Cracked head, now what?!

[catch2otwo]

So due to a failed radiator hose and an inexperienced driver I have a cracked head on my 350.

Here is what I know. Motor is a reman Kragen 350 yr 1972. No idea on miles or previous owner maintenance. Does use some oil I've noticed between changes. Never had a compression test or leak down test, so not sure on the condition of the rings.

So...

My plan was to pull the motor, have the machine shop clean up the block and repolish the crank so I can put new bearings in the bottom end. Also just go 30 over or something to put new slugs in.

Find some stockish heads, get them rebuilt, maybe put an rv cam in. Reuse my single plane edlebrock intake and holly carb. Fill with oil and drive away.

Does this sound like a economical and reliable thing to do? This is not a hotrod, but more like a daily/weekend moto hauler. I need reliability before I need hp.

Never done a build before but i will be attempting a reassembly at home. Does anyone have an parts suggestion or general advice? thanks!

[71K20chevy]

I can tell you from my experience is that single plane intakes and RV cams do not mix well.

If you're going for low end torque, you would want a dual plane, something like a Edelbrock Performer (it's got a large powerband- idle to 5500).

The single plane intakes are great for high rpm, but that's what my truck has and it's a slug as far as torque goes. Mine also has an RV cam. So you mix a low-rpm range cam with a high RPM intake, that's when things start going to crap.

[catch2otwo]

Originally Posted by 71K20chevy

I can tell you from my experience is that single plane intakes and RV cams do not mix well.

If you're going for low end torque, you would want a dual plane, something like a Edelbrock Performer (it's got a large powerband- idle to 5500).

The single plane intakes are great for high rpm, but that's what my truck has and it's a slug as far as torque goes. Mine also has an RV cam. So you mix a low-rpm range cam with a high RPM intake, that's when things start going to crap.

Thats what I thought, the truck came with a single plane which i thought was strange. No problem, I will ditch that and go dual.

[cableguy0]

A few things to consider. A single plane intake and a stock-ish engine are a terrible combination. If your engine is a parts house rebuild don't plan on being able to rebuild it again. They use the cheapest garbage that can be had. Its likely you will find its already bored at least .030 that's if all the holes are bored the same.Its common for the rebuilders to bore each hole differently meaning if cyl 1 takes .040 to clean up but the rest only need .020 they will bore the one hole .040 and leave the rest .020. The crank has likely already been cut .020 or worse. In all reality you might be leaps and bounds ahead to just start over with a gm 290hp crate engine and be done with it. At least that way you know what you have. The mass rebuilders are notoriously bad about putting junk together. I wouldn't plan on anything being reusable other than the parts bolted to the outside of the engine.

[catch2otwo]

Originally Posted by cableguy0

A few things to consider. A single plane intake and a stock-ish engine are a terrible combination. If your engine is a parts house rebuild don't plan on being able to rebuild it again. They use the cheapest garbage that can be had. Its likely you will find its already bored at least .030 that's if all the holes are bored the same.Its common for the rebuilders to bore each hole differently meaning if cyl 1 takes .040 to clean up but the rest only need .020 they will bore the one hole .040 and leave the rest .020. The crank has likely already been cut .020 or worse. In all reality you might be leaps and bounds ahead to just start over with a gm 290hp crate engine and be done with it. At least that way you know what you have. The mass rebuilders are notoriously bad about putting junk together. I wouldn't plan on anything being reusable other than the parts bolted to the outside of the engine.

When you say "rebuilder" do you mean joe blow off the street of these crate motors from Autozone and the like? From what I was told by the PO, this motor was bought as a rebuilt motor from Kragen Autoparts.

[Marv D]

Not to speak for cableguy, but he is speaking of the Kragen / Autozone / etc engines. You would not believe some of the nightmares I've seen come from the mass rebuilders that supply those places.

I too suggest you don't throw good money after bad on this motor unless you KNOW it's components and what you have to start with. Why don't you just match up a head like the one you have, put it back on the road and save for a nice crate motor. Take your cracked head to a reputable head shop and they will find a like core, load it with seats / valves and springs,, and your back in business.

The $ you save here will go a long ways towards a GM crate motor.

[catch2otwo]

Originally Posted by Marv D

Not to speak for cableguy, but he is speaking of the Kragen / Autozone / etc engines. You would not believe some of the nightmares I've seen come from the mass rebuilders that supply those places.

I too suggest you don't throw good money after bad on this motor unless you KNOW it's components and what you have to start with. Why don't you just match up a head like the one you have, put it back on the road and save for a nice crate motor. Take your cracked head to a reputable head shop and they will find a like core, load it with seats / valves and springs,, and your back in business.

The $ you save here will go a long ways towards a GM crate motor.

The guy at the machine shop said the same thing, just buy heads and bolt it back together and go. I was on that plan, until my OCD kicked in, you know take care of this since its already apart. We all know how quickly that spirals out of control. Im still not opposed to getting some heads and driving. Just wanted to see what opinions are out there.

[cdowns]

your plans seem quite ambitious// you should add up all that you are wanting to have done and see if that is close too or exceeding the cost of a crate engine with all new parts and a longterm warrenty with a long history of proven success



dump your single plane manifold

[65GMCFirstride]

I am doing a similar rebuild. Its about 550 of machining (block and crank), 450 for all new parts including RV cam and Hyper pistons, and 250 for rebuilt heads that includes new valves, springs, and seals. I started with a 5.7 motor that had 160k on it and never rebuilt. Bought it on CL from original owner. So, I will be about 1250 all in. Probably quite a bit cheaper than going with a mass produced long block.

The downside is you have to deal with machine shops. I have not had good luck with them so far. But, at least I get to see what they do and correct it verses it crappy machine work and bolted up by a mass producer. Its a bigger hassle for sure, but you will know what your got when your done.

[mongoose]

Originally Posted by 65GMCFirstride

I am doing a similar rebuild. Its about 550 of machining (block and crank), 450 for all new parts including RV cam and Hyper pistons, and 250 for rebuilt heads that includes new valves, springs, and seals. I started with a 5.7 motor that had 160k on it and never rebuilt. Bought it on CL from original owner. So, I will be about 1250 all in. Probably quite a bit cheaper than going with a mass produced long block.

Its a bigger hassle for sure, but you will know what your got when your done.

i'd spend the extra 500 for a gm longblock..

[cdowns]

Originally Posted by 65GMCFirstride

I am doing a similar rebuild. Its about 550 of machining (block and crank), 450 for all new parts including RV cam and Hyper pistons, and 250 for rebuilt heads that includes new valves, springs, and seals. I started with a 5.7 motor that had 160k on it and never rebuilt. Bought it on CL from original owner. So, I will be about 1250 all in. Probably quite a bit cheaper than going with a mass produced long block.

The downside is you have to deal with machine shops. I have not had good luck with them so far. But, at least I get to see what they do and correct it verses it crappy machine work and bolted up by a mass producer. Its a bigger hassle for sure, but you will know what your got when your done.

no you will not know fer sure till you test the results/// i've seen many many posts over the years "my new rebuilt blew up with 50miles and no real warrenty"