Thread: 355 build HP and Torque?

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Update on this thread: (5/31/2012)
I have edited this first post for the benefit of those who haven't read the subsequent remarks and followed along on my evolving engine build journey.

If you are looking for pictures, I have posted a bunch of them starting somewhere about page 3 of this thread.

Initially I started this thread looking for advice and directions, and believe I have hit gold when it comes to good advice.

My newly revised goals are:

Build a 350-400hp 350 engine with good low end torque and street manners that will perform impressively in my 3500lb 67 Camaro while running on cheap pump gas.

Initially I considered rebuilding an original 327, but am well on the way to putting together a roller cam 350 as shown:

Here is my original posting: I hope you enjoy the read and I appreciate your patience as I am learning as I go, Thanks, Rollie

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I'm building a 355 and have just about decided on most of the components. I am impressed by many of the comments I have seen by others here particularly techinspector1 and was wondering if he or someone could run some numbers for me. The CompCam software using the following specs predicts this combo to be somewhere around 400hp, 462torque, but I think that is high. What do you think? (See note from dyno-sym output at end of this post)

Some of these are based on my own spreadsheet calcs.

89 350 block w/ roller lifters
3.48 stroke
4.020 bore
Deck 9.013
Piston pin to top 1.561
Piston to Deck .012
Head Gasket GM 14096405, compressed height 0.028"
Quench 0.040
Vortec Heads 64.0cc (after milling) w/26915 beehive spring set
KB142 Pistons 18cc D-Dish
Static Compression 9.1
Dynamic Compression 8.2
Cam CompCam 08-410-8 260HR IVC=29 ABDC @.050
Edelbrock intake manifold, 2716 Performer Vortec EPS
Proform 67207, 650cfm carb, vacuum secondarys, electric choke
Full length 1-5/8" headers, Hooker -2130-xHKR
2-1/4" dual exhaust
Hooker Max Flow mufflers with H-Pipe

And what ever other variables I need to run a sim.
Thanks
------------------–--------------------------------------------------------------------------------
02-12-2013
Here's an updated cut and paste from a different thread after techinspector1 ran the numbers on his dyno sim program: (thanks Richard)

RPM HP TQ
1000 59 310
1500 103 360
2000 155 406
2500 200 420
3000 237 416
3500 274 411
4000 304 398
4500 317 370
5000 312 328

My first impression after seeing these numbers, was a little bit of disappointment. In my mind I was hoping for Horsepower numbers somewhere close to the 400 hp range, and the 317 peak at 4500 rpm in this table was quite a bit short of that. On the other hand, the Torque numbers are very high, in fact the peak 420 ft lbs at 2500 rpm and the flat torque curve from 2000 to 4000 rpm match or beat many of the 400+ hp engine builds I have seen. If you look closely at many of the 400 hp engine torque/horsepower curves, they will look similar to this chart up to about 4000 rpm except they continue to have strong output into the higher rpms where they reach their hp peak. I'm thinking now, for a street driven car, my engine build should be quite comparable to many higher hp engines, particularly when the rpms are kept at the low to mid range as typically used on the street.

As an interesting note of trivia, regarding my drive to build this engine, part of it is nostalgic, as I am somewhat trying to recapture experiences I had 30 years ago when I owned a similar 67 Camaro with a 400 hp 327. Looking back, and knowing what I know now, I'm thinking this new engine with a 700R4 and 3.55 rear end, will actually have better launch then my old high revving 327 with a TH400 and 2.73 rear end.

We will see.

IMO, that is a little optimistic. I would guess closer to 375 hp/420 ft. lbs. With only 206 degrees duration @ .050, you are not going to see 400 hp. Something closer to 220 degrees @ .050 would probably do it. As is, it should be a nice performer though, and a big improvement over a stock 350.

Concur w/Lynn - the 260HR is the entry level to "bad-boy" cams and is an excellent choice for "streetability". Lot of vacuum and just a bit of lope to let the trained ear know and bring a smile to your face about 1500rpm! Most folks don't drive in a manner that will notice the difference in 25 horsepower or torque one way of the other.

