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 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!

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UrbanPhil



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Join date : 2017-07-26
Age : 39
Location : Buffalo, NY

PostSubject: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Sun Aug 05, 2018 12:22 pm

Hi all,

My '96 RMW has been up on rollers since December while the LT1 was being reincarnated as a 355. (bored .030, new cam/pistons/180cc Dart aluminum heads etc) I'm almost done, and eager to get this beast back on the road, but getting bogged down by the details. I could use a little help from the community (both advice and tracking down the remaining parts) Any help would be appreciated! Here's what I need:

1. Does anyone know where to find the inner fender splash guards? (pic below) Mine fell apart during the process of detailing the engine compartment. The compartment looks beautiful; can't put these ratty splash guards back in there. New ones would be great, but very good condition used guards would work too.

2. This car was missing the plastic part (shroud?) that connects the top of the radiator to the cross beam at the front of the engine compartment. I'm not sure what it looked like to begin with. I included a picture of what I think might be the part. Can anyone verify that? Or shoot me a picture of what its supposed to look like? If anyone has the correct part for sale, I will buy it from you.

3. Radiator--Given the extra power/heat, I need something better than the chintzy radiator currently installed in the car. I think I need something like a 4-core radiator with the trans cooler in it. Any suggestions on manufacturers/models?

4. Headers--This is the biggest question at this point. Someone told me 1 3/4-inch "Tri-Y" style headers are the way to go. If there's a way to do this without buying new cats that would be great. (i.e. bolt up to the existing cats) I'm just not finding much info on header applications for this car/engine combo. Please advise.

5. Torque Converter--I'm staying with the existing 4L60E transmission for now. My aim is to make the car as streetable/driveable as possible given the setup (I'm not taking this car to the strip etc). I need to verify the rear-end gearing (I think its 2.56...is that the standard, non-tow package gearing?) I would welcome any suggestions on an appropriate TC/stall number.

I think that's all for now (still the programming to contend with, but that's for another day) Thanks in advance for your help! Best,

Phil







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jayoldschool

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Sun Aug 05, 2018 12:46 pm

Your number 1a and B priorities need to be a converter and GEARS. 2500-3000ish stall (but you need to match that to the cam specs), and at least 3.42s (with a new 3 series posi carrier).
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silverfox103
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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Sun Aug 05, 2018 12:48 pm

Here's the answer to #1: https://www.rubbertherightway.com/1996-buick-restoration-parts-a-58451-prd1.htm

Great quality product and made in the USA.


Tom
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UrbanPhil



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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Sun Aug 05, 2018 3:59 pm

Thanks Tom!  I just put the order through.  Beautiful cars you got there.

Jay, I agree with you re: the gearing/TC.  I know I need to do something but my knowledge on that point is limited.  I keep going down internet rabbit holes on gearing etc. and getting no closer to an answer.  3.42 seems more aggressive than I want to go, but I could be wrong. These are the cam specs:

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jasonlachapelle

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Sun Aug 05, 2018 4:14 pm

nice cam. Jay is right. Gears/posi/converter 1st. Then headers. 3.42 or 3.73 gears. I like the truetrac posi best but the eaton clutch type works well too.

Tri-Ys I think are 1 5/8'' and are good for what you are trying to do. Clear image automotive sells them, as does stan's headers, both in WA. They pop up used on ISSF regularly. They do not bolt up to stock cats, but they come with either offroad/cat-delete pipes or their own converters.
If you can get you hand on a set of SLP shorties or AS&M shorties, you'd be good to go with stock cats. Performance is decent as well. Probably less than 1/10th difference from tri-ys. Probably a 20hp difference with all the supporting mods.
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UrbanPhil



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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Sun Aug 05, 2018 7:20 pm

Thanks Jason. I appreciate the info. I'll poke around the net and see what I can find. As to the gearing, assuming this car has 2.56 (no posi), what's the most direct way to swap out/upgrade the gears? Am I looking at swapping the entire axle assembly out?
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Fred Kiehl

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Sun Aug 05, 2018 9:23 pm

You can look at the SPID on the right gate jam. If it has GM8 it is 2.56.

You can put any gear ratio in the housing, but you need to set it up properly. The axle carrier for the 2.56 is different than the others, but the housing is the same. You also need a gearset with pinion shaft that will accept the correct tone ring for the anti-lock brakes.

I just finished building a rear with 3.42 gears, and it was not difficult. The special tools you need are the yoke holder with a couple of 2 foot pipes to fit over the end of it and the breaker bar, an in. lb, and ft. lb. torque wrench, a dial indicator gauge with a magnetic holder, bearing race installer, depth micrometer or calipers, a pinion depth gauge, and a 3-5 lb. hammer. Pieces of pipe and rod stock can be used to install the bearings, and remove the bearing races. The gears come with instructions, and the install kit has all of the shims you need. If you get a Truetrac, you need different set of carrier bearings. I suggest Moser axles, and new bearings if your axles are worn at all. They use a C clip to hold the axle spacer in, and if you lose it, I have extras. You can borrow a lot of the tools from Autozone or O'Reileys.

There are some secrets in putting a rear together that make it easier. If you decide to build one, let me know, and I can share them.

