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73-87 Chevy _ GMC Trucks => Performance => Topic started by: Ronno6 on November 06, 2018, 10:27:54 PM

Title: 350 On to the Camshaft
Post by: Ronno6 on November 06, 2018, 10:27:54 PM
So far, the engine is shaping up like this:
1984 C10 Stepside.
350 2 bolt bored .030 over.
10:1 pistons
mechanical fuel pump.
Aluminum heads 2.02 intake 1.6 exhaust
64cc chambers
7/16 screw in studs w/guide plates.
Headman long 1 5/8" tube headers into dual 2 1/4" exhaust Walker turbo mufflers.
Dual plane intake, not chosen yet.
600 Holley for now, but changeable.
Muncie M20, 2.52 first gear.
3.73 posi diff.
Set up for roller cam, so that is how I want to go.
I would like some nice power, but not too radical.
Noticeable idle desired, and power range idle to 1500 on the low end to maybe 5500 or 6grand.

What should I be looking for in a cam?? (needs fuel pump lobe)
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 09, 2018, 08:55:23 AM
Looking for opinions on the LT4 Hot Cam, p/n  24502586
How well would that work for me in my application?

Advertised Duration
   279 int./287 exh.
Advertised Exhaust Duration
   287
Advertised Intake Duration
   279
Basic Operating RPM Range
   1,800-5,800
Cam Style
   Hydraulic roller tappet
Computer-Controlled Compatible
   No
Duration at 050 inch Lift
   218 int./228 exh.
Exhaust Duration at 050 inch Lift
   228
Exhaust Valve Lift with Factory Rocker Arm Ratio
   0.492 in.
Intake Duration at 050 inch Lift
   218
Intake Valve Lift with Factory Rocker Arm Ratio
   0.492 in.
Lobe Separation (degrees)
   112
Notes
   For pre-1996 LT1 and L98 engines the dowel pin in the end of the camshaft must be pushed in so extension from end of cam is between 0.290 in. and 0.310 in. For 1996 LT1 and LT4 engines, the dowel pin is in the correct position extending 0.620 in. from the end of the camshaft. This cam has a fuel pump lobe. Valve lift shown is with factory 1.5 rocker arm ratio, the lift with a 1.6 ratio rocker arm is 0.525 in.
Quantity
   Sold individually.
Valve Lift with Factory Rocker Arm Ratio
   0.492 int./0.492 exh.
Valve Springs Required
   Yes
Title: Re: 350 On to the Camshaft
Post by: VileZambonie on November 09, 2018, 02:57:40 PM
You have the roller setup already?
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 09, 2018, 04:11:05 PM
You have the roller setup already?

I have the 880 roller ready block.
I have not as of yet purchased the other components.
Title: Re: 350 On to the Camshaft
Post by: VileZambonie on November 10, 2018, 07:01:40 AM
If you go roller you need everything that goes along with it. You can buy them kitted so everything comes with it or you can source the factory setup and reuse some of the original stuff if you are trying to save some coin. I would recommend you do your homework and pick a cam that does everything you want right in the middle.

http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=CTGY&Store_Code=CC&Category_Code=RLERCAMXE
Title: Re: 350 On to the Camshaft
Post by: 75gmck25 on November 11, 2018, 07:01:31 AM
That cam is about the max I would use for a DD in a heavy truck, but should work fine with your compression and heads.  The 4 speed will help since you can get the RPM up to offset a cam that will probably be a little soft until you get off the line. 

Do you also have large tires?   3.73 will be fine with something close to stock height tires, but you may need lower gears if you have 33's, and definitely if you have 35's.

I happen to like the Howards line of roller cams, and they might be cheaper than the GM products.  Also verify the lift that your heads and springs can handle. It should be fine, but you should check anyway.

Bruce
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 11, 2018, 03:41:46 PM
If you go roller you need everything that goes along with it. You can buy them kitted so everything comes with it or you can source the factory setup and reuse some of the original stuff if you are trying to save some coin. I would recommend you do your homework and pick a cam that does everything you want right in the middle.

http://www.compperformancegroupstores.com/store/merchant.mvc?Screen=CTGY&Store_Code=CC&Category_Code=RLERCAMXE

OEM roller lifters are about $100.00/set of 16
Pushrods $50.00 or less
Spider and guides about $50.00

Heads come with guide plates and 3/8" or 7/17" screw in studs.
I'll need new rockers if I go with 7/16"studs
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 11, 2018, 04:05:18 PM
That cam is about the max I would use for a DD in a heavy truck, but should work fine with your compression and heads.  The 4 speed will help since you can get the RPM up to offset a cam that will probably be a little soft until you get off the line. 

