SpeedTalk Store - Opinion Columns

Sbc 350 build for drag racing

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Re: Sbc 350 build for drag racing

Postby monzter » Sat Oct 13, 2012 8:47 am

Thanks for your input Dezza. As I should have mentioned before I really don't insist on using these cams mentioned above. Would it be best to go with custom camshaft for my combo, or would something off the shelf work just as well ?

Randy - i as well as you found that odd also, so i spoke to 3 different guys over there at Comp Cams and two of them recommended that 12-824-14 cam while the other guy recommeded the one size smaller cam #12-908-9 IIRC
monzter
Member
Member
 
Posts: 55
Joined: Sat Feb 21, 2009 8:41 am

Re: Sbc 350 build for drag racing

Postby dezza » Sat Oct 13, 2012 4:43 pm

The comp cam would work fine but there is more to be had .
Most cams should be ground for there use .
dezza
Pro
Pro
 
Posts: 354
Joined: Thu Aug 19, 2010 3:25 am
Location: australia

Re: Sbc 350 build for drag racing

Postby barnym17 » Sun Oct 14, 2012 7:06 am

Call Mike Jones (Cam King) for just a little more than a shelf grind he will set you up right.
barnym17
Expert
Expert
 
Posts: 898
Joined: Fri May 12, 2006 3:37 pm

Re: Sbc 350 build for drag racing

Postby monzter » Sat Jan 05, 2013 9:35 pm

What kind of rear gears could i use in my car for optimum n/a performance. don't mind to spin some rpm's as long as this thing goes fast while doing it...
i'm also in the process of doing a little diet on the car. Should be 2750-2800 lbs on the line when ready. The converter as mentioned above is supposed to stall at 5500-5800.. And i'm also going to port match the heads and intake to 1206 gasket and do some plenum work to the intake along with a 4 hole spacer that has been recommended. I have also bought a belt drive system i'm going to use.
monzter
Member
Member
 
Posts: 55
Joined: Sat Feb 21, 2009 8:41 am

Re: Sbc 350 build for drag racing

Postby Nitrousknob » Sat Jan 05, 2013 11:12 pm

That aint a street car anymore with the 5800 stall......Lighten it up. 2200 lbs should be no problem. 5.60 something gears. 250 shot NOS. If your running a stock block, hard block it from water pump holes down. I'm building a 327 with a Bullet S/R 278 and 292 @ .050 .725 IN .708 EX 110 L/C, 2 stages NOS, AFR 210. Them small motors will kick ass if done right and you'll have fun doing it.
Nitrousknob
Pro
Pro
 
Posts: 226
Joined: Fri Sep 18, 2009 8:13 am
Location: Vilonia, AR

Re: Sbc 350 build for drag racing

Postby monzter » Sun Jan 06, 2013 7:01 am

Yes i guess that you're right about that no street car thing and that's fine by me i guess. As i would like to keep the car all steel beside the hood i'm not sure how to lighten it up to those numbers above...
I was thinking about running it only n/a so 5.xx gears might be good for max effort 1/4 mile ?

The guys that had replied before seemes to like the smaller camshaft better, but all threads i read about similar race 350 engines with too big heads 220-235cc everybody seem to recommend an awfully large camshaft and big rpm's
Would it be possible for me to make around 600 hp with my engine n/a ?
monzter
Member
Member
 
Posts: 55
Joined: Sat Feb 21, 2009 8:41 am

Re: Sbc 350 build for drag racing

Postby RichardThiessen » Sun Jan 06, 2013 11:21 am

I used that Comp cam (non 4/7 swap version) in a 355 in a drag race S10 that weighed 3,000 lbs with me in it. 13:1 comp and Dart 230's, 5500 stall. Went 10.50's on good days, and as slow as 10.80's on bad days. It was definately not a streetable though.

