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Old 02-23-2007, 10:00 PM
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Budget 350 build

I have gone through a few calculations to figure out a budget 350 build, I am not sure how close it would be because I cant find flow numbers for factory gm heads the numbers used were desktop dyno values for gm 882 heads. The heads are sort of an issue right now I have three set of gm castings 882s, 993s and 493s all are 1.94I 1.5E(I think the 493s have a 1.6E) the 993 need guides I would replace the valves/ springs on whatever ones I use I don't plan on increasing the valve size(minimal gain?) but I will do a mild port. I am not considering vortecs because I have an intake and the cost of the heads plus the machining/rebuilding to run the higher lift would put me into the cost range of a pair of Dart heads.
The block(010 with 010/020 cast) is a two bolt main 350, crank is polished stock cast, , the cam choice is comp cam http://www.compcams.com/Technical/Se...umber=12-246-3 or I have a 270 magnum. The pistons are Keith Black hypo dome pistons .100" that displace .5cc of cylinder volume they are a small dome.The pistons with a .017 thick head gasket and a stock deck height of .025" gives me a quench height of .042" with the piston compression height of 1.561(I think)? The rods are 5.7" (scat or eagle I beam) using that rod length my dynamic compression is 7.92 and my static is 9.77, cylinder pressure max is 185.5 @4000 rpm and the ve is 92.5% at 4500rpm with a 750 cfm carb(we have a quad, holley(3310) 750,650 and an elderbroc 600) and a high flow dual plane manifold(according to dd dyno) The engine use will be a strip steet car, auto 3000 - 3500 stall.

If the following numbers are good Id be happy with them and I know all the calcs should be based on actual measurements but I just need to get in the ballpark first? DD dyno spit out 413hp @5500 rpm and carried it to 6000, The torque was 440 max at 4000 rpm.... Does anyone se any major screwups or have suggestions, the heads I have are the cheapest alternative right now so one of the 3 will be used.

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Old 02-24-2007, 03:51 PM
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The 882's are probably the best of the bunch. If not cracked. You can make a decent set of heads out of these, If you port match the intake side. carve all the rough/sharp edges out of the bowl. Smooth the short side radius of the exhaust and try to do all port work on the exhaust in the upper part of the port. Leave the floors alone. 1.94 Int. valves are fine but use some stainless 1.5 exhaust valves with a small back cut. You will have a budget screamer.
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Old 02-24-2007, 04:32 PM
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Look around and see if you can find a set of 441 heads, they are similar to the 882's but are a bit thicker and less prone to cracking-I've never seen one crack. The 882's are a little prone to cracking but they do produce some good power for a smogger head-especially if you open them up to 2.02 or 2.05, do a good bowl blend, raise the roof a little and narrow the port divider as mush as possible-they'll support 500hp if done right but it's a lot of work.
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Old 02-24-2007, 04:38 PM
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http://www.chevyhiperformance.com/te...ench_database/
http://www.kendrick-auto.com/head_flow_figures.htm
http://users.erols.com/srweiss/tablehdc.htm
http://www.dw1977.cz28.com/photo2.html

Those are a couple sites with chevy head flows. I didn't take the time to see if they had all the flow numbers you need, but I know they have some.
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Old 02-24-2007, 07:21 PM
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Thanks for the info Ill take the 882s apart and have them checked out, I bought Vizard book on porting chevy heads and read the standard abrasive instruction along whatever else I can find on the web. I figure it take some time to port them and my time is limited but the budget for this one is more limited so Ill give it a shot. I am building a simple manometer to use for comparison hopefully it will work. Also please disregard my post on factory heads I posted it thinking I screwed up this one and it didnt post sorry about that....
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Old 02-24-2007, 09:52 PM
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Kgriff, check the compression height on the pistons you have, some of the rebuilder pistons end up .020 down in the hole on TDC and if that's the case you'll want to run a steel shim head gasket like original or have the block decked to zero and use a .040 composite head gasket. Try to keep the distance between the quench area of the head and the piston at .035 - .040"-this gives you the best burn.
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Old 02-25-2007, 12:37 AM
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Take a look at your other post. The 882 heads are the worst of the bunch. The popular flowbench data base specs for these heads is full of it. If you'd like to do it right for less $$$ overall consider what I posted on your other thread on factory heads.
if you'd like to do it and come up 35-50 horspower short then proceed as discribed in this thread.

None of these heads will support 500hp without extensive welding and reshaping of the ports and combustion chamber.
It will take all and more of the porting effort and time you can stand to do just to get close to 400hp on 882's. They are junk. Do not waste your time or money on these heads.
reguardless of which head you start with you will need to do more than a little porting to get enough flow for 400hp.
if you lie to Desk top dyno, It will lie right back at you.

http://www.ryanscarpage.50megs.com/combos5.html
Combo 38 remember that that is after $1250 of head work on 882's.
Vortecs look a little cheaper now?

Last edited by F-BIRD'88; 02-25-2007 at 01:07 AM.
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Old 02-25-2007, 06:30 AM
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Look at combo 54- 510HP http://www.ryanscarpage.50megs.com/combos7.html

Combo 38 uses a set of 882's with $1250 worth of head work-funny how they didn't increase the valve sizes from stock? What did $1250 buy?....
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Old 02-25-2007, 09:44 AM
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I looked through all of the combinations listed on the link none of the 882 head combinations made 400 hp which I find interesting because alot of the published flow data says they can. I did not input the 882 data in the dd dyno program it came with it. I have pulled the 882 heads and took a good look at them while I am no expert I am very skeptical of them supporting 400hp without extensive work. Compairing the three heads(actually 4 I have a set of 450 305s too) the 993s look alot more open/larger ports. In general none of them look very good. Right now I am leaning towards the 993s one combination on the link page that supported over 400hp


Combo 53.
Combos 53-54 come from pages 58-60 of the October 1990 Hot Rod Magazine. Back in 1990, these combos were two examples of the engines offered by American Speed. Both engines make some great power and torque.

