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Old 10-20-2008, 12:19 AM
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high horsepower 350 build up

Whats up guys,
I got a late 70's 350 motor out of a old project I finished a while back. I recently decided to rebuild it and have an extra GOOD motor lying around instead of an old junky looking motor crowding my garage up. anyways... i have built several 350's so im not an idiot or beginner, but this project will be the biggest to tackle yet. I am taking it to the shop tomorrow to see if it will need to be bored or not so im not sure on that yet. but i want this to be a very high horsepower 350 like no other, it will be a slow and steady build so no rush and cost will pretty much not be a factor ( to an extent). but i would like to know if any of yall out there have tried different combinations and what the results are. and if you could give any info on certain heads regarding CC size, cam size and carbarator size. Or if a 383 would just be the way to go with the same questions for that too. thanks in advance

I dont want such a severy cam that i have to idle at 2000 RPM and look like its jumping off the ground, but a really nice muscle lobe and nice reasonable idle would be perfect

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Last edited by 350cruiser; 10-20-2008 at 12:25 AM.
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Old 10-20-2008, 01:08 AM
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I guess the first thing I'd be looking at is the available fuel. If you have E85 available, then you could probably get by with 13.0:1 static compression ratio or maybe a little higher. If you have only 92 octane pump gas available, then you may be limited to somewhere around 10.0:1 or a little higher, depending on combustion chamber design, squish and the intake closing point on the cam lobe. These variables are tweaked to allow use of the available fuel in a certain range of cylinder pressures. Of course, there are other crutches such as water injection which will allow higher cylinder pressures than would be possible on the available fuel alone. Crane Cams advises around 160 psi as the top limit of cylinder pressure on pump gas, but many builders have eclipsed that mark by tweaking the aforementioned variables.

The static compression ratio/camshaft choice is a balancing act. Any cam you bolt into the motor will have an effective operating range of about 3,500 rpm's. In other words, it will be efficient from maybe idle to 4000 or 1500 to 5000 or 3500 to 7000 and so on and so forth.

A cam that is meant to operate in a range of 500-4000 for instance, might have a window of static compression ratio of 7.5:1 to 9.0:1. Moving up to a range of 1000-4500 might require a range of 8.0:1 to 9.5:1. A range of 1500-5000 might require a range of 8.5:1 to 10.0:1. A range of 2000-5500 might require a range of 9.0:1 to 10.5:1. A range of 2500-6000 might require a range of 9.5:1 to 11.0:1. A range of 3000-6500 might require a range of 10.0:1 to 11.5:1. A range of 3500-7000 might require a range of 10.5:1 to 12.0:1.

These, of course, are generalities and are presented here to help bring you up to speed.

If you're using an automatic transmission, a looser torque converter will allow a higher idle with a more agressive cam without "stoplight creep".

Look through these magazine dyno tests and see if any of them are of interest to you. They were all done with streetable compression ratios so that pump gas could be used.
http://www.ryanscarpage.50megs.com/combos1.html
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Old 10-20-2008, 06:02 AM
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350

Do you think that one day that type of gas will sky rocket then you will be stuck with a high octane engine? It's just a thought.
Be good! RJ
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Old 10-20-2008, 08:17 AM
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hey tech, thanks for the website, thats exactly what i needed to see. but how long of a duration, and big of a lift do you think i should go before i start having trouble with the idle? like i said i dont want it jumping off the ground at a red light, but i want people to know im not playin around either. I've only done mild to moderate rebuilds so i was never really concerned with the idel cause it wouldnt really be a factor, but building this motor now i wanna do all my reasearch before i start dumping money. I would like to run 93 pump gas, but where i work i have access to pretty much every alcohol, methanol, and whatever else you can imagin in 55 gallon drums for pennies a gallon, so mixing fuels is no problem
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Old 10-20-2008, 08:43 AM
How fast is fast enough?
 
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where do you want your peak power? the idle can usaully be fixed after deciding that. For a street engine I wouldn't set it much past 6,000 RPM otherwise you'll need to get a lot of specialty race parts that do not take well to street use.