Not to say there wouldnt be a better combination than what i ran, but just for information purposes. It made 550 hp on the dyno. Did not make much torque, needed rpms to run those times.
RichardThiessen
Pro
Pro
 
Posts: 252
Joined: Wed Jul 14, 2010 8:37 am

Re: Sbc 350 build for drag racing

Postby monzter » Sun Jan 06, 2013 12:27 pm

Can you tell me more about the combo you where running Richard, tire size, gears, intake, carb and such, what was the trap speed and how high did you spin it ?
based on your combo and the advices the guys have given me the smaller cam would probably do better in the engine... Is this comp camshaft an old design ?
monzter
Member
Member
 
Posts: 55
Joined: Sat Feb 21, 2009 8:41 am

Re: Sbc 350 build for drag racing

Postby randy331 » Sun Jan 06, 2013 1:07 pm

I certainly wouldn't buy a different cam at this point. I would use the Crower cam you have, or re-install the 230/236 cam and use that belt drive for what it's for, easy cam position changes. Trial fit all the cams you have and check for valve to piston in full advanced position and full retarded poisition, to see where you can run them, and/spring coil bind/retainer to seal clearance etc. Then run them all in different positions with tight and loose lash and get some data before deciding on a different cam.

I helped a friend with a 355 in a 3000lb nova. 5800 stall 5.43 gear. With a 210cc head and 264/274 duration cam it was making peak hp over 7000 rpm. It ran a 1.349 60'/ 6.37 1/8 @ 105+ /10.11 1/4 @ 130 mph. We tried a professionally ported set of pro1s that CCed 236 and best 60' was 1.395 despite the 45 lbs lighter the car was with the aluminum heads. Stall speed was 300 rpm less with the bigger heads.(5500 now) Optimum shift rpm went way up. it was being shifted at 8000 rpm and probably needed more with the 236cc heads, but with steel valves, stud mount rockers and 5/16 pushrods, I wouldn't go past 8000.

With an automatic car, one of the most important factors in ET is the power in the first few 100 rpm above stall speed. That determines 60' ability and shift recovery in some cases.
You already have a too big of head, don't bandaid it with too big of cam.

Randy
randy331
Guru
Guru
 
Posts: 1886
Joined: Mon Dec 04, 2006 7:30 pm
Location: N.W. MO.

Re: Sbc 350 build for drag racing

Postby monzter » Sun Jan 06, 2013 1:24 pm

Thank's for a great response Randy. I have some questions about this Nova. Do you remember how tall the tires where, because I see it had a very deep rear gear !
And how did the bigger heads compare to the smaller 210cc heads at the strip. et and mp/h wise ? and what kind of heads where those ?
monzter
Member
Member
 
Posts: 55
Joined: Sat Feb 21, 2009 8:41 am

Re: Sbc 350 build for drag racing

Postby levisnteeshirt » Sun Jan 06, 2013 1:30 pm

randy331 wrote:I certainly wouldn't buy a different cam at this point. I would use the Crower cam you have, or re-install the 230/236 cam and use that belt drive for what it's for, easy cam position changes. Trial fit all the cams you have and check for valve to piston in full advanced position and full retarded poisition, to see where you can run them, and/spring coil bind/retainer to seal clearance etc. Then run them all in different positions with tight and loose lash and get some data before deciding on a different cam.

I helped a friend with a 355 in a 3000lb nova. 5800 stall 5.43 gear. With a 210cc head and 264/274 duration cam it was making peak hp over 7000 rpm. It ran a 1.349 60'/ 6.37 1/8 @ 105+ /10.11 1/4 @ 130 mph. We tried a professionally ported set of pro1s that CCed 236 and best 60' was 1.395 despite the 45 lbs lighter the car was with the aluminum heads. Stall speed was 300 rpm less with the bigger heads.(5500 now) Optimum shift rpm went way up. it was being shifted at 8000 rpm and probably needed more with the 236cc heads, but with steel valves, stud mount rockers and 5/16 pushrods, I wouldn't go past 8000.

