Inliners International Forums General Discussion Engines 76 & 79 Chevy 250 performance Q's

Hi all,

You guys always have great advice and I'm in need of some now.
A friend recently wrecked his 76 chevy truck and gave it to me for hauling it away.
The motor (a 250)recently had a complete rebuild...aprox 20,000 mi. ago.
I used to have a few chevy I6's in some 60's trucks I had years ago and I always really liked them.
I would like to put the motor in a 71 chevy 1/2 ton to use as my everyday driver in the summer. I will occasionally be hauling a load, I do light handyman/construction work, or pulling a trailer/boat, nothing over a ton.
After looking up the engine specs.I was thinking of upgrading the intake/exhaust manifolds and maybe sliding in an RV type cam to improve the HP and torque without sacrificing gas milage.
However, as you already know, it has an integrated head,(never heard of such a thing before)so I guess my options are limited.
I have another friend who has a 79 chevy junker that he will trade me for a little work. I originally thought it was a 292 and it was my understanding that they don't have integrated heads, but alas, it's a 250.
When I looked up the specs on that motor I see that the ratings for the 79's show 20 more HP and 30 more ft/lbs torque and new to the 79 is a 2 bbl carb.
Now here's where I need the advice:
Did they remold the head in 79 to improve flow and/or accept the 2 bbl?
Is that the only improvement to account for the extra power?
Is the cam improved also?
Can I put the 79 head on my 76 and expect the power increase?
Can I put in a new cam also and further improve power? and what cam would you reccomend?
Or would I be better off with the already rebuilt 76 and maybe a new cam?
Can I put the 2bbl on the 76?
Are there any other easy upgrades you could recomend to improve power/milage?

Any advice is greatly apreciated.
Thank you

Welcome aboard Biff. First since you are putting the engine in a 71 truck, I don't think we have to worry about meeting emission control standards, but if you have any kind of state inspection you might want to verify that. From 1964 on all motors were built for some emission control and that did limit their performance to some extent. The integrated head is not thought of to highly by most folks. I've read comments that it is prone to cracking and I've read one source that said it was a reasonable head and to run it. The integrated head will limit what you will be able to do with the motor, since the intake manifold and exhaust manifold are cast as part of the head. The 292 also used the integrated head. You can verify whether it is a 292 by measuring the height of the side covers if they are 6" high it's a 292. The good news is that you can put an earlier head on the without much problem.

The two barrel could account for the power difference, there may have been other changes as well. You should be able to get another 20hp with your motor fairly easy with out going to the integrated head.

If it was up to me I'd verfiy that the 79 is not a 292, get a casting number or check the side covers as I mentioned. If it is not a 292 stay with the 76. Look at having the HEI on the 76 recurved to 1963 advance curves. Put an RV cam in it. Can you get the two barrel from the 79 for not much. Find an Offy four barrel manifold with a small four barrel or the 79 2bbl. Another option would be Tom Langdons (Stovebolt Engineering) Holly/Webber with an adapter. Oh and headers.

Larry

Thanks Larry,

I think you misunderstood though. The 76 has an integrated head already, I was hoping to get a regular head so I could change intake/exhaust, but was trying to do it on the cheap.
The 79 is definately a 250, integrated head
If I have to buy another head, intake, exhaust, cam, carb, I could find a (sorry I don't wan't to use the V-word on this forum) cheaper. Although I have wanted another I6 for some time. It takes me back to my teenage years and they aren't making any more.
Since I don't have access to a non-integrated head that's cheap/free, I thought I would make due with what I have.
Will the 79 2bbl carb bolt right on to my 76 1bbl manifold?
What would you recommend for a cam?
What did you mean by recurving the distributor, just setting it to 63 specs, or actually doing modifications to it?
Also, I live in Alaska, we have plenty of fresh air up here, so emission controls aren't required. Is there any that I could remove to improve power/milage?

Thanks again for any help.

My fault I didn't think they were using the integrated head that early. I haven't worked with an engine that had all the smog on it, haven't read of many that have. I would think the 2bbl head should bolt on, check to see if the head gaskets are the same.

I used a J.C. Whitney RV cam in my 292 and I'm happy with it. The cam was ground by Elgin didn't come with a cam card, did come with lifters. I haven't been able to fully tune the 292 yet because of a compression problem, too much.

Recurve the HEI by changing vac advance, springs, and weights. IF you look at the curves for the six cylinder HEIs they all have less vac adv and the advance comes in later. There is also less advance on the later distributors. If you do a search on the web there are articles on how to do it.

Larry

The integrated head came on 75's and newer. Trucks i think came in a little later 78/79????

I think the 1 bbl. integrated head was a hit and miss between 1975 and 1978. I had a '78 C10 that had a bolt-on intake head. It was in a light-duty emissions truck. Came with converter, but got lost after the warranty ran out. I have seen some '75 - '78s that had either setup, at least the trucks. Possibly they used whatever engine was available to throw at a 1/2 ton since all the heavy-duty (non-catalyst) 250s were non-integrated.

The conclusion I've come to is that they started using the integrated head in 75, but also still used the non-integrateds until 79. there dosn't seem to be any real pattern for which models used which head. Have never heard of a non-integrated head from 80 on.
Now that I own an I6, I've been talking to everyone I can and they're everywhere.
My friend, who was going to give me the 79 head also has a 73 1/2 ton with a rebuilt 3-speed manual trans., that he would give me for helping haul it away. I asked him what motor it used to have in it and he says it's still got the 250 I6 in it, needs rebuilt though.
Think I'll pull all three 79, 73, and 76. All 250s with 3 on the tree.
Also my neihbor across the road has a 64 1/2 ton with a 292, 4 speed. Think he would give it to me for a 6-pack of beer. Been sitting there for 15 years, so no hurry on that one. If he knew I wanted it he'd probably make me haul it acsross the road.
Also realized all the inlines I already own:
68 mercury outboard 125hp I6
79 mercury outboard 50hp I4
89 suzuki GSXR 1100 (150hp) I4
80 case 580 backhoe I4 deisel
Looks like I'm an Inline man now.
I have a few other rides that need motors, 62 Impala, 64 Jeep truck, now I'm thinking about 6s.
I've had a lot of fun reading posts and talking to people about I6s, the last few months.
Had kinda lost my interest in cars lately (about 10 years), but now I'm all excited again. Best part is, now the wife will let me do whatever it takes to just get them moving.
She used to complain when I worked on cars all night, now all I hear is "why don't you go out and get that piece of **** running?" so I guess she's as excited as me.


Thanks for the help everyone.
Biff