Inliners International Forums General Discussion Engines What is your "favorite recipe" for a 250?

Ok so this is Ken from Oakland again. You all were so helpful last week in helping figure out my 250 block casting ID # (turn out it was originally a Beaumont/Chevelle from Canada...) that i thouught I'd ask a few of you "old timer" Inliners for your suggestions. Like many, I come from the 350 Chevy world so this will be my first inline 6 rebuild and I know you guys are a wealth of knowledge so here goes.

Here is the deal: I have a 63 Nova with a tired 194. I have a doner 250 that needs rebuilding. My goal here is to drive the 63 Nova most everyday 25 miles each way to and from work for a year and see if it is possible to use that car as a true daily driver. I want to build a "driver with muscle" essentially. My question is: WHAT is you guys' "favorite recipe" for a 250 based engine with that dual use of BOTH commuting and fun? Specifically, what cam,head, header, manifold, and carb would you suggest to achieve that marriage of daily drivability, decent gas mileage, and a bit of fun when you romp on it? I want to spend $ where I will truly see a difference and not waste $ buying silly shiny stuff cause if I wanted to keep doing that, I would just keep building 350's, right? So, if a stock part works just fine, please say so. Thanks in advance for you suggestions. I figure i will save a lot of time going out to you guys cause many of you could recite off the top of your heads what you would do. Thanks in advance for your perspectives. Pics and a performance review of this motor will follow!

Oh yeah: that info would help....
So far, to keep costs down, I would keep the stock 63 transaxle and it has a 3 on the tree, which I really like so a manual transmission. The low seems a bit too low as it is but third gear seems pretty good as is freeway cruising. That said, if you have a suggestion for a different gear on either end of the equation for the transmission, please let me know....

I reasoned the 250 wiould be plenty of power for the little shoebox Nova and it was just given to me. 25 miles EACH WAY, so 50 miles per day and 80% at 65-70mph. Urban Bay Area driving.

Budget? What's that? I would like to spend 2-3K if possible and it am aiming at that "tipping point" between longevity/durability/decent mileage(20-ish??) and FUN when I want. Now what do you think, Mr Panic guy???

I may have a different view on this than most of the guys on this board. If you want a good daily driver I would basically do a stock rebuild on the 250, maybe .030 over, but have a good balance job done. Put on a good harmonic damper (Fluidamper seems to be a good brand, keep the stock manifold and 1 barrel(but rebuild it and add a manual choke), get a set of Tom Langdon's cast headers, a floor shift, and drive it! Don't forget a good distributor! Keep the stock trans and rear gear, especially if it's a 3.55 or 3.70. I actually drove an older version of this for about 6 years. I had a '40 Chevy coupe I rebuilt a 235 for. It was .060 over with Jahns pop-up pistons, the mildest McGurk cam, Fenton cast iron headers, and a Mallory dual-point distributor. This was in 1973 - I started out with 3 -1's on an Offy manifold, but once the gas crunch hit I went back to one 1 on the stock manifold and switched the gears from 4.11's to 3.55 (it was a '56 Chevy rear). It was blast to drive!

Hey Vstock,
Thanks much for the reply! Though opinions may vary on the board here and my idea here is to gain a variety of opinions from which to settle on a final build, I DO understand the wisdom of a mildly warmed over 250 (maybe +.30) and good attention to the final balance. I run a stock single barrel Rochester on my 72 Chevelle and all I did was have the machine shop polish the heads and runners etc. basically just pay attention to the fit and finish of the internals during the build and it made for a fun, reliable, economical car. It took me YEARS to realize I was over carbing my cars with 650+ two barrel carbs for around town use and was just running rich and wasting gas. Anyway, thanks for your point of view, I share some of your POV. Anyone else have a "recipe" to share please and thank you?

First off,a 292 will be bad on gas,more hassle to install etc etc etc,,besides,, you already have a 250.

Install cast 307 .030 SBC flat top pistons w/4 valve reliefs,& I do mean flat tops, no chamfer,no dish,other than the valve reliefs.

Offy intake,w/a 4 bbl carb, or 2 bbl depends on how much power you want.

Zero deck the block,yes,just do it :-) It will payoff,w/no detonation.

Camshaft .480-.500 lift , duration @ .050- 210-220 or there abouts w/a 112 lobe center. With a OD trans you can get up to 25 MPG

My combo where I got 21 MPG was a hyd cam ,specs of .520 lift 230 degress duration 10.5 to 1 compression,5 speed manual.90 OD IIRC,Carter AFB 400 CFM 4 BBL.headers,& 2.5" single exhaust.410 gears,in a 3400 LB Camaro,no driver.Ran low 14's @ 3000ft altitude track.

