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Topic Review (Newest First)
10-25-2012 09:13 PM
Originally Posted by hcompton View Post
I do agree they are easy enough to do. Just lots of hard work that needs to be right if its going 100k miles. Just want to give the best advice based on car and work needing to be done. If it was a ragged 89 mustang i would have different advice. As the job is easier and car does not have large collector value. A vette with a toasted indepentent rear is parts. New rear done by a good shop is 3k more at time of sale. So that is where my advice is coming from.
I have 200K race cars dropped off at my shop and they get treated exactly the same as a guy with a rusted out Camaro. Both car's get the same quality work and both customers are treated with respect. As far as gear work... There is NO way I could spend 3K for diff work on that car. Way out of hand..

If the OP has some mechanical knowledge and some patience he can do it and try and save some money.
10-25-2012 08:42 PM
Originally Posted by 1975yellowC3 View Post
I have the original 3spd auto in there now. I believe it is a TH400. I think even if it is a TH350 they both have 1:1 final ratio.

ssmonty - I have toyed with the idea of OD tranny. I have really been reluctant to change gears because of the higher highway rpm. Not sure I want to do that, but I realize it's a tradeoff and without it I have what I have!

The motor sounds really really good right now. I honestly don't really care about the sound, just want some good off the line power.

So...I have read many a thread on here that gears are by far best bang for the buck. I am just curious how much it would really help. It will turn the tires from a stop as is (P295/50R15s) have to floor it and it will spin probably 20 feet. I started out on this journey just wanting some neck snapping take off. It takes off pretty well, but I was expecting much more. I am assuming it has to be my gears.

Do you think it is worth changing cams? Will I really notice that much seat of the pants feel between what I have and the 268 off the line?
I have less motor then you, stock converter, and 411's.....29" tall tire, and from a roll can destroy them as long as you keep your foot in it. Yah, on the highway I cruise at 3000rpm, but its so worth it lol. I recently hurt my TH350 so will likely build a 200r4 with a 3500 converter in the spring and get the best of all worlds.....
10-25-2012 07:01 PM
prostreet6t9 Any shop that charges more just because he see's a Vette badge is a BS shop. The Vette diff is not any more difficult that any other diff but the gear sets are a little costly. Once you have the diff on the bench the labor should be reasonable.

If that 1200 includes: Posi.. gears.. complete O/H kit and bench labor..Its a little high. If a posi was not included than it's too high.

If you wanna try it yourself get ya some parts and we can walk you thru it.
10-25-2012 06:27 PM
1975yellowC3 For anyone intersted, here is a link to the hot rod article I built my motor around. I did pretty much everything they did except my heads are different.

Small-Block Chevy Build - We Increase The Cheap 350's Grunt To 420 HP - Hot Rod Magazine is a link to an article that did a comparison of several different cheapo heads. Mine are in there and are the floo-tek's. Might be useful to other folks.

Eight Budget Small Block Chevy Heads Tested - Car Craft Magazine
10-25-2012 11:06 AM
Originally Posted by hcompton View Post
Have you seen what a empty case cost?
Either you're missing my point or I'm missing yours. What I suggested was to buy a used pig....I've seen them on craigslist for $300/$350. Take it home, tear it apart, install whatever gear you wish, do the pig swap over the weekend, then put your original pig on craigslist and recoup your $300/$350.
10-25-2012 08:36 AM
spinn That is a big cam, plus you have an auto with 2.76 gears . Not good for driving fun. If you had a nice restoration take advantage of the long strokes torque boost with a reasonable cam. A cam with duration and lift like that is going to sound like a demented popcorn maker. Weird but that sometimes people like that. They make for poor overall performance, from a drivers perspective, to me at least. If you had .450-.470 lift it would make a sexy bubble. You made what made. Now spend a day swapping the ring and pinion to 4.10 and pay the piper.

If you built it for that cam, you should have gone high stall, big gears. Hot rod did this build?

Nothing to be scared of using a 262. Dynamically it is a better choice.

Finish the combination you made and enjoy it. It will be highwayable with 4.10s , just busy.
10-24-2012 08:27 PM
vinniekq2 couple typos, trailing "arms" and 1962 technology not 1062,sorry. the 1963 corvette has the same suspension we have now.

