How much cash you got?

 

That's about 275 crank hp, getting to 375 is going to take some effort. Cam change might add 25-40 at peak but would pick up some torque everywhere, you will need to look at changing valve springs, too.
Headers if you don't have them. 15hp
Good 650 Holley. 10hp
High(er) rise intake and carb spacer. 10hp
Nitrous? 250hp

 

Money is not the driving factor for the engine, I just don't want to drop it into someone and hand over a heap of cash for HP.
Would like to get a plan and do bit by bit learning on the way.

I was looking to start with a Comp Thumper cam(08-600-8) Grind 283HR7...paired with valve springs s , retainers and locks.. This should produce the nice Leopy idle hot rod sound and good low to mid torque.

Drop the heads in to get valve train done?

 

Do a search for the thumpr cam on this forum. Start reading this part of the forum to expand your knowledge of what to look for. I like the comp XE 256 for performance and torque. Others here find that cam small but gobs of torque. Good luck with your engine.

 

If it has 062 Vortec heads and they have decent compression (9.5?), you have a good starting point for about 330-350 crank horsepower. However, stock Vortec heads are limited for lift, so you will need to have them reworked or use different springs if you want lift over about .420 inch. A true Vortec short block should also be set up for a roller cam, so I would not even consider using a flat tappet cam.

Both the Thumper and the XE 256 cams have too much lift for stock Vortec heads. The Thumper 08-600-8 also has too much duration to work well for a medium build.

If a reliable 330-350 horsepower build would keep you happy, I would find a replacement roller cam with duration of about 215-220 degrees @ .050 , a good dual plane intake (Edelbrock Performer, etc.), 650 cfm carburetor, and headers with full dual exhaust. You could try using a more aggressive cam, but would probably need both lower rear end gears and a high stall torque converter to make it work well.

Bruce

 

Keeping the cast heads will cost you a lot in other modifications to reach your goal of +100 hp, and that 100 hp will be out of your typical RPM range on the street. Just get a good set of 65cc AFR 195 or 64cc Profiler 195 heads, an XR270HR roller cam, a Performer RPM Air Gap, and a 750 Holley/Quick Fuel 4150 with vacuum secondaries (preferably 4-corner idle). If you only want 50 hp, then keep your Vortec heads.

 

That is a Mexican built L31 Vortec motor, with the stock roller cam having a duration of 191/196 degrees at .050 inch lift with lift .414/.429 an LSA of 112 degress. This is a factory roller cam. These are rated 250 hp and 330 foot pounds as originally installed in fuel injected 1996 through 2001 pickups and vans. The 062 head is the factory 64 cc chambered Vortec L31.

Converted to a 4bbl carburetor and high rise intake they probably would deliver about 280 hp on an engine dyno.

A cam with timng similar to the Comp XR270HR would add a hundred HP with modifications to the upper valve guides for lift clearance. This pretty normal for any performance cam on these heads.

Bogie

 

That is a Mexican built L31 Vortec motor, with the stock roller cam having a duration of 191/196 degrees at .050 inch lift with lift .414/.429 an LSA of 112 degress. This is a factory roller cam. These are rated 250 hp and 330 foot pounds as originally installed in fuel injected 1996 through 2001 pickups and vans.

Don't forget the 250 hp was "SAE net" as installed in a truck with water pump, alternator, fan, pulleys, muffler, etc., whereas crate engines are rated in "gross" horsepower. That's why the RamJet engine is rated at 355 hp with the same heads and slightly larger cam than the L31 engine. It would probably be 280-300 hp if rated "net". Same is true for the 260 hp base Goodwrench engine (with small 4bbl and headers). With its very low compression and poor heads, it would probably be around 190-210 net.

 

I wanted to go further with my comments but had to break for other matters.

Getting 370 to 380 hp at about 5600 RPM and about 400 pounf feet of torque around 3500 RPM with these heads in stock condition other than molesting the top of the guides for clearance is a well worn path. This power benefits from an Edlebrock Performer RPM intake or equivalent, a 650 tp 750 cfm carb be that Holley, Edlebrock or something else of similar size. It's simpler to go further with the 750, a simple street version with vacuum secodaries is adequate nothing race ready is necessary. Plus long tube headers and dual exhaust with quality mufflers. This is crankshaft power not rear tire. Exhaust systems and drive trains can eat a lot of power so attention to installation details is of utmost importance.

This engine with these heads can easily produce into the lower 400's with a .030 mill cut on the heads and a .015 felpro gasket, 1.6 roller rockers dont forget the factory roller lifters use a 7.2 inch push rod not the standard 7.8 incher.. Plus a light port job. In terms of effort and cost it doesn't take much to make an L31 rock.

These heads crack if cooked, that makes the cooling system very critical, there is no room to cook these heads. Running them dry is what does it, you cannot loose coolant, you cannot boil the coolant, the absolute temp within reason is not the most critical thing, but coolat loosing contact with the metal surface either by boiling off or draining off results in cracked heads.