With an automatic car, one of the most important factors in ET is the power in the first few 100 rpm above stall speed. That determines 60' ability and shift recovery in some cases.
You already have a too big of head, don't bandaid it with too big of cam.

Randy

=D>.,, sell the big heads and do what his buddy did
levisnteeshirt
Guru
Guru
 
Posts: 1602
Joined: Tue Aug 18, 2009 1:53 pm

Re: Sbc 350 build for drag racing

Postby TMSJoe » Sun Jan 06, 2013 1:55 pm

I don't think you are going to get those 235cc #-o heads to take off right ever with a 350. Now if you install a nice 5 speed and launch @6500 we may be getting somewhere.
TMSJoe
Expert
Expert
 
Posts: 516
Joined: Wed Dec 29, 2010 8:53 am

Re: Sbc 350 build for drag racing

Postby monzter » Sun Jan 06, 2013 3:07 pm

So there's really no chance for me to get these big heads to work on my small cid engine... That's not good because it's really not an option to change them at the moment.. At least not this year.

Best regards.
monzter
Member
Member
 
Posts: 55
Joined: Sat Feb 21, 2009 8:41 am

Re: Sbc 350 build for drag racing

Postby RichardThiessen » Sun Jan 06, 2013 3:35 pm

monzter wrote:Can you tell me more about the combo you where running Richard, tire size, gears, intake, carb and such, what was the trap speed and how high did you spin it ?
based on your combo and the advices the guys have given me the smaller cam would probably do better in the engine... Is this comp camshaft an old design ?


It's been a while, I think it was 28" tires, 4.56 gears, 850 demon carb, single plane intake, 1.8 rockers, big headers, th350.. I think trap speed was 127 mph, but would have to look up old time slips... That could be wrong. I think I took it to 7500 rpm with stock polished rods with arp fasteners... Motor probably wouldn't have lasted long the way I was running it so built something better.
RichardThiessen
Pro
Pro
 
Posts: 252
Joined: Wed Jul 14, 2010 8:37 am

Re: Sbc 350 build for drag racing

Postby randy331 » Sun Jan 06, 2013 5:06 pm

I'm not suggesting selling the heads. Im not one to just spend money without a clear picture as to why. You may go up in cubes someday and then the heads will be a better match.
What I'm saying is, I think the heads are big for a 355 with a 5500 stall speed, so don't make matters worse with a too big of cam.
That's why I suggested testing with the cams you have. Learn something about the engine before you spend money.

This idea that a big head with big valves needs a big cam is backwards. With a fixed starting line rpm, you need less cam as the ports get bigger. You have a 5500 converter. That converter sets the bottom of the engines rpm range. For lowest Et you need the heart of the HP curve to be 5500-7000 rpm. If you keep moving the power curve up in the rpm range you will start hurting power at stall speed, and that 5500 rpm converter will become a 5300 converter or worse, and then you will be able to measure your 60' time with a sun dial. The first 60' is way more important than the last 60'. MPH doesn't give you ET, but 60' time will.

We dynoed a 383 Friday. With a 236/248 on a 108 cam and 210 cc heads with 2.02/1.56 valves, it would make peak HP around 6800. We changed to a 252/260 on a 108 lsa with more lift and it made peak power at 7100 rpm, but was only up about 12-15 HP. Peak TQ was less and 400 rpm higher than with the smaller cam. Both cams were tested in several positions to find the best power. With the bigger cam it would need a 6300-6500 stall for best et.

Where do you think a 355 with 235cc heads and that cam comp recommended would make peak TQ and peak HP?
With an automatic you want all the power piled just above stall speed.

Randy
randy331
Guru
Guru
 
Posts: 1886
Joined: Mon Dec 04, 2006 7:30 pm
Location: N.W. MO.

PreviousNext

Return to Engine Tech

Who is online

Users browsing this forum: 1972ho, 8ad-f85, Bing [Bot], emleydon, o2man98, steve316, The Radius Kid, twl and 39 guests