Also if you have the low profile hood I have to assume your car is down on power as there is not enough room under the hood for a good intake.
You can put 3 inch exhaust through the transmission x member if you do not have side piped
10-24-2012 08:21 PM
vinniekq2 I use 3.50 gears in the same car as yours.I went from a 4 speed to a 5 speed.My O/D works out to almost the same as what I had with none o/d and 2.73 gears. The diff is a little bit of a pain to work on. Before you change gear sets,make sure you have the Dana 44 not the Dana 36. These are reasonable weight cars and they hook quite well.If you really need to go 3.73 gears make sure you have the 30% O/D.No reason for you car to be slow off the line.Not a big fan of big hydraulic flat tappet cams but it should work well from 3,000 to 6,000 rpm.
NOTE: when you are under the back of that car,dont be surprised if it needs trailing are work and all the bushings. If you have soft or single fibre glass transverse spring,then that too needs to be upgraded to stop the car from squatting on launch. The car can be very difficult to launch and keep straight. When I did my car I also upgraded the 1/2 shafts and u-joints to big block or better.
Now that you see closer to 2k,you might consider up grading to a true independent rear suspension.The car has 1062 technology in the suspension
10-24-2012 08:05 PM
techinspector1 Great!! Here are some diff guys if you need parts or help....
Home Page
Moser Engineering - Moser Engineering - Home
Ring & Pinions, Front Axles, Rear Axles, Differential Covers and more from G2 Axle & Gear
PRO GEAR DIFFERENTIALS - San Diego's Original Gear and Axle shop. Differential parts and repair.
10-24-2012 07:57 PM
ssmonty IMO, a thumper cam with its narrow LSA coupled with the 2.73 gears would make for a real dog off the line and give up alot of midrange acceleration even with a slightly higher than stock stall convertor.
A 270HR cam with just a 3:42 gear would make enough of a night and day difference to justify the cost. But then again, I'm not the one paying for it and I don't know if your more concerned with HP numbers or a broad torque range from idle to redline. How often do you turn 6500rpm?
I don't care for the bigger cams on the street as they use alot of gas, don't have the same instant off idle throttle response, and wear out an engine sooner because of the higher optimun rpm range. I much prefer the good driveability of milder cams, but then again it may be because I'm getting too old.
I've attached a link to a site that you can download a Static/Dynamic CR calculator that I think is one of the better ones around. I would try to give you some numbers for the cam I suggested, but I don't know the required parameters of your engine.
I will say that using Comp Cams camquest software and what I'm approximating your engine specs are, that I get about 450 ftlbs of torque as low as 2500rpm with a peak of over 470ftlbs at 4000rpm, and 415HP at 5000rpm useing Comp's pn 12-420-8 270HR. I'm not saying thats the best for your application or driving style, but I know it would put a smile on my face, but thats just me.
Good luck,ssmonty
calculator site location
Dynamic CR
10-24-2012 07:51 PM
1975yellowC3 I like your style tech! I have read several posts about changing the gears and it kind of scared me off. But what the heck, I hadn't ever torn down a 350 before I built mine. I put it together and it is still running!

Thanks for the encouragement...I think I might try to give it a whirl!
10-24-2012 07:25 PM
Originally Posted by 1975yellowC3 View Post
I guess I am just looking for a bigger smile when I hit the go pedal!

I had checked on gears a few weeks ago and they were talking what i thought was crazy money to change them. Around 1200 (2 shops about the same price) dollars if I just dropped the car off. This was figuring on replacing bearings/seals. I was expecting it to cost in the neighborhood of 600! I am thinking about taking the rearend out and just delivering it, which would save me considerable labor money.
You're a hot rodder, right? Well, hot rodders figure out how to do stuff. What if you purchased a used pig and changed the gears yourself? You could then change 'em out and sell your stock pig. Here's a reprint of the original factory service manual from Faxon. It's 2 3/4" thick and costs $74....With this manual, a few tools and a little time, you could learn how to do it yourself....
1975 Chevrolet Repair Shop Manual Reprint Set 75 -- All Car Models
10-24-2012 07:01 PM
1975yellowC3 I guess I am just looking for a bigger smile when I hit the go pedal!

I had checked on gears a few weeks ago and they were talking what i thought was crazy money to change them. Around 1200 (2 shops about the same price) dollars if I just dropped the car off. This was figuring on replacing bearings/seals. I was expecting it to cost in the neighborhood of 600! I am thinking about taking the rearend out and just delivering it, which would save me considerable labor money.
10-24-2012 06:46 PM
Originally Posted by 1975yellowC3 View Post
Do you all think I would be safe on my cam/rod clearance when changing?
If you used Scat Pro Stock rods, they will clear. Any other rods you will have to check the clearance for yourself. Easiest way is to use a long tie wrap. If the tip clears, you're golden.

If you're not concerned with idle quality, then there are better cams than the one I spec'd above. I picked it because of its 106 degree LSA. If you want to give up some lumpy, a cam that wil extend the range out a little further and give a little better idle quality can be chosen, using a 110 LSA.

But before you do anything, you need to take all the options into consideration and decide where to put your money. My opinion right now is that a set of 4.11:1 gears would push you back in the seat hard enough that you would be happy. Even a set of 3.73's would be a day and night improvement. But then, a looser converter would get you up in the power range of the cam sooner. I suggest you get prices on gears and prices on converter and leave the cam alone for now. 8.19:1 DCR ain't all that bad, if you could get up on the cam earlier with either a converter or gears.
10-24-2012 06:32 PM
Originally Posted by hcompton View Post
That being said you may need a bit more stall. But dcr should be ok at 9.5 and al heads.
Please be careful when you say these things. At 9.50:1 DCR, this motor would rattle like a can of marbles on pump gas and nothing short of alcohol could make it stop detonating. Of course that's just my opinion.
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