from many walks of life with different backgrounds, that have one thing in common... old trucks. Nuff said!

LockDoc

[LockDoc]

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If the truck was mine and it was pretty much original I think I would buy a new or reman. original type Quadrajet for it. The carb that was on it obviously worked good for a lot of miles... I had the Quadrajet on my big block rebuilt and I am happy with it. Many people that rebuild carbs overlook one of the most important repairs, re-bushing the throttle plate shafts, so the carb still does not work after the rebuild.

LockDoc

[2tons of fun]

the problem is that it makes it very hard to understand and pick out the questions and relivant info.

[Sinister]

Welcome to the Board. Summit has rebuilt Quadrajets for $300.

[hootz]

I think as well that you are better off staying with the Quadrajet. Not to say that the Holley (or any other aftermarket) won't work but you will most likely have to tinker with the Holley to find the right jetting and from your post sounds like you are not real familiar with carbs. Verify that the carb you have now is the right application and then order a quality reman that matches it.

[68350]

What the others have said. Go with a rebuilt quadrajet. I know you can send it in to someone who for the life of me I can't think of and he'll rebuild it for less than or the same cost as a new holley or edelbrock. Trust me, you'll like the quadrajet better in the long run. They get decent mileage and have massive secondaries, so when you kick it down you'll feel it.

[BB72CHEVKT]

My Mom always told me if I did not have anything nice to say to say nothing at all. I think this applies here.

Originally Posted by 2tons of fun

your typing is horrible.


the 650 should be ok for mild driving but ultimately they are both too small.

a basic rule is 1.8 cfm x the ci, ie a 402 should run a 700 cfm carb.

Originally Posted by 2tons of fun

the problem is that it makes it very hard to understand and pick out the questions and relivant info.

[redbaron69]

i agree with what is said above, get yourself another q-jet. some people will bash them but i have good results with them over the years. and you can keep the original look.

[Jim_PA]

Ship out the original Qjet, and have it completely torn down and repaired. There isn't anything out there better for your truck.

[Jim_PA]

Originally Posted by 2tons of fun

the problem is that it makes it very hard to understand and pick out the questions and relivant info.

HA HA! and you can't spell

[Jim_PA]

Originally Posted by LockDoc

-
If the truck was mine and it was pretty much original I think I would buy a new or reman. original type Quadrajet for it. The carb that was on it obviously worked good for a lot of miles... I had the Quadrajet on my big block rebuilt and I am happy with it. Many people that rebuild carbs overlook one of the most important repairs, re-bushing the throttle plate shafts, so the carb still does not work after the rebuild.

LockDoc

Not only that, but they use old kits with rubber materials that don't hold up with ethanol.

[mclairmo]

Originally Posted by hootz

I think as well that you are better off staying with the Quadrajet. Not to say that the Holley (or any other aftermarket) won't work but you will most likely have to tinker with the Holley to find the right jetting and from your post sounds like you are not real familiar with carbs. Verify that the carb you have now is the right application and then order a quality reman that matches it.

I agree with this and make sure they bush the shafts if necessary.

[superchevy]

Stick with the q-jet. I would highly recommend Sean Murphy for your q-jet rebuild. They will rebuild your q-jet, or better yet, you can buy one of their Stage 1 carbs...custom built for your truck engine/drivetrain/usage specs...starting at $325.
I've bought 3 q-jets from them over the years. Each one custom built to my application. I'm just about ready to order another one for my 468 cube K25.
You can check them out at this link...you won't be disappointed:

http://www.smicarburetor.com/product...2/productID/18

[Mike C]

I put a JET Stage II Q-jet on my 70 GMC with the 402 in it. It was a huge improvement over the parts store rebuild. Mileage jumped from 11 to 13. I also liked having the electric choke over the hot air choke of the original. Just order up from Summit and put the original away in a box.

[1956cameo]

I have two big block trucks, a 70 and a 72. Both have the original quadrajet carbs and they both run great. Like everyone else is saying, go with an original quadrajet.