76 292 intake/exhaust recommendations

[cerial]

I picked up a 76 c30 last night with a 292. The thing has what sounds like a exhaust leak and it seems like the linkage or something on the carb is off.

It runs great does not bog down, surge, or anything. It idles great right after you start it. But after I get up to 2k or so then drop the rpm down to where idle should be the thing keeps dropping and the truck dies. Turn the key and it fires right up. Get it back up and drive to the next light or just put it in neutral, it drops down and dies.
I will play with it this weekend. It had me avoiding stopping as much as possible during the 45 mile trip to the folks place.

The thing has all stock parts on it and I would like to add a little bit of performance in the way of a intake/headers. It has been a while since I have had a engine without secondaries and would not mind a 4 barrel 300-500 carb.

The good thing about the 76 is that the valves are good for today's junk fuel. But, it seems something changed in the intake as most sites go etc-1975. I need to retain the ablity to start this thing in temps from -20 to 90F without babysitting it and the intake/heat riser/exhaust all come into play in that.

Any recommendations on intake/carb/exhaust?

What is the reason I can't run the "earlier"(before 76) aftermarket intakes?

[Oregoon]

The reason you're finding intakes and headers for '74 and earlier is that '75 and up used an integrated head where the intake is part of the casting, whereas the earlier motors have removable intake and exhaust manifolds. Also, most of '74 engines I've seen had factory unleaded-valves. Of course, given that we're talking about trucks that are around 40-years old, it's not uncommon to find that it's already had a head-job at some point... As for your 292, I've seen both integrated and non-integrated heads on them, and there's a lot of conflicting information about which years did and didn't use them on the 292. Regardless, the availability of interchangable heads and the time-frame make the point moot.

The integrated heads are known for cracking, and are often swapped out for the earlier 230/250/292 head, which are interchangeable. In fact, I think it's only the 194 head that features a smaller combustion chamber, though it too will bolt right up and is a popular way to raise compression.

As for recommendations, Clifford Performance offers a water-heated intake that takes either a 4 or 2 bbl, with a matching header. A bit spendy, but worth it if you live in a cold place.

As to the way your truck is running, it sounds like a clogged idle-circuit or a problem with your float. Does it behave like it's starving for fuel?

I chased a similar problem on my 250 and it wound up being as simple as a partially clogged fuel filter not allowing the float to fill back up after I'd ran it wide-open. It started fine, ran well, but would die as it came back down to idle. I played with float-settings, blew out the passages, fiddled with timing, and scratched my head... Then, I put a new fuel filter on it and laughed at myself!

Hope this helps. Good luck and congrats on your new truck!

[cerial]

The linkage at the front of the carb is loose. I plan on doing all the maintenance things this weekend. The truck has 80k of documented miles. The grandpa sold the truck to his kid and they were in the process of replacing every moving part when he got sick. I did not know them. But it makes a good reason to mmake a driver out of this.

[greg64]

Guys, to my knowledge, no 292 came with the integrated head. That was a 250 thing. Of course, since the heads can be swapped back and forth, it's easily possible that an integrated head wound up on a 292. For intake manifolds, the choice is typically between the Clifford and the Offy (I'm talking the 4 bbl version). The going wisdom is that the Clifford makes more top end horsepower with its bigger runners, but the Offy makes more torque. I have the Offy. For exhaust, I used stovebolt's cast iron headers. They really improved the breathing, and are so tough they'll last forever on a daily driver (a plus for me). You can get proper headers, but I don't want to deal with the rust/leaks fit up problems. If you're going 4 bbl carb, the Holley 390 is thought to be the best.

[Oregoon]

Originally Posted by greg64

Guys, to my knowledge, no 292 came with the integrated head. That was a 250 thing. Of course, since the heads can be swapped back and forth, it's easily possible that an integrated head wound up on a 292. For intake manifolds, the choice is typically between the Clifford and the Offy (I'm talking the 4 bbl version). The going wisdom is that the Clifford makes more top end horsepower with its bigger runners, but the Offy makes more torque. I have the Offy. For exhaust, I used stovebolt's cast iron headers. They really improved the breathing, and are so tough they'll last forever on a daily driver (a plus for me). You can get proper headers, but I don't want to deal with the rust/leaks fit up problems. If you're going 4 bbl carb, the Holley 390 is thought to be the best.