Have fun - it'll be a screamer with great manners and a surprise for for anyone you catch napping in the passenger seat. What's the recipient of this engine?

Regards,
Glenn

Thanks for your comments, I hope I'm on the right track.

Engine is going in my 67 Camaro.
I hope to turn a pony car into a muscle car.

Originally Posted by rollie715

I'm building a 355 and have just about decided on most of the components. I am impressed by many of the comments I have seen by others here particularly techinspector1 and was wondering if he or someone could run some numbers for me. The CompCam software using the following specs predicts this combo to be somewhere around 400hp, 462torque, but I think that is high. What do you think?

Some of these are based on my own spreadsheet calcs.

89 350 block w/ roller lifters
3.48 stroke
4.030 bore
Deck 9.013
Piston pin to top 1.561
Piston to Deck .012
Head Gasket GM 0.028
Quench 0.040
Vortec Heads 64cc w/26915 beehive spring set
KB142 Pistons 18cc D-Dish
Static Compression 9.03
Dynamic Compression 7.68
Cam CompCam 08-410-8 260HR IVC=56 ABDC
Edelbrock 2716 Performer Vortec EPS
Edelbrock 1406 600cfm carb
Full length 1-5/8" headers
2-1/4" dual exhaust

And what ever other variables I need to run a sim.
Thanks

Have the machine shop check the roundness and parallelism of the main caps. If any are off, then either align-hone or align-bore the main saddle/caps. Measure the block deck height on all 4 corners. If it isn't within a couple of thousandths, front to rear on both sides, then cut the block decks to square everything up. The heads will then sit squarely on the block and the intake manifold will sit squarely on the heads.

Use a 12cc dish instead of the 18cc and make absolutely certain that the compression height is at least 1.560". Shorter pistons with a 1.540" compression height will wreck your squish if you don't make allowances for it by cutting the decks. If you're using GM L31 Vortec heads, the chambers are likely a little larger than the advertised 64cc's, maybe 66-67. If we figure them at 66 cc's, then using 12cc pistons will put you at around 9.43:1. Then, if you use a camshaft that closes the intake valve at say.....35 degrees after bottom dead center, the resulting Dynamic Compression Ratio will be 8.30:1 and you'll like the motor a whole lot better. You have nailed the squish at 0.040", so the motor should run on cat-piss pump gas and make good power throughout the rpm range. Here is such a cam.....
HR-216/339-2S-12.90 IG Hydraulic Roller Camshaft for Chevrolet 1957-1987 V-8, 262-400
This cam has a smaller base radius than a standard cam, which will allow rod clearance at the cam if you want to rebuild the motor as a 383 down the road.

You'll want to get a couple of adjustable pushrods from the cam supplier to check for the exact pushrod length to use. You adjust the pushrods (one intake and one exhaust) to work with your combination of parts, lock down the adjustment, send them back to the supplier. They will measure them and send you the correct 1-piece pushrods to use with your combo. If you feel the need for more "rump-rump", have the manufacturer grind the cam with a tighter lobe separation angle but keep the same intake close point. The cam I spec'ed above is cut on a 112 degree lobe separation angle, so having a similar cam cut on a 108 or 106 degree lobe separation angle would give you some "rump-rump".