I noticed that you are using roller tip rockers. I recently saw a test of stamped, roller tip, and full roller rockers, and there was no advantage to either the roller tip or full roller rockers under 5500 RPMs, in fact the roller tip rockers fared poorly compared to the stamped units (-4~6 hp). Run 1.6 ratio stamped units unless you are headed over 5500 RPM. Even then, the full rollers may not perform any better, because the ones in the test were a higher ratio than the stamped ones. If I were to do my 454 over, I would use the stamped rockers, and less expensive valve covers.

I have an excellent upper radiator support for sale. $55 shipped
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sherlock9c1



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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Sun Aug 05, 2018 11:25 pm

silverfox103 that link is great! I thought those things were long gone. I also see they sell the radiator seals - urbanPhil - having the best radiator in the world is useless if you don't control airflow around it. Make sure the area around the radiator is as sealed as possible and all of your lower airdams below the radiator support are intact.
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81X11

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Mon Aug 06, 2018 9:51 am

Nice Project!   The upper plastic radiator support is VERY common.   Was used in both Roadmasters/Fleetwoods and Caprice models without the towing packages.   Find a 94-96 Caprice/Roadmaster/Fleetwood in a wrecking yard and you'll be set most-likely.

Keep us updated on the car!   I really want to upgrade the 2.93 rear in my '96 tow-pack Roady eventually to a 3.23 or 3.42 and am planning to follow-along here!

-Michael
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UrbanPhil



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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Mon Aug 06, 2018 7:33 pm

Thanks Fred! You got a deal on the radiator support. Please send me a PM with your payment info. (I don't have PM capability yet) I appreciate the primer on changing the gears and I'll definitely consult you when I'm ready to go in on that. I have code GW9, so I think I have 2.93's (A Buick dealer told me the same, based on the last 8 of the VIN).

It seems like there's varying opinions on the TC/gear combo. My engine builder suggested 2000 stall/3.55. Others have said 2600 stall is more appropriate. I want some punch off the line, but I need this thing to retain some of its street manners. I live in the city, but I also want to take this rig to the lake on weekends (an hour of mostly highway driving each way) So I'd like to keep the mpg in check to the extent possible (I know that ship may have sailed given the nature of the build...)

Mike, thanks for the encouragement! Of course I'll keep posting progress pics and updates. It's the least I can do for all the helpful advice I've received here.

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Fred Kiehl

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Mon Aug 06, 2018 7:48 pm

Your cam manufacturer should be your go to guy for TC stall speed. I do not think they make a 3.55 for the 10 bolt. 3.42 is a good gear. 3.23 is a 200 mph gear. All of them are a tradeoff of git and mileage.
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UrbanPhil



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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Tue Aug 07, 2018 8:13 pm

I called Comp Cams today. The guy recommended a 2000-2200 stall TC with 3.73 gears. Specifically, the TCI Breakaway torque converter (which seems to be listed at a slightly higher stall number) and Yukon brand gears.
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Fred Kiehl

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Tue Aug 07, 2018 9:54 pm

The stall RPM of a rated converter will vary with the amount of HP applied to it. More HP higher stall...within limits of course.

The converter I have is a 24-2600 RPM stall for my 450 HP 454. It probably stalls at about 2600 under full throttle, and maybe 2400 at light throttle. If it were any lower, the car would become "jerky" at low speeds, because of the slightly erratic idle from the cam. With slightly higher gears, you want a higher stall TC because the engine/gear ratio reduces the frequency of power pulses at the wheel.

Be careful about what gears you use. Yukon are supposed to be good, and so are Richmond if you get the higher priced line. One secret to make the gears stronger is to run your pinion a little on the tall side. It places the contact patch closer to the center of the ring gear, and thus will not deflect as much. You can put an EXTRA .030 to .060 shim under the pinion bearing, and just set the mesh. You may be able to put more shims under the pinion bearing, but unless you are really good at it, stick with" "a little is better" theory in this case. The initial shim stack will be about .030 -.060. If you use a .090 shim stack, it will probably be good. I would still measure it.
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UrbanPhil



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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Fri Aug 10, 2018 10:57 am

Thanks Fred. My cousin is helping me with the gears (he's got much more knowledge in this area than I do) I'll pass that information along to him. This is the TC I'm considering:

http://www.tciauto.com/tc/breakawayr-converter-gm-1984-97-700r4-30-spline-1-703-crank-pilot-1993-97-4l60e-1997-05-4l60e-c5-corvette-lock-up-6514html

I still need to call Yukon re: the gears/rebuild kit etc.

Thanks for sending the radiator support out so quickly. Any chance you could post a picture of your "oriental carpet on the bed"? I gotta see this...
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Fred Kiehl

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Fri Aug 10, 2018 11:40 am


Carpet in the bed picture.
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Andebe

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Fri Aug 10, 2018 2:32 pm

Ever take anyone for a magic carpet ride? Cool cheers Just to be clear,I don't want one. Lol!!!
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phantom 309

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PostSubject: Re: 1996 Buick Roadmaster LT1 355 Project - Need Some Help/Advice!   Fri Aug 10, 2018 10:36 pm

str is what makes a converter more friendly
stall torque ratio. the torque at which it needs to slide to its max rpm
A tight converter will act like a stocker until you push it and it slides
i drove a 95 ss impala with a 3200 edge that acted pretty much stock until you went past 1/4 throttle or so. i had a 2800 vigilanti was tight too. worked great with 3:73's
putting a stall converter up against tall 2.56's will be abysmal,. something a kin to driving a bus.

you'll get a lot of opinions about gear ratio's,. find out which opinions are from practical experience,. and which opinions are just regurgitated internet hyperbole
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