I second what Greg writes. The 390 cfm is generally accepted as the best daily-driver carb for the aftermarket manifolds, though the Weber 38 is reputed to be a real ripper. I'd guess a small 4bbl would be easier to find, though. Dual or triple carb set-ups are cool and look really neat, but are finicky, especially in cold weather. Those linkages...

As to the 292 headss: I've read about (online, whatever that's worth) and heard of factory 292-integral, and have also been told they were an after-the-fact swap, either dealer-done or shop-done, or shade-tree. There's some part-numbers in the aftermarket that cross over, but that could be a typo. I have seen a few those heads on a 292 and each time, we scrapped it and replaced it with a non-integral set-up.

Keep us posted and let's see a few pics of your truck!

[cerial]

Checked it out some more this afternoon and it does have the removable intake.

Turns out the monojet is missing multiple parts that control tucking the choke plate down. I moved it manually and the truck ran great 600-3000 ish.
offenhauser and stovebolt sound like a great combination. I have had webers before and they are cool. But, they are the 2.8 where as the holley is the 350 parts wise. I will have and dig through my carb pile I think I have a few 4 jets in there that I could jet down. The 390 is high on the list if I can not find anything laying around.

[greg64]

One of these days, I'll have to take the plunge into Weber carbs. They have a really good reputation, but I'm not first hand familiar with them at all (and have no parts for them just laying around).

If you go with the Offy intake, (*), get this to heat the underside of the manifold with coolant (assuming some sort of aftermarket exhaust):
http://www.langdonsstovebolt.com/sto...fold/p/1222036

* - that reminds me, don't get conned on eBay with these so-called "NOS Offy intakes". Maybe they are, but the 4 bbl manifold (and others) are still manufactured new.

If you're going to work the truck, and not just show it, I think the stovebolt cast iron headers can't be beat.

[cerial]

Headers are in the mail. Ordering the intake and 390 tomorrow. Is the linkage that comes with the intake junk or is there something better out there?
I have seen a few cable setups in various pictures.

In the meantime I bolted a 87 1 barrel on with great results.

[Oregoon]

As I recall, my buddy fiddled with the linkage for a few days before getting it where he liked it. There were several trips to the store for odds and ends (return springs, cable housing, beer) but as I recall, the stuff he got was decent and worked well. I think he used a bunch of Summit crud too, so you'd be hard pressed to do worse than he did.

[cerial]

That's great thanks

[cerial]

I am having trouble finding new keepers. The curved part that holds down the intake and exhaust.
Anyone have a idea or should I start looking for NOS.

[greg64]

No idea where to find new. What I did is cut off chunks of small channel, either 3/4 or 1" wide and drilled a 3/8 hole through the web. The two flanges push down on the manifolds. I also used studs in the head, because it makes assembly easier.

[cerial]

I picked up a 2.5" x pipe with a few extentions a while back.
For the heck of it I tossed it under the truck and found that the X fits almost perfectly under the clutch linkage arm and aligns great with the rearmost header.
I am not going for classic sound. I am good at whisper quiet exhaust using 4 mufflers.
But I wonder if placing the x basically next to the bellhousing is going to kill my low end. I think being that close to the header there will still be enough heat to keep the charge hot. I am not putting the x in for performance. I am putting it in to avoid the popping.
I will get a picture for a better understanding tomorrow.

[Oregoon]

You could try these guys:

Old Car Parts
7525 SE Powell Blvd
Portland OR 97206
(503) 771-9416

They are walking distance from my house, and all they do is old GM.

The place is unreal... They have everything.

If they won't ship, I'll pick the keepers up for you.