Should I try a new camshaft?

[English]

Okay, here's another post by someone who wants more power... Stick with me!

The truck - 1979 lwb K10. Engine is not original but suffix is TKY, which decodes as a 165hp truck engine.
4.10 rear end, 35" tyres, SM465 gearbox.

The problem - I didn't buy a truck expecting to get anywhere fast, but the performance is REALLY bugging me. There's no power at all low down, but it's surprisingly quick when the revs are above 3000.
It doesn't feel like there's anything wrong with it, as in, it runs fine, but it doesn't make sense tto me that it's so feeble low down when it's more than fast enough when the revs are high. I've taken to an American car specialist, he can't find anything wrong, but suggests that it might have a fast road cam. When I bought the truck it had a 750cfm Holley (too big), a two inch spacer, and the mechanic thinks the Edelbrock intake is a high rise. It also has low vacuum at idle, about 16". Plus Hooker Headers and 2.5" true dual Flowmaster Flowmasters.
I've changed the carb to a 570cfm, which has improved things, but not massively. Vacuum is low but idle isn't noticeably choppy.

Now, I'm not after a fast truck, but it's quite hilly where I live, and it really bugs me that I have to change down when climbing a hill. And pulling away from stop lights is far from exciting! My only benchmark is my old K5, which had a 305, auto, and 35" tyres, and was a LOT quicker.

I'm considering a cam change to the Comp Cams 12-300-4, but am I likely to get much improvement? It's a lot of money when I don't know what my gain is going to be.
Or is my problem a 165hp engine in a heavy truck, with a wide ratio dump truck gearbox?

All suggestions welcome!

[zieg85]

I would look into distributor timing before you dive into spending a ton of money on it.  Where is the base line set, what is total timing?  I am no expert by any means but that is where I would start.  Someone might have put a different cam in it so anything is possible as to what to do.  "Low vacuum is a concern to me"  Could be as easy as the vacuum advance not working or the line is in the wrong place.  Tire size isn't helping but the 4.10 gear should do OK with it.  I am sure others will chime in.

[rich weyand]

That sounds like the 350/290 hp crate engine.  That is *exactly* how it acts.  Oh, and let me guess: your gas mileage sucks as well.

Definitely check the timing.  My sweet spot is 16* BTDC base timing, 20* mechanical advance and 15* vacuum advance on manifold vacuum.

The 12-300-4 will give you a ton of torque -- 420+ lbft at 2500 and over 300 at 1000 -- with stock lift, but will not wind up.  You will probably want to drop the shift points 500 rpm if you go that way, which is easy and I can tell you how to do it.  There's a couple other choices, but you go with more lift.  I'm thinking of 12-300-4, 12-231-2, 12-235-2, and 12-238-2.  These generally are in order of increasing hp and decreasing torque   See my posts in this thread:  http://forum.73-87chevytrucks.com/smforum/index.php?topic=26161.25

And this one: http://forum.73-87chevytrucks.com/smforum/index.php?topic=27345.0

Here is a very long thread on my cam selection process that has a lot of stuff in it for you.  One change: I have since found out that the 3.42 axle ratio noted on the RPO was changed to 3.73 by a PO.
http://www.fullsizechevy.com/forum/general-discussion/c10-forum/514240-seeking-torquer-camshaft-recommendations.html

You should download the Camquest software from Comp Cams and look these cams up. 
http://www.compcams.com/downloads/register.asp

Here is the setup for the low-compression 350.  Setup down the left side is:
Usage 2
Hydraulic
4500 lb vehicle weight
Carbs
Chevy 350
2-valve, wedge, low perf/stock ports_valves
1.940 in
1.500 in
8.50
Dual plane high flow
600 cfm
None
Gasoline
Large tube headers, mufflers without cats

[English]

Regarding timing- I'm struggling to get it anywhere what the Chilton manual says it should be. Currently at about 2*BTDC. However, the mechanic said I was running lean and adjusted my float level, so I'll try to adjust the timing again. Mech and vac advance both appear to work but I didn't write the numbers down.

Regarding crate engine- surely that would be a new engine then? My understanding is that with the suffix TKY, the youngest my engine could be is 1980. It certainly doesn't look new. Mileage is about 13.5 to the (US) gallon.

Regarding cam choice- low down torque is EXACTLY what I want. I very rarely go above 3000rpm. Except when I have to drop a cog to climb a hill. But when she's above 3000 she flies!

Regarding adjusting shift points- it's a manual! And I'm wondering if that's part of the problem. Muncie SM465, wide ratio manual 'box.

I've been reading your cam posts already Rich, that's why the 12-300-4 appeals!

[enaberif]

2* is farr to low. You want a minimum of 8* and work from there. Transmission is fine and won't be a cause of the slowness.

[zieg85]

If you are getting 13.5 MPG on that set up I take my hat off to you.  That is respectable.

[English]

2* is farr to low. You want a minimum of 8* and work from there. Transmission is fine and won't be a cause of the slowness.

I'm wondering if the wide ratios don't help in as much as it's a big drop in revs when I change up.
Will have another go playing with my timing.

[English]

If you are getting 13.5 MPG on that set up I take my hat off to you.  That is respectable.

Well... that was on a long run, but I don't think it's far off that for day to day driving

[enaberif]

2* is farr to low. You want a minimum of 8* and work from there. Transmission is fine and won't be a cause of the slowness.

I'm wondering if the wide ratios don't help in as much as it's a big drop in revs when I change up.
Will have another go playing with my timing.

I'm curious why you think you have a wide ratio SM465?

[English]

Oops sorry, I don't mean it's wider than a regular SM465, just the fact that the SM465 is a wide ratio 'box in itself

[Irish_Alley]

English i think your speedo/odometer might be off a tad. on my truck 350/sm465 and 38s i could only see 10 if i kept it under 55 and driving it like a old man. but if youre in fact getting 13.5 i tip my hat to you and you might of found a setup that would save everyone else lots of money

[English]

I calculated that last year when I had a 200 mile run to do. I know my speedo is out due to my tyre size, so I got the mileage off google maps, which I've always found accurate. And yes I did drive like a grandad!

[English]

The plot is thickening - I think I have a misfire problem. As this thread is no longer about performance or camshafts I'll start a new thread in the appropriate section.