The Stovebolt Site Forums The Shop Area Engine Shop Need help building an inline 6 for my daily driver

Yes I need help and suggestions again. I'm wanting to do some 'mild' customization and 'freshing up' on my 72 LWB. Since it's my daily driver I figured I'd start with the drive train on her. My goal is to have an older truck that is 'reasonable' on gas, fun to drive and does well on the interstate. I don't do red light racing or plan to drag but hate not being able to keep up with traffic going uphill on the interstate. She currently is being pushed around town by an inline 6 (250) and I love having an inline in her. I have a spare 250 (from my son's Nova he's dropping a V8 in her) that I was thinking about doing some work on and then swapping into the 72 when I ran across a 292 after many months of hunting.

So my 1st question is which block to begin with 250 or 292?

Regardless of which block I build I figure I'll have to have some head work done. Is it necessary for me to get 'lump ports' or is that something for those building high performance racing inlines?

I don't plan on breaking either block down completely and replacing rods/pistons/etc. However I do want a bit more agressive cam. What are your thoughts on this one:

Grind Number: 252-56H
Intake Duration (gross): 252
Exhaust Duration (gross): 256
Intake Duration (.050”): 194
Exhaust Duration (.050”): 204
Intake Valve Lift*: .460"
Exhaust Valve Lift*: .470"
Lobe Separation: 112
Intake Valve Lash: .000"
Exhaust Valve Lash: .000"
RPM Range: 1000-4000

The 250 I have currently has an HEI ignition so if I build the 292 can that one be used?
For exhaust which would best suit my needs: full length headers or the cast iron ones that Langdon sells?
For intake which should I go with: Offy 4bbl with Holley 450 or Offy double bbl (on the 250) or triple bbl (one the 292) with the below carbs from Langdon?

"These progressive two (2) barrell carburetors are New, not rebuilt, with electric choke (sold in pairs only). These carbs were orginally used on a very small (97 cu.in.) engine and are not recommended for single carb usage, but are an excellent choice for dual carb setups. Note, order one (1) to get two carburetors." (really leaning towards these carbs on the 292 as my math says 97 x 3 = 291 cu in. Almost perfect carberation for a 292)

For the trans I'm thinking the famous "Frankenstein T-5 (Camero with S10 tailshaft).

I apologize for the many questions but what seems like a good set-up to me on paper may not be a good set-up in practical application. So just wanted to get some opinions before I start buying parts.

Where are you in TN? Any particular concerns?
Jerry

Use the 292, but do not try to get by with a half-donkeyed buildup. Go ahead with a full overhaul. The cam sounds good, slightly above stock, but not so radical as to be a pain on the street. There's no need for radical cylinder head modifications- - - -the 292 has all the torque you'll ever need without getting crazy with modifications.

A single (small) 4-barrel is a better choice than any multi-carb setup unless you're a masochist who likes tinkering with carburetors more than spending your time driving. RUN- - -do not walk away fronm the 3-carb setup! If you just gotta have dual exhausts, use the cast iron headers. My personal choice would be the big-pipe single exhaust from a 292 in a medium-duty truck. Splitting the tailpipe behind the muffler will make the majority of people think you've got dual exhausts, and the performance on the street will be exactly the same as the header/twin muffler/dual pipe setup for a LOT less cost. Most of that junk is eye candy to impress the people who don't know any better.

Your HEI ignition should be a drop-in swap into the 292. Be sure to run a heavy-gauge wire all the way from the ignition switch to the distributor, about a #10 size. The 72 truck will have a nickel/chrome resistance wire supplying the coil, which drops the voltage down to about 9V during normal running. No good for HEI!
Jerry

Start hunting for the right motor mount bracket. A 292 used a different bracket on the frame and a 250 one will not work. I agree with Jerry on the cam, it should be a good choice with single 350 or 400 cfm four barrel. Three carbs are cool, and you might get them to work, but it won't be easy. I am not sure how they rate the cfm on them, but in normal driving, you would only be running on half of each carb. They are a two barrel design using the second barrel for full throttle operation.

No need for head work other then cleaning out the casting flashing and getting a decent valve job. I don't think I would even bother with oversized exhaust valves. The intake to exhaust air flow ratio is pretty good to start with, no need to go messing with it.

If you know the history of the engine and feel confident in it, then just clean it and go. But if there is any doubt, pull it apart for a proper cleaning and inspection. You can re-ring one if the bores check OK and reuse the original pistons. If it needs bored, add propane pistons for a easy compression increase.


I have run a pretty stock 250 at the local drag strip with single exhaust then backed it up with headers, with both running through a 2 1/2" single exhaust system and both times with in the same week under the same weather conditions. All the time slips were identical, the header made no different at the stock rpm (4700 shift rpm) I was running the engine. The original exhaust would have been 2" or smaller, so my 2 1/2" wasn't the choking it at all. Stick with original 2.5" opening 292 truck manifold with a single in, dual out muffler with 2" or 2 1/4" tail pipes. You need to keep the pipe small so the heat can keep it dried out.

HEI is a excellent distributor, no modifications needed to it. 12 to 14 gauge wire, bypassing the resistor wire, straight off the key switch. You do need IGN 1 & IGN 2 tied together at the key switch so the distributor gets full voltage at start and run.

Have fun, Joe.

I'm in Lebanon, TN Jerry.

Thanks for the advice. Since the engine is suppose to still be in the truck I think I'll do my best to score the 292 motor mounts also (after all he shouldn't need them anymore lol).

I didn't realize that dualing the exhaust out really didn't help for a 'mild' build but glad that you all shared that infomation. That just made the build a bit cheaper and cut the exhaust portion down by at least half.

I think I'll also go with the single 4bbl carb as that seems to be the best option for a DD vehicle.

J'aimi

I used to hang out in Lebanon pretty often- - - -went to high school in Mt. Juliet back in the early 1960's when it was full of corn-fed farm boys, not Nashville expatriates! I rode in the Patriot Guard escort to the Lebanon town square on Veterans' day for the man who makes the walk from Legislative Plaza every year. Drop me a PM- - -I might have some bits and pieces you'll need for your project.
Jerry

I know the guy that organizes that march. He use to be in the unit here in Lebanon.

Well went and checked out the 292 last night. It starts and runs. Didn't smoke and sounds good other than noisy lifters. According to the owner the engine has 84,000 miles, which is great for an inline. I'm getting the engine (alternator, starter, manifolds, carb), motor mounts, 4 speed trans and drive shaft for $350.

Now I need to pull the head off the spare 250 and drop it off to be machined. Hopefully I can find a good shop thats not too expensive.
J'aimi

Headworks of Nashville. They're just south of the Briley Parkway/Gallatin Road intersection in Inglewood. I've been doing business with Glen for 30-something years, and he knows his stuff. He graduated from my father's auto mechanics course at McGavock High School back in the late 1970's, and opened up the head shop a few years later. I ran the same school shop for a little over 20 years.
Jerry

I've got the head off my 250 to have it worked to go on the 292. Are there any particular specs/concerns I need to be prepared to discuss with the machine shop when I take them in?