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Joined: Dec 2010
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Hey guys.

I am going to be putting together a 292 for a 1964 chevy van. The van is a hot-rod, but also a daily driver. I will never drag race it, but will be having fun on the street with it. This includes burn-outs and impromptu traffic light competition. I sometimes haul heavy gear with it, but never tow. It currently has a 230 that is getting tired. The transmission is a ultra-wide ratio T10 column shifted 4 speed with 3.44:1 first gear and 2.56 rear axle gears for the freeway. It is effectively a 'poor man's overdrive'. Another way to think of my drivetrain is it is very similar to having a saginaw 3 speed 3.73 geared, with an 4th gear OD.

I plan to run a offenhauser 3x1 intake with three rochestor monojet carbs. The linkage will be progressive so the center carb is primary, and outer carbs acting as the secondaries. I will remove the choke on the outer carbs.

I have two questions I want to put out for discussion.

Exhaust: I have three options: Tubular full length headers, tubular 3/4 length headers or a custom 292 split manifold made by Kraig Sexton (splitz manifolds). I originally felt the manifold would be good to retain the exhaust heat under the manifold, but with the tight doghouse of the '64 chevy van, maybe the radiant heat from the headers would be enough to provide manifold heat. It gets quite hot in the doghouse, on that side of the engine.
How important is it to directly heat the underside of offenhauser intakes? Keep in mind I live in Western washington so our winters are mild compared to other parts of the country. It does get down to freezing temps here, but not very often.

I plan to upgrade the intake and exhaust. I plan to leave the 3927763 head stock, so figure on stock compression ratio. Probably 8:1 or whatever a stock 292 is. I would like to continue being able to run low grade 87 octane fuel in all conditions without knock or pinging.

I would appreciate receiving some cam advice and recommendation to take advantage of the planned intake, carburetion and exhaust improvements. I live in Tacoma, conveniently located to Delta Camshaft, who can regrind my cam to any profile I want.

In regards to this relatively mild street setup, I am considering simply leaving the cam stock, but I wonder if would there be any advantage to changing the cam profile from stock to take advatage of the intake/exhaust upgrades? If so, what new profile do you recommend? Please discuss duration, lift and LSA recommendations and why.

The van weighs about 3000 lbs, but sometimes I haul up to 1000 lbs of cargo, so we can figure on vehicle weight being 4000 lbs.

With my 26.6" tall tires and 2.56 rear gears, my engine is turning 2100-2300 rpm at freeway cruise speeds of 65-70mph. I want efficient operation during cruise, and want to retain the strong low end and midrange torque of the 292. Bottom end is stock, so I do not plan on revving it any higher than a stock rotating assembly can handle. I also understand the stock cylinder head will restrict upper RPM airflow, so I want to focus on having a broad powerband that increases streetable performance as practically as possible given the limitations of the stock engine and head. I figure redline of this engine will be 4500 rpm or 5000 at the most.

I do want a solid idle and a cam that is very steetable, but a little chop or aggressive idle sound is quite acceptable.

Last edited by kookykrispy; 05/22/15 04:35 PM.
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If they fit and are priced reasonable I would go for full length headers, they will add torq all the way down low too.

The short runner options would flow enough air for your engine but would lose a little low end compared to the full length headers. Of course, getting a tight seal would be key with all that exhaust air in the doghouse.

Wow that is a light van, are you sure its only 3000? My 292 63 Nova weighs almost 2900.

I've run the Offy 4bbl and big Clifford 4bbl intakes down here in Cali, never had or needed exhaust heat in the Nova. I think you could get away without it especially with the little Offy intake.

For your use, if the cam/lifters are behaving, you might just leave em as is, I would stay around 200-206 duration at .050 if you do a cam though. That 292 is so much torquier than the 230, its like you can "feel" each piston stroke as you take off from a light.

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I have all three exhaust options hanging on my garage wall already, so price is not a factor. As far as will the long tubes fit? I think they will, but I won't know for sure until the engine is installed in the van and I'm wrangling with the headers.

One thing I love about these little 60's Chevy/GMC vans is that they are so light, which makes them fun to hot rod. They have a U design frame, with the unibody construction built onto the top of the 'U'. The suspension is simple 'gasser' style with a straight front axle. These design features all add to the light weight. Its basically an empty box, which simply doesn't weigh that much. I have never had my van on a scale, but according to the GM heritage center, the published curb weight of a '64 chevy van is actually 2850 lbs. The 292 is a larger block, and will add weight so I figure round up to 3000 lbs.

https://www.gmheritagecenter.com/docs/gm...rolet-G-Van.pdf

According to this site: http://www.amotion.com/amcams.html#19641, these are the specs for a 292 stock cam.

Quote:
CHEV 292 L6 - HYD.
.050 Dur V.Lift Adv Dur LSA
Stock 188/188 .404/.404 276/276 111


188 duration @ .050 and .404" of valve lift seems really small to me, so I am figuring on having this cam re-ground to give me a little more lift and duration. Not too big, but I'd like something a little better then the stock specs since the carbs, intake and exhaust will not be stock anymore.

The cost for the regrind will be the same no matter what duration and lift I want, so the hard part will be determining exactly what specs I want to have it re-ground to.

