I have a 1990 Trans AM GTA that was swapped with a carbed 305. Just picked up a 350 today, not very familiar with Chevys I've been building imports for a while.

Anyways, the motor that I got has an engine code 14093638, stamped 5.7L on the side. It was pulled from a Trans Am GTA but the guy said it had previously come from a pickup truck. Is there a difference between this motor and one from a Camaro or Trans Am?

I have a Holley carb, Edelbrock intake, headers, and exhaust. Was thinking about putting a cam into it but I'm not sure which one to use. Looking for something very budget friendly that will make good low end torque. Also any suggestions of how I could easily make a bit more torque/HP. thanks!!

 

638 blocks are sort of the in between years of the change from flat tappet to roller tappet camshafts. They are roller cam capable, but not all of them were finished. If you look at the three bosses in the lifter valley, if they're drilled and tapped you're good to go. If not, you'll have to drill and tap the bosses or run a flat tappet cam. I highly recommend going the roller cam route, even though it does cost you a few hundred dollars more than a flat tappet setup.

That being said, what are you using for heads? Heads that came with the motor? What are the casting numbers? Target compression ratio? Auto or manual transmission? Rear gear ratio? Tire size? The more info you can provide, the more we can help with selecting a camshaft or any other engine parts.

 

 

083 heads are a stock TPI head, if I remember right. They're not real great, but I've heard they can be vastly improved by some porting. Additionally, they use the 86 or 87+ style intake bolt pattern. Older intakes can be modified to fit if you're handy.

Depending on what your goals for the car are, I would take the opportunity to switch to a better head. Vortec heads, whether GM or aftermarket, are about the best bang for your buck here. The down side to buying used Vortec heads, is that they're somewhat crack prone. I'd say that one out of every six or seven heads that passes through my buddy's machine shop has a crack.

If I were starting from scratch, I'd probably go this route. There's quite a few people here that are very happy with the Patriot Vortec heads (Promaxx now, I guess). After buying my heads, having all the machine work done, new valves, valve job, etc, I'm in this much, if not more, and I'm still stuck with an iron head. Not to mention the hours spent porting. Don't take my word for gospel, though. Do some research and plan out what your goals are, along with your budget.
(Assembled)
https://www.summitracing.com/parts/pmx-2169/overview/
(Bare)
https://www.summitracing.com/parts/pmx-2150/overview/

This will help you find your rear gear ratio.
http://www.how-to-build-hotrods.com/gear-ratio.html

Additionally, do you know for sure that you have a TH350 transmission? These cars came with a 700R4 overdrive transmission from the factory.

 

Those heads aren't bad for a budget build. In a 92 Z28 L98 engine those heads made 245 hp and like 340ft lb of torque with a very mild roller cam. Yes Vortecs will give you more power but if you are happy with upwards of 300HP you can do it with these heads and save some $.

 

I agree they're not bad for a bolt-on stocker type of build. But as I mentioned, it really depends on what his goals are. If he wants performance he's going to need to move to heads that will breath more. Better to pay for it once rather than twice. But that's just my opinion.

 

I would be more than happy with 245hp and 340ft lb of torque. Thanks everyone for the help, I have very little knowledge on the subject so I'm trying to learn. What would a good budget cam be to get those kinds of results? I think I'm going to stick with these heads for now, maybe cruise Craigslist and see if I can't find something better eventually.

 

Check and see if its equipped with a roller cam first and I hope it is. If not flat tappet cams are in abundance and very cheap. Use something 215-220 duration range with under .465 lift and you should make close to 300HP with your headers and other goodies you already have if its tuned in right. What size Holley do you have?

 

How would I tell whether or not I have a roller cam?

 

Keep in mind that those heads run out of steam around 4500 RPM due to the poor flowing exhaust ports and low lift, so you'll want to run a camshaft that will maximize your potential at or before then. You'll probably be looking at truck cams for the most part.

 

The intake on a stock TPI not the heads restrict the engine at 4500 RPM. Ive seen carbed L98s pull good to 5500+ RPM but a cam with max rpm range of 5500 would be most suitable and plenty for a mild street engine.

 

That's why the TPI paired with 083 heads does alright. Tons of torque, and they both peter out around 4500. Theoretically, by the numbers, a 350 that has a head that flows 185 CFM on the intake should peak around 4500 RPM. Of course, the size of the cam will adjust this. Larger duration usually moves the peak and usable RPM range higher in the column. If .465 as you mentioned is the maximum lift he should go, he's going to have a very difficult time finding any sort of cam that is going to move the RPM range higher. And even so, I find it's difficult to think that 185 intake and 110 exhaust CFM at .500 lift is going to make any power up high anyways.

My recommendation to the OP: If you're happy with just a little pick-me-up and don't plan on rebuilding the engine, etc, I would just leave everything as is and swap the 350 in. The 350 will provide a nice bump up from the power that you're used to with the 305. That being said, since you do already have a motor in the car, this is probably your best chance to rebuilt the 350 since it's already out of the car, etc.

 

The 083 heads aren't a bad head. In the days before Vortec head mania, the 083 were the next step down after the Corvette/ZZ4 aluminum heads. GMPP used them on the 300hp/350 crate engine up until switching over to the Vortec version they offer now.

Where you run into problems is the cost involve rehabbing an old set of cast iron heads, vs the advantages of aftermarket aluminum options. Plus the availability of Vortec ports. If they're OK, and fit your goals, there's no reason not to use them.

 

I agree. I think maybe I'm just having trouble communicating my opinion. I feel that if he wants to run them, he should just run them as-is. But if he needs to do anything that involves spending money on them, he'd be better off putting that money towards something else. IF .465 is the actual lift limit, cam selection is very slim. You can't even run a Hot Cam with that. Then you're looking at modifying the heads, screw in studs, beehive springs or what not. If you're going in that far you might as well just get a different head that already has everything you need, but better.

 

His very first post says he was looking for very budget friendly with good torque.. 083 heads he already has along with headers, a good carb, and manifold fits that bill I think. Not a huge selection of roller cams to choose from to go with a stock head but there are some. Herbert cams has some and honestly the stock cam is probably enough for him if 250HP 350ft lb torque is enough to satisfy him.

 

Decided I'm going to go ahead and swap it and keep it stock for now. Gonna clean the motor up as well as I can and see what it will do stock. Maybe later on down the road I will pull it and rebuild the whole thing but I'll see how it is stock for now. Thanks!