Landon cast iron headers http://www.stoveboltengineco.com/acartpro/
split 2" exhaust or "Y" pipe into single 2.1/4" - 2.1/2" Depends on what sound you like.

I would also install Larrys lumps AKA Twisted6
http://cgi.ebay.com/ebaymotors/194-230-2...sQ5fAccessories
If you are not going to rev it past 5000 RPM,a stock damper is OK,not the best but,if you don't race it or rev it much,it will work.

There is more things but that should keep you busy.

MBHD

MBHD,

That's some very good specs. I'm going to leech off this post, and take some notes down for that.

KJY, I'm in the same boat you are, so, just soaking it all up.

Good luck!

-Sam.

Sam, me too! Sam

GOOD JOB, MBHD!!
Looks like I am not the only one trying to settle on the "perfect recipe" for a 250 as I am in good company with "The Sams' now on this forum. This will hopefully benefit us all, guys. Bottom line is I really want to tap into the considerable experience of guys like MBHD, since they have had to learn by trial and error so those of us who come along later (the newbies...) don't have to wander around quite some much in the dark with a proverbial lantern.

Based on what I have learned here, I am planning on decking the block, offy or Clifford intake with a 2 barrel, flat top pistons, fresh stock head with Larry's Lumps, cam per MBHD suggestion. THAT should do it! Thanks everyone, this has been fun. I will get some pics up within the next months as the project comes to realization and as I figure out what I have to sell to do this project. We ALL know how that goes...

If anyone else out there in the "old timers" club has any other opinions, or even "tweeks" to MBHD's recipe, please chime in. I really do appreciate your time and perspective here. Cheers!

KY

OKay here comes my 2 cents. MBHD has it right KY. I also live in the Bay Area and have a 65 Nova and a 250 inliner sitting and waiting to go into it. I found a nice Offy manifold on ePay, bought a heat plate from Langdons and then a new Holley 390cfm four barrel carb. I am still waiting on Tom Lowe and others supply me some tech tips on that carbs and proper mods. Once I get a few bills paid down I will get Lump ported headwork done on my 194 (good casting) head. Don't throw away your 194 head if you would like a little higher compression.
Mike B aka MrHotRod6 sold me a cool Stinger HEI that will work in conjunction with a MSD SS Blaster coil.
I plan to add some Langdon's headers and shop for a good cam set. I have no desire to go above 5500rpm as my Nova will be on the street. But i want it to roar right off the line.
I also plan to rebuild a Muncie M-20 four speed (I traded an old V8 shortblock for it) and I run 3:08 gears out the back for cruising.
When we both get them running we can compare notes.

James

Wow, this site is a wealth of great information. I'm about to buy a nice running 250 and drop it in my truck. Out my old tired 250 is coming and this is getting me hyped up to do my first ever build. I'm hoping to get some "streetable" power as you are, and learning a lot along the way. Thanks for all the information guys, maybe I'll become a contributing member one day as well!

Important: if you're going to run the 3.08 with a Muncie, you definitely want the 2.52:1 (wide ratio) box, not the 2.20:1.
If you don't already have a 4 speed, the Saginaw has some excellent ratio choices as well.
In addition, this isn't where you want a lighter flywheel.

Definately do not use the close ratio Muncie 4 spd,it's good for road racing,circle track stuff.

It will be lousy for a quick take off & 308 gears,I had a close ratio Muncie w/4.10's & even then it was horrible.

I later installed a wide ratio 2.52:1 M21 & was much better.


MBHD

I thought the M-20 was a Wide Ratio? Complete with the "Granny Gear" and great for a good launch with 3:08s back there.

So called Granny first gear trannys are those heavy cast iron units,(forgot the name) can't speed shift those & when in first gear,you can basically let the clutch out w/out giving any throttle to move your vehicle,they came in trucks.

Basically, you never use first gear on those trannnys unless you are carrying a heavy load or are trying to pull out a tree stump ;-)

I thought M20's were close ratio trannys?. It's been a while since I played w/those transmissions.

IIRC the M21 came in close or wide ratios.