I would use only 1.5:1 rockers. More lift with higher ratio rockers can be more of a pain than you want to deal with. If you want to rollerize the rockers, Scorpion is a decent quality aluminum roller. Avoid using a rocker that has only a roller at the tip and uses a conventional slide ball fulcrum at the stud. Tests have shown that the benefit of roller rockers is in the fulcrum, not the tip. The conventional aftermarket roller tips are much too small to complete a mechanical couple with the tip of the valve. They won't be a negative influence, but they won't be a positive influence either. What I'm saying is to avoid those Fosdick Comp Magnum rollers, in my opinion, they're a waste of money. L31 heads used rail rockers. Is that what you are going to use? They were designed for use with a 0.430" lift cam, so pay attention in your mock-up trial assembly. Make certain that the dips made into the rocker arms on each side of the valve stem to keep the rocker centered DO NOT contact the top of the retainers. If they do, you will unseat a retainer, or retainers, during operation and you will not like the results. Pay close attention to the hole where the pushrod comes through the head if you plan to keep the rail rockers. With more valve lift, you may need to do some surgery on the holes to clear the pushrods all the way through the 720 degree cycle. You will also want to pin the studs. They are pressed in and will begin to pull out of the heads at valve spring pressures over about 260 lbs. Use the Mr Gasket kit.....
Mr. Gasket 806G - Mr. Gasket Rocker Arm Stud Pinning Kits - Overview - SummitRacing.com
You can, of course, pull the stock studs, mill the thickness of guide plates off the heads, tap the holes for studs and run the guide plates with conventional (non-rail) rocker arms. If you do that, pay attention to the holes where the pushrods come through the heads. You can use either rail rockers or guide plates, but not both.
Scorpion makes an aluminum, narrow body, self-aligning roller that will work in place of your stock self-aligning steel rockers. All you'll need to do is to pin the studs, install the rockers and check for pushrod clearance where the pushrod comes up into the head....
http://www.summitracing.com/parts/SCC-SCP1035BL/

Use the Edelbrock 7116 Performer RPM intake manifold (if these are truly L31 heads you're using and not some Fosdick aftermarket "Vortec" heads) and a rebuilt Edelbrock AVS carb, vacuum secondaries, 650 CFM.
Edelbrock has these on a broom list right now, so you can save a little on them......
#18259 Edelbrock Reconditioned #1825 Thunder Series AVS 650 cfm Off-Road Carburetor, Manual Choke
I will use nothing but mechanical chokes on anything I build. With a mechanical, YOU KNOW exactly where the choke plate is at any given moment. Mount a microswitch on the choke linkage that will illuminate a lamp on the dash, showing you when the choke is on. Use a drop base air filter housing, like off a Corvette 427, to fab up a 14" x 4" air filter arrangement. Stack two 2" filters if you can't find a 4" thick element. With a good breathing system on the top and good breathing headers on the sides, you'll have a real nice combo going for you in my opinion.

For ignition timing, I'd begin with 20 at the crank and 14 in the weights, all in by 2800. If the motor is a little hard to start (grunts back against the starter motor) with this much initial, interrupt the wire that powers the coil and mount a momentary push-off switch close to your left hand. Turn the key on, press the coil interrupt switch and hit the starter. When the motor has wound up on the starter, let go of the starter key and the momentary switch and the motor will be running with no long grinding on the starter. No muss, no fuss. Slick, no? Use a Crane adjustable vacuum advance kit to dial in the vacuum advance timing. If you play with this enough, you can get it right on the money for your combination.....
Crane Cams 99600-1 - Crane Vacuum Advance Kits - Overview - SummitRacing.com
Use whatever distributor gear the cam grinder recommends for his cam or you could frag the distributor drive gear on the cam. Here's a bronze gear and a composite gear for use with a steel billet cam core.......
http://www.howardscams.com/index.php/distributor-gears

All else looks good and although my DynoSim software is in Phoenix, I would reckon this motor would produce 425hp / 400ft/lbs. Since the cam comes on at around 1600 and the intake manifold comes on at around 1500, I would probably use a slightly looser converter than stock, something like 2000-2200 stall. You can run a 3500 stall on the street without much hassle and the car will be noticably quicker, so maybe a 2500-3000 stall would work better for you. I think most of the subtle stalls (2000, etc.) use a conventional size converter with re-worked internals. The higher stall units will use a smaller diameter converter housing. If you feel like you'd want the best performance at the cost of fuel mileage, then use a 3500 stall unit with a 10" diameter. With a 3.73 rear gear and some kind of posi arrangement, this would be a car that I personally would like to drive. Should be a dream.

