Ultimate daily-driver Gen II A Body to build

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Your mazda would be terrible with an auto, because for what ever reason the continent of Asia cant make a good auto
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One of the most durable automatics EVER built come from Asia. It saw use in Toyotas, Volvos, and even by M-B.

(Note: It was also installed for 14 years by Chrysler.)
 
DionR said:
How do you do fuel enrichment for boost conditions with a 2bbl? Or do you just run it rich when it is off boost?
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If it's like a few blow-thru setups I have seen, it's done simply by raising the fuel pressure. Basically, add 1psi for every psi of boost.

I like the formula, I just don't see it being something I want to drive very far. I've been out of the blow-thru slant six area for a little while so maybe there are some improvements I'm not aware of, but when I was spending time looking into this I didn't think there was a way to make a 2bbl work both under boost and without it. It was either deadly lean under boost or pig rich when cruising. Not a recipe for a good DD in my book.

Now a small 4bbl, that makes more sense to me.

Not trying to start a fight, just asking.
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Honestly...much as I like carb'd hot rods, I would not want a turbo engine without EFI.
 
Bill Dedman said:
The pushrods are not the problem. A cam that lasts at a redline of 5,500 rpm with 340 springs will have lobe (and, or lifter-face wear) to the point of flattening the cam at 6.500 rpm with the (necessarily) stronger springs that will control the valvetrain at that rpm.

I agree that 340 springs are not QUITE strong enough, but the Crane springs (you recommended to me, and I bought,) are. But, they wouldn't do for a 6.500 rpm 170, which would also be working against 12 pounds of boost.

In the interest of preserving the cam/lifter interface in this day of reduced ZDDP levels, I worry about the elevated rpm required with the 170.

There is NO good reason to do it... Putting the cam at risk for no benefit, the way I see it.

My 2-cents...:coffee2:
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For the lifters...just run a pan full of 10W-30 Quaker State DEFY oil, or 5W-40 synthetic diesel oil. :)
 
Jarlaxle said:
One of the most durable automatics EVER built come from Asia. It saw use in Toyotas, Volvos, and even by M-B.

(Note: It was also installed for 14 years by Chrysler.)
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key word is one lol... damn near all the hot imports are stick cars for a reason and the ones that are an auto are usually a glide or other chevy trans, I think I have only seen a supra running a factory auto (built obviously).
 
Jarlaxle said:
Said transmission was, in fact, used in Supras.
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well lets face it... a supra is in a breed of its own compared to most all other imports with an auto. I cant think of one auto import that didn't shift like a wore the F out 904 lol... Im not talking used cars either, I went to drive a Honda fit SI so I could get a 50 dollar gas card (lol) and I hated it... I think the front end was going to fall off when the ABS kicked in as well...
 
Jarlaxle said:
If it's like a few blow-thru setups I have seen, it's done simply by raising the fuel pressure. Basically, add 1psi for every psi of boost.
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That doesn't work with a carb. With EFI, you can raise the fuel pressure to make the injectors squirt more fuel and make up for the greater amount of air being forced into the cylinders (to a point), but it's not quite the same as actually tuning the system for boost. With a carb, you have to do something similar, but it's only because the boost makes it into the fuel bowl and your fuel pressure will actually go down equal to the boost you are running which will starve the carb for fuel. So, you "boost reference" the fuel pump so that for every pound of boost the motor sees, the fuel pump puts out an addition pound of pressure and the carb sees the same pressure it is used to. But adding extra fuel pressure to a carb doesn't do much to add fuel to the mixture under vacuum (at least not until you start pumping gas out the vent tubes), and does absolutely nothing to richen the mixture under boost.

The issue with a 2 bbl is that you really only have one set of jets you an change to adjust the mixture. There is an additional circuit in the power valve that can be used to add fuel when under boost by making it open only while under boost (boost actually pushes it open instead of vacuum holding it closed until vacuum drops below a certain point). The problem is, the PV doesn't have the capacity to go 10 jet sizes (for example). Say the motor needs a 68 jet to run right while under cruise. Runs clean there, and makes for a nice easy driver. But when 12 psi of boost hits, now it needs a 80 jet to be rich enough to keep from melting pistons and detonating since you are pushing close to twice the air into the cylinders. But the PV only gives you the equivalent of a 75 and now you are pulling the head to replace the headgasket that popped, and finding cracked and melted pistons. Or, you run the motor with a 73 jet and the PV brings in the rest under boost, but it's horrible to drive because the kids in the backseat keep throwing up from the fumes and you get 50 miles to a tank of gas. NOTE! Jet numbers are complete made up, FYI.

