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#64577 05/04/11 11:39 AM
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I purchased a freshly rebuilt 292 from Leo Santucci a while ago. It is basically stock with a mild Reed cam in it. It is going in a 79 Chevy Bonanza truck that currently has an intergral head 250 with a TH350 (the trans is staying as is). I have purchased a water heated Clifford manifold and headers.
I want to put a 4 barrel on it that will give me reasonable fuel mileage and reasonable performance. I am more interested in reliability and fuel mileage than performance. The truck is just a weekend driver that I sometimes use to pull my Moto Guzzi sidecar rig on a small trailer on long trips.
From what I have researched it looks like a new box stock Holley 390 would be a good choice. I was just wondering if I could get some feedback from members here on this choice or other choices. I actually prefer fuel injection systems like the FAST system but the cost is out of reach at this time.
Also, I am pulling the 250 out this summer. It is high mileage but in running condition now, with new lifters recently put in. It also has a hand made valve cover on it to replace that ridiculous reed valve cover with the two towers that intergrals had. It came out pretty good and works well. I am giving it away free to the first person who comes to get it out of my garage. So if you are looking for one keep me in mind. I live in Hackettstown, NJ, 07840.

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The Holley List# 8007 390 is the correct one. Once installed, take some time setting up your HEI for proper timing curves and then follow that up with some carb tuning and you will get the best mileage. Tom


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Just curious,
what is the best mileage anyone has seen w/a carbed 292 car or truck, not some lightweight ratrod or simular?

Thanks

MBHD


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I'm curious also!


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I used a 390 out-of-the-box with only an increase in pump shooter size, from - i think - #25 to #37. But I think you will be hard pressed to match the fuel economy of the stock one barrel.

Who cares? Drive it, enjoy it and have some fun.


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I know it is O/T but I'd like to see pictures of your M/G sidecar hack. Thanks.


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Almost O/T - Do the 250 engine side mounts work on the 292 (I know you have to reposition the frame mount)? On earlier trucks the frame side steel was different, but IIRC on the 73-87 the parts are the same, just need to be shifted to the correct location. Wondering because I'm looking to d a swap similar to yours if I find the 292 at the right price.

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I am looking for an answer to this question about MPG as Well, My 65 Chevelle has a bit of a run down 250 in it, and I seem to be getting about 16 mpg highway miles at 50 MPH. I have a stock internal 250 with offenhauser 4 intake,with a Holley economaster 2 barrel, I think they're 350 cfm. Hei,Powerglide car, with 3.08s weighs 2900. What am I doin wrong? 16 Mph I coulda kept the 8.

So 16 MPG is My number anybody else wanna put up theirs?

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I am with Tom on this..Stock HEI's timing curves suck..!!


Jerry Davis II#4711



ol Smokey said "one test is worth a thousand expert opinions."
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Send an email address to sodell@rutgers.edu and I'll send you some pictures.

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You need to advance your timing while in cruise.
Install an MSD 6A box & also use the MSD adjustable timing knob to advance the timing while cruiseing.
The poweglide IMO is not as good on mileage as a TH350, I would swap out that trans, for better mileage & FOR SURE better accelleration.
You would need a short tailshaft TH350 & it's a direct swap.

You could have kept the V-8, but you will not get the looks or the people asking you about your ride.

If the engine is a bit run down, your mileage will suffer also,what camshaft are you running?


MBHD


 Originally Posted By: Overbiter
I am looking for an answer to this question about MPG as Well, My 65 Chevelle has a bit of a run down 250 in it, and I seem to be getting about 16 mpg highway miles at 50 MPH. I have a stock internal 250 with offenhauser 4 intake,with a Holley economaster 2 barrel, I think they're 350 cfm. Hei,Powerglide car, with 3.08s weighs 2900. What am I doin wrong? 16 Mph I coulda kept the 8.

So 16 MPG is My number anybody else wanna put up theirs?


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 Originally Posted By: Overbiter
I am looking for an answer to this question about MPG as Well, My 65 Chevelle has a bit of a run down 250 in it, and I seem to be getting about 16 mpg highway miles at 50 MPH. I have a stock internal 250 with offenhauser 4 intake,with a Holley economaster 2 barrel, I think they're 350 cfm. Hei,Powerglide car, with 3.08s weighs 2900. What am I doin wrong? 16 Mph I coulda kept the 8.

So 16 MPG is My number anybody else wanna put up theirs?


16? I wish I got 16. I am lucky to see 12 rolling downhill with that worn out integral 250. I shouldn't complain too much though. It does have 310,000 miles on it (rebuilt once about 180,000 ago).

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That is the general consensus I see, the 390 with proper timing setup. Though I do not know how to adjust the timing curves or to what spec. I will figure it out as I go and being new to this site I am sure I will be bothering people with a lot more questions. So thanks to everyone in advance for any advice they can give me.

