So my 91 RS, has a 305 TBI, I finished acquiring pieces for the 350. So now the question is while the 305 is out, is there anything I should do under the hood? Modifications to the k-member? Brace anything?

I've always been a Mustang fan, and I know we braced the k-members to keep them from flexing, is this an issue with the third gens?

Is there anything I can do like notch the k-member to get real dual exhaust in there? (I've got a welder, so its not a problem to do it myself) If I can't get dual exhaust in there, suggestions on a cheap "y" pipe, and headers?

 

3rd gen exhaust issues don't start under the hood, they start under the floor pan. Not much need for fancy stuff with a street 350, though - just get aftermarket stuff for the '86-'90 TPI single cat application - you'll be thankful for ground clearance, even if it doesn't fit the 'Stand paradigm.

Subframe connectors are a practical must. About the only bracing needed up front is a "Wonder Bar" (see Board sponsor UMI, Spohn, & others), although a strut tower brace is popular as well.

If you want to go nuts, you can get a tubular k-member.

 

Crap, I didn't even think about running the pipes back. that would be an issue too....

Whats the difference between a strut tower brace and a wonder bar? I've always made my own stuff, so fabricating these things isn't an issue.

Thanks for the reply, by the way.

 

Your 305 TBI exhaust chokes the life out of your 305. Putting more inches in there won't do much good if you make it have to force all of its waste product through that coffee-stirrer sized crap.

The very first mod to a 305 TBI, should be the exhaust. Every single piece from the heads to the bumper. That goes double for changing to a 350.

Dual exhaust is a total waste of time and effort. These cars are highly hostile to it. Instead, get a LARGE (3") single cat-back, from any of the manufacturers of such things; Hooker, Dynomax, Blowmaster, Borla, Edelbrock, etc. Just pick your favorite.

You don't want "cheeeep". If that's what you want, keep what you've got, and there's not much most of us can do to help you further from that point if you're not willing to do what it takes to get it right. We won't even want to listen to the whining about all the problems you'll get to enjoy. There are FEW things in the world that are worse than "cheeep" exhaust, and especially "cheeeep" headers. Good stuff is worth EVERY PENNY and then some. Not only for performance, but for longevity (not rusting through or cracking), reliability (not falling off), fit (not rubbing the car or dragging the ground or getting in the way of other important stuff like the starter for example), freedom from leaks, safety (carbon monoxide poisoning), and so on.

As said, DO NOT get ANY piece that will fit a 305 TBI, because doing so will preserve the bottleneck. This is the size of the Y-pipe and the cat. ANY piece that bolts up to what's already there, will prvent you from deriving the benefit of a larger motor. Instead, get the headers, cat, and cat-back for a 350 TPI of about the same year of your car. You can go ahead and get all that right now and put it on your 305; you might be AMAZED at how bad the garbage that's there is already choking even that little weenie anemic gutless motor. It'll be just that much worse on a motor that has to move more air in order to accomplish anything more than that pitiful thing you have now.

Get your headers ceramic-coated. Again, WORTH EVERY PENNY and then some. The coating keeps them from rusting as bad, improves performance, and reduces underhood temps so you don't constantly fight all your wiring and plumbing disintegrating into dust, and your spark plug wires burning and melting.

Most of what makes TBI cars slow is not the big shiny prominent visible easy-to-get-to stuff up on top. The people who concentrate all their money and effort on that stuff, no matter how much chrome they put up there in plain sight and no matter how much they "clean up the engine bay" (translation from Hilljack into English: hack on stuff), NEVER go fast.

Besides just the motor itself, the things that the car needs are, in order of importance:

SFCs
Exhaust (as described)
Gears and posi (3.42s and a 98-02 Zexel works good)
Torque converter (only if it's an auto.... 2800 RPM stall)


Strut tower brace = goes across the top of the strut towers

"Wonderbar" = goes across the bottom of the body half of the "frame", between the sway bar bushings and the chassis, is bolted on by the sway bar bushing bolts

Neither of those would be particularly hard to fabricate.

 

Sounds like I better quit trying to be a cheap-*** and just buy some exhaust for it. There still seems to be a bit of a limited selection though.

I put a 3.27 and a gear driven posi (torsen, I believe, which would be similar to the Zexel?) when I converted the rear to disc brakes. I do however already have 3.42 sitting in the garage to go in with the new motor.

I'm going to CC the heads tonight as my compression ratio might be a bit out of control.... I ran through the math and I'm coming out with 10.9:1, and thats assuming the heads have not been cut. I want to run premium (not race gas) so I may have to change pistons, or maybe runner a spacer head gasket?

Thanks for the help so far guys, I appreciate it.

 

Zexel = a company; Torsen (short for "Torque Sensing") is one series of their models. So, yeah....

What heads? What size motor? What measurement are you using for deck clearance?

 

I'll go through my whole build up so far, might help some:

The motor is a 350 4-bolt main, 0.060" over, with cast flat tops. 4-valve reliefs per piston. The heads are a camel hump head, 461 casting, 2.02/1.60 valve, 64cc chambers assuming they haven't been cut. Roller rockers for the heads. I measured 0.020" in the hole deck clearance.The guy I bought the heads some said they where just cleaned up (they are freshly done) but said they haven't been cut much. The guy who did the heads, said he cut them 0.070", but I'm not 100% sure he's thinking of the heads I bought, so I was going to CC them the best I could with some water to see where I was at.

The cam I bought is a .465/.488 lift - 224 / 234 @0.050", I'm leaning pretty hard towards choosing a bit nicer cam though. Have matching valve springs for the heads.

Edelbrock dual plane intake, HEI, quadrajet carb.