With a 4bbl, you can tune the primaries for the nice lean cruise you need for a driver, and use the secondaries to bring in the fuel needed when the motor goes from 225 CID to 400 CID. There isn't a way to do that with a 2bbl (that I am aware of).

Besides that, doesn't a 500 cfm 2bbl on a slant make for a doggy unresponsive motor when not in boost? I'd bet it makes for a great race carb where you don't care so much how it runs on the way to the staging lanes or on the return lane, but on the road it just doesn't fit my definition of an UDD.
 
DionR said:
How long did she live here?
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She moved to Spokane as a teenager in the late '60s (she's 62 now) and lived there until about 1988 when she moved to Seattle. We got married in 1996 and I was living in Hayward, CA at the time. We lived there (Hayward) until I retired in 2004 and moved back to Arkansas, where I grew up (Little Rock area.)

Been in Conway since 2004.
 
DionR said:
That doesn't work with a carb. With EFI, you can raise the fuel pressure to make the injectors squirt more fuel and make up for the greater amount of air being forced into the cylinders (to a point), but it's not quite the same as actually tuning the system for boost. With a carb, you have to do something similar, but it's only because the boost makes it into the fuel bowl and your fuel pressure will actually go down equal to the boost you are running which will starve the carb for fuel. So, you "boost reference" the fuel pump so that for every pound of boost the motor sees, the fuel pump puts out an addition pound of pressure and the carb sees the same pressure it is used to. But adding extra fuel pressure to a carb doesn't do much to add fuel to the mixture under vacuum (at least not until you start pumping gas out the vent tubes), and does absolutely nothing to richen the mixture under boost.

The issue with a 2 bbl is that you really only have one set of jets you an change to adjust the mixture. There is an additional circuit in the power valve that can be used to add fuel when under boost by making it open only while under boost (boost actually pushes it open instead of vacuum holding it closed until vacuum drops below a certain point). The problem is, the PV doesn't have the capacity to go 10 jet sizes (for example). Say the motor needs a 68 jet to run right while under cruise. Runs clean there, and makes for a nice easy driver. But when 12 psi of boost hits, now it needs a 80 jet to be rich enough to keep from melting pistons and detonating since you are pushing close to twice the air into the cylinders. But the PV only gives you the equivalent of a 75 and now you are pulling the head to replace the headgasket that popped, and finding cracked and melted pistons. Or, you run the motor with a 73 jet and the PV brings in the rest under boost, but it's horrible to drive because the kids in the backseat keep throwing up from the fumes and you get 50 miles to a tank of gas. NOTE! Jet numbers are complete made up, FYI.

With a 4bbl, you can tune the primaries for the nice lean cruise you need for a driver, and use the secondaries to bring in the fuel needed when the motor goes from 225 CID to 400 CID. There isn't a way to do that with a 2bbl (that I am aware of).

Besides that, doesn't a 500 cfm 2bbl on a slant make for a doggy unresponsive motor when not in boost? I'd bet it makes for a great race carb where you don't care so much how it runs on the way to the staging lanes or on the return lane, but on the road it just doesn't fit my definition of an UDD.
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I thought you can open up the passages and the "restrictor" so the PV can flow even more.
 
Bill Dedman said:
She moved to Spokane as a teenager in the late '60s (she's 62 now) and lived there until about 1988 when she moved to Seattle. We got married in 1996 and I was living in Hayward, CA at the time. We lived there (Hayward) until I retired in 2004 and moved back to Arkansas, where I grew up (Little Rock area.)

Been in Conway since 2004.
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I've been here since like '77, graduated HS in '87. What did she do here?
 
805moparkid said:
I thought you can open up the passages and the "restrictor" so the PV can flow even more.
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I don't believe there is enough capacity in the PV circuit to make up for it.

Here is a post I made on SS.org back in '06 where I said I was going to run a 2bbl on my project. Maybe the PV is an option, don't know, but I don't think so.

I'm not saying I know for certain, I was asking the question because I wondered if someone had made it work.
 
DionR said:
I'm not saying I know for certain, I was asking the question because I wondered if someone had made it work.
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Pishta did a turbo slant with a 350 or 500 2bbl. I've never gotten too many details on how it ran or anything. Should get him to jump in here. He did the line to the fuel pump weep hole.
 
DionR said:
I don't believe there is enough capacity in the PV circuit to make up for it.