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 Originally Posted By: SCRAPIRON, #4711
I am with Tom on this..Stock HEI's timing curves suck..!!


How do you figure out what the right ones are and how are they changed?

D13 #64606 05/06/11 01:15 PM
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 Originally Posted By: D13
Almost O/T - Do the 250 engine side mounts work on the 292 (I know you have to reposition the frame mount)? On earlier trucks the frame side steel was different, but IIRC on the 73-87 the parts are the same, just need to be shifted to the correct location. Wondering because I'm looking to d a swap similar to yours if I find the 292 at the right price.


From what I see the left side is OK but the right side moves. But the frame rails on my 79 truck will handle that it looks like. If anything maybe drill some new mounting holes in the frame rail.

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I run a stock cam, I'm gunna buy another engine soon and the SPA turbo manifold swap the cam a and few other parts and all will be good again.

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 Originally Posted By: sodell
I purchased a freshly rebuilt 292 from Leo Santucci a while ago. It is basically stock with a mild Reed cam in it. It is going in a 79 Chevy Bonanza truck that currently has an intergral head 250 with a TH350 (the trans is staying as is). I have purchased a water heated Clifford manifold and headers.
I want to put a 4 barrel on it that will give me reasonable fuel mileage and reasonable performance. I am more interested in reliability and fuel mileage than performance. The truck is just a weekend driver that I sometimes use to pull my Moto Guzzi sidecar rig on a small trailer on long trips.
From what I have researched it looks like a new box stock Holley 390 would be a good choice. I was just wondering if I could get some feedback from members here on this choice or other choices. I actually prefer fuel injection systems like the FAST system but the cost is out of reach at this time.
Also, I am pulling the 250 out this summer. It is high mileage but in running condition now, with new lifters recently put in. It also has a hand made valve cover on it to replace that ridiculous reed valve cover with the two towers that intergrals had. It came out pretty good and works well. I am giving it away free to the first person who comes to get it out of my garage. So if you are looking for one keep me in mind. I live in Hackettstown, NJ, 07840.


Is the trans a TH350C (lockup converter)? If not find a lockup version - direct bolt in and you will save about 5-10% on the highway. All you need to control it is the lockup switch kit that TCI and others offer. Runs off the ported vac port on the carb.


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Let me get out my soap box.

Get rid of that 3.08, it is good for nothing behind a six, you will spend too much time on the power stage of ANY carb trying to go up any incline or pull any load (even a bed full of ping pong balls).

The PowerGlide only suffers from a too tall low gear ( its a rugged tranny, rugged with beefier planataries than the Torque flites), and with out a lockup torque converter its no different than a turbohydreamatic in the final 1:00 to 1:00 drive ratio. Now a turbo 350- will scat fron the light better due to the difference of a 1.82 vs. a 2.56 low range ratio, the 4-speed autos really shine with their 3.06 or 3.08 lows, but with a 3.08 rear gear you are doomed in the o/d position.

It will take a 400+ engine to be "happy" with a 3.oh my aching back 8 rear gear.

I would try removing out one of the stock dist. centrifical weight springs and run only run one of the weakest springs you can find (keeping an ear open for pinging) to try to put a little snap back in the buggy-- I'm afraid the 3.08 wont let to go that far. But you can alway start back by getting a little heavier spring and maybe go back a pair of weak ones--Set the static timing at 10 degrees at idle with the vacumm can connected to MANIFOLD VACUMM anywhere below the throttle butterfly. This hot timing setup may force you to burn a better grade of gas, but it sure will feel better. Its nearly free cost wise (springs- not rear gear change-but not all the Chevy twices suffered with the Salisbury design rear ends), and the results may pleasantly surprise you.

As long as your high milage motors are firing on all holes your milage will not suffer as greatly as some may lead you to believe- I fell that your milage will begin really to go south when you start running on less than all cylinders rather than six weak ones. Perhaps with six crippled cylinders you may see a max of 10 to 15% reduction in mpg. But MPG is one of the most incorrectly and inaccurately measured factors seen. Most of the errors are thinking the amount of gasoline placed in the tank is actuaaly the amount consumed at that filling. If you trust that thinking, them the challange is to run another tank through it an compute that--and then keep a running total going - the more tankfuls, the less quanity of fuel errors. We all have had the neighbor with the (one tank check) 24 mpg lincoln with the 462 motor! And keep a close eye out fot those pumping losses.;

