Carb/torque Converter Tech Question for a 350

[SPEEDROCKET]

Ok, I made up my mind that I am going to run a 112 degree 224/234 .496/ .520 cam with an edelbrock performer rpm intake. I have 7a heads that will see a machine shop before putting together engine. I will port match intake/ heads/ headers also. I have flat top forged pistions so I hope it's safe to assume that my compression will be somewhere around 10:1 or so. My rear gears are 3:73. Does anybody know what CFM of carb I need and what stall converter I'll need to maximize this set up? I don't want to end up with a dud like last build I did when something was totally amis.

[SPEEDROCKET]

Oh yea, I will have a 400TH behind the engine with shift kit and full clutch packs. If this is important to an answer.

[88 coupe]

Originally Posted by SPEEDROCKET

........ what CFM of carb I need ........

The Q-jet, that came on it, is more than you will need.

........ I hope it's safe to assume that my compression will be somewhere around 10:1 or so ........

It is not safe to assume anything. Your engine builder can help you sort everything out.

........ I don't want to end up with a dud like last build I did when something was totally amis.

Before you repeat the same mistake(s), I suggest you find out why it was a dud.

Originally Posted by SPEEDROCKET

........ 400TH behind the engine ........

350 is lighter, and robs less power than a 400. At your level, a stock rebuild with a transgo 350-1 reprogram kit would be more than adequate.

Norm

[SPEEDROCKET]

Originally Posted by 88 coupe

The Q-jet, that came on it, is more than you will need.

I don't have a q-jet, got the car a couple of years ago and it was already tainted with a carb that is shot. Plus it came with a 403 in it and I have this 350 begging for action in the garage, although nothing is wrong with the 403 I just don't like the HP/TQ difference in it.

It is not safe to assume anything. Your engine builder can help you sort everything out.


Before you repeat the same mistake(s), I suggest you find out why it was a dud.

My engine builder says it was a dud because on the carb/ cam/ torque converter/ rear gear setup, but he's not a 100% olds guy so I was looking for those of you with olds experience.

350 is lighter, and robs less power than a 400. At your level, a stock rebuild with a transgo 350-1 reprogram kit would be more than adequate.

Once again, I don't have a 350th for this car, it came with the 400, and by car I probably should mention it's a 73 cutlass. So I only have a 400th to work with. I have a tranny shop willing to do the rebuild in it for $400 and they are the best down here in hell paso. BTW, the last 3 built 350th I have had all ending up in a heap of scrap. So I'm kind of excited to see what the built 400th can do for me for once.

Thanks for the reply.

Norm

[88 coupe]

Originally Posted by SPEEDROCKET

........ but he's not a 100% olds guy ........

Shouldn't make any difference. Basics are the same, no matter whose name is on it.

Norm

[Olds64]

Speedrocket, what kind of carburetor came with the engine? You mentioned that there was one on it but it was "shot." Is it a Carter AFB, Edelbrock, Holley? What Norm said is right on though, the Quadrajets were good carburetors and with a little bit of care they can be very streetable. The only problem I have had with Quadrajets is that they usually need a rebuild with new throttle plate bushings. If you search around you might find someone on the website that would trade you a Qjet for your old carb. I know 2Blue442 has alot of parts.

[captjim]

As others stated, any 750 cfm carb will work fine, Q-jet, Holley, or E-brock. Any chance I can talk you out of that cam? There are better ones out there with faster ramps that will build cylinder pressure better, IMO. That is an old grind, and a lot of cam for a 10 to 1 350. Again, IMO. A converter in the 2800-3000 range should work well, but why take my advice? Call a pro and have him build you one, it costs about the same $. I used Coan, fabulous customer service and product. They built me a street/strip nitrous converter, about $650, IIRC. IMO, the converter is NOT the place to try and save a few bucks.

[SPEEDROCKET]

Originally Posted by Olds64

Speedrocket, what kind of carburetor came with the engine? You mentioned that there was one on it but it was "shot." Is it a Carter AFB, Edelbrock, Holley? What Norm said is right on though, the Quadrajets were good carburetors and with a little bit of care they can be very streetable. The only problem I have had with Quadrajets is that they usually need a rebuild with new throttle plate bushings. If you search around you might find someone on the website that would trade you a Qjet for your old carb. I know 2Blue442 has alot of parts.

Yep, it was a q jet that was shot. I wouldn't mind trading a q jet for it. What do you think of a stage II jet performance q jet? Think it would do the job? I've tried to rebuild them before and that ended up in total disaster.

[SPEEDROCKET]

Originally Posted by captjim

As others stated, any 750 cfm carb will work fine, Q-jet, Holley, or E-brock. Any chance I can talk you out of that cam? There are better ones out there with faster ramps that will build cylinder pressure better, IMO. That is an old grind, and a lot of cam for a 10 to 1 350. Again, IMO. A converter in the 2800-3000 range should work well, but why take my advice? Call a pro and have him build you one, it costs about the same $. I used Coan, fabulous customer service and product. They built me a street/strip nitrous converter, about $650, IIRC. IMO, the converter is NOT the place to try and save a few bucks.

