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Author Topic:   rear end and exhaust
chevelle
Dirt Full Roller

Total posts: 71
posted March 13, 2003 05:01 PM  
I am going to be running a 73 chevelle in a roadrunner class, if a 12 bolt rear was available in that car we can run it otherwise not, and no intermarriage(fo ford nine inch it out). My question is how hard is it (and costly) to find a 12 bolt for a chevelle?
My second question concerns the exhaust. Must run stock manifolds(no center dumps or ram horns, or headers). What is the next best option? And also would there be any gain to having an exhaust shop do pipes with a crossover, or a y into one pipe? Also what size pipe would be optimal?
Thanks

loojack
Dirt Maniac

Total posts: 196
posted March 13, 2003 05:25 PM  
I tried to find a 12 bolt for a car once, wish I'd run the 10 bolt, waisted the season looking for one. From what I understand a 12 bolt isn't that much stronger, just more gear ratios available. As far as exhaust I hear that manifolds off a Chevy truck with a vortec motor flow best. The EXPERTS say a cross over will add quite a bit of low end torque. Hope this helps..loojack

racinrich1
Dirt Full Roller

Total posts: 46
posted March 13, 2003 07:04 PM  
I found Just changing from stock y pipe w/glasspack...TO...custom pipes w/Flowmaster y pipe (collector) and 3 inch flowmaster muffler made a noticable difference out of the corner...
The new series I will run this year limits pipesize to 2 1/2 inch and says "no aftermarket "H" or "y" pipes...Any Ideas?
Rich

racer17j
Dirt Forum Champ
Total posts: 5390
posted March 13, 2003 08:26 PM  
Hey racinrich thats goood to here on the y pipe.I was running a 2.5 in with x last year it was getting beat up all the time.This year I got a flowmaster 3" in 4" out y merge collector with a 4" dyno max bullet muffler behind it sounds tits.Waiting to see if it helps,I was hoping it would work coming off the corner already have surplus of top end.

Pickel
Dirt Forum Champ
Total posts: 784
posted March 14, 2003 07:37 PM  
Thanks for all the info. I will probably stick with a ten bolt, since that is what it has now, and I also have a line on two more chevelles for parts. I am looking for any power advancements (without cheating)as I will be running against the smaller (lighter?) metric cars.

chevelle
Dirt Full Roller

Total posts: 71
posted March 17, 2003 05:20 PM  
One more question. I see Advance has a three core radiator for a chevelle for $99. Otherwise I will probably go with a four core from summit for $169. The class I'm going to run has to use a brass/copper rad. Would a three core be sufficient or would I need a four core.

racer17j
Dirt Forum Champ
Total posts: 5390
posted March 17, 2003 08:03 PM  
You have to be carefull not to oversize the radiator....You can lose turbulance which helps the cooling process....I went to Stewart for help and learned some interesting things that go against common beliefs...
Rich

Pickel
Dirt Forum Champ
Total posts: 784
posted March 17, 2003 09:10 PM  
As long as the radiator is new you will have no problems. I ran a 3 core when I first started, unfortunately it was about 10 yrs old and I didnt know anything then. I blew up (overheated) two motors in two weeks before someone suggested trying a new radiator. Come to find out my old one was so plugged up that it wouldnt flow good enough to cool properly. Wish I knew that in the begining......Live and learn......Have run a new 3 core ever since and have been more than happy with the performance.....

racinrich1
Dirt Full Roller

Total posts: 46
posted March 18, 2003 06:08 AM  
One more thing on cheap (offshore) radiators..
Some times they are light on solder in the seams and it is a good Idea to let a radiator shop go over them...
But then again...you could just spend the extra $ to buy a better quality one in the first place....

YOU GET WHAT YOU PAY FOR...

Rich

dirtrace54
Dirt Maniac

Total posts: 192
posted March 27, 2003 04:17 PM  
Not completely sure on this, but some of those chevelles did come with 8.5 10 bolts. Buy most rules if its available for that car, you can run it. The 10 bolt rear ends are easier to find. If you want some good exhaust manifold...check out brezenski. There on the web and they do a great job machining them to flow close to the big ram horns. I suggest running exhaust no larger than 2 1/4 unless you have alot of horses and are turning high rpms. The bigger size can loose torque. And definitely run a crossover. Check brezenski for their design on exhaust for some good ideas to for tuning with exhaust

chevelle
Dirt Full Roller

Total posts: 71
posted March 27, 2003 05:00 PM  
We have to run stock manifolds(no ram horns or vortec), so I'm sure the brezenskis would be out. Someone suggested '87 and up pickup or blazer manifolds. Would these be vortec? Would camaro manifolds be good? Sorry to be so stupid, but all my other projects have been stock Mopars.
Thanks

dirtrace54
Dirt Maniac

Total posts: 192
posted March 30, 2003 02:59 PM  
I'm not completely sure but the vortec didn't start till about 92 so I think the 87-90 or 91 would possibly work. Heres a place to get a free catalog that has some ggod factory parts www.sdpc200.com Check it out

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