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 Originally Posted By: efi-diy
 Originally Posted By: sodell
I purchased a freshly rebuilt 292 from Leo Santucci a while ago. It is basically stock with a mild Reed cam in it. It is going in a 79 Chevy Bonanza truck that currently has an intergral head 250 with a TH350 (the trans is staying as is). I have purchased a water heated Clifford manifold and headers.
I want to put a 4 barrel on it that will give me reasonable fuel mileage and reasonable performance. I am more interested in reliability and fuel mileage than performance. The truck is just a weekend driver that I sometimes use to pull my Moto Guzzi sidecar rig on a small trailer on long trips.
From what I have researched it looks like a new box stock Holley 390 would be a good choice. I was just wondering if I could get some feedback from members here on this choice or other choices. I actually prefer fuel injection systems like the FAST system but the cost is out of reach at this time.
Also, I am pulling the 250 out this summer. It is high mileage but in running condition now, with new lifters recently put in. It also has a hand made valve cover on it to replace that ridiculous reed valve cover with the two towers that intergrals had. It came out pretty good and works well. I am giving it away free to the first person who comes to get it out of my garage. So if you are looking for one keep me in mind. I live in Hackettstown, NJ, 07840.


Is the trans a TH350C (lockup converter)? If not find a lockup version - direct bolt in and you will save about 5-10% on the highway. All you need to control it is the lockup switch kit that TCI and others offer. Runs off the ported vac port on the carb.


I don't know but I will look into it, thanks for the tip.

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Just look for a square (well kind of square) electrical connector behind the shifter shaft...

lockup


connector

Last edited by efi-diy; 05/09/11 11:33 PM.

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 Originally Posted By: Overbiter
I am looking for an answer to this question about MPG as Well, My 65 Chevelle has a bit of a run down 250 in it, and I seem to be getting about 16 mpg highway miles at 50 MPH. I have a stock internal 250 with offenhauser 4 intake,with a Holley economaster 2 barrel, I think they're 350 cfm. Hei,Powerglide car, with 3.08s weighs 2900. What am I doin wrong? 16 Mph I coulda kept the 8.

So 16 MPG is My number anybody else wanna put up theirs?


The 3.08 rear gears are great for the freeway & mileage, do not change them.
Your Chevelle is pretty light.
You can improve mileage plus better acceleration if you change the rear gears & a 200R4 trans.
Depending on what tire size you use, I would suggest 3.42 -3.73 range rear gears w/an OD trans.
Also the PG glide not only suffers from a tall first gear it also suffers from the large gear gap from first to second causing your vacuum to drop more between gear changes while keeping the pedal in the same position. (Puts more load on your engine)

My moms stock 73 4 dr Nova had a PG & 3.08 rear gears, 26 " tall tires.. It ran fine day to day driving, great on the freeway.
Normally it would get 16, until I started working on it & advance the timing, then it whould get 18 - 19 tops MPG, all stock were talking here,w/90,000 + mileage.
It got a best of 19 MPG on the freeway, but that was above the speed limit speeds.
I estimated the Nova weighed 3400-3600 lbs.
A TH350 would have been better for it & a 200R4 would have been better though the first 3 gears, OD, with 3.08 is too much for just cruising @ 65,OD would have been use when going 85 + MPH

MBHD


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Putting up with a 3.08 rear gear is about the dumbest thing I can think of to do to a poor ol' six cylinder. About the only thing dumber is to use a 2.78 or even a lower numerically ratio.

I know that it is a major task to pull the entire rear axle just to change a ring and pinion, not to mention the expertise needed to accurately set up the gears for quiet operation- I cant help that. If finances cause you to be stuck with a far too low numerical rear gear ratio, then so be it. My only solution is to search the junk yards/ swap meets. Tom Lowe sets up 12 bolts I hear, maybe even 3.55 ratios!

On this forum I have continually read of people running much larger than stock camshafts, bigger than stock intakes with larger carbs that cause much losses of torque/ horsepower at the lower rpm ranges, actually advocate the very same tall ratios that keep the poor ol' motor mired down in those low powerless rpm ranges where it could not peel off the skin of a grape. Maybe a solution would be a granny low 3/4 ton truck tranny, but you cant shift them very fast, have big ratio spreads and are VERY HEAVY. The lack of power/torque at these lower rpm ranges demand the carbs to be tipping into the carb power circuits to produce enough ummmph to keep the vehicle propelled on level ground, possibly never getting enough airflow signal through the venturi to even abandon the idle circuit's usage.

What possible fun could it be to drive a vehicle with that kind of bottom end? You practically need to open the door, stick your foot out and give it some help to leave the intersection.

You gotta get to 30 mph before you can get up to 70 mph (which with 27" tires and 3.08 gears is 1150 rpm at 30 mph and 2684 rpm at 70 mph) Lots of single bbl model b rochesters when on the fast idle cams of their chokes can see 1100 rpms at "idle".

292s with 194 intakes (markedly smaller intake passages) and 194 carbs running 6.17 rear gears have unbelievable botton end torque, but are at the extreme other end of the spectrum. You would be probably ready to go into final drive wether PowerGlide or the highly taunted 200r4 with their ULTRA CLOSE gear ratios just getting through the intersection.