Santucci's book offers a couple cam suggestions for a 'street' 292. (page 81) These are reportedly what various inline six experts said:

Tom Langdon: #WG1179
duration 194/204 (intake/exhaust)
lift .464/.494
LSA 110

Pat Smith: custom grind
duration 212/218
lift .518"/.530"
LSA 109

Mike Kirby (Sissel Auto)
grind #248H
duration 192/200 (intake/exhaust)
lift .448"/.460"
LSA 112

So.. do these sixes seem to prefer a straight pattern where intake and exhaust duration & lift are equal? or would it be preferred to use a split pattern with a little higher duration and lift on the exhaust side? It seems all the cam recommendations above from Santucci's book are split profiles that have higher duration and lift on the exhaust. Is there any reason to favor the exhaust side? Also, any thoughts on lobe separation angle? I'm wondering what the stock LSA is and if having the cam reground on a little tighter LSA such as 110 or 108 might help overcome this engine's lack of compression. I don't want to go too tight though, since I want to retain my ability to run 86-87 octane regular low-grade unleaded.


What do you guys think?

Last edited by kookykrispy; 05/23/15 02:02 AM.
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Sounds right on the stock 292 cam, I have measured a couple.

On the cam choice, the split pattern thing I think is not just a function of engine (or engine color LOL) but how the intake vs exhaust flows, so I find in the Gonkulator that you have to dial in the whole engine, then see what split it wants if any.

FWIW here is what the Gonkulator said about your 292, I assumed 8.2 CR
1-5/8 x 37" open headers
All cams advanced 4 degrees (they are usually ground that way)

188-188 cam stock
Torq 275 at 2900
Powr 200 at 4400

194-204 cam
Torq 282 at 3000
Powr 209 at 4400

199-199 cam (I made the 194-204 into a straight pattern)
Torq 282 at 3000
Powr 214 at 4400
It liked the straight pattern better with open headers
Sometimes with mufflers split duration works better
Not a whole lot of diff either way

212-218 cam
Torq 283 at 3300
Powr 226 at 4600
This will idle rougher, use more gas, and likely need screw-in studs due to the lift and loads.

192-200 cam
Torq 283 at 3000
Powr 203 at 4400

206-206-110 .473 .473 cam, Comp 252H
Torq 281 at 3100
Powr 217 at 4500
Good numbers for low lift you could likely stay w press in studs.
Most of Tom Lowe's dyno series ran straight pattern cams, not sure if that was deliberate or just availability.

Also at 8.0 - 8.2 CR you don't want a big cam to start killing low end below 3000 if its a daily driver / tower / cruiser.

Well you decide, not a bunch of difference either way. You have a stick so could get away with a rougher cam, depends on use and how much gas you want to put in it. Cams drink gas like crazy in the city.

If the stock cam is good, I'd build it that way, enjoy it, then decide if you want more cam. Or maybe add a lump port head with screw in studs etc and then a big cam with it. Lots of options.

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OK, thanks alot for running this information.

This is for a 'daily driver' type street vehicle so I am most concerned with maximizing low & mid range torque output. I think the gains in this area will be minimal from re-profiling the cam. I notice that none of these options offer any substantial torque increase improvement above stock, so I will just stay with the stock cam.

I know the terms 'fuel economy' and '292' are not usually used in the same sentence, but I would like to keep it reasonable. The van with the current 230 gets about 15 mpg cruising on the freeway. I hope the 292 swap will not reduce that figure too much. Right now the 230 struggles to make it up the hills and requires full throttle operation. I'm hoping that the increase in stroke may actually improve freeway cruising fuel economy by making it so I don't have to have my foot in it so much.

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Alrighty....so you want low to mid rang torque. The stock cam will do fine. A little more cam won't hurt a thing though. Something around 240-250 duration...and about .450 lift on a 110 lobe center. Delta can custom grind a cam to any number you want and may even have something very similar to what I just mentioned off the shelf. These engines will NOT run higher than 4500 stock. 4000 is the red line, but since I'm crazy I have reved my old 292 higher. lol 3 carbs, long tube headers, hei and a little more cam will make for a nice improvement. Though a single 4 barrel carb would make for better drive ability and less tuning. Full length headers and a single 4 barrel will be fine, and like I said...make for better drive ability. The stock compression ratio was 7.6.1 - 8.0.1. The stock dish depth of the piston is .300 deep. Summit Racing sells pistons with a .150 dish and that will bump you compression up to just under 9.5.1 and 87 octane will still be use able, though you may have to retard the timing just a hair. Link to pistons:
www.summitracing.com/parts/slp-w980p20/overview/make/chevrolet There's a bunch more you can look at from summit as well. Keep in mind these are cast stock type pistons with a shallower dish to give more low end power. For head work I would have a 1.86 intake valve grind done and have lump ports installed. It'll help alot with flow in itself.


1966 C10 292/tko600 http://67-72chevytrucks.com/vboard/showthread.php?t=596643
1964 C20 292/sm420
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I would never use a stock cam when there is so much more readily available.

You really need to upgrade to a different camshaft.
You will get more power & better mileage.
The stock camshaft is very anemic.

Rhoads lifters will make a bigger camshaft feel like a small camshaft @ low RPM & give you more power when need in the upper RPM range.
Better idle, smoother.
So, in short, go with a larger spec camshaft it will be worth it.

I have used Rhoads lifters on a couple of engine builds.
They are a bit noisy, sounds somewhat like solid lifter camshaft.
http://www.rhoadslifters.com/


MBHD


12 port SDS EFI

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