Buncha newbie q's

Okay, so I'm new to the world of making my Chevy purr, but it needs some help so I'm going to try to learn enough to bring it up to date.

Here's what I've got:  A 1975 Chevy 1/2 ton, 2wd truck in excellent mechanical shape, 180,000 miles, original engine (fluids of course have been changed regularly, but everything else is bone stock), TH350, 3.73 rear end, 265/75-R16's on Centerline wheels.  The truck is basically my dirt bike/mountain bike hauler and my camping/hunting vehicle that I mostly drive long distances on the freeway and then slow speeds with a little light off road use.

Here's what I want to do: Install a 700R4 (on the way -I already know I have to cut the driveshaft and move the crossmember), Edelbrock Multiport EFI system, Edelbrock Performer Plus Cam, Roller rockers (probably Summit 1.5:1), Headers, Dual exhaust, and A/C!

Most of this stuff seems straight forward until I get into the cam and rockers.  I see rull roller rockers in Summit with 7/16" studs and with 3/8" studs.  Which do I need?  There are several lengths and diameters of pushrods too.  Will I need new ones and which ones?  Could I use the pushrods that are already in the truck?  I saw somewhere that with roller rockers you usually want to run guide plates.  Should I worry about this for my mostly lower RPM, non-racing running?  Is there anything that I'm forgetting or can anyone point out potential problems for me before I get into this project? 

Thanks!

IMO, you answered your own questions by stating that your truck is "mostly lower RPM, non-racing." 

1.  Spend your money on something other than roller rockers!  For your application, you'll see z-e-r-o benefit using 1.5 rollers.  If you fall prey to the advertising then you'll need rollers for use with OE heads (3/8" studs).  The only benefit you might witness is if you stepped up to 1.6 rockers which will create increased valve lift.   

2.  Guide plates require screw-in studs.  I doubt if you have them on your heads.  [More $$ you don't need to spend.]  

3.  If your current pushrods are straight and not worn, you certainly can use them again (and again).  With 180,000 miles on them, check to ensure that the centers aren't plugged with sludge.  You use pushrods other than standard length if you're trying to correct the valve train geometry (which is often altered by using non-standard ratio rockers).

Net net, the OE stamped rockers are just fine for your application.  Think of all those screamin' small-blocks ('Vettes, Z/28s, etc.) from the factory which had them.

Okay, maybe if I state the problem I'm trying to correct that might explain why I was looking at roller rockers.  Right now the truck is stock as stated, I forgot to mention that it's only got a 2bbl carb on it too.  It can't be making a ton of horsepower or torque. 

The major problem is that for some reason this truck has always had an overheating problem.  It didn't originally have A/C, so it only had a single core radiator.  Now it has the A/C sized radiator and the water pump is working and in good shape, but it still heats up more than I'd like to see.  I took off the catalytic converter (maybe plugged?) to see if that would help  and it did a little, but still it gets hot. 

As an example, if I'm driving down the road at 65mph in the summer here (Phoenix, AZ so maybe 110-115 degrees outside), the engine will be at about 220-225 degrees.  I was coming back from hunting a couple of weeks ago climbing a long, steep hill and hit about 225 degrees pushing about 55-60 up the hill.  Sometimes sitting at a stoplight I'll see the temp climb that high as well. 

The standard flex fan is on the truck, of course with no silicone drive, a 195 thermostat that's been checked and is good, and a standard pressure radiator cap.  I was trying to think of ways to reduce friction (and heat generated by that friction), thus the roller rockers.  I want to make sure I've got the truck running cool enough that when I install the A/C system I can actually use it. 

Do you think that with the Edelbrock EFI, headers and dual exhaust and 700R4 with a lockup converter things will run cool enough while also pulling an A/C system?  Should I be looking into heads or maybe a full block with heads at about an 8.5-9:1 compression?  Any other ideas or questions that might help me out?

You're right about rollers producing less friction, thus less heat.  That's their primary benefit - but, you wouldn't know that by the advertising hype.  However, let's be realistic... the benefit of less heat is during extended high-rpm operation not at 2,000rpm.  That's why I mentioned that you'll see zero benefit from using them.

Onto your real problem... continuous operation at 220/225* is on the warm side.  I'd focus on the radiator (proper size) and the pump to ensure it's flowing properly.  If the 220* is while cruising down the road, then the fan isn't the problem.  Another area you might explore - especially with 180,000 miles on the clock - is to have the radiator and block flushed.  If you get the cooling system to properly work, you shouldn't experience overheating even with the A/C on.

hello 

save u'r money skip the rollers

as far as runnin  hot..

you don't say if the truck has a "fan shroud"

and if the fan(not stock) if centered in it..

if no shroud .. find one..

