Righ tnow I have this combo:

*'91 350, 4 bolt, 1 pc rear main
*Trickflow heads
*Dished pistons (~8.6:1<-[edited 7/14] Compression ratio)
*Roller Rockers
*Edelbrock Performer RPM Cam 308*/318*(advertised) 234*/244*@.050"......488"/.510"
*Edelbrock Performer RPM intake
*Edelbrock Performer 1411 Carb (750 CFM)
*H.O. air cleaner, w/proper ducting
*Edelbrock TES headers
*LB9 dual-cat Y-pipe (stock, with stock cats)
*LB9 intermediate pipe
*Flowmaster Muffler
*2" tail pipes.
I think the exhaust is in sufficient, and want to upgrade. I think the Edelbrock headers are too restrictive, w/their "D" slot collectors. Is this true?

Will this exhaust physically fit our cars?
http://www.macperformance.com/store/...Product_ID=458

...or could it be made to fit w less than ~2 hours of work?

Thanks

 

No they won't fit. I would look at SLP's 1 3/4" headers if you are concerned about primary tube shrouding. Most shoty kits desinged for 3rd gen's will support your 400 hp goal. If ground clearance is not a problem I would consider long tubes.

 

on a single 3" system I would ditch the flowmaster for something with a straight thru design.

 

Hooker Aeroflow. I have it on my 3" setup and it sounds pretty damn loud but has a nice idle, not annoying for being stuck in traffic. I got the 3" in centered, 3" out centered.

 

Thanks for the replies. Let me ask this question:

Are the Edelbrock TES "headers" a restriction for this engine, with their "D" slot collector design? As compared to other shorty 1-5/8" headers on the market?

Thanks for responding. Bummer about the LT1 system not fitting.

-Tom

 

I would say yes only because the Edebrock hedders leave a lot to be desired even on mild 305 cars. Even though they are advertised at 1 5/8" I think parts of them are crimmped down to a slightly smaller size. This was one of my main descisions for not buying them. The Hooker 2055's would work but you may want to grind the inside of them a bit to reducer the tiny bit of shrouding there will be. You could also, go with the SLP 1 3/4" that will swallow the whole port up nicely. I am sure pasky, Texas LT1, and Z28ri*cer will respond. I think most of them are running long tubes though.

 

..for the opinion and input. This exhaust thing is bothersome to me. When I look at the components, IMO everything from the heads to the tail pipe SHOULD be changed, but I didn't want to waste money on a header change that wasn't effective.

At first glance, it's obvious that the muffler and the factory "Y" w/cats needs to go. Then really the 2.75" intermediate pipe is too small, and if you replace all that, then the headers are looking pretty suspect.

Futhermore, if I want to run a Y pipe LS1 style, the Edelbrock headers (and most F-bod Shorties) exit pointing in the wrong direction on the drivers side.

What to do, what to do....

 

If you want to run an LS1 style y-pipe you are better off going with long tubes. The shorty hedders desgined for our cars have the collectors pointing straight down. That would be really tight to have ice smooth bends connecting to them (besides using a stock style y-pipe).

 

Yep, I hear that point for sure. I have it broken down into two plans at this time, neither of which I can decide on:

1. Keep the F-bod shorty style headers, and build my own mandrel bent, 2.5" Y-pipe following the factory route.

2. Buy Hooker super comps and do the LS1 style Y.

As for 1-3/4 vs 1-5/8 headers, there seems to be a debate about which is better on this board. If I had a 400, it would be obvious, but with a 350, it seems more ambiguous, which to use.

 

The general rule of thumb is that 1 5/8" heeders are fine on a 350 up to 400 hp. If your motor makes less than that but makes most of its power past 3,000 rpm than you can get away with 1 3/4". Mot people suggest the 1 3/4" for an LT1 because of the shrouding that most 3rd gen hedders have on the D-ports. You can alleviate this with a little grinding but you can avoid it with the larger primaries. Also, the LT1 makes power throughout its whole band including in the upper RPM's. If you look at hedder selection for 4th gens you will see that there are more with 1 3/4" than 1 5/8". Both make serious power gains when compaired to the stock manifolds.