Engine Rebuild Question- Cam Options

[5Tractorguy]

Well, the engine in my '88 V30 finally went a couple weeks back.
I found a replacement 350 from an '80 C30 that was "freshened up" in the early 90's and then left in a cellar. I'm going to have it fully rebuilt before it goes in the truck.

My main question is about the cam. I move a lot of equipment, that truck usually pulls an 18ft trailer or has the bed loaded with tractors/parts.

Both my '77 K25 and '79 C30 have some kind of towing or RV cam that the previous owners installed and seem to do just fine.

Would the same generic towing cam be best for this truck as well? I'm completely oblivious when it comes to this which is why I ask. At this point, given the rebuild is going to cost around 3K, figured it may be neat to put something in a step above an RV cam to get some lope out of it, but I don't know how much that effects mileage/performance.

Any ideas?

[Ziegelsteinfaust]

Please consider a roller cam. Today's oils do not support flat tappets due to lack of zinc. Or add a bottle of break in additive each oil change, or you may wipe a cam lobe. I haven't pulled apart a flat tapper cam motor that was not heavily worn in recent years. Where 20 years ago it was not a issue.

A cheap option maybe to use a 95+ Vortec 350 long block to get a good roller cam cheaply.

[Corts60]

You’ll want to stick with a cam that is ground especially for torque. That’s usually why everyone opts for an RV cam when pulling power is required.

[GSP7]

I have a Elgin performance cam in my 350 in my 81 K20 truck, I really like , It is not a high lift cam so it is made for long life and easy on the valve train, I have the spec card, id have to dig out. My machinist that builds race motors refereed this cam to me. I have way over 100k miles on it and is crisp as new. Has a nice little lope at idle, and Im running the Doug Thorley headers, Its got a built '73 010 block with 10:1 pistons, and '72 High perf heads, running a quadrajet carb. Ive been running Delo 15-40 oil in it for quite some time now. Change oil every 3000-4000 mi

[Pontiac1976]

You’ll want to stick with a cam that is ground especially for torque. That’s usually why everyone opts for an RV cam when pulling power is required.

As said RV or towing cam

[5Tractorguy]

Thanks Folks! I'll tell the rebuilder that I want a towing/RV cam installed.

Roller would be nice but the funds aren't there to do a high end build on this block. I could look for a roller cam block too, but being that this is my winter driver, I want the engine back in the truck before the cold weather hits to make sure everything checks out.

[N444TX]

The 1980 engine is different from a 1988 engine. The early engine has a two piece rear main, the heads/valve covers are different. You are going backwards with the early engine.

I am not sure when the blocks were factory set up for roller cams, but the 1988 might be. I had a 1990 (or 1992) in my 1972 2nd blazer and installed a Caprice cop car roller cam in it. Easy, cheap, strong running, plus bolt in change to do. Look for bolt holes in the middle of the lifter valley for the roller guide hold down. Will also have factory bolt holes behind the cam gear for a thrust plate.

GM

[Getter-Done]

Here's some good info.

I have always run Crane Cams.

You want to stay somewhere in the range of the chart on page 19.

https://cranecams.com.au/pdfs/2013-m...atalog-v2B.pdf

[SunSoaked]

Roller cam. Buy once, cry once. You'll make up for it in the price of oil. Non-roller and you'll be buying VR1 or a zinc additive.

[MJN]

I used a Melling MTC-1 cam in my 350, good low end torque and driveability plus it sounds pretty good- no issues with oil but I do run Amsoil Z-Rod made for flat tappet engines.

[5Tractorguy]

Bringing this thread back for a quick question guys...

What does it take to swap Vortec heads onto a 350? (1980 engine to be exact). I have the Edelbrock intake with the canted canted bolts (from a previous TBI to Carb swap), are any other modifications required? Assuming all coolant passages are the same? I know roller cams are nice, but the flat-tappet rockers will bolt to these as well, correct?

Since the start of this thread, had an engine rebuilt, ran it since Nov of last year, #3cyl was buring coolant, turns out the head is cracked, found a set of good Vortec heads for $150 that are cleaned up and ready to go. Would like to swap them on...

[Rickysnickers]

It should be a bolt on and go affair. The only thing that might be of issue is if the heads you are looking at have been shaved. This would potentially change the length of the pushrod you need.

[LT7A]

What did you decide on for a cam with your rebuild last year? Did it work out the way you hoped? I'm curious since the lope usually has to do with a motor that is set up to spinhigher RPMs and make power up there, rather than a torque motor. Lope sounds cool, but I choose cams that give a smooth idle and low end torque, so I'm curious if you're happy with what you got.

Regarding the vortec heads, just be sure that they are not cracked as well. They are prone to cracking and hide the cracks well. Don't want you to end up with the problem you're fixing.

[5Tractorguy]

Originally Posted by Rickysnickers

It should be a bolt on and go affair. The only thing that might be of issue is if the heads you are looking at have been shaved. This would potentially change the length of the pushrod you need.

That's what I was hoping! Did some research and I'd have to change the intake, reroute water pump, different rockers, etc. Decided to fix the crack instead.

Originally Posted by LT7A

What did you decide on for a cam with your rebuild last year? Did it work out the way you hoped? I'm curious since the lope usually has to do with a motor that is set up to spinhigher RPMs and make power up there, rather than a torque motor. Lope sounds cool, but I choose cams that give a smooth idle and low end torque, so I'm curious if you're happy with what you got.

Regarding the vortec heads, just be sure that they are not cracked as well. They are prone to cracking and hide the cracks well. Don't want you to end up with the problem you're fixing.

This engine got the Melling MTC-1 cam. I'll give you a solid update on performance within the next few weeks... It does sound righteous at idle before you bring the timing up! But needs a lot of advance to run properly.

Unfortunately with the cracked head, leaking valve stem seals and an over fueling Quadrajet, performance was lacking throughout the past year. There was definitely a noticeable power increase from the previous engine though, but all the other factors really hindered performance.

Took a chance and brazed the crack in the head. Braze wet into the cast nicely so I think it'll be okay. In the process of re-assembling the heads now, should be back up and running end of next week.