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1st Engine Build: Modifying heads
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For a 1st Time Engine Build, which size motor should one build?
355 chevy
38%
 38%  [ 5 ]
383 chevy
61%
 61%  [ 8 ]
Total Votes : 13

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GTAracer
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Joined: 04 Dec 2002
Posts: 36
Location: Southeast, AL
416.22 points



PostPosted: Wed Dec 04, 2002 11:56 am    Post subject: 1st Engine Build: Modifying heads Reply with quote

My first post here, appears to be a knowledgeable, helpful sight.

I'm beginning a rebuild on an 89 350 L98 roller motor.
For the 1st part of my rebuild, I want to modify the heads. My objective is to get mid-high 12s in qtr, or very low 8s in 8th before nitrous.
With the above stated goals, what should I do with these heads?

I was thinking:
1) screw in studs
2) basic porting using deluxe standard abrasive porting kit
3) keep 1.94/1.5 valves
4) valve job (David Vizard recommends some kind of 30 degree stuff)

Do I need 2.02/1.6 valves?
New guides (thick bronze)? I haven't checked guide clearance yet. Still buying necessary tools.
Should I go ahead and install new springs before building my short block and deciding on cam? I plan to run these heads on stock motor with stock cam for a while (few thousand miles). I will use Comp Cams Pro Magnum Roller Rockers Self Aligning, also for a little extra on the lift.
Do I need to mill these heads? Angle mill possible?
What compression ratio should I shhot for? Thinking 10:1

My plans for other aspects of motor:
1 3/4" headers
Accel LTRs with some porting
ported plenum
either an Accel base I have or a ported stock base
I don't want to rev much past 5500, with a possible red line at 6000 or so
Forged flat top pistons, new rods
Cam yet to consider.
Street and raced often
3.27 or 3.45 gears



Thanks for any responses or recommendations.


Last edited by GTAracer on Wed Dec 04, 2002 2:22 pm; edited 1 time in total
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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Wed Dec 04, 2002 1:56 pm    Post subject: Reply with quote

GTAracer...welcome to the site.

You have high goals to do you heads for under $500 and see some changes. Since the car has 184K on the clock it's probably time to rebuild the motor especially if you plan on racing it. I wouldn't recommend working on those heads. A better bang for the buck is the GM vortec heads. I'd order a set of vortec heads along with Scoggin Dickey TPI base manifold for those heads. Check out the kit that they have for your application. But that is outside of you budget. I would also recommend to change the cam on your motor, consider the lingenfelter 219/219 cam @ 0.05.

It's really hard to recommend a set up for your car with the budget. Keep in mind the more air that goes into the motor the more fuel you'll burn. The more fuel you burn the more power you'll make. After you make the power then you have to put it to the ground.
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GTAracer
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Posts: 36
Location: Southeast, AL
416.22 points



PostPosted: Wed Dec 04, 2002 2:33 pm    Post subject: Reply with quote

My original post may have not made a lot of sense, so I edited it.
All I really want is some suggestions on what to do with the cast iron heads to achieve the results sought. The book I was reading by David Vizard says that 85-90% of the flow can be achieved with basic pocket porting and a good valve job.

I have decided not to go Vortec route.
I'm willing to spend the money for AFR heads...but I don't have enough experience yet IMO to justify spending gobs of cash when I'm not sure what the heck I'm doing. Just trying to rebuild the motor right the 1st time, and get the best results I can. Next motor I will spend the big money on, after I have some experience.
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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Wed Dec 04, 2002 3:19 pm    Post subject: Reply with quote

Based on your post it sounds like you really want to port a set of heads and rebuild the motor. It sounds like a good approach to get your feet wet rebuilding a motor. The risk is minimal on those heads since if you make a mistake you didn't wreck a set of expensive heads. The only porting I've done on heads is gasket matching and removing some casting flash. I paid someone to port my heads and had exactly what you describe done. The bowls were blended, some chamber work done, and a good 3 angle valve job. I think your time is best spent exactly where you say in the bowls. Another good improvement in airflow can be made from undercut high flow valves.

