Help me make some chevy power!

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I have just bought a 350 GM crate motor in need of a +30thou bore job. I want to build this engine to make around 350 horsepower. It has standard heads (33417369) which i don't really want to change yet, for cost reasons. I want to use this truck fairly regular and with the UKs high fuel cost i did'nt want to go for a m***ive carb!

I would love to hear everyones opinions on different parts including pistons, cam, intake, carb and torque converter.

This engine is for my 1960 apache panel which is currently running a 305. It has a TH350 and a 3.23:1 positraction axle.

Thanks in advance, Steve.
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flat top pistons, 262xtreme entergy comp cam, performer rpm intake, 600cfm holley, 1600 to 1800 stall "you can get by with a stock one. You should be in the 300hp range and get very decent fuel mileage with that setup.

 

if you want that kind of power you'll probably need to either set up the truck to run at higher rpm, or else get some better heads.

or just put a little blower on it, and pay LLL for petrol....

 

On the "cheap" with those heads? OK, flat top pistons for sure! Comp Cams 260H, Edelbrock Performer intake (NOT the RPM one), have the bowls blended under the valves, and a 600/650 Holley double pumper carb. I used to suggest the 3310 Holleys, but they ain't what they used to be. Also curve the distributor to limit some of the mechanical advance so you can run a few more degrees initial. You've got a fairly heavy vehicle, so don't get carried away with mods that'll kill low RPM power. Id even consider an SP2P intake. Tiny *** runners, but very crisp in response. I don't remember who makes it, but they're usuall really cheap cause noone wants em

 

Agree w/Groucho! If you've got a choice too, the exhaust side benefits w/lesser diameter pipe and longer lengths-to make torque, there are some guys on here who know this science cold. I don't know a better street cam than the GM 327ci/340HP hydraulic cam. Good mileage, great HP, and just a hint of rough idle. These guys know the newer, aftermarket cams, I did like the stock GM selection since they were a bargain.

 

OOPS! Add flatop pistons to my #4 post

 

For a heavier vehicle like your Apache I'd do one of those Comp Cams X-treme 4x4 cam kits, cast pistons, stock rods with ARP's, Performer intake, 600 4bbl, HEI ignition, long tube headers, and a stock converter. This should make around 260hp at least but a real good 350ft/lbs down low that you need with your gear and vehicle weight.

 

Then you need to try the 262xtreme entergy comp cam, it has a lope to it, gets 20+ MPG in my coupe, and it will run like a ****d ape. I have almost exactly the same combo that I mentioned EXCEPT I have better heads. With the 260H cam or the 262 xtreme cam, the performer RPM would match those 2 cams better as far as having a matching combo.

 

I'm not familiar with the casting numbers on the heads, but sence you will probably be looking at a valve job to go along with the rebore, you should think about putting in bigger valves, to go along with this other stuff. With the right parts a 350 will put out more than enough power for daily use. I'm running early 305 4bbl heads on mine that were ported and have 1.94 intake valves, a Comp 268 High Energy cam, and flat topped pistons, with a tweeked "Canadian" 2 bbl intake and 500 cfm Holley. It hauls my full size pickup around very nicely.

 

What Groucho said. Plus, I'd add top-quality spark plug wires and an MSD ignition system- dizzy, 6A box and coil.

That's basically what I had in my '55 Chevy.

 

I don't think any mild 350 chev will make 350hp with a 600 holley. Maybe a 650 DP but not a 600 vac. I'll go with everything everyone said with 2 exceptions. Use a 750 vacuum carburetor for power/mileage, and don't use an SP2P intake, they have distribution issues and encourage detonation. For the 1hp per cu number, consider a performer RPM intake. Good luck.

 

Thankyou for all your replys. At the moment i'm swinging towards the 260h or xtreme 262 cam and dual plane plus a 600 holley which i can pinch from the 305 motor. Can anyone recommend a particular brand of piston or material and compression ratio (current heads 76cc)? Also would a "saturday night special" be about right as far as torque converters go?
Would this kit suit my needs? Idle-7200 rpm range apparently?!
http://www.jegs.com/webapp/wcs/stores/servlet/product_10001_10002_28878_-1
Thanks again for everyones help. Steve.