2) in front of the radator behind grill ...

u'll see a big space...  the air goes through the grill and into here..

you want it to go through the radator  not around it..

make a cardboard(for a test) shroud to fit in this space so that the air going through grill can't go anywhere else but through the readator...

leave the bottom open but add a airdam(from any 80's g.m. car/ they are bolted to the radator suport...) 

this way the air rushing under truck goes through radator...

if this fix the runnin hot  make a better box for infront of radator..

Hmm...  Interesting idea!  Thanks!  I've got the fan shround and the fan is centered in it.  As far as I know the fan has never been changed from what came with the truck in 1975.  I was thinking of adding a fluid drive fan to reduce some HP requirements there. 

Out of curiousity, would I see any improvements using 1.6:1 rockers with the stock or Performer cam?  Headers and Edelbrock EFI are going on either way. 

I'm trying to figure out the compression ratio of the engine too, but I haven't found that anywhere.  I know it's a 4 bolt main block, but I don't really know anything about the size of the valves or compression ratio or anything.

If you decde on a clutch fan try to get a 5 blade.They came on police cars and towing packages.You should upgrade to a 4 row i cant believe it has a 2 from the factory.It sounds more lije the stright six radiator.With that kind of milage the watter pump fins could be worn away from electraylsis.  

hello  comp.if stock is 7.8to 1 to a high of 8.2 to one..

1.6 rockers on the exh  side  will help.. valve size  1.92 intake/1.50 exh.

change over to vortec heads you'll get better ports and up the comp. a point  ...  there  cheap..229.00 each..  new!!!!  valves and all...

I finally found it!  I was looking in the wrong sections of the manual.  Compression is 8.5:1 according to the manual specs.  Also according to the manual specs, HP is 145@3600rpm and TQ is 250@2200rpm.  Pretty sad lookin' numbers.  I've got a I-6 with a turbo that makes 226hp@5200rpm and 280lb-ft@3200rpm.

Would the 1.6 rockers on the exhaust help with low-end torque? 

If I changed over to Vortec heads, would they bolt up to a vortec manifold or would there be special machining required on the vortec manifold to get it to bolt to the block?  Actually, does the manifold even bolt to the block?  I thought it did, but mine's never been off, so I'm not sure...  Also, changing heads, would I need to worry about machining the block?  Or how likely would it be that I would have to machine the block?  If I'm pulling the block anyway, why not get a Vortec crate motor with zero miles? 

Part of what I'm trying to accomplish with the whole thing is minimal down-time too. 

180,000 miles is a lot to ask of a bottom end that would have to accept new heads, cam, induction. Doubling the power, which would be very easy to do, on an engine this old will take out the bottom end in pretty short order.

You'd be further ahead to put a long block or crate engine in it. You should take a look at the Pace, Sallee, or Scoggin #### web sites and look at their replacement engine selections.

If your actually putting a 700R4 in your truck, you might as well go with a newer engine that uses the one piece rear seal, these often included the needed flexplate. If you end up staying with your present transmission then you need to either use an engine with a two piece rear seal which lets you use your current flex plate; or go with a new flex plate for the one piece seal engine,  that will then allow the old transmission to mate with a one piece seal engine's crankshaft.

If your subject to a smog inspection and especially if you live in California, the Vortec heads can be a problem as they are not approved by CARB or the EPA for use on engines earlier than 1996 unless you bring all the 1996 emission controls into the receiving vehicle. So beware, there's a lot of California guys that got nailed by the emissions people and had to remove the heads. These heads use center bolts on the rocker covers and have a different intake manifold bolt pattern from earlier heads making them easy to spot by inspectors. This is not all bad news, there are a lot of aftermarket heads that are as good or better than the Vortec and have CARB/EPA exemptions. This is also not to say that the Vortec makes SMOG, it doesn't, GM simply hasn't put the effort (read cost) into getting these heads approved in Calif. or states that use Calif. law and proceedures. While this keeps the cost down for GM, it has alienated them from a large market segment.

Bogie

The 700R4 is on the way.  I bought it about three weeks ago.  It's one of those Raptor transmissions built to handle (according to them) 600hp and 600lb-ft.  I had them build it stronger than I'd probably need so that it can handle my minimal abuse and hold together, hopefully forever.  When I ordered it, I told them what it was going on, so they were building it to bolt right on.  If I change the engine (and flexplate), am I going to need a different torque converter? 

Another part of my orignal plan was to get some power out of the current engine and reduce the heat buildup, figuring that the systems I put on would work with a newer engine later when the old one finally gives up.  For now, the engine that is in the truck only uses minimal oil (puffs on startup sometimes -valve guide seals, I think) and seems pretty strong.

I'm not in CA and I haven't ever been subject to emissions testing, so my options are fairly open.