One problem with your motor will be even if you get the heads to flow really well the intake will choke that motor. Here are some flow numbers from Accel's fuel injection manual.
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clay
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1972 Chevrolet Nova

PostPosted: Fri Dec 06, 2002 5:20 pm    Post subject: Reply with quote

Not a fuel injection guy, (will be one day when I can afford it) but I can tell you about my experiences with heads. Vizards books are excellent. I have the head book, the camshaft book, intake and carb book and building smallblocks on a budget book. Just finished modifying a set of Sportsman II heads and his book was VERY helpful. Had a 355 in a 3500lb car that ran a best of 7.96 on motor with a basic setup. Had 9.3 - 1, Lunati mechanical cam (specs 239 at 0.050", 0.517 lift intake, 249 at 0.050", 0.543 lift exhaust) installed 4 advanced, untouched Sportsman II heads, Hooker 1 3/4 super competition headers, Victor Jr. intake, 750 vacuum carb., Turbo 350 with TCI street fighter (about 3000 stall) and 4.11 gears. Same motor went best of 7.01 with a 180 shot of gas. Later tried a ATI supercharger and to make a long story short got greedy with boost and timing - result, detonation cracked every piston. Crying or Very sad Vortec heads have almost identical intake flow and slightly better exhaust flow than untouched Sportsman II's. Currently have a 383, build one and you'll like it. Cost isn't much more than a 350. Crankshaft is only additional cost and Scat cranks are pretty cheap. Let me know how it comes out.

Clay
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86GN
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Joined: 10 Jun 2002
Posts: 290

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1990 Chevrolet Corvette

PostPosted: Sat Dec 07, 2002 10:26 am    Post subject: Reply with quote

Those iron L98 heads are a decent set of heads with a little work. If they're like the L98 aluminums, 2.02 intakes won't fit. 2.00 max. A machine shop can turn down 2.02 for less than 2.00 valves will cost. If you're going to stay with the Accel base with bigger tubes the heads will be the restricting factor. I've seen numbers around 220 cfm intake flow @ .500", 28" out of L98 aluminums.

Stick with the way you're going and pay attention to the details. We all learn from our mistakes, and it sure sucks to "F" something expensive up learning.

The 211/219 would be a good cam or the TPIS ZZ-9.

If you want to get into the 12's work on the convertor and the rear suspension. Hook is the cheapest way to get a good ET.

I've got a friend with a '91 vette. He traps between 107 and 109 and runs 12.teens. 1.60 60 fts. The car still hasn't made 300 rwhp. I've trapped as high as 118.2 and have been a best of 12.17. 1.96 60 ft best so far.

See how important hook is to ET.
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Xhiron
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Location: Guelph, Ontario Canada
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PostPosted: Sat Dec 07, 2002 11:40 am    Post subject: Heads Reply with quote

I've got a set of S/R Torquers if you want em. 76cc chambers, almost new valves, no springs or retainers and they're unported. Just an idea.
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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Thu Dec 12, 2002 12:40 am    Post subject: Reply with quote

Here's a good link to check out for head porting. http://www.sa-motorsports.com/diyport.htm. I know you have the David Vizard book but thought you might be interested anyway.

BTW... how is the DV head porting book? I've thought about picking it up myself but haven't got around to it.
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GTAracer
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Location: Southeast, AL
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PostPosted: Thu Dec 12, 2002 10:24 am    Post subject: Reply with quote

Actually, their porting kit is the one I have ordered.

I have the DV book "Building a Chevy small block for power on a budget" ( or something like that). Lot of material on all aspects of the engine. There is a great deal for me to absorb from this book, so I'm reading it kinda slow to prevent brain overload. Lots of good ideas. I got it at Books a Million. Usually I just read stuff and don't buy it. But I bought this book.

I've decided to order some Manley Stainless Steel pro flow valves in stock sizes. I'll get a valve job, and do only some minor porting...such as intake and exhaust port matching, and eliminating any sharp turns and such. That should get me what I want... We'll see.
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SMOKEmUP
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1979 Chevrolet Camaro

PostPosted: Thu Dec 12, 2002 11:14 am    Post subject: Reply with quote

I have that book too. He also has a book just for head porting. I think I'll ask Santa for that one.
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heavychevys
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Joined: 18 Nov 2002
Posts: 81
Location: South Carolina
754.46 points


1964 Chevrolet Belair

PostPosted: Thu Dec 12, 2002 5:53 pm    Post subject: Reply with quote

GTAracer,this is the build for a 357ci I built for the 69 Nova.