Also, a nasty idle does NOT mean a faster car- it just means you waste a lot of gas out the tail pipe.

build the engine for the power and let the idle sound how it will. the oly time you should build for sound is when you don't want speed and its a trailer queen for shows only.
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Old 10-21-2008, 02:04 AM
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ok after much research I believe I am comming closer to the final product. I believe i will stroke it to a 383 while running a Comp Cams hydraulic roller, with 230/236 of duration @ 0.050 in. lift, and 0.510/0.520 in. lift with airflow reasearch 190 cc heads. I have seen this combination many times, and producing many high number on HP and Torque. What do yall think of this combination? and would that particular cam be a bit to radical for street driving? just lookin for any input on the subject, Thanks.
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Old 10-21-2008, 05:58 AM
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Sounds like you're on the right track. The AFR on a 383 is a hard combo to beat. Of course the same setup on a 406 is good but if you already have a 350 block I'd stick with the 383.

A lot of Lingenfelter 383s (FI and carbed) made great street-able power and gave amazing throttle response. They made power in the 3000 to 6000 rpm range that was more suited to a heavy street car. His focus was an engine that accelerated a heavy street car well, gave decent manners, and LASTED. IMHO his recipes are as good as they get for making a car FUN to drive.
Here's a link to dyno tests of some of his engines. Maybe this will help you fine tune your choice.

http://www.geocities.com/MotorCity/7610/dyno.htm?200624

The carbed ones are towards the end. Depending on the car this is going in I'd really look at the Schmidt 383. It has a very small cam "Competition Cams hydraulic cam, 211/221 @ .050, .442/.465 lift, 112deg lobe sep" but in this combo puts out over 500 Ft/lbs at 2800 rpm and 410 HP at 5000. This build used 200CC iron sportsman's but a set of AFR 195 eliminators world work very well (maybe better). I know there are engines with bigger peak HP numbers to be had but a torque curve this flat in a 3500LB + car and you better have sticky tires and a tough transmission. The low RPM nature of these engines allows the use of very "common" internals, especially the valve train, keeping cost down and longevity up. The "seat of your pants" feel of power in these low RPM high torque engines is the perfect match for a street cruiser IMHO.
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Old 10-21-2008, 06:53 AM
How fast is fast enough?
 
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the cam you selected will be great for a light car, but for a heavier car with an auto most people would go with less duration... I would pick a cam with more duration and raise the comp up to 11:1- but I like living on the edge.

So in your case I would recomend less duration along with some high ratio roller rockers to keep your lift up. Here's a link to a shelf cam from lunati-http://store.summitracing.com/partdetail.asp?part=LUN%2D501A4LUN&autoview=sku

226/234 looks a little better to suit ya- and it has more lift, so its a win/win. I would call up Lunati and have them grind it with a narrower LSA though- about a 109. 383's tend to like tighter LSA's and it'll also help give you the idle you want and a few more peak hp.
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Old 10-21-2008, 08:40 AM
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Mr 350,
Your engine setup sounds good if used with 10 to 10.5:1 cr, 3.73 gears, 2800 to 3000 stall, full length 1-5/8 headers, performer rpm intake, holley 750 3310, 2.5" dual exhaust with a cross over pipe, and a set of hooker aerochambers and a set of hooker bullets (yes, 4 mufflers).

Not that big of a cam. should run OK on the street. I'm guessing it will idle at 1000 rpm with 12 or 13 inhg. and should make power to 6500 rpm. Use hyper cast pistons and arp rod bolts. Get an internally balanced 383 kit if you want to use the 350 balancer and flywheel.
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Old 10-22-2008, 01:15 AM
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alright guys i think i got it figured out. I got the perfect word back from the machine shop. there going .030 over on my 350 block so i am in fact strokin to a 383. so as for components, i got AFR 195cc heads with 65cc combustion and 64cc exhaust and straight plug port. with hypereutectic flat top aluminum pistons, + 7.00cc piston volume. forged 4340 SCAT crank with 3.75 stroke and 5.7 rod length. as for the cam i picked out a comp cam with 230int./236exh. duration at 050 lift and 510/520 lift with factory arm ratio and 110 lobe separatio paired with hydrollic roller lifters as well as roller rockers. i think that about covers it for the most part. and would it be better to stick with 1.5 rockers or go with 1.6 for a little extra lift? and would this whole combination give me a pretty reasonable idle and streetable engine? I dont think it would be a problem, but i wouldnt have to worry about clearences between the piston and valves right? thanks for all the help guys.