Do you also have large tires?   3.73 will be fine with something close to stock height tires, but you may need lower gears if you have 33's, and definitely if you have 35's.

I happen to like the Howards line of roller cams, and they might be cheaper than the GM products.  Also verify the lift that your heads and springs can handle. It should be fine, but you should check anyway.

Bruce 


I would really like to have a 5 or 6 speed...maybe someday.
But I got a deal on that M20 setup that I couldn't pass up.

If memory serves, my truck curb weight is about 4000lbs.
A bit more than a Camaro or Chevelle, but not grossly so.
The aluminum heads, intake and headers will help pare that somewhat.

My tires are 29" O.D,
I'll take a look at Howard's Cams for selection and price.

My machine shop guru is big on Erson Cams.  I'll be looking at them as well.

As for springs and such..the heads are going to be machined and built from raw castings.
The shop will assemble with appropriate springs for whatever cam I select.
Title: Re: 350 On to the Camshaft
Post by: 75gmck25 on November 12, 2018, 07:49:25 AM
The one big advantage you have over most folks is that you are starting with decent heads and 10:1 compression.   Many guys start out with a stock SBC engine that has old smog heads and about 8.2 compression, and then try to "fix" it with a big cam and a better intake and exhaust.  It just doesn't work very well because the compression ratio and head flow is a poor match to the cam upgrade.   

The other common problem is when someone tries to add 35"  tires to a truck with a stock TH350 (no high stall converter) and high rear end gears  (3.07?) , which completely kills the ability to get rpm up off the line.   Your four speed, 3.73's and 29" tires will let you slip that clutch and get the engine up into the power band quickly.

Bruce
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 12, 2018, 12:55:07 PM
I have received some pretty spot-on advice so far from my machinist, who is an accomplished engine builder
in regards to parts selection.

One point of interest: the M20 Muncie has a bot more separation between gears than the M21 or 22.
Rather than the 2.20:1 first gear of the M21 and 22, the M20 has 2.52:1.
That'll help out when accelerating from a stop. (I didn't want to say "off the line" cuz I don't plan on much racing.)
That's one reason I opted for 3.73, though I had considered 3.42 gears for a bit better MPG on the highway.

My C10 originally came to me with a TH350 and a 2.73 open diff.

So I'll be looking in the .470 to .490 lift, 210 to 225 duration range and minimum 110 LSA range, probably 212 would be better for vacuum power brakes.
Mechanical FP lobe a must.
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 13, 2018, 02:25:45 PM
Howards Cams is recommending cams with 5.25 lift I/O, 219int/225exh duration and either 110 or 112 LSA.

Close to but a bit different from the LT4 hot cam.
I'm sure those would install without a problem.

Are those getting more radical with the higher lift?
Title: Re: 350 On to the Camshaft
Post by: VileZambonie on November 13, 2018, 03:31:36 PM
Yes and what heads are you using? Do you know what the max lift is with your springs?
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 13, 2018, 06:06:52 PM
Yes and what heads are you using? Do you know what the max lift is with your springs?

They are aftermarket aluminum, off-share I believe.
The machinist said he will set them up for whatever cam I select.
Springs should not be an issue.

Also going to use 7/16" screw in studs and guide plates.
Title: Re: 350 On to the Camshaft
Post by: VileZambonie on November 13, 2018, 07:14:25 PM
Well just make sure they match the cam lift you choose and that you don't run into clearance issues or coil bind. I'd be leery of no name cylinder heads
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 13, 2018, 10:12:29 PM
Well just make sure they match the cam lift you choose and that you don't run into clearance issues or coil bind. I'd be leery of no name cylinder heads

Should be no problem on the springs.
As far as no name heads, I have a large amount of trust in the machine shop who is building them.
I know of a few others who are using them as well.
They seem to be a good product.
Title: Re: 350 On to the Camshaft
Post by: Ronno6 on November 20, 2018, 07:31:20 AM
I opted for the LT4 Hot Cam and purchased one reground from Willhoite's in Oklahoma City.
He ground it with a built in 2 advance and instructed me to install with timing marks aligned per factory.
I will still degree the cam when installing so I know what I have.

We'll see how it goes.....