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I got a header kit for a third gen (going on my 1986 transam)--it is an old SLP kit that the guy had hanging around, but never installed from years back. trying to find out some info on it.
Headers have the smog tubes on them, and it comes wit the Y pipe.
The adapter (part number SUM-SLP30036) has a manufacture date of 10/11/1999 (again, never installed, clearly). This header adapter has a 4 bolt flange for bolting to the catalytic converter. The cat is currently stock, and does not have a 4 bolt flange. Is ther an additional adapter, or am I just better off not using this adapter, and using standard pipe to run from the headers to the cat?
Also, the kit did not have the AIR 90* hose to attach to the injection hose. says it is part number 80401. any thoughts on a replacement?
I know I am dealing with parts that SLP no longer makes, so just some questions on replacement parts--surely someone on here has the SLP headers on their car form back in the day!
that 4-bolt flange is for the earlier cat design.Beware that SLP headers,very good materials and design,often had shoddy assembly quality....test fit the whole assembly on a spare engine to check fit and adjust as needed-especially the fit to the heads. I have used 2 sets of these headers,one from 1996,the other 1999-that last set needed a lot of work before they would even fit the heads correctly....
Do not use your stock catalytic converter.
Upgrade - don't downgrade. Put a new high flow cat in there to complement the headers.
Those headers are 409 SS and uncoated. While they will not rust, they will turn brown.
If you got a great deal on them, consider having them coated.
Uncoated will also raise your underhood temperatures quite a bit.
A high temp coating will help with that also.
Do not use your stock catalytic converter.
Upgrade - don't downgrade. Put a new high flow cat in there to complement the headers.
Those headers are 409 SS and uncoated. While they will not rust, they will turn brown.
If you got a great deal on them, consider having them coated.
Uncoated will also raise your underhood temperatures quite a bit.
A high temp coating will help with that also.
these actually have a coating on them. I got them from a guy as an afterthought--went o buy na engine block, and when I mentioned the 86 transam, he asked if I wanted these--he had bought them for an 85 camaro, and then the camaro got destroyed prior to installing them. Sold me th eheaders, the header/cat pipe, and some other stuff to go along with them for $100 all in.
that is the same set I have except mine are not coated.you will need "shorty" spark plugs. The first design SLP headers were an exotic tri-y design and the set was ~$1200 about 1990
knowing the cat pipe is designed for an older style cat. any recommendations for Hi flo/HP converter that will bolt up, but still use the stock mounting location to the transmission?
Looks like the 4 in to 1 1" 3/4 tube headers with single cat Y pipe.
looking at your cat, I'm not sure it's factory, looks to be a replacement. Which means you may or may not need to use that adapter.
OK, so im back on this old thread. Headers are installed on a new motor (357, not yet fired). Long story on how we got here, but my son spun a bearing on the 305 on the #4 rod.
I am having a hell of a time trying to find something that can adapt the Y pipe to the factory cat.
I was looking at changing the cat out to the 4 bolt flange style, which would fix the Y pipe issue, but creates an issue at the intermediate pipe. I do not see anything out there that has the 4 bolt flange on the intermediate pipe.
You have the LG4 coffee-stirrer exhaust. The adapter you have is for the L69 / LB9 exhaust. VASTLY superior.
DON'T downgrade your headers somehow, so that you can retain The Bottleneck Of The LG4 and keep your car slow. Get the correct cat https://www.summitracing.com/parts/mpe-93940, and then a 3" cat-back of your choice. You'll need a 4-bolt adapter for that, but that's eeeeezzzzy... pretty much any muffler shop can make that up if you draw what you want and take it to them.
The difference between the LG4 cat & exhaust compared to the good one is probably something on the order of 30 HP, WITH A 305. Probably closer to 50 with a 350. Don't shoot yourself in the shorts that way.
The current intermediate pipe is a 2.5" mandrel bent dynomax pipe (brand new--installed just prior to purchasing the vehicle). 3" might be in the future, but for now, we just want to get the car up and running.
To make a "custom" one, all you'd have to do is, take a piece of about ¼" stock about 4" × 6" or whatever, cut an oval hole out of it, drill 4 holes in it, smash one end a piece of tubing to the same size & shape as the oval, and jam it in and weld it. Use the cat gasket as a template. You could smash the tube first and then cut the hole to match, to guarantee a good fit.
Without dimensions I have no idea whether those other parts would work.
You'd need to re-do that for the more appropriate size of exhaust when you realize that the 2½" is too small to begin with.
To make a "custom" one, all you'd have to do is, take a piece of about ¼" stock about 4" × 6" or whatever, cut an oval hole out of it, drill 4 holes in it, smash one end a piece of tubing to the same size & shape as the oval, and jam it in and weld it. Use the cat gasket as a template. You could smash the tube first and then cut the hole to match, to guarantee a good fit.
Without dimensions I have no idea whether those other parts would work.
You'd need to re-do that for the more appropriate size of exhaust when you realize that the 2½" is too small to begin with.
still have to drill the holes once the cat/gasket arrive….but made the flange.