Last edited by 350cruiser; 10-22-2008 at 01:16 AM. Reason: missing info
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Old 10-22-2008, 01:49 AM
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65cc chambers with flat-tops, Fel-Pro 1003 gasket, zero piston deck will yield 11.03:1 static compression ratio. Too high for pump gas.

Back off to the 75cc heads, flat-tops with 5 to 7cc valve reliefs and an absolutely flat piston crown with no recess whatsoever, 1003 gasket and zero piston deck height for a static compression ratio of 9.79:1. This will work great with the cam you chose. Use an Edelbrock Performer RPM intake manifold with 750, 800 or 850 carb and 1 3/4" headers. With zero piston deck height and the Fel-Pro 1003 gasket (recommended by Airflow Research for this application), your squish will be 0.041" and the motor will operate well on pump gas.

I want to be clear about the pistons. Do not use a piston that has a machined recess on the crown. The crown must be perfectly flat except for the valve reliefs in order to facilitate the proper squish connection with the underside of the head. I have included a photo of the piston crown type NOT to use...

Use a piston that has a compression height of somewhere between 1.425" and 1.450" for use with a 5.7" rod. Using a piston with less compression height than 1.425" will result in an excessive cut on the block decks to arrive at the zero piston deck height and could result in manifold/head alignment problems. Keith Black #KB134 has a compression height of 1.433" and uses 5/64" rings that will work better on a street motor than thinner 1/16" rings. Assuming a virgin block with a block deck height of 9.025", the decks would only have to be cut 0.017" to arrive at a zero piston deck height with the KB pistons.

Use a Scat kit, cast steel crank, capscrew 5.7 rods and hyper pistons as described above.

Playing with my DynoSim software, I have observed little or no difference between 1.5 and 1.6 rockers. Use the 1.5's and worry a little less about piston to valve clearance.

Here's how it plays out on the software.....(with 750 carb)
RPM HP TQ VE BMEP
2000 143 375 71 147
2500 181 380 73 149
3000 233 408 79 160
3500 300 450 87 177
4000 365 480 93 189
4500 423 494 98 194
5000 471 494 101 194
5500 502 479 100 188
6000 513 449 98 176
6500 503 406 93 160
7000 467 351 89 138

Talk with AFR about the valve springs. They have some spring options for roller cams that will allow a little over the normal 6000-6200 rpm limit caused by the very agressive lobe profiles of roller cams. This motor is still making real good power at 6500, so you would want to be able to rev to at least that. Notice that volumetric efficiency exceeded 100% at 5000 rpm's. This will be a sweet motor.
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Old 10-22-2008, 06:35 AM
How fast is fast enough?
 
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Quote:
Originally Posted by techinspector1
65cc chambers with flat-tops, Fel-Pro 1003 gasket, zero piston deck will yield 11.03:1 static compression ratio. Too high for pump gas.

Back off to the 75cc heads, flat-tops with 5 to 7cc valve reliefs and an absolutely flat piston crown with no recess whatsoever, 1003 gasket and zero piston deck height for a static compression ratio of 9.79:1. This will work great with the cam you chose. Use an Edelbrock Performer RPM intake manifold with 750, 800 or 850 carb and 1 3/4" headers. With zero piston deck height and the Fel-Pro 1003 gasket (recommended by Airflow Research for this application), your squish will be 0.041" and the motor will operate well on pump gas.

I want to be clear about the pistons. Do not use a piston that has a machined recess on the crown. The crown must be perfectly flat except for the valve reliefs in order to facilitate the proper squish connection with the underside of the head. I have included a photo of the piston crown type NOT to use...