For all you other guys, I have cleaned out my PM's, so you can get in touch with me if you need to.
Richard

Richard,

I feel honored to receive personal attention from you. The engine build you describe would be very impressive indeed and is in step with your previous advice to others allowing them:"to come galloping in like Caligula, lopping off heads and taking no prisoners."

I'm tempted to follow your advice to the letter as I trust it, however in your absence, I have already purchased or acquired some other parts. Hopefully they will be useful in a slightly modified build, although I am not against cutting my loss on some items and purchasing something different.

My goal has been to build an impressive street machine with very good street manners and be somewhat fuel efficient. I felt like I should focus on torque instead of horespower, but did not want to go to a stroker at this time. I already owned an Edelbrock 1406 600cfm carb which I understood would help with the mileage but not particularly give the most horsepower. I also just purchased an Edelbrock 2716 Vortec Performer EPS instead of the RPM because I heard it was better at producing low end torque. I also just ordered a Comp Cam 08-410-8 260H, not sure what all the specs mean, but had a few reccomend it.

I have not decided what pistons to go with, If I reach a comfort level on the 12cc over the 18cc dish as not producing unneeded detonation when balanced with the other components, then I will go that way if you suggest. Do the 12cc ones you linked to with the 4 way valve relief have sufficient flat area in the quench are to be the most effective?

The heads are genuine GM 906, very low mileage, look almost new.
I have not cc'd the heads, but am making up a kit to do it.

So, Do rods typically need replaced? The remanuf. ones you linked to would also fit my 350?

As well as the crank and bearings, although I would get the new one for the 1 piece oil seal which my block has.

I appreciate your direction on the block. I'm planning a trip to the machine shop soon. I'm not sure what order I need to do with the machine shop other then what you mentioned.
Is this the proper order? Seems like a lot of trips back and forth from the shop if I want to do the most I can myself.
Drop off bare block
Have cylinders checked to determine what bore size is needed or should I push for the .030 over?
Purchase new pistons
Machinest bores depending on new actual piston size in hand
Bring block home
Assemble bearings, crank, and 1 rod and piston, and check piston top to deck on each corner using same rod and piston.
Take block back to machinest
Have decked to square with crank and for proper calculated deck height for desires squish.
Bring block home and start assembly process.

I have a lot of other details I haven't got to yet, some you already mentioned, but I wanted to get the basic plan worked out first.

Thanks
Rollie

Just ordered a new crank kit and rods on Ebay.

Late Chevy 350 5.7 Crankshaft Crank Kit 1986-2005 1pc. | eBay

Rebuilt OE connecting rods Chevy 305 350 307 327 5.7" | eBay

Trying to decide between 12cc or 18cc dished pistons. Here's a link to the 12cc ones on Ebay: I'm also wondering if I should buy the .030 over pistons now before I take the block to the machinest or have him check the size, then wait for the pistons and then proceed to bore according to the actual piston sizes. I've never done this before, I'm learning a lot on the computer, but don't have much actual engine building experience.

SPEED PRO Chevy 350 Hypereutectic Coated Flat Top Pistons+Cast Rings 9.3:1 | eBay

Originally Posted by rollie715

Trying to decide between 12cc or 18cc dished pistons. Here's a link to the 12cc ones on Ebay: I'm also wondering if I should buy the .030 over pistons now before I take the block to the machinest or have him check the size, then wait for the pistons and then proceed to bore according to the actual piston sizes. I've never done this before, I'm learning a lot on the computer, but don't have much actual engine building experience.

Those pistons should work fine, plenty of squish pad and the correct compression height. I strongly recommend getting as close to 9.5:1 SCR as you can, in order to use the cam timing that I linked earlier, or something very close. Your first task will be to cc the chambers. Without that info, you have no idea where you are, so you have no idea of where to go. Haul the block to the shop and have the machinist look it over for main bearing alignment, size and roundness. The block may need to be align-honed or align-bored to get the holes perfectly round and parallel with each other.

