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 Back in a Formula Again 
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Post Re: Back in a Formula Again
That's super cool at the grad night!

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86 IROC
LQ4/T56/3.50 8.8 (next step..TC76)
Build thread: http://ls1tech.com/forums/conversions-hybrids/1819001-1986-iroc-turbo-lq4-t56-build-ac.html
Formerly 95 LT1 [LE2.2]/T56/4.11 9 Bolt..12.6@114MPH


Wed Jul 05, 2017 11:23 pm
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Post Re: Back in a Formula Again
Well......looks like Photobucket has completely trashed this thread!

Guess I have a pile of editing to do. :evil:


Sun Jul 16, 2017 7:50 am
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Post Re: Back in a Formula Again
OK....all the links have all been transferred over to Flickr......Photobucket can kiss my butt!

Oddly enough there is 1 post on page 10 that the site would not allow me to edit......anybody have any insight as to why that might be?


Sun Jul 30, 2017 8:47 am
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Post Re: Back in a Formula Again
Back when I first bought this car it had numerous brake issues that I documented early on in this build thread. To get the brakes functioning normally required a new master cylinder, new flex lines, & all 4 calipers were rebuilt. The existing pads and rotors appeared to be in relatively good condition so they remained & I have been driving with them since. Despite most of the braking system being new though, I would not describe the braking performance as "Good"..........."Adequate" would likely be a better description.......they stopped the car.

Fast forward a few years now & I got a Wholesale Closeout email from RockAuto in which I discovered new front brake pads for $8 and new rear pads for $7.....I decided to finally dig into the brakes to see where some improvements could be had. What could it hurt.....all new pads all around for $30 shipped to my door! After all, the existing parts would likely be upwards of 10 years old from what I know of the history of the car.......I really don't know if pads age and lose performance like a tire would for example, so to cover that base, and for the sake of $30, why not just replace the pads.

Now I decided to tackle the rears first for a couple of reasons. Driving the car gave me the impression not much was happening back there......that impression seemed to be backed up by the fact that, while I was constantly having to clean brake dust off my front wheels, the rears remained relatively clean.

So I set about resurfacing the rotors & popping the new pads in. After bedding the pads in, I did note an improvement, but it really wasn't anything to write home about. That's when I came across a thread on thirdgen.org that intrigued me.

https://www.thirdgen.org/forums/brakes/ ... grade.html

So I headed over to my local Acklands Grainger & ordered up some new springs for the proportioning valve.

Image20170803_114649 by Shane Hewitt, on Flickr

Now being the person I am, I wanted to devise a way to determine if the new spring actually made a difference other than "it feels better". What I decided to do was to drive around my block somewhat aggressive & measure the temps of my brake rotors immediately after rolling into my garage. With the OE spring installed my rotor temps were as follows.

Front rotors.

Image20170803_114358 by Shane Hewitt, on Flickr

Rear rotors.

Image20170803_114346 by Shane Hewitt, on Flickr
Image20170803_114340 by Shane Hewitt, on Flickr

Once that little test was completed I proceeded to swap the new spring in.

Image20170803_115414 by Shane Hewitt, on Flickr

New spring on top, old spring on bottom.....note the new spring has notably thicker coil wire.

After bleeding the system, I then went out to perform the same test. Upon returning to my garage, the front rotor temps remained essentially unchanged as I would have expected. My rear rotor temps changed though!!

Image20170803_130147 by Shane Hewitt, on Flickr
Image20170803_130128 by Shane Hewitt, on Flickr

The 30 deg increase in rear rotor temps would lead me to believe that the rears are working a little harder now! Given my test drive was only less than 3 minutes, its hard to say if there is a seat of the pants improvement or not.........I'll report back on that later once I have logged some more miles with this spring installed.

I also have 4 more springs out of the 5 pack available if this is something of interest to anybody else.


Thu Aug 03, 2017 3:58 pm
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Post Re: Back in a Formula Again
Got out for a nice hour long cruise yesterday so I thought I would post a follow up on how the proportioning valve spring is working out.

It would seem that the pads have bedded in better as my rotor temps have gone up a little more in the rear. Instead of the 60 degree difference front to back I initially saw after putting the spring in, I'm seeing about a 45-50 degree difference. So if the front rotors are at 195 - 200 degrees, I'll typically see 145-150 on the rears. Having said that, during regular cruising around, you can tell the rears are participating more in the fun now.