 

You have a heavy vehicle, a tall axle ratio, tall tires (guessing) and a wide ratio transmission.
How did you arrive at 350 hp? What you need is 500 ft. lbs., not 350 hp. 7,200 RPM is the last thing you need.
You also need to be very careful about converter choice because your engine is turning slow at cruising speed, and if you're not above your stall speed your mileage will be terrible.
Just curious - why did you start with a crate motor when you're going to replace most of the parts?

 

This one's easy.....speed pro flat tops, HEI dis, vortec heads ($480.00 a pair best buy on Earth) edelbrock performer#2116, 750 cfm holley # 0-4479, comp cams xe-268H-10, valve springs, roller rockers...good headers........makes 384hp@5700rpm 354 lb.ft. torque on a superflow dyno

 

my wild guess is that when you go shopping for small block Chevys in England, you kind of have to take what you can find?

 

Squirrel, thats exactly right, chevy engines are few and far between over here.
Panic, i understand what your saying and totally agree (27" tyres)but just want to make a strong and suitable lump and thought i'd chase down some advise from people who know there chevys!
I'd like to take the vortec route but with shipping them and import duty on top its out of the budget for the time being. At the moment i'm thinking speed pro flat tops, extreme energy 260 cam with a performer intake and 600 holley. It wont make 350hp but hopefully a strong 300-310hp and a good basis for a head upgrade one day! What torque converter would suit- standard? sizzler? sat night special?
Thanks again for all your replys, Steve.

 

I'd be looking for 2200ish stall. In the states, torque converter rebuilders can tweak a stock one into what's commonly referred to as corvette or S-10 spec, coincidentally around 2200 stall.

 

2200 stall limits your cam choice quite a bit. You won't have serious power until much higher with a hot cam, and with your gears your launch will be "flat". Idle quality is also down since the engine is already trying to pull the car at idle. I have a 9.5" converter in my street car because it has manual brakes and rough idle - much easier to drive.

 

Back for more advise! Looks like my budget (wife!) is gonna stretch to a new pair of vortecs! I'm thinking summit rebuild kit with flat tops and moly rings, stock vortecs, comp 268h cam, performer intake, 600 holley carb and a saturday night torque converter.
Does this sound like a combo that will work for me? What power would it make? And what rockers are recommended?
Any advise or suggestions would be great. Steve.

 

Glad your budget has changed. Here's what I'd do

First off, dump that 600 holley in the ocean, don't even bother with a rope, it's too small to be an anchor. 600 holleys have no business on any performance 350. I understand if you need to use it for now & plan to replace it later. That carb will negate gains from the heads & cam.

If you have the hood clearance, get the performer RPM and see if you can use an open 1" spacer too. The 350 you describe will respond to the extra plenum volume and the torque tradeoff is nil.

Vortecs have small combustion chambers, I don't know the octane of the fuels available, but you're on the edge of acceptability here in the states. A GMPP 350HO, (330 hp, 380 ft-lbs) which also uses vortec heads, has dished pistons.

Rockers, you'd probably be fine with anyone's full roller. But avoid those using only a roller tip with a stock type ball fulcrum, I've seen many horrendous rocker failures with those "longslot" rockers. FWIW I used to be a manufacturing engineer at an aftermarket company that made rocker arms for a half dozen automakers and most of the US performance retailers. I won't reveal any of their secrets or quality specs, but I will tell you since then my good engines run comp cams pro magnums. And yeah, they're pricey. But so are dropped valves from busted rockers knocking the retainers off.

However, I also have a set of harland sharps on a 383 chevy that have been rocking happily since 1988. Wowzers

Summit's engine kits were kinda pricey the last time I checked. Don't know if they export, but try northernautoparts.com for good prices on rebuild kits. TRW forged pistons are cheap and proven.

good luck

 

if you want to buy cheap, quality speed parts try www.compe***ionproducts.com the best prices anywhere.

