rebuild details

officially began rebuild. transmission will be done in about 2 weeks. engine reboring and rebuild is scheduled to begin in about a month. my goal is to have it going down the road by next spring. since it has not run in about 10 years, besides some body work and details, what all should I plan on rebuilding and/or replacing. if I am going to all the trouble of new engine and trans, should I just plan on starting new with all other items? I am thinking about: water pump, starter/solonoid, carburetor, alternator, coil, fuel pump, etc. what am I missing? also, a fuel tank that is now 50 years old and has been sitting for the past 10 years....... thanks for your input in advance.

What engine?  if its a six, the only new ethanol resistant one barrel carb on the market is the Daytona, around $300, but works fantastic, I bought one and IMHO well worth it!  BTW, They are made from old Holley molds.  If you are going to the expense and trouble of rebuilding the block, I'd certainly go for all the add on's too like an HEI distributor (eliminates coil) and modern 1-wire alternator and certainly a new ethanol proof pump plus treat the tank, be careful with it, they are very hard to find, refurb your old one at any cost....then you can move on to the suspension, drive train and brakes? Steering gear? King pins, etc...

yes it's a 230 6-cyl, I think I heard it would be bored out 40. I have decided to stay mostly stock, but when you mentioned a 1 barrel carb it did raise the question of: are there some medest upgrades I can do which would enhance the performance? i'm not looking to hot-rod my van, or to pimp my ride.........just looking for ideasre: reasonable upgrades without major alteration of originality of the van.

that was supposed to be 'modest', not 'medest'.

If you are going to redo the trans than by all means do the rear differential also I'm interested in how much it will cost you to have the trans done cause I'm going to do the same on my 67. When I have my engine done I will be putting an RV type cam in it to give me good low end performance. You don't have to go .040 in the calendars just go enough to make the holes round again, could be as little as .010.Good Luck

so when you say I don't have to do a boring of 40, might only need 10, is there any drawback to more (I was thinking the advantage might be a little more oomph when i'm going up mountain passes)? is it an engine integrity issue? is it a cost issue (from removing more block metal costs more, to possibly bigger rings, etc. cost more)? if there is no advantage to boring more, i'd probably opt for a minimalist approach). thanks.

Not worth the money to just bore the cylinders bigger. If you want more power recam the motor and put a bigger carb on it.

Build a stroker, you can do this for cheap, and its well worth it:  The 230 and 250 engine used the exact same block, they share the same bore size.  If rebuilding, find a 250 crank, which is 3.530" stroke (compared to the 230's 3.250").  It is a direct bolt in.  Use 250 pistons, or 307 pistons, since the 307 had the same stroke and bore as the 250.  You will gain 20 more cubic inches, all in stroke, which equals 20+ more ft-lbs = 10% more of low-end torque & power.  No reason not to do this.  You have the buy new pistons and machine the crank anyways, so why not add more cubes? Do not spend a dime on the 230 crank. Toss it in the trash and look for a 250 crank to use as the base for your rebuild.  Factory compression was usually a lame-o 8:1. If you want to increase compression ratio to get closer to 9 or 9.5:1 for better performance, you can order 307 chevy pistons to get off-the-shelf available flat-tops.  These are the same as the 250 pistons, but just don't have the dish the 250 pistons usually do.  Use the stock 230 rods, which are the same as in all the various inline sixes... just have your machinist check them and re-size if necessary.  Have the entire rotating assembly (including the flywheel and balancer) balanced for best performance.

Casting numbers when looking for cranks:

250 Crank #'s: 3876802, 3876804, 3855914, 3876840, 460407, 480407, 9790154


I would rebuild the carb you have.  Works fine.  I rebuilt mine myself.  Its easy.  A rebuild kit is about $35. You can't get any simpler than an old 1bbl downdraft carb to rebuild, and you'll take pride knowing you build it yourself.  It will take you about an hour in your shop.  My buddy William just rebuilt his in his living room during the commercials while watching monday night football, and it runs good!
Some people really go overboard on all this worry about ethanol in the gas, and needing to replace it with something that is marketed to be "ethanol resistant".  Thats the silliest thing I ever heard.  A new carb rebuild kit is going to have quality gaskets, accelerator pump diaphragm, and everything else you need, and I'm sure its designed for modern fuels.  We've had ethanol in gas for how long now? At least a decade.  I'm sure the gaskets in the carb rebuild kits are all designed for that now.  I rebuilt my rochestor monojet with a Napa Echlin rebuild kit back in 2008 and it still runs great.  I've been running it on 10% ethanol gas for years, because thats what we have around here and no problem.  One good tip is use locktite on screws when reassembling the carb, so they don't loosen up over time and cause your carb to leak.

The 'daytona' carb Vantasia is talking about is a holley #1920, which was originally used on slant six engines and other smaller 4 and 6 cylinder engines.  Nothing special about that. The holley 1920 was never used as a stock carb on factory GM products, so you will have to use adapters on both the throttle linkage and the air cleaner tower.  The holley 1920 it is smaller and flows even less than the stock GM carbs: Carter YF, or Rochestor B, or monojet, and these stock offerings are already flow challenged to feed a 250 engine what it needs at higher revs. Your air cleaner will need an adapter to choke it down to the 1920's smaller bore size.  If you really want a holley 1926, I have one on my shelf that came off a chrysler slant six, you can have it for $50.

In my opinion, the best 1bbl carb for a six is an early pre-smog Monojet with the 1&1/2 venturies, which is rated at 250cfm.  Still not a whole lot of flow once you get into higher RPM's.