Use a piston that has a compression height of somewhere between 1.425" and 1.450" for use with a 5.7" rod. Using a piston with less compression height than 1.425" will result in an excessive cut on the block decks to arrive at the zero piston deck height and could result in manifold/head alignment problems. Keith Black #KB134 has a compression height of 1.433" and uses 5/64" rings that will work better on a street motor than thinner 1/16" rings. Assuming a virgin block with a block deck height of 9.025", the decks would only have to be cut 0.017" to arrive at a zero piston deck height with the KB pistons.

Use a Scat kit, cast steel crank, capscrew 5.7 rods and hyper pistons as described above.

Playing with my DynoSim software, I have observed little or no difference between 1.5 and 1.6 rockers. Use the 1.5's and worry a little less about piston to valve clearance.

Here's how it plays out on the software.....(with 750 carb)
RPM HP TQ VE BMEP
2000 143 375 71 147
2500 181 380 73 149
3000 233 408 79 160
3500 300 450 87 177
4000 365 480 93 189
4500 423 494 98 194
5000 471 494 101 194
5500 502 479 100 188
6000 513 449 98 176
6500 503 406 93 160
7000 467 351 89 138

Talk with AFR about the valve springs. They have some spring options for roller cams that will allow a little over the normal 6000-6200 rpm limit caused by the very agressive lobe profiles of roller cams. This motor is still making real good power at 6500, so you would want to be able to rev to at least that. Notice that volumetric efficiency exceeded 100% at 5000 rpm's. This will be a sweet motor.
If you don't want to run 11:1 I can't blame you- thoguh many people do. I wouldn't drop all the way down to 9.79 though. Find some heads at about 65 cc's and a piston with a reverse dome of about 10 cc's and 2 valve reliefs- that'll put you almost exactly at 10:1 with a much better package for flame travel. Be sure to get "reverse dome" pistons and not "dished"- the photo techinspec supplied is a piston with a dish. If you go with a head like the AFR 195 you can even run slightly higher compression- just keep your piston to head clearance between .035-.045. I would also suggest going with some coated hyper Speed Pro pistons. KB makes SOME pistons that aren't worth the package they come in. Also, you can run 1.5 rockers if you want, but you will see power gains with the 1.6 ratio- just make sure your valve train can handle them.
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Old 10-22-2008, 08:17 AM
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hey yall thanks a lot for all the info and especially the dyno sim, thats pretty bad *****. i think im going to love this motor. Just one more thing though, I have heard horror stories about cast cranks around the 500 HP range before, thats why i was going to go with a forged instead, just to make sure i was well over its stressing point. whats yall imput on that? and as well as H beam vs. I beams on the rods.... thanks.
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Old 10-22-2008, 08:40 AM
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Compression ratio

"65cc chambers with flat-tops, Fel-Pro 1003 gasket, zero piston deck will yield 11.03:1 static compression ratio. Too high for pump gas."
Actually, assuming 4.1 gasket bore and .041 thickness (minimum I would run with a zero decked block), I come up with 10.67:1 compression. Not tons less, but well tuned with conservative timing and 92 octane should be just fine.
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Old 10-22-2008, 10:30 AM
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350,
you live in Louisana=95*+ summer days!!!!
high ambient air temp does increase detonation risk with higher CR's....

reserve a chunk of your budget for for the best possible cooling combo to keep the cylinder heads temp down!!!! (very good oil cooler/WP/rad/cold air induction/ceramic coated headers/etc/etc)

or you will likely have to back off of the timing,,,and that will cost you signifigant HP/TQ,,,alot more than you gained with a higher CR....

techinspector's 9.8CR is plenty for the cam you chose and buys you some ping protection on a hot summer day with some less than best gas in the tank....

each additional full CR point added (ex:9.0 to 10.0) only typically adds 2-3% to the peak HP in the real world (and that's not something you can "feel")....
but it does change the dynamic CR value signifigantly depending on the cam duration....
that's why the different cams operating range (aka duration) have a static CR range, so that the dynamic CR stays within a reasonably safe range....

a favorite Max Keith (a member) saying: "ALOT more gooder is not necessarily more good"

if you do buy the smaller chamber heads for 11/1,,,smart move is buy a knock sensor retard system...
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