Bogie

 

I agree to all this, and I'm driving with a similar set up.
But be aware that already at a lift around .530 you might run into reatiner to seal clearance problems. This will vary between heads, as we are talking about very small differences. You MUST measure to find ut the maximum lift on YOUR heads.

My cam lift is .500, and fron the start I used1.6 rockers. Those got overheated, probably because of clearece issues, as my second measurment check showed me that my heads could only take app .520" lift.
Changed to 1.5 full roller rockers, and haven't had any problems after that.

I choosed a cam with nless overlap, because I like a nice low rpm idle, low fuel consumption on low rpm highway driving (OD trans) and enough vacuum for my brakes.
But less overlap will lower the max hp a bit, and more overlap will make the engine able to increase the rpm faster.

 

You need to get the CR up to make best use of the cam. There are a lot of reasonable aluminum heads available, I have Dart SHP 180 heads and matching dual plane intake on my 355, CR is close to 10:1, it makes consistent good power. Cam is a Lunati 268/276 FT grind, used their roller rockers.


We all know the old saying, speed costs money, how fast do you want to go?

 

Thank you for all your comments, After reading posts on Thumpr cams I will rule that out, I think the plan to move forward is to get a comp cam xtreme XR276HR, sits in a good rev range and should get a good sound and power.. use the heads i have, performer manifold, and a 650 Holley. Hopefully the head shop will know how to set up the heads.

 

For max power with one 4-barrel on the street, use this manifold. DO NOT USE THE AIR GAP MANIFOLD UNLESS THE MOTOR IS 100% RACE, DUE TO STALLING AND BUCKING OF THE MOTOR AT LESS THAN FULL THROTTLE IN COOLISH OR COLD WEATHER. A street motor needs heat in the intake manifold to help atomize the air/fuel mix before it gets to the combustion chamber.
https://www.summitracing.com/parts/edl-7116/overview/

For acceptable operation of power brakes, you will need some sort of auxiliary producer of vacuum because this cam will make only about 12" of vacuum, while a power brake system needs 20" to operate properly. That's one reason the factory uses a short cam. I know there are fellows on this site who will say that I am full of beans for saying that, and that you only need 19 or 18 or 17 or 16 or 15 or 14 or 13, or 12, but that's only because they don't want to be made to look like they don't know what they're doing. Probably the best thing you could do is convert an Astro hydroboost or a hydroboost from another model of car or truck......
https://bangshift.com/general-news/.../tech-how-to-swap-a-junkyard-hyrdoboost-on-your-classic-gm-muscle-car-or-truck/

.

 

x2 on the air gap. I ran it on my BBC and was not happy with it. A true dual plane is the right way to go on the street. As far as brakes go, mine work just fine with 13" vacuum at idle in gear. I'm not disagreeing with Tech, I just know what has worked on my car.

 

I've never found vacuum levels around 13-14" to be a problem with power brakes either.

I will go on to say why does anyone but a Grandma or a soccer mom need power brakes anyway?? All they are is a convenience item...a car doesn't stop in any shorter of a distance just because it has power assisted brakes....manual brakes will stop it in the exact same distance.
You want shorter stopping distance you have to make changes at the wheel, either rotor diameter, caliper , or pad size/compound.

All power assist does is reduce the amount of pedal pressure the driver has to apply.

I removed the vacuum booster assist from my Nova and converted it to manual brake master cylinder and pedal....it doesn't stop any different than it did before removing the assist, and now I don't have to worry one bit about how much vacuum my cam lets the engine produce.:thumbup:

So many out there in hotrod land seem to think that power assisted brakes means shorter stopping distance….it don't.

 

I think that folklore may come from the old days of 4-wheel drum brakes. Took forever to stop them. I had a 1969 buick that way. Then drove a car with front disc and no power assist and it stopped way better than the Buick.

 

I didn't read all the posts above, but that 880 block is probably machined for a roller cam, and may even have one now. I suggest you determine the cam's specs and move forward from there. If it is a roller, there's no reason to even look at a flat tappet cam. And the roller lifters should be re-usable.

The 350 RamJet crate engine uses that block (or one very similar) & head combo along with a 196/206 roller cam with 1.6 rockers to make 355 HP at the flywheel. I have that same combo in my 82 pickup, but have added LS6 valve springs with Comp #787 retainers and #648 locks. My Eagle rotating kit with 9.005" deck makes for approx 9.4:1 compression.

Anyway, my engine makes around 19-20" vacuum, pulls from right off idle, and accelerates the 3800 lb truck quite well, especially considering it has a 2.73 axle.(!) I can only imagine how well it would accelerate your light 32 roadster with 3.75 axle.

The cam costs $220 new, but you can find them for much less on the Internet as brand new "take-outs" from RamJet and HT383 engines. There is also a good section of aftermarket rollers, but I suggest you check max valve lift at EACH valve before choosing a cam. Even if you go the LS6 spring route.