I have heard from school bus folks, dump truck owners, and others that run 'em that the 292s are a bit thirstier than the 230/250s. The fact that the stock 292 carbs are jetted richer for their tasks in life than their lighter loaded passenger brethren-this may be part of the problem.

Low numerical rear gears puts more load on your engine too.

later, gators


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 Originally Posted By: edski
Putting up with a 3.08 rear gear is about the dumbest thing I can think of to do to a poor ol' six cylinder. About the only thing dumber is to use a 2.78 or even a lower numerically ratio.

I know that it is a major task to pull the entire rear axle just to change a ring and pinion, not to mention the expertise needed to accurately set up the gears for quiet operation- I cant help that. If finances cause you to be stuck with a far too low numerical rear gear ratio, then so be it. My only solution is to search the junk yards/ swap meets. Tom Lowe sets up 12 bolts I hear, maybe even 3.55 ratios!

On this forum I have continually read of people running much larger than stock camshafts, bigger than stock intakes with larger carbs that cause much losses of torque/ horsepower at the lower rpm ranges, actually advocate the very same tall ratios that keep the poor ol' motor mired down in those low powerless rpm ranges where it could not peel off the skin of a grape. Maybe a solution would be a granny low 3/4 ton truck tranny, but you cant shift them very fast, have big ratio spreads and are VERY HEAVY. The lack of power/torque at these lower rpm ranges demand the carbs to be tipping into the carb power circuits to produce enough ummmph to keep the vehicle propelled on level ground, possibly never getting enough airflow signal through the venturi to even abandon the idle circuit's usage.

What possible fun could it be to drive a vehicle with that kind of bottom end? You practically need to open the door, stick your foot out and give it some help to leave the intersection.

You gotta get to 30 mph before you can get up to 70 mph (which with 27" tires and 3.08 gears is 1150 rpm at 30 mph and 2684 rpm at 70 mph) Lots of single bbl model b rochesters when on the fast idle cams of their chokes can see 1100 rpms at "idle".

292s with 194 intakes (markedly smaller intake passages) and 194 carbs running 6.17 rear gears have unbelievable botton end torque, but are at the extreme other end of the spectrum. You would be probably ready to go into final drive wether PowerGlide or the highly taunted 200r4 with their ULTRA CLOSE gear ratios just getting through the intersection.

I have heard from school bus folks, dump truck owners, and others that run 'em that the 292s are a bit thirstier than the 230/250s. The fact that the stock 292 carbs are jetted richer for their tasks in life than their lighter loaded passenger brethren-this may be part of the problem.

Low numerical rear gears puts more load on your engine too.

later, gators



My truck has 30" Michelin's on it and will stay that way.

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 Originally Posted By: tlowe #1716
The Holley List# 8007 390 is the correct one. Once installed, take some time setting up your HEI for proper timing curves and then follow that up with some carb tuning and you will get the best mileage. Tom


I believe this is the path I will follow. Thanks for the advice.

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your rpm numbers will be even lower than the above examples...and will stay that way

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ULTRA CLOSE gear ratios?
200-4R:
2.78:1
1.57 (56% recovered)
1.00 (64% recovered)
.67 (67% recovered)

Muncie M20 std. ratio:
2.52:1
1.88 (75% recovered)
1.46 (78% recovered)
1.00 (68% recovered)

Muncie M21 close ratio:
2.20:1
1.64 (75% recovered)
1.28 (78% recovered)
1.00 (78% recovered)

Really close ratio?
Harley-Davidson "M" ratio:
1.99:1
1.44 (72% recovered)
1.04 (76% recovered)
1.00 (96% recovered)

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I have read on this bulletin board several times, several places, that the 200r4 has closer ratios than the 700r4/4l60e trannys and how much better the grand national boys like them because their r's dont drop so badly and what a difference that closer ratio really makes at the drags. All those people and myself cannot be wrong?

Shame on you for trying to confuse the discussion with the facts!

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sodell,

30" tall tires changes things a bit. 3.55's would do pretty good for the rear, since you are staying w/your trans.
Your fresh 292 will have a lot more torque than your worn 250 did.
Not sure on your rear gear ratio is, I am guessing it is 3.08's?

My previous post was for overbiter.

The 200R4 is not a close ratio trans, it just has better gear spacing/closer than a 700R4/4l60E/4l65E


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Hmmm thanks hank something to consider, I was planning on change my trans at some point-even considering a manual gearbox, I have an old 3 speed from something or other, I hadn't really even considered changing rear gears, I'm not really looking for low drag numbers just a little easier on the wallet-for now,I am thinking of using a 200c My cousin has laying around, it has no OD but it does have the extra gear and the lock up. That trans should be more than fine for my meager power.


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