350 build advice.Heads,Cam .Etc.

[Snoots]

I'd deck the block and heads.

And I DO know everything! I just can't remember it all.

Signed,
Not Annoyed Enough

 

[GXPWeasel]

Glad to see this post guys. I'm a noob as well (to this site), and within the next few months will be pulling and rebuilding the 305 in my '82 Sierra. I've build a few engines before, but I've learned a lot since then. I'm happy to hear that I'm on the right path when it comes to finding a very reputable machine shop, and spend my money there correctly, before just dumping a bunch of expensive parts into the engine, and expecting miracles. I think I made that mistake with my first engine build at the age of 16. I was too green.

 

[QBuff02]

I have in my vast collection of junk.A good 350 target master engine shortblock.I have a pair of 993 casting heads, and a pair of swirl port 193 throttle body heads. Also have an edelbrock performer mani. W/ egr provisions.Carbs I have a vac secondary 600 Holley.An edelbrock performer carb and a rebuilt qjet. Last but not least a pair of long tube headers.Going into a 1985 C10, goal 400 ft lbs torque and somewhere around 300hp with reasonable gas mileage.My thoughts are the qjet, run the egr, the swirl port heads, and a isky 264cam. .480 lift 264 advertised duration 214 duration at.050 108 LSA. Any input would be appreciated.

In my opinion I would use the 993's over the swirl ports. The swirl ports just don't have "it" up top. Any intake is going to be better than a stock intake and for best all around i'd use your q-jet to get the most bang for your buck. Almost any head you use will need some kind of machine work and spring work if you get in the area of .440 lift or more because At that it's getting pretty tight for coil bind and encroaching on the valve seals on MOST stock heads. If you're going to run any kind of performance cam you'd be money ahead to have the springs set up to match the cam you decide to install. If you use heads that have pressed in rocker arm studs, you'd be wise to have them upgraded to screw in studs as you risk pulling them with more aggressive cam profiles. No matter the head you use, you should have them gone through, cleaned up and some valve work performed at a minimum. But have the springs, pockets, and valve seals set up for a good cam. Compression is key, and most factory heads just won't get you there, so plan on a good flat top piston and decking the block and heads both to help get your compression up, and your quench area down. As far as a cam goes, you'd be well off with a cam in the .205-.215 duration @.050 and somewhere around .425-.450 lift and 110ish LSA for a build like yours. basically building a good all around little engine. If you set it up right 350hp and 400ft lbs is easily attainable and probably all below 5,000 rpm.

 

[QBuff02]

You didn't annoy me.I was trying not to annoy you guys.And I never tell people right off what I've done seen etc. I don't want to come off like a know it all.Nobody knows it all!!!.Just like I sometimes wonder why take 30 thousandth off the top of a block for zero deck or mill a head for compression when I could offset grind the crank,to get zero deck or gain compression.It makes sense to me just haven't tried it yet.But I am sure someone knows why it's a bad idea.

Reading back through I saw this post so figured i'd throw my .02 in on it. The biggest reason, it's just not feasible. especially cost wise. Decking a block and milling heads are done for two separate reasons. All things being equal, you deck a block to get as close to or right at "zero" deck height. The most effective, most efficient is to have the piston within zero to a few thousandths from zero. A little wiggle room for piston rock isn't a bad thing. Decking heads is done to raise compression. (obviously decking either is also done to clean up mating/gasket surfaces) If you offset grind the crank, you can in theory simply go to a smaller journal connecting rod but now you have to buy custom pistons with an offset piston pin to counter the offset crank throw. And when it's all said and done, those parts are now specific to that very engine block. say you get it hot and warp or crack it, if it was setup for a theoretical -.030 deck height offset ground into the crank journals but your replacement block is closer to .005 (this theory by the way is measuring the correct way from the crank journal to the deck surface) you now have to cut .025 off of every piston or order a set of pistons that are .025 shorter from the head to the wristpin. Even though i'm using theoretical numbers here, You see where this is going right.. All manufacturing processes have tolerances of +/- a certain amount, so you measure up from the crank journals to the deck of the block and figure out how much to take from there if you want to achieve zero deck height. And then if we want to get critical we measure across the surfaces of the block from crank journals up from front to back of the block to see how much variance there is. it can be off up and down as well as front to back. that's part of engine blueprinting-making sure the engine is "square" and everything is equal. You can't gain compression by offset grinding the crank, all things equal the pistons would be sticking out of the bores. That's why there's flat top and domed pistons, you either make the combustion chamber of the head smaller or the piston heads themselves larger to increase compression. BUT, for a cheater engine offset grinding a factory crank is a great way to make cubic inches and or rpm's! And it all looks stock by the numbers if the engine ever gets teched! So I've heard anyway.. Lol

 

[MikeB]

the 993s are runners up but they do have some hope. They are a heavy enough casting you can port them. You can put bigger valves in them like 2.02 int/1.60 exh... for starters. But still a large chamber so it's tough to get any compression without domed pistons.

Yes, even a flat top piston (with 4 valve reliefs) in an otherwise stock 350 (76cc combustion chamber, .038" gasket, and 9.025" deck height) will get you only around 8.5:1 according to my calcs.

