Ok, so I have an 86 Coupe that I bought new, only has 12,000 miles on it (original tires too). Yea I know... I need to drive it more. Anyhow I want to do some upgrades. Have been reading a lot of posts the last couple of days. What I'm thinking is this. I want to start with changing the rear ratio, it's an auto, so while I haven't checked I'm pretty sure it has a 2:59 in it. I ordered the performance gear upgrade but the computer kicked it out because of the Bose Stereo System. I was thinking either a 3:54 or 3:73. I realize it's a Dana 36 and also realize that the engine needs to have the breathing upgraded...( I'll get to that. ) Since not going to be a high HP engine, do you guys think the Dana 36 will be fine? I'm sure I'll make some trips to the track but this isn't going to be strictly a track car by any means. I'm keeping my eye open for the right Dana 44 setup just in case the future holds a different engine and more HP but I think I can spend my money a little wiser to start. Next I would probably upgrade the exhaust. I don't like really loud exhaust noise so I have to find the right mufflers for the job, would probably go with long tube headers as well. Intake runners ( what brand ) and maybe porting the lower intake and plenum would go with that. I am really confused with the runners.... seems like the best ones were AS&M or TPIs but from what I saw they aren't made anymore. Would be nice to see some actual airflow numbers from someone with a flow bench...but I haven't seen anything with regards to that. I am open to a performance chip change but not sure what that will give me performance wise.
I took it to the track when it was newer (LOL) and ran low 14.10's to a best of 13.98. The 13.98 ( all on the original tires ) was leaving it in drive with no power braking....just mashing the gas when the last amber light came on. It would hook right up with no wheel spin at all. I'd like to get it into the lower 13's and I think I'll be happy with that for now. Let me know what you think.

 

That looks like a very nice corvette zbo. Are you sure you what to scratch and mark it up working on it? Seriously C4's are fairly cheap and I'm sure you could find a high mileage C4 in good enough condition to hack up as much as you want w/o affecting it"s value. A perfectly stock car with low miles like yours is nearly unobtainable and restoring a average C4 to that condition outrageously costly.
Your vette deserves just sunny day cruises.
I guess what I'm saying is modifying for performance will accelerate wear and tear that almost can't be undone.


But nothing wrong with learning how to performance tune your computer - adds power without turning a wrench and is the basis for any performance improvements. Tuning programs like WINADL are free but you need a older laptop with a RS232 port.

Good luck.

 

Thanks...… well I'm getting peer pressured by my younger next door neighbor... he's a Ford guy....lol
Do I have to say more? Besides when the car was 1 year old my 4 year old was chasing his 9 year old brother around the car with a bent piece of copper and missed him with it and hit the top of the hood and took a little chip out of it.... so it's no virgin.
Besides all that, I have been tossing the idea around for years. When I had just got my license in 72, across the street from one of my good friends was a guy kinda like me now. He had a 67 435 HP 427 Red and beautiful. All he did was race it at Atco Dragway, tinkered with it all week and raced on the weekends...…. till the divorce.... then he had to sell that car. What a shame. Mine has been sitting toooooo long it needs to have some fun...just like me, keeping up with my neighbor...lol

Joe

 

I would go" thrifty " and look for a good used 3.07 D36 assembly and swap it in. Then do other mods to boost the L98's performance.

 

Well if I'm gonna make a change I don't really want to just go to a 3.07. I'd want to go to at least a 3.45. I've see some 3.73 D36 center sections but they are always in the 500 to 700 buck range. I think I'd rather just double that and make the full D44 switch. Then I don't think I'd have to worry about the rear.... I'd never build anything with more than 400 to 450 RWHP and the 44 should take that...… I think I would worry to much about the 36 for that kinda future HP. Especially if I were to leave the original D36 setup in there. Would have to figure out the speedometer, I know they have a digital speedo correction device but I can't seem to find it. They didn't offer the lower ratio rears till 89 and that had a different trans than what I have so I'm not sure if changing to those speedo gears and speed sensor would work.
Joe

 

What?

 

That car with such low mileage, I'd not modify at all. I'd leave as is and buy another one to mod, or sell it as is.

In any case, yes AS&M and TPiS bigmouth runners and base are the best TPI-style runners and intake manifold.

Hooker 2149 or TPiS are the best headers, make sure they are ceramic coated. However, headers gets loud and it will drone, with or without the main cat in pace. Corsa are recognized as the quiet cruising muffler that only gets loud when you stand on it.

The aftermarket chips are useless, just wastes of money. If anything, you need a custom tune AFTER your major mods are done.

 

Exactly what I said when the salesman called me just before they started to build the car.....

 

Vader. I hear that...….. . I'm not gonna chop it up or do anything that isn't reversible. Shame the AS&M and TPiS stuff is so hard to come by. What about the speedo correction....will the gears and speed sensor from a 90 work on my 86 to get it close. I'm hesitant about doing the headers to begin with..... maybe if I were to put a 383 in it I'd do that. I could do a Cat back with a higher flowing Cat. I have some searches running for the runners and intake base so I'll just have to wait and see what happens with that. I have all winter to see where this project takes me.
Joe

 

You can use the "thick" gears with the higher numerical carrier..

https://www.randysworldwide.com/diff-wizard/?diffyear=1986&make=Chevrolet+%2F+Chevy& model=Corvette&drivetype=Rear+Diff+-+RWD&diffid=124

 

I saw that thanks...…. but in thinking about it.... I think the money would be better spent on a Dana 44 setup. It wouldn't cost that much more to do it verses replacing the gears in the 36 if I can find the right one ( I think I have ). The would leave the original rear untouched and sitting in my garage.