For high performance, there are dual carb and triple carb manifolds made by offenhauser.  One of these setups will be better to help feed high performance builds at higher RPM's.   To figure your engine's CFM requirement, use this handy calculator:

 http://www.summitracing.com/expertadviceandnews/calcsandtools/cfm-calculator

There are tricks on the head too, you can add larger valves, and do the 'lump port' mod, and do porting too, with a larger cam to increase upper RPM power.  It is said the lump port mod will help increase power and torque at low RPM's too.  seems like a really good idea.

this sounds like a great idea, kooky.....great and in-depth info. many thanks. one question, since the carb requirement CFM would be a little anemic at higher RPM's.....if I didn't go the entire 9 yards to dual carbs, etc., could I squeeze a little bit more out of the single carb just by changing the size of the nozzle, changing the mixture, just tinkering with the equation of the mix? I will go to dual carb if I have to, but hope to keep it as simple as possible. thanks

since no takers on that last question, I am posting it again. see above, and thank you.

You can change the carb jets for a little more power but not much. You can only get so much air/fuel mixture with a single bore carb/intake. There are dual, triple, and 4 barrel intakes to be had. Then you can cam, bore, and stroke, your engine, but it all costs money. You want more power!!! Look for a chevy 292. They are all over the place. I found one out of a 1969 Chevy C20. I was lucky and stole it for $175. I found another 292 in a 1969 Chevy C60 dumptruck. The only difference between the blocks is that the 292 is a little taller due to the taller deck height. And the right motor mount is about 2" forward so the mount would need to be modified.

Best bet would be to keep it original.  Do the rebuild with a semi-mild cam. You will have torque with reasonable gas mileage. Install the Offenhauser 2 carb manifold and you should have all the power you need. I did some research on 3 carb and quad carb setups. Great for drag racing but you will get under 10MPG.

softesttouch wrote:this sounds like a great idea, kooky.....great and in-depth info. many thanks.  one question, since the carb requirement CFM would be a little anemic at higher RPM's.....if I didn't go the entire 9 yards to dual carbs, etc., could I squeeze a little bit more out of the single carb just by changing the size of the nozzle, changing the mixture, just tinkering with the equation of the mix?  I will go to dual carb if I have to, but hope to keep it as simple as possible. thanks

The actual CFM of air a given carburetor will flow is a function of the size of the throttle bore, and the size of the venturi.  

Jet changes will effect performance... but have nothing to do with the CFM rating of the carb. This is simply an expression the amount of air that is able to move through the carburetor at a given calibrated pressure.

The maximum CFM rating of a given carburetor is only a factory when the engine is operating at the maximum RPM.  At lower RPM's, you engine is going to be pulling less air.  A smaller carb will not adversely affect low or mid range operation, or 95% of normal street driving, as long as its properly tuned.  

A too-small carb is a potential limiting factor on top-end max RPM power.  If this is a factor for you, then consider a dual or triple carb setup.  

I disagree with GMman about a triple and 4 barrel carb giving poor fuel economy.

You set up an offenhauser 3x1 carb with progressive linkage, so the center carb is the primary, and the outer carbs are the secondaries, so they open only when you put your foot in it.  At normal part throttle cruise, the engine is just running on the center carb only, providing good fuel economy with the outer carbs staying closed.

Same with a 4 barrel.  No reason you would necessarily get crappy fuel economy.  You could run a quadrajet or a 390cfm holley.  Both would be good performers, and both would probably net good fuel economy and drivability on the street with the small primaries.

Not to thread jump;
Hey Kooky...did you do anything camshaft wise,other than stock,to increase performance? Any suggestions?

What Kooky is saying is right,(no disrespect Kooky). You can get good fuel economy with 3 or 4 barrels, But- once you open up those extra barrels your fuel economy will drop. You have to decide on how much power you want. A 2 carb manifold with the second carb throttle set up as secondary would work out pretty good. If you are going for an other than stock cam, Call Summit Racing's Tec department or a cam shaft company like Crower Cams, and their Tec Specialists should tell you what the right combination of carb and cam would be, depending on your power/economy preference.

I have used Crower mainly - since 1965-never had a cam or lifter go bad!! Also engle & old isky too. Even today - I will not buy any new cam from the newer cam mfg's -mainy due to so many mass producing the parts!! Sales , Sales & more sales- not -Quality & controll of the parts. There are sever small cam grinders out there also- will grind what u want too & just be sure the cams get ="PROPERLY HEAT TREATED"- non- roller lifter cams?? NEVER run any =Without a Quality Zinc Addative!! Add it to the oils -even if the oil u r using says= it has the zinc addative in it!!!!!!!!!!!! Best insurance u can buy for that cam & engine!

GMman wrote:What Kooky is saying is right,(no disrespect Kooky). You can get good fuel economy with 3 or 4 barrels, But- once you open up those extra barrels your fuel economy will drop. You have to decide on how much power you want. A 2 carb manifold with the second carb throttle set up as  secondary would work out pretty good. If you are going for an other than stock cam, Call Summit Racing's Tec department or a cam shaft company like Crower Cams, and their Tec Specialists should tell you what the right combination of carb and cam would be, depending on your power/economy preference.

Oh, yes, halfway decent fuel economy is only going to happen if you are running just on the primaries while driving slow and easy like grandma. If you have your foot in it, and the secondaries are open, then yeah, its gonna suck some gas. But if you're foots down, you want to get up and go, and you're probably not concerned about saving gas at that moment.

Here is a good book on the Chevy Inline 6 power build.

I paid 27.99 for mine. Lots of info.