Towards the end of my drive I decided I should really do some hard braking to get a feel for how the brakes work now so I know what to expect if I really have to lay on them. So I went out to my "test facility" & got up to 130'ish km/hr and progressively braked harder and harder. Ultimately I got to the point where the rear tires were starting to howl warning of impending lock up before the fronts. :shock: At this point I'm hoping the front brakes pick up some power when I put the new pads on to balance the system out again as I really don't want the car to be tail happy under hard braking. Hopefully I'll get time to give the front brakes some love this week. On a positive note though, this is the first time the rear brakes have had the power to lock the tires up, & the brakes definitely whoa the car in a hurry now, so definitely a pretty significant upgrade.

So I would now upgrade my assessment of the car's braking performance from "adequate" to "pretty good". A little more power & initial bite from the front brakes would earn the car an "Excellent"......hopefully that will happen this week.


Last edited by auto_god on Mon Aug 07, 2017 7:57 am, edited 1 time in total.



Mon Aug 07, 2017 7:15 am
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Post Re: Back in a Formula Again
While I'm posting follow ups I should make note of a trait the car has picked up since installing the subframe connectors.

Before I installed the subframe connectors accelerating aggressively out of a corner (such as turning through an intersection) would of course twist the body some, unloading the inside tire causing a nice progressive drift around the corner. Since installing the subframe connectors, the body twist has been pretty much eliminated keeping both back tires planted. This has made the grip level notably higher exiting corners, however the downside is once you get to that limit, the car is far less progressive now. Instead of a nice progressive, controllable drift, the car now has a tendency to snap loose.......so higher overall grip level, less forgiving when you get there. Now that I know what the car is going to do & am expecting it, its lots of fun, but the first time it snapped loose on me it elevated my heart rate a bit! :shock:


Mon Aug 07, 2017 7:53 am
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Post Re: Back in a Formula Again
Mid summer last year this happened.

Image20170815_194852 by Shane Hewitt, on Flickr

I've been on the lookout for a suitable replacement since. Here we are a year later & I finally found one in good enough condition & a close enough colour match (note the center portion of the base of the seat has a slightly darker shade of grey to it). While the colour is slightly off and I'm sure it will fade some, the slight colour mismatch offends my eye less than the giant rip in the old seat !!

Image20170815_194840 by Shane Hewitt, on Flickr

One thing to note about this swap though. When I was searching for a replacement seat, I read on thirdgen.org that the seat bases are interchangeable from side to side, so this seat is actually a passenger side seat from the car it came out of. Obviously from the picture the swap from passenger side to drivers side can be made to work, but in this case it was not a direct bolt in. The 2 bolts on the outboard side that secure the seatback to the base went in fine....I was able to locate the appropriate holes under the fabric and run them in without issue. The inboard side however (by the console) has a Torx bolt to secure the back to the base. I did have to drill and tap a hole for this fastener slightly ahead of the existing hole in the base. This actually had a surprise benefit. Previously whenever I would drive the car I had a bit of a gangsta lean going on......the seat had a bit of a lean towards the center of the car. Because I had to drill and tap a new hole for the Torx bolt on that side and it having to be located slightly ahead of the existing hole (less than and inch at most), the net effect is that I now sit straight!! If you were to look REALLY close at it you would see that the seat back is not 100% straight in relation to the base, but to the casual observer, its not noticeable...........the rip in the old seat was IMMEDIATELY noticeable.

So I'm satisfied for now. I may still keep watching for the correct seat, but in the mean time I now have a much more comfortable seat with no rips.....and sit straight in my car!


Wed Aug 16, 2017 8:11 am
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Post Re: Back in a Formula Again
So several years ago when I first put this car on the road it had a ticking noise that fluctuated in loudness with how much I was on the gas. It would put you in mind of a header leak, and I spent the first summer trying to isolate the noise without success. The car drove well, and after a while I eventually didn't notice it when driving the car. That winter I put my Lunati cam in, set the valve lash to 0 lash plus half a turn.......got the car out the following spring, car drove well, made good power, noise was unchanged. Last winter I put my ported heads on, same routine setting the lash......0 lash plus half a turn. Car now made great power, drove well, noise was unchanged.

Since I put the cam in, the car also developed a mild misfire........you could tell it was not just cam lope at idle. Driving around it was imperceptible, but looking at the data I'm constantly recording, it was quite visible in the o2 waveform too. (misfire events circled in red)

ImageLash too tight by Shane Hewitt, on Flickr

Given that the car drove so well I didn't worry about it too much, but next summer is going to involve passing an emission test again, so I've been focusing on resolving these issues, making sure my ignition system is in top notch condition, going through my tune with a fine tooth comb.