350 bored .040 Silvo-lite pistons(cast),stock crank and rods(resized and new bolts),Comp Cams Dual Energy 275/277 w/ Rhoads lifters,1.6 Hardland Spark roller rockers,461X stock heads fully hogged out w/ 2.02-1.60 S.S. valves,screw in studs and girdles,true roller timing chain,Carter Strip mechanical fuel pump,Edlebrock Performer RPM w/ 1/4" phenolic spacer and a modified 650 dp,MSD Billet Dis w/ advanced locked out,MSD 6T box,NGK XR5 plugs indexed,1 5/8" Hooker headers w/ 2 1/2" Flowmaster 3 chamber mufflers,Moroso Al. water pump w/ electric pump drive,Electric fan and other non preformance related parts.

The timing is at 38 total and is all in at before 2000 rpms.

The has a T350 trans w/ manual valve body and a TCI street fighter convertor.The rear gear is a 3.90 spool,was a 3.73 w/ posi.Tires 26-10-15 MT slicks.The car has a South Side Lift bars and 90/10 shocks up front.Also frame connectors.That is it pretty much for suspension.It weights 3600+ with driver.The car has run 7.97 @ 85 mph 1.74 60ft in the 1/8 on motor.With 3.73 it ran a 8.04 @ 82 mph with clutch fan and crank drive water pump.The best on NOS is a 7.26 @ 92 mph w/ 1.501 60ft this with 3.73 and C.D.W.P..I hope this helps out a little.This is a very inexpensive engine to build and is very street able.

_________________
1964 Impala 468BBC 6.986 @ 98.69 MPH 1/8 mi

(Bothers) 69 Nova 408 BBC 6.94 @ 96 MPH
96 F250 4X4 PSD 8.24 @ 84 MPH @ 7000 lbs

www.musc.us/drag
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osmiumfoot
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PostPosted: Thu Dec 12, 2002 8:37 pm    Post subject: Reply with quote

HeavyChevy - Ever run the same exact setup but without the girdle? I'd be interested to see if they make any difference below 6.5k. Try it once and see, then I'll know if I should get one for my Christmas present. Also, does anyone know if I should put a rev kit in a solid roller 355 (16 lash). Machinist says yes, Comp Cams says no but the guy on the phone sounded like he was studying for the SAT. What do you guys think? The shift point will be close to 7k, springs will be 440 over the nose with titanium retainers and locks.
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heavychevys
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Joined: 18 Nov 2002
Posts: 81
Location: South Carolina
754.46 points


1964 Chevrolet Belair

PostPosted: Thu Dec 12, 2002 10:08 pm    Post subject: Reply with quote

Haven't ever tried running with out them.The reason I run them is because I am using street style screw in studs(with out a boss).They have a tendance to back out.I don't use a rev and don't know how it would do.I have heard good things about them though.They say,also tested,that it is worth a least 15HP.
_________________
1964 Impala 468BBC 6.986 @ 98.69 MPH 1/8 mi

(Bothers) 69 Nova 408 BBC 6.94 @ 96 MPH
96 F250 4X4 PSD 8.24 @ 84 MPH @ 7000 lbs

www.musc.us/drag
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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Thu Dec 12, 2002 10:30 pm    Post subject: Reply with quote

heavychevys... what's the compression ratio on that motor?
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heavychevys
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Joined: 18 Nov 2002
Posts: 81
Location: South Carolina
754.46 points


1964 Chevrolet Belair

PostPosted: Sun Dec 15, 2002 8:21 pm    Post subject: Reply with quote

The compression is about 10.75 to 11.00.It will run all day on pump gas though I mix in a little 114 for the NOS.
_________________
1964 Impala 468BBC 6.986 @ 98.69 MPH 1/8 mi

(Bothers) 69 Nova 408 BBC 6.94 @ 96 MPH
96 F250 4X4 PSD 8.24 @ 84 MPH @ 7000 lbs

www.musc.us/drag
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