Some common performance questions

[Chris6060]

Hey guys

I've finally figured out where I'm going with my motor parts, but I just can't quite seem to find the right camshaft for the job.

Heads: http://www.summitracing.com/dom/parts/sum-151124/overview/
Gonna be using an edelbrock high pressure fuel pump capable of 225lp/h.
What I wanted to to do was use this intake manifold: http://www.summitracing.com/dom/parts/sum-226018/overview/
and then use a carb to throttle body adapter. Would I be a lot better off going with the Edelbrock intake manifold thats already setup for TBI? Or would the difference be minimal?
I was looking at this cam http://www.summitracing.com/dom/parts/cca-12-243-3/overview/
but I'm wondering if maybe the power range is just too large. I want this truck to be pretty fast, while still being able to tow things while not being revved right out.
The bottom end is still just gonna be a stock TBI 350 for a while, so 6000 RPM is probably a ways out of reach. I don't wanna blow the thing up.

So I think my BIGGEST question here is what cam/torque converter combo should I go with to combine the best of everyday driving, performance (speed wise) and towing performance? I never tow anything over like 2200lbs, so.

Once I've got all of this, who should I go to for a chip? Because this is gonna be a lot of opened up airflow compared to my stock TBI heads and stuff.

 

[michael hurd]

You have a lot of conflicting wants... towing anything with a higher than stock stall converter is going to send transmission temperatures up quite a bit.

That camshaft has a lot of duration, and not necessarily a good match for towing. It appears those heads have been modified for .520 lift as per the specs on Summit. I would suggest a small hydraulic roller instead, like the Comp 08-302-8.

Find a newer engine with a factory roller ( caprice, pickup from 1996-1998 or van ), remove the lifters, dogbones, lifter valley spider and pushrods, this way you save on having to buy these new. I would check with Summit, but I don't think those heads will have springs strong enough for that cam, a roller takes a lot more spring to control.

If you don't run the engine into valve float you might even get away with running 1.6 ratio rocker arms on there to push the valve lift up to .512... although that's closer than I would like to run. If you machine down the guides you can get away with more lift, however you will need to buy valve seals. At that point your price / performance ratio goes down.

A hydraulic roller will have less friction than a flat tappet cam, and make a LOT more power due to the shape of the lobe, the valve opens much quicker and closes faster. The result is better cylinder filling and less pumping losses.

You didn't mention what you are running for exhaust, but I would suggest a set of 1 1/2 or 1 5/8" primary headers with a 3" collector. Dual 2 1/2" should be plenty for that power level.

Alternately, you could drop in a stroker and make the same power with a lot less work on your part.


http://www.cnc-motorsports.com/crate-engines/sb-chevy-383-stroker-performance-tbi-engine-87-95-gmc-chevy-truck.html

 

[Chris6060]

Its super rare that I actually do tow. The most weight the truck usually sees is 600lbs in the bed and around 2000 lbs on a trailer and both of those things are super rare, few times a year type things.

I want it to be leaned more towards street performance than towing.

I'm not going the roller conversion route, its more work than I want to have to deal with I think (but I'm also not entirely sure what all it entails)

I mostly just wanna have to buy bolt-on parts. Heads are take off, put on, as well as everything else. Only real big thing is the cam install, and thats just because it has to come out straight through the front of the motor.

I have true dual 2.5" with hi-flow cats and dual flowmaster 40s. Headers are next. (Shorties or long tubes?) Is it true that its pretty much impossible to get headers to stay tight on these trucks or does that problem get eliminated with Vortec Heads?

I don't mind doing the work installing parts at all, I have enough time.

The truck is a DD so. When it is down, I have to make it a reasonable time bracket.

Whats another flat tappet cam option that would work well? I don't wanna push the heads so far that they aren't going to last long.

Thats the one big thing I'm really lost on is cam choice. I don't know THAT much about cams and thats why I'm really looking for advice on it

 

[michael hurd]

The block is equipped for roller cams, it has raised bosses tapped for bolts in the lifter valley. All that is needed is a set of roller lifters with the lifter guide plates ( they look like dog bones ) as well as the spider that goes in the valley and shorter push rods. You will also need a different ( melonized ) gear for the distributor, forgot to mention that.

http://www.chevyhiperformance.com/techarticles/148_0307_converting_hydraulic_roller_cam/photo_09.html

If possible I would install long tube headers instead of shorties. If you use a flex joint ( like FWD cars ) off of the collector and the exhaust system is properly supported, the gaskets should last a long, long time. Quality headers use a thicker flange, and stainless is always nice for keeping away the rusties in Canada. Ebay is your friend here.

 

[michael hurd]

A stock bottom end with good bearings and proper oil pressure should have no problem at all spinning 6000 rpm, it's generally the valve springs as a limiting factor.

 

[Chris6060]

So longtubes with a flexjoint it is

Oil pressure is always awesome in this truck. I don't know how the bearings are doing. Its got 210,000km on it. Runs really well though. Just runs rich at the moment.

Roller cam sounds expensive is all

 

[michael hurd]

If you have the other parts required the only extra expense would be for the cam and valve springs, but would pay back in better power and economy.

 

[Chris6060]

Found this cam ...

Lunati 10120702
Specs:
Lift: .468" / .489"
Advertised Duration: 262 / 268
[email protected]": 219/227
LSA: 112degrees
RPM Range: 1400-5800

Thoughts?

Also: Is my truck a hydraulic flat tappet cam or a mechanical flat tappet cam? And whats the difference?

 

[michael hurd]

Yours is a hydraulic flat tappet camshaft, and that one is a more appropriate choice than the first one, it has a bit less duration than that comp grind.

A solid will make more slightly more power, but you will have to adjust the valves occasionally, a pain in the butt on a DD. Hydraulic or hydraulic roller is more appropriate for the street.

 

[Chris6060]

So ya think this Lunati cam would do well?