He will measure the bore and tell you where the bore needs to be for new pistons. DO NOT EVER BORE A BLOCK UNTIL YOU HAVE THE PISTONS, RINGS AND COMPLETE INSTRUCTIONS FROM THE PISTON MANUFACTURER. Cylinder wall hone finish will depend on the ring material used. I highly recommend moly rings rather than cast iron or chrome. They break in quickly and will last longer.

Once the block is bored and honed for the new pistons, you can haul it home and check the block deck height on each corner. The machine shop can do this for you also, but their labor is more costly than yours. You will know that the crank radius for a 350 crank is 1.740", the rod length is 5.700" and the piston compression height is 1.560". Therefore, your "stack" of parts will measure 9.000". If, for instance, you measure #1 piston deck height at 0.024", use a Sharpie to write 9.024" on the block deck at the #1 cylinder. If, for instance, #7 hole measures 0.012", write 9.012" on the block deck at #7 hole. Going to the other side of the block, let's say that #2 measures 0.017" and #8 measures 0.020". The shortest hole will be #7 in this case and so you will use that as your standard from which to cut the decks. Did you read my instructions anywhere about finding piston deck height with a steel rule and a set of feeler gauges? If not, I'll outline it here for you. I know some of these guys gripe and moan about using old tools to do this stuff, but it's not rocket surgery. If you're within a couple of thousandths on the piston deck height on all 8 holes, wonderful. Pistons will grow taller as they heat up and the rods and crank will bend and stretch a little as well, so don't think that you have to have everything to the nearest ten thousandth of an inch. David Vizard found that he could set the squish as close as 0.026" before the piston began kissing the underside of the cylinder head, so we know the "stack" gets taller under engine operation.

I recommend that you purchase and read through this offering from David Vizard before going any further.....
They're showing 26 used from $10.94 plus shipping.....
Amazon.com: How to Rebuild Your Small-Block Chevy (9781557880291): David Vizard: Books

Taking a light cut on the cylinder head surface will decrease the chamber volume if you need smaller chambers to reach the desired SCR. On L31 heads, each 0.0065" (six and a half thousandths) cut will reduce chamber volume by ONE cc. Therefore, a +/- 0.020" (twenty thousandths) cut will reduce chamber size by 3 cc's in addition to trueing the head surface to flat. By the way, if you haven't magnafluxed the heads, do so before you do any work to them. They're thin-wall castings and could be cracked.

Don't buy anything else until you have engaged the auto machine shop that you will use. Those fellows will have suppliers that may be cheaper or have better products than you have access to.

Thank you Richard.
I'm not sure of my schedule, as this is a spare time project, but you have given me a lot of good direction that I can go to work with. I will get back and update this thread when I have something useful.

I just ordered the book you suggested on Amazon.

To add a small detail to Richards advise,Once you decked the block and maybe cut the heads,your going to have whatever intake cut to fit what you ended up with.My point is your not going to be able to buy a intake and bolt it on.Which is fine,I just wanted draw your attention to it.

Originally Posted by 1gary

To add a small detail to Richards advise,Once you decked the block and maybe cut the heads,your going to have whatever intake cut to fit what you ended up with.My point is your not going to be able to buy a intake and bolt it on.Which is fine,I just wanted draw your attention to it.

