Aluminum Head / Cam Recommendation needed for 1972 Blazer K5

[74javelin]

Hello Folks,

I have a clean very original 1972 Chevy Blazer K5 4x4 and I looking to build up a period correct "looking" 350 in combination with doing a clean OEM style engine bay.

The engine in the truck currently is a tired 1979 Camaro 305 that has been in the truck since I bought it. Has always run great, but starting to burn oil so ready to do something nicer.

The Blazer is a factory AC truck with everything intact on the dash, so long term goal would be get a vintage air kit or other going in combination with the factory AC system. I have the factory brackets and some compressor stuff in a a bin from the previous owner.

The engine that I am going to be building up is actually from a 1972 Blazer that is getting a LS swapped, and I'd like to use the factory power steering pump, alternator bracket etc, for a very OEM engine bay look.

I'm open to aluminum heads and a cam, as more power, torque and efficiency would be welcome.

That said, I'll need some recommendations of what combination makes sense, here are my goals:

1. Relatively mild idle, probably like what back in the day was called an "RV Cam" in terms of idle. I'm going to post a video of what the truck currently idles like. I'd like the idle to be the same as the current engine.

2. My wife enjoys driving the truck as well, and it is currently used as the nice weather summer station wagon, taking the kids and bikes to the park, little league games, camping, hence the desire to keep things mild.

3. Occasionally the Blazer tows a light aluminum enclosed motorcycle trailer, that weighs 2000 - 3000 lbs loaded up.

4. Want to mount all the factory accessories to the front the engine in the factory locations.

5. Open to either Roller Cam or flat tappet cam, the local machine shops in my area would very much prefer a roller cam, and I am fine with that as long as we can pick one that is sounds like what my current setup sounds like at idle.

6. Would like to run AC with this engine.

7. Block is a 1972 350 Truck Engine (factory Blazer engine)

Knowing all this is there an aluminum head / cam combo that you could recommend that would fit the bill?

Here is the idle that the truck has currently, I'd like to match character of this idle, but just gain some power and efficiency.

https://www.youtube.com/watch?v=kv_7xXpZwl0

Thanks! -Ian

[PbFut]

I would call the cam manufactures. If using a vintage block use a retro roller kit to avoid the oil issues. Given towing and street manners a priority, find one for high torque low rpm. May be even low compression so you can use low octane. Dont try to find something that says it provides that old school lope. Might sound cool but you give up way too much low end. Also, with today's labor cost, a create can be a better value unless you are self building

[LS short box]

I would peruse the Engine Masters tv show. They have tested everything under the sun engine wise.
Not trying to be a smart aleck but why not start out with 350 roller cam block to begin with? All stock GM parts for the roller cam parts wise and then add aftermarket roller rockers?

[binford]

https://www.summitracing.com/parts/flk-1200hrac505a

Link to summit racing.

[74javelin]

Originally Posted by PbFut

I would call the cam manufactures. If using a vintage block use a retro roller kit to avoid the oil issues. Given towing and street manners a priority, find one for high torque low rpm. May be even low compression so you can use low octane. Dont try to find something that says it provides that old school lope. Might sound cool but you give up way too much low end. Also, with today's labor cost, a create can be a better value unless you are self building

Thanks! This all makes good sense, I'll look into the retro roller kit, and call around and describe what I'm looking to do. The idea behind using this particular block is just the sentimentality of using this particular engine from a 1972 Blazer into another 1972 Blazer, also like having the threaded hole for the ball stud, if I ever want to run a factory 4 speed.

[74javelin]

Originally Posted by LS short box

I would peruse the Engine Masters tv show. They have tested everything under the sun engine wise.
Not trying to be a smart aleck but why not start out with 350 roller cam block to begin with? All stock GM parts for the roller cam parts wise and then add aftermarket roller rockers?

Good advice, agreed using a 350 roller cam block would be the most cost effective way to go, the reason was the sentimentality of using this particular engine from a 1972 Blazer into another 1972 Blazer, also like having the threaded hole for the ball stud, if I ever want to run a factory 4 speed. Was planning a more stock rebuild, but both machine shops I talked made a good argument to use the aluminum head roller cam combo.

[74javelin]

Originally Posted by binford

https://www.summitracing.com/parts/flk-1200hrac505a

Link to summit racing.

Thanks for the link! Have you used this particular head for a similar style build? If yes, curious to know what cam you used it with and how it worked out?

[MARKDTN]

I'm going to go a different way and say go find a 96-99 Vortec 350 and buy an aluminum intake for it to fit a Q-jet. You get great heads, factory roller cam, 1-pc rear seal and other than center bolt valve covers you can't tell it from a '72 350 once you paint it orange.

