1968 k20

[tonyr0774]

Hey guys,

Looking for a little help. I have a 68 K20 that I purchased my senior year in high school some 15 years ago. The service tag states that the truck was originally equipped with a 327. Would this have been a 2 or 4 bolt main block? It currently has a freshly rebuilt 350 4 bolt main #3970010 block bored .30 over with 991 heads, 172/150 valves. Stock cam, Headers, 2&1/2 inch exhaust with dual flow masters, edelbrock performer rpm intake and carter afb 600 cfm carb. Whoever had the truck prior performed an axle swap so that I now have, what I believe to be a 71 or 72 Dana 44 front because it has disc brakes, and a gm corp. 14 bolt rear. I believe the ratio to be 4:10 as the truck is an automatic TH350/NP 205.

Given the current config. Is it worth looking for a 4 bolt main 327 or should I stick with the 350 I have? What would the stroke difference mean in terms of torque/hp and overall performance desired for a 4x4? If I stick with the current motor what are your thoughts on the heads? I've been told they are ideal for the application due to their low end torque generating capabilities and have also heard they don't breath well and are garbage. I am considering a new set of aluminum heads but would like to hear some suggestions on brand and matching cam config. Also .194 or .202?

Lastly, my column shifter needs to be rebuilt. The shifter is sticky and it is difficult to pull toward the driver to shift and is worn. What parts do I need to replace and where are they located in the column? And where in the hell does one find the lower shifter rod bushing?

Overall thoughts on current mods?

[52napco]

No 327 engines were 4 bolt mains. In 1968 it would have had a large journal
Engine but 4 biolts did not come along till 1969. It wojld not be worth tbe effort
Just enjoy it as is.

[trac209]

Welcome to the board,I agree stick with your 350 engine and as for your column being hard to pull forward to shift first you could remove the indicator light housing and grease inside the shift mechanism. What you do is remove it then shift into low and you'll see what needs greasing. Then you can also remove the shift lever and grease in there too.

I was having the same issue as you and it was just because it was dried out in there,after greasing it was operating perfectly.

[jocko]

Another vote for go with what you've got. It would be nice to have THE original 327 and install it IF you were doing a frame off resto. But, if that is not the case, then enjoy the 350 and spend the $ elsewhere. You CAN restore the 350 to look just like the 327, including the manifold oil fill tube. Here's my 68 327 (transplant from a 68 Camaro into my 57 - can you tell this is an old photo? ha, circa 1983-ish, when vel stacks were "cool"...), wish I still had it!

[tonyr0774]

Thank you guys for your input thus far. What are your thoughts on the "heads" question?

[trac209]

As to your heads question what are you looking for in a truck? Most aluminum heads are designed to increase flow especially at higher rpms. For a 4x4 low end torque is usually what's needed best.
Off idle torque and throttle response are assets a 4x4 needs IMHO. And since most aluminum heads are of the 2.02 1.60 variety some off idle to mid torque is lost.

[tonyr0774]

I would like to retain low end and gain a little mid power. Would switching my# 991 172/150 with some 194/150's help? Does no one make a set of aluminum for a 4x4 application?

[57taskforce]

Have you considered the gm performance parts iron vortec heads? You could even rob them from a 96-99 truck 350 if you wanted. They flow pretty good and make the power where you need it in a 4x4. You'd have to get a vortec carb intake.

[tonyr0774]

I would rather not have to convert to Vortec heads to achieve the desired power band due to the cost associated with such a conversion.

[mechanicalman]

Originally Posted by tonyr0774

Hey guys,

Looking for a little help. I have a 68 K20 that I purchased my senior year in high school some 15 years ago. The service tag states that the truck was originally equipped with a 327. Would this have been a 2 or 4 bolt main block? It currently has a freshly rebuilt 350 4 bolt main #3970010 block bored .30 over with 991 heads, 172/150 valves. Stock cam, Headers, 2&1/2 inch exhaust with dual flow masters, edelbrock performer rpm intake and carter afb 600 cfm carb. Whoever had the truck prior performed an axle swap so that I now have, what I believe to be a 71 or 72 Dana 44 front because it has disc brakes, and a gm corp. 14 bolt rear. I believe the ratio to be 4:10 as the truck is an automatic TH350/NP 205.

Given the current config. Is it worth looking for a 4 bolt main 327 or should I stick with the 350 I have? What would the stroke difference mean in terms of torque/hp and overall performance desired for a 4x4? If I stick with the current motor what are your thoughts on the heads? I've been told they are ideal for the application due to their low end torque generating capabilities and have also heard they don't breath well and are garbage. I am considering a new set of aluminum heads but would like to hear some suggestions on brand and matching cam config. Also .194 or .202?

Lastly, my column shifter needs to be rebuilt. The shifter is sticky and it is difficult to pull toward the driver to shift and is worn. What parts do I need to replace and where are they located in the column? And where in the hell does one find the lower shifter rod bushing?

Overall thoughts on current mods?

Stick with the 350. Do you have dish or flat top pistons? What size are your tires?

[sboris]

Welcome to the forum. Have any pictures of this bad boy?

[tonyr0774]

I'm not sure which pistons I have. I think they are flat tops but can't remember. Rebuilt the motor with my dad for his 71 2wd farm truck some 10 years ago before he passed three years ago. He never really put any mileage on it other than to and from the local feed store. I do remember the cam having one of those adjustable keyway sprockets that he set for more torque. I just don't remember which type pistons or if the setting on the keyway sprocket was advanced or retarded for more low end torque. I have 33's sitting on 16.5 aluminum slot mags with a 3 inch lift. Again it has the corp. 14 bolt rear with what I believe has 4:10 gears due to the TH350 tranny.

[mechanicalman]

Originally Posted by tonyr0774

I'm not sure which pistons I have. He never really put any mileage on it other than to and from the local feed store. I do remember the cam having one of those adjustable keyway sprockets that he set for more torque.

33 tires, 411 gears and the cam is set for more torque. Headers, 2.5" ex with flowmasters, RPM Edelbrock. From a performance standpoint, those 1.72" intake valve heads are a bottle-neck for air flow and I think they were mostly for 2V carbs from the factory. Those heads don't go with 411 gears.

But, what do you want it to do, more top end power? Do you depend on it as a daily driver at this time? Can you tear the heads off to see what pistons you have for sure and be able to wait until you can get a set of heads?

A good set of heads and an RV style cam will get you 60HP above what you have now easy. If you have flat top pistons, you will need larger chamber heads no smaller than 72cc no larger than 76cc. Most aftermarket aluminum heads have 64cc chambers, and Vortecs have 64cc chambers, too much compression for that heavy a vehicle unless you are running dish pistons or special fuel.

If flat-tops I'd recommend these assembled heads, 1,072.06$ for a pair shipped. Cast iron, and I'd use the fel-pro steel shim head gaskets on them and that will put you at about 8.8:1 compression. Check piston to deck clearance before you order heads or gaskets.
http://www.summitracing.com/parts/wr...make/chevrolet

This cam
http://www.summitracing.com/parts/cc...make/chevrolet

These lifters are the best you can get for durability.
http://www.ebay.com/itm/SBC-BBC-283-...707f91&vxp=mtr