Hey advise like this is why I'm asking questions. I think if you have done this before and got a good combo out of it, then it's worth listening to and maybe learning something. Do you have grind range in mind that would be good for about a 10:1 engine? I'm not sure if that's what it is or not because the engine is apart and painted on the floor. Could be more, or less till I talk to machinist and find out for sure.

[SPEEDROCKET]

Originally Posted by 88 coupe

Shouldn't make any difference. Basics are the same, no matter whose name is on it.

Norm

That's what I would of thought, just making sure, I've heard otherwise and I'm trying to sort it out.

[70Wcars]

Not trying to force a sale on you, but I have been building Q-jets for years and have built some for guys on this site as well. I would be happy to work with you on a carb that will work well with your combo. I run nothing but Q-jets ...even run one on my mid-11 second Bracket car. Check with TexasRed for a testimonial about my carb work.

I also agree with Captjim on the cam. The old generic 224-234 has been much improved on.

Just some more info for you to process.

Danny

[SPEEDROCKET]

Originally Posted by 70Wcars

Not trying to force a sale on you, but I have been building Q-jets for years and have built some for guys on this site as well. I would be happy to work with you on a carb that will work well with your combo. I run nothing but Q-jets ...even run one on my mid-11 second Bracket car. Check with TexasRed for a testimonial about my carb work.

I also agree with Captjim on the cam. The old generic 224-234 has been much improved on.

Just some more info for you to process.

Danny

I'm not looking at it as forcing a sell. How do you do it? Do you have some built already or do you need mine to rebuild?

Any idea on cam profile then? Trying to figure this out? like who makes it and so forth. I haven't bought anything yet and won't tile next month at least. I set times like this so I don't rush into something.

[Olds64]

Danny is awsome when it comes to Qudrajets. Oldsguy (my dad) bought a rebuild Qjet from him and is very happy with it. The price was decent too as I recall. Kudos to Danny.

Its probably just me but I like tinkering with Qjets. I have done a couple of them before and I usually get lucky I guess. I haven't rebuilt one for a performance engine though. I just got a FREE one today. It is sitting next to my Christmas tree.

[70Wcars]

I would check with Terry at FCR Performance and with Bullet Cams for advice on your combo. Both companies can make recommendations as well as sell you a cam and any related valve gear you may need to go with it.

On the carb issue, I have cores that I rebuild and I have some ' 73 as well as the later '70s vintage carbs that flow 800 cfm. All of my builds are done one at a time for each particular engine/drivetrain combo. I re-bush the throttle shafts as well. Settle on a cam and exhaust and Converter choice and then we can narrow down which way to go with the carb.

Danny

[SPEEDROCKET]

Sweet I keep it all in mind. I do know q jets can be a hell of a carb. I'm starting to get a little itchy with getting this thing built!

[captjim]

I have dealt with Bullet, too, ask for Tim, super-nice guy and knows Oldsmobiles. As for the cams, you NEED to know the EXACT compression ratio. Measure everything. IMO, a 350 Olds is very easy to over-cam, so I normally err on the conservative side. I have this http://www.holley.com/60803.asp going into a 10.7 to 1 355. The 20-22 Engle (226/230, 496/512 on a 110) would be good at 10.2 or better, Crane and Lunati make good Olds cams, too. Flat top pistons, 68cc chambers and .045 quench gives you 10.3 or so, pretty good for the 20-22. But cc the heads, they could be anything. And measure how deep in the bore the pistons are.

[SPEEDROCKET]

Originally Posted by captjim

I have dealt with Bullet, too, ask for Tim, super-nice guy and knows Oldsmobiles. As for the cams, you NEED to know the EXACT compression ratio. Measure everything. IMO, a 350 Olds is very easy to over-cam, so I normally err on the conservative side. I have this http://www.holley.com/60803.asp going into a 10.7 to 1 355. The 20-22 Engle (226/230, 496/512 on a 110) would be good at 10.2 or better, Crane and Lunati make good Olds cams, too. Flat top pistons, 68cc chambers and .045 quench gives you 10.3 or so, pretty good for the 20-22. But cc the heads, they could be anything. And measure how deep in the bore the pistons are.

I bet that (overcam) was one of the problems with it last time, the guy told me he had a 455 cam in there.
I do have flat top pistons for it. 7a heads. A 70 350 block.
And as far as how deep the pistons are, when they are down or up?

[SPEEDROCKET]

Originally Posted by 70Wcars

I would check with Terry at FCR Performance and with Bullet Cams for advice on your combo. Both companies can make recommendations as well as sell you a cam and any related valve gear you may need to go with it.

On the carb issue, I have cores that I rebuild and I have some ' 73 as well as the later '70s vintage carbs that flow 800 cfm. All of my builds are done one at a time for each particular engine/drivetrain combo. I re-bush the throttle shafts as well. Settle on a cam and exhaust and Converter choice and then we can narrow down which way to go with the carb.

Danny

PM me with prices if you will so I can figure it into my build. After I rebuild the 400th, I will only have 3600 (hoping that in some math problem this will equal close to 400HP) to do this motor and exhaust (which will cost about 300), so I guess I'm down to 3300. This will all go done Jan/ Feb time frame. Thanks.

[captjim]

You move the piston to the top of it's travel then measure how far down they are. Speed Pros are generally in the .035-.030 range. So, deck the block to have the pistons down .015, use a .028 Corteco gasket for .042 quench, just right.