Here is a post I made on SS.org back in '06 where I said I was going to run a 2bbl on my project. Maybe the PV is an option, don't know, but I don't think so.

I'm not saying I know for certain, I was asking the question because I wondered if someone had made it work.
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That's a really important point... deserves researching, for sure.

You go lean, even for an instant, and you'll have a long time to think about it...:sad3:
 
75slant6 said:
Pishta did a turbo slant with a 350 or 500 2bbl. I've never gotten too many details on how it ran or anything. Should get him to jump in here. He did the line to the fuel pump weep hole.
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That would be very helpful!!! Hope he sees this...
 
Better get Pishta in a hurry, he is working on EFI/Electronic advance. Once that is done, one often forgets about carbs and mechanical advance. :)
 
KitCarlson said:
Better get Pishta in a hurry, he is working on EFI/Electronic advance. Once that is done, one often forgets about carbs and mechanical advance. :)
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when i get a chunk of cash i'll be going mega squirt/XFI with cop

someday
 
805moparkid said:
i said for the swinger, not the 68. and im still on the fence whether i'll go that way. i may try and build a "modern" engine out of a slant lol, ought to be interesting.
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Most modern engines are turbocharged... was that a hint??:cheers:
 
I made it here. I read Dion's post and there are 2 points that I want to throw my .02 in on. PVCR's are huge in blow through turbos. PVCR's are worth 7 jets stock. Drill them out 1.5X and now they are worth 10+ jets. Hanger18.com mod is to drill them out .071, looks about 3X what they were. When the power valve spring overcomes the vacuum that keeps it SHUT, thats alot more raw fuel into the intake. Also the boost referenced pump is to keep fuel in the bowl as well as keep it going into the intake. When you run a carb that is sealed (as in a paxton style box or sealed up under a bonnet) the 9 psi over ambiant air pressure tends to want to push the fuel out of any passage that it can:, the boosters (although they are neutral at this point as 9psi is all around them), or even the fuel inlet. If the stock pump is still putting out a lazy 4-5 psi and is trying to fill a 9psi environment, things get ugly. Simple: run a T off the waste gate feed to the weep hole on the pump. now you pump is pushing against a spring and compressed air, more pressure to the inlet.
My car did run and pretty good. But the fact that I didnt have a proper A/F gauge to monitor the mixture steered me toward EFI in a hurry. It put out some noticeable rich smoke on boost, safe but nasty. The EMS Im working with a few guys on has narrow/wideband outputs and basically keeps the mix between 12 and 15 automatically, as do most EFI systems. It was just a change in direction of the build, sort of a right turn when I found these guys. Oh, did I mention the bare PC board is only $15 bucks? And the firmware is FREE??? Stay tuned......
 
pishta said:
I made it here. I read Dion's post and there are 2 points that I want to throw my .02 in on. PVCR's are huge in blow through turbos. PVCR's are worth 7 jets stock. Drill them out 1.5X and now they are worth 10+ jets. Hanger18.com mod is to drill them out .071, looks about 3X what they were. When the power valve spring overcomes the vacuum that keeps it SHUT, thats alot more raw fuel into the intake. Also the boost referenced pump is to keep fuel in the bowl as well as keep it going into the intake. When you run a carb that is sealed (as in a paxton style box or sealed up under a bonnet) the 9 psi over ambiant air pressure tends to want to push the fuel out of any passage that it can:, the boosters (although they are neutral at this point as 9psi is all around them), or even the fuel inlet. If the stock pump is still putting out a lazy 4-5 psi and is trying to fill a 9psi environment, things get ugly. Simple: run a T off the waste gate feed to the weep hole on the pump. now you pump is pushing against a spring and compressed air, more pressure to the inlet.
My car did run and pretty good. But the fact that I didnt have a proper A/F gauge to monitor the mixture steered me toward EFI in a hurry. It put out some noticeable rich smoke on boost, safe but nasty. The EMS Im working with a few guys on has narrow/wideband outputs and basically keeps the mix between 12 and 15 automatically, as do most EFI systems. It was just a change in direction of the build, sort of a right turn when I found these guys. Oh, did I mention the bare PC board is only $15 bucks? And the firmware is FREE??? Stay tuned......
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Thanks for the good info!!! Can you tell me whether a sealed carb enclosure will affect the mixture/signals in the manner that would negate the need for blow-thru modifications to a carb in a forced induction system, or doesn't it work that way? I am wondering whether a normally-aspirated carb could handle boost with no modifications, if it were in an enclosed box...

Probably not, huh????

Thanks for any info...
 
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