Fast forward to the past couple weeks since I brought home my spare motor I've been fiddling around with. The person I bought it from told me the van it was pulled from sat in a field for 2 years before the motor was liberated from it. As I mentioned in my other thread about that motor, the lifters were all stuck solid........the thought went through my mind that the Formula sat in the previous owners garage for over 5 years.........hmmmmmm. If the lifters were in fact stuck and not just pumped up as I assumed when I put them back in the motor, adjusting them to 0 lash plus half a turn would actually have them too tight, likely causing the valves associated with the stuck lifter to be hung open probably .020"........that would definitely cause mild misfires, that would definitely cause an audible ticking through the headers that would fluctuate with engine load.

In order to test this theory, I popped the valve cover off the drivers side bank (the bank that has the o2 sensor on it) and backed the lash off a quarter turn to see if matters improved. On one hand I really wanted to get to the bottom of this issue, on the other hand I was hoping matters didn't improve as this would mean the intake manifold coming off to remove the lifters again this winter.

I plugged in TunerPro & went for a drive........

ImageLash backed off by Shane Hewitt, on Flickr

Misfires on bank 1 pretty much gone......DAMN IT!!!!

Based on that I pulled the valve cover off bank 2 and backed the lash off and went for a drive......ticking noise has virtually vanished. Idle has settled way down (actually sounded cooler before!). So I guess my manifold will be coming off AGAIN this winter to pull the lifters out for rebuild, but the upside is the ticking noise should finally be gone, should make even more power, & hopefully make passing emissions far more likely.


Wed Oct 18, 2017 9:05 pm
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Post Re: Back in a Formula Again
As a follow up to the above post, I've made the decision to not tear the manifold off & pull the lifters this winter. This will be the first winter since I've owned the car that I've just put her cover on & let her rest till spring.

The reason I've decided not to pull the lifters is the motor I have sitting on my stand. Unless something catastrophic happens to one of my friends cars, or someone makes me an offer on my short block that I can't refuse, I'm about 75% sold on the idea of that motor going into the Formula next winter. It seems silly to be driving around with a 30 year old mill with almost 200,000 kns on it when I have a fresh ready to go mill sitting on my stand.

There are a couple of things that only have me 75% sold on the idea.

1. It really goes against my desire to keep the original engine in the car, however unless someone were to go checking casting numbers etc, one is visually indistinguishable from the other.

2. The dished pistons in the Vortec motor will drop my compression ratio from 10.35:1 to 9.7:1 using the same head gaskets. The simulations I've run on that scenario suggest that would cost me around 10 hp & 10ft/lbs of torque on paper (more on this subject later). This should however also allow for me to be able to use 91 octane fuel again instead of the 94 octane it demands currently.


The upsides to swapping mills.

1. With the motor out, the remainder of the engine bay can be completely cleaned & detailed to match the rest of the car, & the motor will now be a fresh, newly painted piece instead of the 30 year old rusted lump that is in there currently.
2. The few minor leaks I currently have "should" be resolved......no more sweating horsepower!
3. The Vortec block is a 4 bolt main while the L98 in the car "should" be a 2 bolt.
4. The Vortec block is equipped with a factory windage tray which "should" recover some of the lost power from the lowered compression ratio. The L98 block as I understand it doesn't have a windage tray.
5. The Vortec block is equipped with a 1.5mm/1.5mm/3.0mm ring pack, vs the L98 block being equipped with the standard SBC 5/64" rings, also recovering some of the lost power from the lower compression ratio. Definite advantage Vortec block.
6. The starter on the Vortec block is a tiny little thing.....should clear my headers WAY better than the big beast of a starter on the L98 block.
7. Given that my ported heads/manifold/cam etc would be transferred from the old mill to the new one, that will give me an opportunity to swap valves in my ported heads. Having been able to compare a stock L98 valve to a Vortec valve, its quite clear that there are flow improvements to be had there. Whether I back cut the original valves, source stock Vortec valves, or go with aftermarket valves, I'm not decided on that yet, however this would be the ideal time to do it. There is clearly more power to be had there.

So realistically, when all is said and done, I would expect the Vortec block with its thinner rings, windage tray, and the cylinder head tweaks I have planned, to at least equal the current mill, if not make more power and do so on 91 octane which is a win in my books. Throw in the drastic cosmetic improvement in the engine bay and the seems like a easy decision to make.

Given the fact that this is costing me essentially nothing (I sold the heads from the Vortec engine for WAY more than I bought the entire engine for LOL!), the only real cost to me to do this swap is my time......which I will have lots of in the winter next year!


Wed Dec 27, 2017 9:07 am
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Post Re: Back in a Formula Again
The latest tweak to the current powertrain!