MBHD

My first choice would be the Chrysler A833 4-speed with the wide-ratio gearset as used in the Slant 6 and 273. 1st gear is 3.09:1, works excellent with tall axles, it even has enough torque multiplication to use an aluminum flywheel and still keep the clutch alive.
Leaving out the tire diameter, the torque to the wheel is simply 1st gear × axle, and if you don't have at least 9 you'll never get your foot off the clutch.
With a 2.20 you need at least a 4.09 axle, 2.52 needs 3.57, etc. but 3.09 with 3.08 axle has stronger take-off power with 9.52 total.

I run a 250 with 307 flat tops.block cut .018 head cut.013. comp cams 260 H cam and kit plus their rockers push rods and gear set. I don't have lumps in my street engine but I have the bosses cut to a knife edge and some bowl work with stainless proflow valves and hardened exhaust seats. I built my own intake and am currently running a quadrajet on it(had an Edelbrock and it ran rich most of the time increased power and mileage with the Qjet. I run a med duty exhaust manifold with the 2 1/2" three bolt flange. It is installed in a 41 Plymouth 2 dr sedan and I got 20+ mpg towing my roadster on a trailer going to convention last summer with the air conditioner on. I also run a built 700r4 and a 9" ford rear with 3.50 gears and 215 75 15 radials (27" tall). It tows my roadster like it isn't even back there. I also run a complete MSD ign including distributor, blaster coil, 6A box, and wires.

Ok I know some folks are going to shake their heads...

Before spend $$$ you may want to look at this thread..

http://inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=48429&Main=6462#Post48429

It'll run rings around even a hot 250 and get 25+mpg with bone stock reliability.. just not for everyone.

efi-diy,

What trans do you have to run w/the 4.2,, 4l65E,4L60E ?
Also what trans controller can you use?
Cost?

MBHD

MBHD

4L60E For a stock 4200 its more than plenty. Before the turbo went on it got a severe upgrade. So now its more like a 4L70E.

Originally I was shifting the trans manually using 2 toggle switches. Before the snow hit in Dec. I started beta testing the megasquirt transmission controller. It ought to be available by May. No set price yet but it'll be at LOT less than the commercial units. Wild ass guess under $250.

Didn't mean to hijack the thread.

Recipe for cost effective 250....
1. 2barrel Rochester BC carb, (orginal 305 cid V8 carb) with adapter, or change manifold to Langdon/Clifford.
2. HEI ignition.
3. split manifold/headers/cast manifold
4. 2" -2.5" double exhaust
5. Turbo it!

GODDAM, this has been more FUN than a barrel full of monkeys!
I was out of the country on business last week and stopped checking in on this thread for over a week and am amazed at the "riches" I came back to...

THANKS ever so to efi-diy,Big Bill, MBHD,Panic, James at Freds Garage and Leaded from Norway for all the sage advice. Or at least, identifying the great diversity of options from which I may choose. I am still digesting the advice, but I am leaning towards doing pretty much with Big Bill suggests with 307 flat
top pistons, cut the case and heads, 260 Comp cam with matching push rods, Landon cast iron headers (maybe Larrys Lumps as a "poor mans" solution to the lump port advantage?),a good fluiddamper, some sort of HEI ignition, Offy or Clifford intake with a modest 2 barrel Rochester or equivalent, and a 2 or 2.5" collector. I like the "turbo it"! commeent from our esteemed colleague Leaded from Norway and I have seen the pics of his engine so I know he speaks from experience. Ok, socks first, then shoes.... I will get the engine apart and cleaned, checked out, then I will start on and purchase the build specs. I will bounce back to the group with pics as the saga (or debaucle...) goes on,... and on... and on... Remember: "budget??? what's that?" Ok thanks to all of you and you have been a wealth of information and advice. Hope my first inline 6 does not blow sky high! Either way, this will be fun and instructive for us all, yes?

Cheers, mates and thanks again!

efi-diy,

Just a few questions. What are the bore and stroke for a 4200, what kind of manual trans will hook up to it, and how long is it relative to a 250?

Zeke

Bore 3.660"
Stroke 4.02"

Length is very close to the 250, it fits into the same hole where I had the 292 installed. Its wider than a 250/292.

Manual trans .. bolt in - 5 spd out of a colorado pu. Others can be used - be it needs an adapter plate as the 4200 has an oddball bell housing pattern. I'm working with CNC dude to make an adapter plate - just waiting for CNC Mill time.

Yes, but... it's almost 3 feet tall.

Its shorter than a 292... once you move the sump to the rear where it needs to be for most installs.