Inliners International Forums General Discussion Engines New member intro with an HEI question...

Hello fellow inliners! My name is Bob, I'm a member of Los Boulevardos car club and a life long Chevy 6 nut (thanks Dad!). My main project is a '62 Buick LeSabre mild custom. But the reason I signed up here is because of my "new" daily, a '75 GMC half ton short bed. The truck has a good running 250 (uni-head) with a 3 on the tree. I just picked up a 292 that I will be rebuilding with a 5 speed to back it up. But until the 292 is ready, I want to squeeze all the performance and efficiency out of the uni-head that I can. Here's my question: the GMC came with an early style HEI (with the coil mounted to the side covers) and the 292 came with the later style HEI. Is one better than the other? Thanks for any info or opinions that you guys can provide and thanks for having me

As far as I know inside both are the same. You can switch from one style to the other by changing caps. I like the separate coil style better. Welcome to Inliners I hope you will join the club as well as the board. Beater

bob_o

Not to deter you, but have you considered installing a vortec 4200 out of a trailblazer? Stock out of the box they make 275 or 290Hp year dependent. All the parts are available except motor mounts(which you would have to deal with on the 292 anyway).

I know from personal usage that the 4200 willl almost double the gas milage of a well built 292 and have another 75hp to boot.

M

All OEM HEI distributors are smog distributor, as such their advance curves were limited. The amount that they were limited got progressively worse. The 75 being one of the first HEIs would have better advance than the later coil in cap HEI. The advance curve kits for the v8 Hei will work in the l6.

Larry

THANKS LARRY I NEEDED THAT INFO....
REGARDS
BOB

Beater, Larry, thanks for the info. That's what I needed to hear.

M, though I'd love to have one, a Vortec 6 is WAY out of my budget. I picked up the 292 (complete) at a local pick-a-part's 50% off sale for $155. I figure I can get this thing rebuilt the way I want over the course of the next several months for less than a grand. Plus, I've always wanted one

M, I was just reading in the "4200" thread that your 292 only made about 10mpg? What mods did you do? Or was it stock? The reason I'm asking is because I plan on driving this truck daily and that mileage just won't cut it. I'll be happy if I can get into the high teens on the highway. And as tempting at the 4200 sounds, I sold my newer car and bought this truck because I was tired of computers controlling my engine and transmission (among other reasons). All of that over-complicated stuff simply does not hold my interest. Is there a way to delete all the electronic stuff on the 4200 and run it in a more "old school" way? Carburetor instead of efi, etc? Also, is the bellhousing pattern on the 4200 the same as used on the 194-292 sixes and sbc/bbc? Thanks.

Just curious as to what carb you were running on the 292?
What intake manifold also.
Got any pics of that old 292 combo?
Was it ever fuel injected?
What were the camshaft specs? Compression, etc...
I do not remember seeing your complete build on your 292 you had.
Maybe I overlooked it?
Thanks

I think Tlowes Elky get upper teens in mileage w/his 292?


MBHD

Hi all ! .

I just replaced the points Dizzy in my '69 C/10's 250 with one from a '75 Nova 250 (God bless Pick-A-Part !) , the one with the separate coil , it's an [i][/i]AMAZING[u][/u] improvement ! once you open up the spark plug gaps , good by miss & skips from oil going past those wobbly old valve guides .

Even when cold , no more fouled spark plugs .

Power to spare , if I'm heavy on the throttle , the 350TH will chirp the tires shifting into 2nd gear .

I bought a 292 to overhaul and install , now I'm re thinking my old 250 as this is a daily drive Shop Truck for an old man (me) in L.A. traffic , I need fuel economy more than low end grunt .

Did you put in a advance kit in it?

A lot of inline dizzys in the junk yards I have pulled, the mechanical advance mechanisum would not move, meaning, it would not get any mechanical advance if I did not take it apart & clean it all up.


MBHD

Bob,

Well it is possible to convert it to carb/dist. it would involve a lot of custom one off fabrication. You would have to build an intake from scratch. Jerry W. has a conversion to install a distributor onto a 4200.

The bell housing is unique to the 4200.

Transgo makes a vacumm modulator kit for the 4L60E - I used one before I got my transmission controller working. They work well to control the line pressure.
It is possible to use relays to control the shift pattern - this is only manual shifting though. A vac. switch like GM used on the TH350C can be used to control the t/c clutch.

So yes it is possible, but you most likely would lose mileage.

The way I look at it is a daily driver is something you put gas in and change the oil etc. when needed. Leave the hood closed and don't mess with it. With this in mind once all the crap is turned off in the PCM engine box it does a good job of running the engine.

If you look around a complete 4200 can be had for $800-900. If you can get a good 4L60E trans out of a full size truck/Astro Van/S10 - change the bell housing or get one out of a 2wd colorado and bolt it in. Call it $300 for the trans.
Jeremy can do the PCM changes - he has a dedicated thread here.

My suggestion - make the motor mounts, get the PCM done and bolt it in - change the oil and drive it.

By the time you fix the 292, your at equal $$ to doing the 4200. Even if it cost $400 more to do the 4200 - you'll make that up in mileage.




My 292 was well built

8.5 cr (for turbo)
lump + ported head + 1.96/1.6 valve
turbo cam >> ask Tom L. for the spec's
forged pistons
offy intake
headers
holley 600 vac. carb
HEI with a curve


This engine was sold to Tom Lowe and this short block was the one he tortured on the dyno for all his testing - made over 500 pulls on it.

Around town 11-12 MPG, highway 14 mpg best and the plugs were whitish/tan after coming off the highway. This was in front of a 700R4 with 3.50 gears in the 9" and a 27" tall tire.

Once I put the stock 4200 in with a 4l60E no other changes mileage jumped to 27 MPG highway.

Edit... I did TBI the 292 - just running it in the shop - never drove it. This was done a day before I hauled it out to start the 4200 swap. For the $$$ I spent on the 292 build I could have bought a fresh 4200 crate motor from GM.