Image20180107_115230 by Shane Hewitt, on Flickr

This is the Sonnax TV Cable Corrector Kit AS1-01K


https://www.sonnax.com/parts/2765-tv-ca ... rector-kit.

I'm hoping this little kit puts a little pep back into my 700R4's step again. Over the past couple of seasons since I've done all the engine modifications, I've run into the situation where the engine is developing so much torque now that during regular cruising around, I use notably less throttle input to accelerate than stock. Less throttle input for a given amount of power results in the TV cable not being as advanced as it normally would be resulting in short shifting and soft shifts. I found myself shifting manually if I was in a spirited mood to prevent the short shifting, but the shifts were soft still. Hopefully this little mod resolves both issues!

Now I just have to hurry up and wait for a couple more months to try it out and see how it does..... :(

On another note........these kits come as a 5 pack, so if anybody would like a kit, I have 4 more available.


Sun Jan 07, 2018 3:48 pm
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Post Re: Back in a Formula Again
The decision has been made.......the engine in this thread will be going in the car likely this coming winter.

viewtopic.php?f=41&t=15889

The reasoning behind the decision came from PurelyPMD on Thirdgen.org. As some of you may know he is the resident guru involving production numbers etc.

When I first got the car, like most of us, I read up on what sort of numbers of Formulas were produced in 1991. My reading revealed there were 5497. I wanted to narrow that number down further so I contacted PurelyPMD. Initially I asked how many of those Formula's were Arctic White cars with the L98 engine. Turns out there were only 203! I then asked how many of those cars had T-tops............SIX!!!!

So it would seem that pulling up at a light beside the identical car is never going to happen! While that is a pretty cool statistic, it doesn't really make the car any more desirable or valuable all of a sudden, but, it does make me think differently about what I do to the car now. When I first got the car, it was just to have something to drive the hell out of and have a great time with (and it still is), but now when I'm making a choice regarding modifying something, being able to put things back to original easily is a consideration to me.

With that in mind, every piece I've ever removed/replaced from the OE engine I've boxed up and stored, so once the new engine goes in, I have everything I need to refresh the original engine & put it back to its original condition. The original cam, heads, exhaust manifolds., emission pieces....hell, even the original Y-pipe is stored away. So my current plan is to tear down the OE L98 engine, rebuild it, and put it back to all original condition & store it away. The day may come that I want to put this car back to original condition....now I will have everything I need to do that!


Last edited by auto_god on Fri Feb 16, 2018 8:34 am, edited 1 time in total.



Wed Feb 14, 2018 8:37 am
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Post Re: Back in a Formula Again
Good idea..I've done the same with mine, although the car is not as rare. I have every single original part to put the car back to 100% original.

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86 IROC
LQ4/T56/3.50 8.8 (next step..TC76)
Build thread: http://ls1tech.com/forums/conversions-hybrids/1819001-1986-iroc-turbo-lq4-t56-build-ac.html
Formerly 95 LT1 [LE2.2]/T56/4.11 9 Bolt..12.6@114MPH


Wed Feb 14, 2018 8:50 am
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Post Re: Back in a Formula Again
6speedIROC wrote:
although the car is not as rare..


Is it bad of me that I so badly want to email the previous owner and say "So.....remember the Formula I bought from you dirt cheap? Well......." Lol!


Sun Feb 18, 2018 9:03 am
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Post Re: Back in a Formula Again
Being a beautiful day today, I decided to do a lap around the block to evaluate the effect the Sonnax TV cable spring has had on the performance of the 700R4. It made a HUGE difference, that's for sure! Too much of a difference actually. As the spring comes from Sonnax, the shift points are too high and the shift firmness too firm. I came back to the garage, popped the spring off and cut about one and a half coils off the spring, re-installed it and went out around the block again to evaluate the change. That small change makes the transmission pretty much right on the money. Shift points have been raised just enough to match the torque curve of the engine with the Lunati cam......doesn't feel like its short shifting anymore, and the shifts are just the firmness I'd like, firm but not jarring.

Hard to form a solid opinion from driving around the block twice, but my initial impressions of this modification are quite positive. Time will tell once I put the car on the road for the summer & can drive it more, but I'm very pleased at this point.


Mon Mar 26, 2018 2:38 pm
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Post Re: Back in a Formula Again
Finally got out for a good drive this morning. After driving for a bit I decided the shift points and firmness were still a touch too high. After cutting another half coil off I am finally satisfied with the transmission performance.....took a little fiddling but definitely a worthwhile upgrade.


Sun Apr 22, 2018 3:16 pm
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