4-2-1 exhaust options

manoa matt · Post by **manoa matt** » Sun Aug 19, 2007 7:39 pm

I got a 78 1800 with a 4-1 manifold. Looking to upgrade to a 4-2-1

Options are: 1). 68-73, 4-2-1 set up with 4-bolt flange
2). 1980 FI, 4-2-1 set up with 6-bolt flange

Which set up is more compatible with the 1800 block?
Which set up is less restrictive?
What set ups' downpipe won't hit the tie rod?

Matt

So Cal Mark · Post by **So Cal Mark** » Sun Aug 19, 2007 9:06 pm

none of the setups should hit the tie rods, all the steering linkages are the same. Don't expect any huge perf increases though. The 4-2-1 manifold while marginally better still has runners that are too short to make a big diff. And the downpipes are all pretty small, no matter which set up you use

mbouse · Post by **mbouse** » Mon Aug 20, 2007 8:05 am

So Cal Mark wrote:none of the setups should hit the tie rods, all the steering linkages are the same.

on a vehicle that has not been lowered, or otherwise altered.

gotta put in that footnote, as we have seen very frequently that people omit some important facts.

Couple that 4-2-1 swap with a test pipe, and dump the air pump...if you can....you will be amply pleased

So Cal Mark · Post by **So Cal Mark** » Mon Aug 20, 2007 10:22 am

lowering shouldn't have any effect on clearance; the idler is mounted to the unibody so the height of the damper and center link remain the same. The only thing that will change is the angle of the tie rod ends from the steering damper to the knuckle

manoa matt · Post by **manoa matt** » Mon Aug 20, 2007 3:44 pm

The car is not lowered in any way, its low enough as is. Air pump and smog stuff are gone. "Amply pleased" you say Mike? If I'm going to invest some money and time I would like to be "plesantly supprised"

Here is what I was planning. Some form of less restrictive manifold, either 4-2-1 or performance, remove cat and replace with straight pipe, free flow ANSA center muffler (resonator), and a stock rear muffler.

How are IAP's performance headers, (Clearance / Performance)? I know a guy here on the island that has a set for a 78, but he sold his Fiat and got an Alfa before installing them. He's had them in storage for some time, I might be able to get a good deal and would not have to pay shipping to Hawaii.

The 4-2-1 set up I'm looking at is going to run me about $120 (includes shipping to Hawaii). I "might" be able to get the performance headers for just over $200.

With the perf. headers the only thing I'm worried about is my expansion tank. My expansion tank has developed a "bulge" at the corner closest to the 4-1 header. The manifold still has the heat shield too. I've heat protected that corner, but I guess I could relocate the bottle to the front by the wiper bag.

Would performance headers be overkill for an engine with no other performance modifications?

So Cal Mark · Post by **So Cal Mark** » Mon Aug 20, 2007 3:52 pm

headers are not overkill for a stock engine, just don't expect miracles from a cast manifold or even the IAP header. I'm installing one now for a customer, and quality and design pale vs my system. But, you get what you pay for generally, and if you don't pay much, don't expect much

racydave · Post by **racydave** » Mon Aug 20, 2007 6:34 pm

An engine could easilly be compaired to a vaccum sweeper. It takes air in and pushes it out. I like to think of the valves as halfway. Sometimes you will need mods on both sides to make a noticable improvment.Then comes the valves,valve springs, ported heads, camshaft... Since mines runnin pretty well, and the fact that you are only lookin at around 100 HP, Im happy findin thoes 5 to 10 percent gains.

mbouse · Post by **mbouse** » Tue Aug 21, 2007 8:36 am

Cost to ship to the Island is the cost of choosing to live on the island....man, we really feel for ya; with all that sun, and surf, and bikinis and all ! that $80 sounds like chump change for what you will eventually need. don't settle for half way if you can afford the price.

Just goin' with the 4-2-1 as dave says won't do much at all. what are you using for a carb? and how about the pipes AFTER the down pipe? all of that needs to be looked at if you expect to be surprised. A knot in the hose is still a knot; if you are restricting the air flow somewhere, the restriction will be your limiting factor.

i've run a 4-2-1 with OUT a heat shield all year, and see no affect on any engine part, or the expansion tank. but i'd keep an eye on that situation if i were you.

Mark, how does your header system address the heat issue?

So Cal Mark · Post by **So Cal Mark** » Tue Aug 21, 2007 10:14 am

if the stock coolant reservoir is used, I raise it up and add a heat shield, and keep it full of coolant

mbouse · Post by **mbouse** » Tue Aug 21, 2007 11:35 am

So Cal Mark wrote:keep it full of coolant

prolly the best part of that advice.

racydave · Post by **racydave** » Tue Aug 21, 2007 6:53 pm

Another item affected by the heat, dizzt wires. I re-routed mine. I guess Ill settle for this mid-west humidity, as opposed to payin $7.00 for a gal of milk! Aloha!

mbouse · Post by **mbouse** » Tue Aug 21, 2007 9:38 pm

milk? they still make that stuff?

manoa matt · Post by **manoa matt** » Tue Aug 21, 2007 9:45 pm

Good thing a gallon of beer is cheaper than a gallon of milk!!

Shipping parts out here is crazy expensive, unless you use USPS, then it's reasonable. Sometimes I ship parts to friends and relatives if I'm going home, or they are comming out here. My dad brought a rear muffler out here for my wedding.

Anybody comming out to Hawaii anytime soon? I need a few parts delivered. I'll even give you a ride to your hotel.

I also heat protected the vac advance on the dizzy. That rubber diaphram sitting right above the manifold can't last long with all that heat.

I had a header wrap around my downpipe for a few weeks untill I read a few articles about what happens to the metal pipes. I quickly took it off and now I use the wrap to protect components themselves. I've wrapped the rubber heater hose that attaches to the water pump, the vacume advance, and part of the coolant bottle. Not the prettiest thing, but it works and makes parts last longer.

So Cal Mark · Post by **So Cal Mark** » Wed Aug 22, 2007 1:09 am

good move with the header wrap!

manoa matt · Post by **manoa matt** » Wed Aug 22, 2007 9:08 pm

So my local guy wants $150 for the never installed IAP headers, Is that a good deal?

Matt