Decking the block to 9.005" with the same flat top pistons gets you 8.8:1, which is fine for a mild cam and iron heads. Heck, the basic Goodwrench engine which is spec'd at having 8.5:1 and is actually closer to 7.9:1, makes very nice "everyday use" power in a truck with a small 4bbl and dual exhausts. Yes, I know the cam is small and the heads aren't great, but the engine makes lots of torque right off idle, and pulls to around 4500 RPM. I say this having used one in my 69 C10, and installed others in a 51 pickup and 55 sedan.

You wouldn't want to go much tighter than .043" quench, which is .038" gasket + .005" "piston down the hole", so the only way I see to get any more compression is to use 64cc or 72cc combustion chambers.

However, I think 8.8:1 would be fine, especially if that cam you listed has a 108 LSA (does it really?), which closes the intake valve sooner on the compression stroke that a similar cam with a 110-112 LSA.

One final note: I'd have the heads magnafluxed for cracks before you put any money into them. Also, be sure to use new valves springs recommended by the cam manufacturer.

Edit: Just noticed the 993 heads have 75cc chambers (nominal of course) so my CR numbers above would be around 0.1 higher. Whoopee!

 

[bft305]

Hey Ricko, I have a similar set up. Found a clean tbi motor and didn’t want to spend lots of money. I used a lunati voodoo cam 10120701. With the tbi heads and an elderbrock RPM intake manifold, truck avenger carb. Oh and of course new valve springs. Figure I am around 250hp and 400ft/lbs. Is it a speed demon.... no, but I mostly off road and it has great torque. You can also look up Rich wayand’s posts about cams. I would say go for it and skip spending money on vortex heads. That will run you about $600 just for the vortec heads.

 

[MikeB]

I just read that you want to use the truck to tow. if that's the case, you'll want something not much bigger than a stock cam, and definitely not 214 degrees INTAKE duration, unless your truck has 3.42 or 3.73 gears. 204/214 on a 110 LSA would work OK, and the 214 exhaust lobe might help out a poor exhaust port. Most 204/214 cams have a wider LSA, so look around.

I like these cams for general street use and towing, even with 8.0-8.5 compression: Crane #100032 or the Summit Racing version #SUM-K00032.

I also like the Isky cam that is 208/208 duration with 108 LSA. Can't find the P/N but I think it would work great with stock compression, and would place an emphasis on mid-range torque.

 

[Ricko1966]

Reading back through I saw this post so figured i'd throw my .02 in on it. The biggest reason, it's just not feasible. especially cost wise. Decking a block and milling heads are done for two separate reasons. All things being equal, you deck a block to get as close to or right at "zero" deck height. The most effective, most efficient is to have the piston within zero to a few thousandths from zero. A little wiggle room for piston rock isn't a bad thing. Decking heads is done to raise compression. (obviously decking either is also done to clean up mating/gasket surfaces) If you offset grind the crank, you can in theory simply go to a smaller journal connecting rod but now you have to buy custom pistons with an offset piston pin to counter the offset crank throw. And when it's all said and done, those parts are now specific to that very engine block. say you get it hot and warp or crack it, if it was setup for a theoretical -.030 deck height offset ground into the crank journals but your replacement block is closer to .005 (this theory by the way is measuring the correct way from the crank journal to the deck surface) you now have to cut .025 off of every piston or order a set of pistons that are .025 shorter from the head to the wristpin. Even though i'm using theoretical numbers here, You see where this is going right.. All manufacturing processes have tolerances of +/- a certain amount, so you measure up from the crank journals to the deck of the block and figure out how much to take from there if you want to achieve zero deck height. And then if we want to get critical we measure across the surfaces of the block from crank journals up from front to back of the block to see how much variance there is. it can be off up and down as well as front to back. that's part of engine blueprinting-making sure the engine is "square" and everything is equal. You can't gain compression by offset grinding the crank, all things equal the pistons would be sticking out of the bores. That's why there's flat top and domed pistons, you either make the combustion chamber of the head smaller or the piston heads themselves larger to increase compression. BUT, for a cheater engine offset grinding a factory crank is a great way to make cubic inches and or rpm's! And it all looks stock by the numbers if the engine ever gets teched! So I've heard anyway.. Lol

Just saw this, but decking the block, running a thinner head gasket,milling the head, flat top piston or parking the piston higher in the bore will all raise the compression.I have built 1 bored, decked, and squared 355. Most of my engines have been zero deck but not done exactly right. I assemble the shortblock measure my deck height disassemble and have it decked so I have.040 squish when I reassemble it.Now for made up numbers if the piston is parked .030 down the hole and you have the crank offset ground .020 now you are parked .010 in the hole you use a .030 head gasket and you'd have a cheap 0 deck motor.With stock rods and piston just .030 rod bearings.Now it over heats and your next block is..010 shorter you run a .040 head gasket and your still in good shape
The offset grind strokers I built, I built,not a kit. I had cranks ground offset for the rods I was using figured out what rods and piston would park my piston where I needed them and all was good.Just a cheap way to build a bigger engine.