 

Thanks for the replys, i will be using the holley as i already have it- what carb you recommend for future reference? Also according to the kit i looked at i should achieve 9.5-1 compression with 64cc vortecs and flat tops. Do you think thats ok- i think fuel round here is 91 octane and equivalant to $9 a gallon- scary huh!!!
Are the self alligning comp magnums ok? Whats the heavy duty stamped rockers like?
What horsepower do you reckon this will make?
Steve.

 

I use enginetech for my cheaper car parts.

I am building a similar engine, but here in canada I have a larger pile of parts to pick from. 400 sbc with dish pistons, 462 casting double hump heads, 224@50 gm camshaft. I would be be happy with 350hp, but I am really shooting for torque.

 

I have heard that putting a set of 305 heads with 58cc chambers on a dish piston 350 with a small cam like a 327/350hp would make a decent little budget motor has anyone used these heads on a performance application?

 

This should make a real torquey motor, but the small ports will hold the RPM's down, I actually did one simialar, a 327 with 283 heads and that exact cam, sounded great, pulled hard, but ran out of steam pretty low (can't remember what speed). Would be a great setup in a heavy vehicle, especially if you happen to have the parts laying around that you know are good and wouldn't have to spend a ton of cash on.

 

The ports on the 305 heads are pretty small and will limit your top end. Plus the valves are smaller, although you can put bigger valves in. There are better choices, but if you already have them and limited budget, go ahead. There are worse choices as well.

 

If you want neck snapping response and killer throttle control (but don't care about the 3mpg loss) try a 650 or 700 double pumper.

If you want an efficient carb that can still whoop *** at WOT, but gets reasonable mileage, use a spreadbore 750 vacuum secondary.

Actually, I'd like to modify my intake recommendation. The vortec performer RPM won't accept a spread bore carb without an adapter, and spread bore adapters are notorious for robbing power. So if your heart is set on a spread bore, get the regular performer and use a spacer with it too. Personally, I like the rpm/double pumper combo for my rides. You just can't beat the response of those mechanical secondary carbs, and the RPM is hands down the most versatile performance intake ever offered for a SBC.

good luck (and avoid cheap aftermarket rockers! Stock or full roller, no in between)

 

With todays **** quality fuel ( why do we put up with this..!) what ias MOST important is Quench. Try and get the head to piston clearance in the quench area as small as possible to encourage swirl and reduce the chances of detonation. If you look on the some the many Chev forums the move today is to steel shim head gaskets rather than the thicker composite types. This is to reduce that quench volume as much as possible. I'm not too sure what the closest clearance is but it's almost in the area of contact. If you are financial enough,get the block decked to reduce the volume as much as possible. Pistons popping up above the deck are OK as long as remember to measure torqued gasket thickness!!!
Next,fabricate or purchase a baffle to fit under the intake to keep the intake air charge temp down. I would even go as far as polishing the outside of the intake and block off the exhaust heat riser .
Cold air makes power so set up a good duct for your intake air. You should be able to run a range colder with your plugs if this works out for you,further reducing detonation .
I realise your climate is cooler in the UK,but a thermo which allows the engine to run in the 75-80 C region is a good idea.
No ones mentioned push rods,do you know what type you have now? some are moly and some are mild steel. Go for moly ones if you don't have them already.
And really,I'd forget horsepower figures,you should really be seeking Torque,because on the street Torque is king!

 

^^^^^

Moroso makes a nice intake valley baffle like Mercmad describes, no drilling or tapping, it's held down by 2 leaf springs that press against the bottom of the intake. Reasonably priced and minimizes hot oil splash.

 

Build a bullet proof stock type motor and when you need the power, hit the nitrous. You don't have to pay the price of a big cam, carb or expensive heads every time you start the motor. When you really need the power, pull the trigger. It's kinda like having a big gun. Only shoot it when you need it and you don't have to buy bullets except when you use it.