 

After a year and a half of being busy I am getting back on track with this project. Picked up a SuperRam, waiting on the TPiS long tube coated headers and Y pipe to show up. Also picked up a D44 3:45 setup to install as well. Big time undecided on a cam though. Was contemplating changing the heads but I think I'm gonna pass on that for right now. Was kinda hoping that this had a roller cam in it, any chance a late April car might? LoL Seems like all the good cams are roller. I guess I'm gonna have to browse the cam sites to try to find a flat tappet close to the 219.
I guess worst comes to worst I could get a set of 1.6 rockers... although I would rather change the cam and springs.

 

Did muffler deletes on a friends 86. Sounds great and added little more power

 

Looking at these 3 flat tappet hydraulic cams.

Crower

Part Number: 00230
Chevrolet Hydraulic Flat Tappet Camshaft

Chevrolet - 262, 267, 283, 302, 305, 307, 327, 350 & 400
Performance level - EFI, Forced Induction & NOSINT/EXH - Dur @ .050” Lift: 214°/222° RR: 1.5/1.5 Gross Lift: .450”/.470” LSA: 114° RPM: 1300 to 5800 Redline: 6300



Part Number: 00231
Chevrolet Hydraulic Flat Tappet Camshaft

Chevrolet - 262, 267, 283, 302, 305, 307, 327, 350 & 400
Performance level - EFI, Forced Induction & NOSINT/EXH - Dur @ .050” Lift: 222°/230° RR: 1.5/1.5 Gross Lift: .470”/.488” LSA: 114° RPM: 1500 to 5900 Redline: 6400
Learn More



Comp Cams 12-366-4

Small Block Chevy 262-400ci 1955-98

Excellent mid-range for TPI 350 with chip upgrade, injectors, plenum and exhaust system.
Operating Range:
2000-6000 RPM
Duration Advertised:
268° Intake / 280° Exhaust
Duration @ .050'' Lift:
224° Intake / 231° Exhaust
Valve Lift w/1.6 Rockers:
.520'' Intake / .515'' Exhaust
Lobe Separation Angle: 113°

 

Leaning towards the bottom one.

 

OK, Unless someone has a better idea I am going to go with this Comp Cam. I am also putting 24# Bosch injectors in. I "might" put a BlowerWorks 6 or 8 psi Super Charger on this in the near future which factored into this decision. But I could be persuaded to look at a different cam.Comp Cams 12-366-4 Small Block Chevy 262-400ci 1955-98

Excellent mid-range for TPI 350 with chip upgrade, injectors, plenum and exhaust system.
Operating Range: 2000-6000 RPM, Duration Advertised: 268° Intake / 280° Exhaust, Duration @ .050'' Lift: 224° Intake / 231° Exhaust, Valve Lift w/1.6 Rockers: .520'' Intake / .515'' Exhaust, Lobe Separation Angle: 113°

Do I "need" to upgrade to 7/16 rocker studs for something like this or are the 3/8" good enough?

I am going to use their Ultra Pro Magnum Rockers and BeeHive valvesprings and hardened pushrods.

I am just waiting on the headers before I start my tear down.... They tell me the cam is less than a week away.

 

I'd say that cam is a big as I would use on a TPI.

With stock iron heads I don't see the need for high ratio (1.6) rockers as most of those stock heads don't flow much past 0.5" valve lift. When you use higher ratio rockers with iron heads you need to elongate the slot in the head that functions as a guide plate. If you don't your valve train will have a short life.

7/16" studs are truly better but I feel it would be added expense for those heads with really nothing to gain. But for the same price I would do it. Remember to check you rocker to stud clearance if you do. So are you having your heads redone also? I didn't read that anywhere but if your adding studs usually the heads come off. Take off the heads then gett'm pocket ported - best bang for the buck.

Lately I've been told the stock p-rods are too flexible so upgrading those is a good idea. Pro Magnums are good rockers though.

 

Comp is recommending the 1.6 rockers for that cam. I realize it's a little bigger lift wise for the stock aluminum heads, but I am thinking "future" if I put the Super Charger on it. I am thinking about yanking the heads but haven't totally decided on that option. Ligenfelter does them for 1,595 but I would have to pick up a set of 88 or later cores for them to do. Not really looking to spent 2 grand on heads at this point. If the Super Charger happens these heads would be fine anyhow. I don't want to put a roll cage in this car for sure and if the heads are done and I put 8psi on it I might be getting a little too fast...lol. ARP make a set of 7/16" studs that have 3/8" base threads so they would screw right in...that has to be better than the stock setup. I am getting rid of the stock push rods in favor of the .080 hardened ones.

 

Okay I see you have the L98 aluminum heads. Couldn't verify that yesterday and all I found was iron heads for the '86 corvette. Well it looks like you haven't shopped for sbc heads lately. Many brand new performance heads are far less than $1595. Just stick with reputable brands like Brodix, Dart, TrickFlow.
Your aluminum heads should have large p-rod slots and use guide plates so using 1.6 ratio rockers is just a matter fitting the guide plates since 1.6 rockers move the p-rod in closer to the rocker fulcrum and might rub severely on the guide plate slot.

But pulling the heads gonna make it a lot more work for this project and cost a good amount more $$. If you plan to use a supercharger in the future then that would be the time to get larger chamber heads that will work well/much better with the supercharger.

Well it looks like Ultra Pro Magnum Rockers using 7/16" studs are pretty much same price as the 3/8" stud set. Yea, that's good idea then just remember to order the right ones for your studs. Man those Ultra Pro Magnum Rockers look great - wish I had'm.

Good luck.

 

I hear you on the heads and am rethinking them. I have to start looking at the specs. I hate to give up the 58cc chambers but the better flow would probably make up for the loss of compression.