Good point. The machine shop will have charts to know how to cut the intake manifold, depending on the block and head cuts. Even at that, you should mock up the assembly and verify that there are no gaps and that the intake gaskets will be pinched all the way around each and every port. Plan on sacrificing a set of intake gaskets for that purpose. If you don't get the ports sealed, the motor will pull oily crankcase vapor into the cylinder through the intake valve and you won't like the results.

most all intake s will (china????) fit at 9.010 and 010 off heads no big deal but need s to be checked so china wall air gap so it will not bottom out then your just not cutting the sides its the bottom of intake as well as bolt holes may hold it up to. the intake gets cut to match ports from intake to head it takes a hell of alot for it not to bolt on . there is no need to wast new gaskets just shim the 4 corners of the intake with a chunk of gasket or what every thats 060 thick. tape some washers or cheap frozen pizza. check bolts for fit or just keep a old clean set of gaskets to see were it is . there no hard fast rules but have taken 045. off from deck and heads and intake did fit what head gaskets come in to play to how thick they are . when the intake will or will not fit has some thing do with the marker of intake too . do not forget to check the distributor depth shim if needed .one thing i will add getting a block decked will not help much if not centered threw mains and cam bore like with a BHJ tru-deck setup like i use so side to side threw main and cam center line is dead on no up hill or down hill on the deck. when deck is 90 and front to back square then i base my boring bar off new deck. by a dial gauge so new piston bores are were they should be . some other things to think about re built rods will be shorter by .003 or more . crank stroke can be off as well a guy may off set the crank to save it and can be just one throw . same with rods a set up rods can be up and down from centers .005 ez. not all pistons in the set will have the same CH as well . so i do this nit picking all the time if i am short blocking or doing all machine work .i work out the deck height with head gaskets with your rods and pistons then deck with BHJ or if you have a number i can land on it if the block has not alot of offset threw center line or what we call twist side to side and i like to be less then .002 side to side then done

techinspector,
I'm trying to balance what I have already purchased with my goals of running cheap gas and having good street torque.

I already have this cam:
08-410-8 - Magnum

I was planning to purchase these 18cc D Dish pistions:
Keith Black/KB Pistons KB142-030

This was based on advice you gave in this thread:
SBC 350 build

where you were talking about matching components and this was one of the options relating to a build very similar to mine.

"Now, if a fellow moved to an 18cc D-cup instead of a 12cc,
KB Pistons for Automotive Applications
then the static compression ratio would be somewhere around 9.1:1 and you might use a camshaft such as this one....
COMP Cams 12-410-8 - COMP Cams Magnum Hydraulic Roller Camshafts - Overview - SummitRacing.com

It's all about the combination. You have to choose pieces that will like each other and make max power for the combination."

I'm not trying to be difficult and I do value your input. At this point I'm leaning to using my existing cam and going with the 18cc piston. Can we make this work?
Thank you.

Originally Posted by rollie715

techinspector,
I'm trying to balance what I have already purchased with my goals of running cheap gas and having good street torque.

I already have this cam:
08-410-8 - Magnum

I was planning to purchase these 18cc D Dish pistions:
Keith Black/KB Pistons KB142-030

This was based on advice you gave in this thread:
SBC 350 build
where you were talking about matching components and this was one of the options relating to a build very similar to mine.
I'm not trying to be difficult and I do value your input. At this point I'm leaning to using my existing cam and going with the 18cc piston. Can we make this work?
Thank you.

The 08-410-8 closes the intake valve at 29 degrees after bottom dead center and will want a static compression ratio of 9.00:1 to 9.25:1, so the deeper pistons should work fine.

Originally Posted by techinspector1

The 08-410-8 closes the intake valve at 29 degrees after bottom dead center and will want a static compression ratio of 9.00:1 to 9.25:1, so the deeper pistons should work fine.

Thanks for the reply. Where do I find the 29 deg ABDC number?
The CompCam link says 56 deg. Am I reading it wrong?
Here's the link:
08-410-8 - Magnum

If it was 56 deg, would the 18cc dishes still be ok? I haven't bought the pistons yet, so if the 12cc dish would be better, I would be open to getting them instead. I hope to be verifying the cc's on the heads in the next couple days and can calculate the actual SCR and DCR before I order the pistons and have the block bored.

I purchased and am studying the following two books by David Vizard. Thanks for the suggestion.
How to Rebuild Your Small-Block Chevy
How to Build Max Perf Chevy Small-Blocks on a Budget