Hey Everyone.

Ive got my 5.3 + 4L60e mounted up in my car.

I used S&P Style motor mounts, and ive got a '96 4L60e With a convertor pilot spacer.

These mount's sit my engine about 3/4" - 1" Further forward then it would be originally.

The truck manifold's i have dont work. One ear's for the exhaust stud hit's into the side of the frame.

Are F-body manifolds different? will i still hav clearance issues?

My next question, if my engine is a little less then 1" further forward, if i pickup some Stainlessworks headers, will i have any clearance issue's?

Thanks!

 

From everything I've read, the F-body manifolds work just fine on our cars. Don't know about the header issue you're talking about, I think that this is the first time I've heard of someone's engine being offset by an inch...

 

if its an inch forward the pan should hit the k-member if your using an fbody pan as there is not an inch to spare between the pan and the K, if you are using the stock K

how are you basing that you are an inch forward? to the front clip or the firewall

The truck manifolds exit what looks to be too far up and back and flare out to the side, the fbody ones do work, ideally the ones from 01-02 as they are more tubular

 

Im using a S&P Style mount. The back of the motor sits about 3/4" further forward then the back of my 305 did. Maybe this is normal?

Ill measure how much space ive got between the back of the block and the firewall for comparison.

 

You cant really compare how and LS1 sits vs your stock engine. There is nothing about them that is the same. You have two limiting factors that determine where the LS engine will sit.

1. As said above the oil pan. Unless you have a custom made/modified pan the F body LS1 pan is the only one that works. If you are running your stock k member it will literally be 1/8" away from your stock K member its soooooo tight there. Many of us ( me included ) ground down the welds on the back side of the stock k member and slightly ground the corners where it gets close to the pan.

2. Driveshaft and torque arm length. Again unless you are going to order custom pieces you will have to drop the trans output shaft in the same area as your stock trans or none of this will fit and you will need custom pieces.


These S&P mounts do they adapt to use your stock third gen mounts? Or do they adapt the LS1 engine mounts to your third gen?

 

Im going to be getting a f-body pan next week. Ive got about 2" Clearance between the k-member and my truck pan.

The S&P mounts use the 4 bolt holes on the LS1, and then adapt the mounts. It would use the lower center hole on the stock thirdgen mount, and front lowest hole on the ls1

 

The adaptors use my stock mounts. The picture shows the clamshell, then it just bolts to the stock rubber peice in the engine bay.



here is a picture of the mount adaptors i made:

 

I see. I havent seen any other posts where those kind of plate adapters were used on a third gen swap.

Fow whats its worth I made my own mounts. I did however use the LS1 mounts on the engine and made up adapter horsehoes for the k member. To located everything I bolted the engine and trans together and dropped in in the car then bolted the headers on and shifted the engine around until i was pleased with the clearance of everything then marked the mount location and pulled everything back out then drilled and bolted down the mounts.

Not sure if you will have to do this or not running those mounts but heres a thread that has some good info

https://www.thirdgen.org/forums/ltx-...light=mounts+s


As for the manifolds yes the F-body ones fit and yes they are different from the truck manifolds. There are two series of these and the newer ones are better performing units. In fact they work as well as shorty headers

 

Can you confirm "how newer" that is? Mine are 2000, the pics I've seen of 2001 (or what was claimed to be 2001) don't look any different.

 

Off the top of my head I believe its 01 and newer. They are easy to spot. The older style are more of a log like stock third gen manifolds and the 01 and newer style actually look sort of like shorty headers with a much longer primary section than the older design. I'll see if i can find some pics

 

Mine don't look like logs (to me). I'll post pictures after I get home tomorrow.

 

last I checked the casting number was the same for all the ls1 f-body years and even the med. duty truck (delivery style one w4500 gas 6.0 2005?) the only differance was egr hole being drilled on the early years and the truck had nothing drilled not even the o2 hole. everything was there are far as the shape and spots. (I had a pic on my phone but it looked real bad and had no detail)

perhaps the first year 98??? had the log type of manifold that carried over to 99 or so??? (I know gm does this odd stuff. and then made the new casting the replacment?)

 

IIRC the newer style are cast iron and the older style are welded stainless

 

Id just like to point out, that even though my engine is sitting 1" further forward then it should be, the truck engines have a clear interference with the thirdgen frame rails. I know that LS1's have been used with manifolds which leads me to beleive their different.

My manifolds are from a '03 LM7