Combo 53 uses rebuilt #993 GM heads with 2.02/1.60 in. valves. The camshaft is a healthy grind, with 234 of duration @ 0.050 in. of lift. This 355 cu. in. engine produces 421 HP and 438 ft-lbs of torque.
Displacement: 355 cu. in.
Carburetor: 750 Holley vacuum secondary
Heads: GM #993 castings, ported, with 2.02/1.60 in. valves and a 3-angle valve job
Intake: Edelbrock Victor Jr. and a 2 in. open-plenum spacer
Camshaft: Cam Dynamics 290, with 290 of duration, 234 of duration @ 0.050 in. lift, and 0.494 in. of lift
Headers: 1 7/8 in.
Pistons: Speed-Pro forged flat tops
Rods: stock
Crank: cast
Comp. Ratio: 9.0:1 to 10.0:1

MAX HP: 421 @ 5300
MAX Torque: 438 @ 4700

I am still going look at a few other combinations and price it out to see what the cheapest option will be.
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Old 02-25-2007, 11:50 AM
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Or just clean up all the old heads you have and list them as rebuildable sets on ebay, I've sold pairs of beadblasted 882 cores on ebay for as much as $178 in the past. Put your ebay sales profits together and buy a pair of aftermarket heads. If you consider what it costs to have guides put in and seats ground and new valves and springs you'd probably be dollars ahead.
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Old 02-25-2007, 12:00 PM
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Notice the cr "9.0 to 10.0" which is it. probabily 12:1.
Some of the magazine stuff ya just have to take with a grain of salt. None of those heads fow more than 200cfm stock. None will make more than 330hp stock at pump gas compression ratio. You can be sure that if the motor did make 420hp with 993's they were highly modified by a pro.
The exhaust side of the 882's is very bad. The 441(x)'s and 487X head are the best of the bunch. I like the 920's. they don;t flow any better stock but the casting is better. You can make a better ported head. All have a too large chamber. there are 2 versions of the 993's old and new ( heco en mexico. Both stink actually but the new ones are better.
Don;t know where yu're getting your flow info but none of them flow enough for 400hp.Just cause you have a set doesn;t mean that is the cheapest route to getting 400hp.

Milling the head to reduce the chamber size costs money.
its cheaper to just throw that stuff out or sell it and start with a better head. The #450 305 heads are not he same as the 416's. The 416's are easy to find. The TPI heads work good too once ported. ( NOT TBI swirl port) The chamber is much better. these are the cheap low buck budget hi perf heads to get and port yourself. Don;t think yu can do it with a minor pocket port job on any of these heads. They will all need a full work up. You are going to get dirty.
barring that get a paper route and buy a set of Brodix IK200's for less than $1000 and bolt them on.
Ya cannot make a stud out of a dude. If it was so easy to get 400 hp out of the 882's and 993's etc there would be no market for entry level performance aftemarket heads like the Performer RPM's or Dart Sportsman II's etc etc.

Last edited by F-BIRD'88; 02-25-2007 at 12:11 PM.
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Old 02-25-2007, 12:15 PM
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Quote:
Originally Posted by baddbob
Look at combo 54- 510HP http://www.ryanscarpage.50megs.com/combos7.html

Combo 38 uses a set of 882's with $1250 worth of head work-funny how they didn't increase the valve sizes from stock? What did $1250 buy?....
i don;t know, did not write the article. All this stuff is pulled form mag articles. Some of which requires a grain or two of salt to swallow. use your own judgement.

Comb o 54 likely were Fully Ported 034 Bowtie heads. they were not open chamber smoggers. Not a chance. Not without a $$$ full "Super Stock" work up. have you ever seen a NHRA Super Stock head?
may have had "10:1" pistons but I'll bet he heads are angle milled to the max cr being over 13.5:1. can't fool an old fooler.

Last edited by F-BIRD'88; 02-25-2007 at 12:23 PM.
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Old 02-25-2007, 03:00 PM
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The information I used was what came on dd dyno which was somewhat backed up by Car Craft http://www.carcraft.com/techarticles/116_cylinder_head_database/stock_iron_882_head.html since posting this and judging from most of the posts I sensed some do not believe the flow data. So I have researched it a bit further using books by Lingenfelter and Vizard. Vizard supplied Superflow Data for the 993s and Lingerfelter wrote that the 993s were better flowing than the 882s. Using this information inputted to dd dyno with my above combination listed above the best I could expect out off stock 993s is about 340hp the car craft info is either based on a magical stock 882 head of the info is flawed. Vizard also supplied Superflow data on a set of pocket ported 993s inputting this data that above combination on dd dyno would be slightly above 400 hp. I think in reality with me doing the porting its going to be a tough nut to crack, and it would be easier going aftermarket but its cold out the houses are far apart and I am not in that good of shape to deliver that many newspapers to buy a set of Brodix heads. I am going to search for a set of the 413 305 heads this week that does sound like a good option and I just picked up a 350 with flat tops in it.
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