All '72 accessories will bolt up. You just need to be sure that the distributor gear is compatible with a roller cam.

As far as A/C you probably just need a Sanden compressor and bracket kit and a hose kit to hook to original A/C stuff in dash and condenser.

[MikeB]

Originally Posted by MARKDTN

I'm going to go a different way and say go find a 96-99 Vortec 350 and buy an aluminum intake for it to fit a Q-jet. You get great heads, factory roller cam, 1-pc rear seal and other than center bolt valve covers you can't tell it from a '72 350 once you paint it orange.

Very good idea. The L31 5.7 Vortec engines made 255 net horsepower, which is about the same gross hp as a 72 350 Blazer engine.

I bought a used one several years ago for $150. The heads had hairline cracks (very common) so I replaced them with new Vortecs. Short block was in great shape, but I went through it anyway.

However, it won't look 100% stock in your 72 because of the valve covers and aftermarket intake.

Here's mine during installation. Exhaust manifolds are from a late 90s engine, as I recall, but you can use earlier manifolds. On some Vortec heads, the exhaust ports are a little taller, so you may have to open up the exhaust manifold ports a little.

[pjmoreland]

The l31 Vortec engines I have in my two trucks are not machined for a mechanical fuel pump. Apparently, some are, but I wasn't so lucky, so I had to go with electric. Other than that, I am very happy with the engines.

[truckster]

Here's what I ended up doing. It's an L31 Vortec 4 bolt main. The block was already drilled for a fuel pump rod. I used the HT383 cam and had the valve springs reworked so I can go bigger in the future if I want. I decided to use the serpentine belt setup from the donor truck. Hot Rod magazine built an identical engine years ago and it put out 330 HP and 400 lb/ft of torque on the dyno.

[MikeB]

Mine was machined for a mechanical fuel pump. Seems like that was the case with 4-bolt blocks used in 2500/3500 series trucks. The crank was also different from the 1/2 ton application. Ductile iron? Nitrided? Or maybe forged.

One-piece main seal cranks from Mortec.com listing.

14088526...305,350...cast....medium journal...3.48" stroke
14088532...350.......forged..medium journal...3.48" stroke
14088535...305,350...cast....medium journal...3.48" stroke
14088552...350.......forged..medium journal...3.48" stroke

[pjmoreland]

I pulled one of my engines out of this 2000 3500. It has 4-bolt mains. The crank is cast. There's the possibility that it isn't the original engine to that truck though because there is no VIN on it anywhere.

[ullose272]

something with a 170-180cc runner and a small roller cam would make good power. vortec heads are great, they can be susceptible to cracking.

[MikeB]

Like Momma said, "Life is like a box of chocolates. You never know which block, cam, or crankshaft you'll get."

[Rick Bollinger]

When I did mine I used the Edelbrock 338 hp top end kit. But I put it on a 383 and ended up with 404hp and 465 torque. This also runs a stock torque converter and a 700 r4. A smooth idle and claims with a 9:1 stock 350 set up will produce 338 hp. All stock components bolt up.
https://www.summitracing.com/parts/edl-2038

[Accelo]

Originally Posted by MARKDTN

I'm going to go a different way and say go find a 96-99 Vortec 350 and buy an aluminum intake for it to fit a Q-jet. You get great heads, factory roller cam, 1-pc rear seal and other than center bolt valve covers you can't tell it from a '72 350 once you paint it orange.

All '72 accessories will bolt up. You just need to be sure that the distributor gear is compatible with a roller cam.

As far as A/C you probably just need a Sanden compressor and bracket kit and a hose kit to hook to original A/C stuff in dash and condenser.

I highly agree with these suggestions.
If you want the original block, you can use it, but it will get expensive to change to a roller cam. I highly recommend the roller cam. Quality control on flat tappet cams is out the window. It's like a 50% chance of failure.
Stay under 212 deg duration at .050 at the intake on the cam, you will be happy. You will get 75% of the power gains without the headaches. Especially towing and the wife driving. Try to avoid the temptation of going big on the cam.
Cheers

[MikeB]

Originally Posted by Accelo

I
Stay under 212 deg duration at .050 at the intake on the cam, you will be happy. You will get 75% of the power gains without the headaches. Especially towing and the wife driving. Try to avoid the temptation of going big on the cam.
Cheers

I agree. Some would say that's too small, but it's interesting that GM used "only" a 196/206, .431"/,451" roller cam in their RamJet 350 and HT383 crate engines.

I used that cam for a 355 with Vortec heads in a 82 C10. It was essentially the RamJet engine, but with a carb instead of EFI.

The engine had tire spinning torque right off the bottom, even with a 2.73 axle! And it easily revved to 5500, which I rarely did.