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Author Topic:   rear end and exhaust
chevelle
Dirt Roller

Total posts: 9
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: 133
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: 42
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: 1565
posted March 13, 2003 08:26 PM UIN: 54865418
the only real advantage to a 12 bolt like loo said is the gear selection and it's getting pretty hard to find a good 12 bolt anymore it's to the point i have seen them with possi in them go for over 1000 on ebay. as for the exaust yes a cross over of some kind will help we used to have to run the stock y pipe untill a guy spent some money on a hifi set up so now they are outlawed we have to run dual exaust. right now we just have the mufler shop bend us up some that clear the floor board and then just come straight back a ways then we paint the pipes with a rattle can and start the car up and let it run for a while the paint will burn off so far and that where we cut it and turn it down that is suposed to be the best way to get max torque with a dual set up with no cross overs

mudcat #34
Dirt Full Roller

Total posts: 38
posted March 13, 2003 10:51 PM UIN: 114549278
hey 17j do you cut the pipe where the paint stops burning off?thanx

racer17j
Dirt Forum Champ
Total posts: 1565
posted March 14, 2003 12:02 AM UIN: 54865418
yup thats how we do it

dirtracer7
Dirt Maniac

Total posts: 106
posted March 14, 2003 02:10 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: 564
posted March 14, 2003 07:37 PM UIN: 25419780
the 12 bolts a getting hard to find and when you do find one they want a few bucks for it..I like the 10 bolt cause of they still a bunch out there..I a 538 in mine and ran a 1/2 mile and a 3/8 mile and did good with it..

chevelle
Dirt Roller

Total posts: 9
posted March 14, 2003 11:25 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 Roller

Total posts: 9
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: 1565
posted March 17, 2003 08:03 PM UIN: 54865418
a 3 core will work but 70 more bucks is cheap insurance

racinrich1
Dirt Full Roller

Total posts: 42
posted March 17, 2003 08:17 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: 564
posted March 17, 2003 09:10 PM UIN: 25419780
I have always ran a 3 core copper/brass radiator and it has always kept my car cool. I have run a 355 11-1 with hump heads 202 valve and electric fans and it kept the car plenty cool. As long as you have good airflow through the radiator you should be in good shape

NYhick
Dirt Forum Racer

Total posts: 82
posted March 17, 2003 09:40 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: 42
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 Forum Racer

Total posts: 91
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 Roller

Total posts: 9
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 Forum Racer

Total posts: 91
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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