HELP!! LSx install in SBC chassis?

[BigAl1]

After 2+ years of building, I'm finally close to engine install! But, when mounting the engine mounts on the adapter plates, found the LS1 Corvette A/C compressor will not clear the engine mount. It looks like the engine mount needs to move to the rear by 1" for compressor clearance. But, this relatively moves the engine forward 1" and there is no clearance to do this as the Corvette water pump pulley nose is within 1/4" of the firewall (according to my measurements of the engine on the stand). My questions follow;
1. Has anybody installed a LSx engine in the SBC style Ultima chassis, and mounted the regular LSx A/C compressor in the lower RH position?
2. What adapter mounts were used? The Street and Performance style (with/without 1" shift?), or the rectangular design?
3. Did the chassis mounts have to be moved rearwards?

I'm using a 2002 Camaro LS6 block, LS1 heads with Corvette accessories. This puts the A/C compressor lower RH, and the Alternator upper RH.

Thanks in advance,
Allan

[BigAl1]

Thanks for the info and links. Scott's doesn't have the A/C shown, and Mark does not have A/C. Jeff S has the LSx chassis, so different mounting setup. The black GTR in Toronto area with LS1 did not have the A/C connected - don't know why. I have heard the Camaro accessories belt path is ~3/4" farther forward compared to the Corvette, so need to know if the A/C compressor is farther forward, or just the nose is longer?
Anybody out there with this setup???????

Allan

[BigAl1]

Thanks for the input everybody. Yes, moving the engine 1" farther forward will clear the Corvette A/C compressor past the mounts. But, according to my measurements the nose of the water pump pulley will just clear with the current setup, and interfere by ~3/4" with the rear firewall if the engine was shifted forward. I *believe* the LS2 Corvette water pump pulley is ~2" shorter, so that may be the way to go. I must verify these details, then will post up the findings.
Any others with this setup out there?

Allan

[BigAl1]

Thanks for the pic Crafty. It looks like the water pump inlet has been shortened, and the curved pipe installed to avoid the firewall. Another thing to consider is what trans you have. Is the G50/52 shorter by 25mm from axle CL to bellhousing mount face? This would allow the engine to pull back from the firewall for more clearance. I have a G50/03, so if I understand the differences correctly, I will have the worst case fit problem. The new motor mount adapter plates will be installed in the next 2 days, so I'll take more measurements then, hopefully with the LS2 water pump too.

Allan

[BigAl1]

Jeff S - thanks for the spacers idea. Last night I verified the fit of the new apdater plates and the motor mounts vs. the A/C compressor in the standard location. They will fit, but the A/C compressor needs to be installed after engine is in and the motor mounts are tightened up. The A/C hoses will need to exit to the side, which there are adapter fittings available for custom setups. Or the 2004+ GTO setup has a compressor with ports on the side, and has the belt path close to the block like the C6 Vette. Still waiting for the new LS2 water pump to final check dimensions.
Jeff-Texas - The A/C side looks solved, but the Alt bulky bracket is bugging me! I'm considering designing my own that puts it down low LH side. The difference vs GM Camaro/Firebird setup is the belt path is closer to the block, so AFAIK the GM F-body bracket will not align the alternator pulley with the Corvette crank pulley. Maybe the GTO setup could work? An additional grooved idler pulley needs to be located, and the smooth idler needs to be mounted on a new structure as the big Alt mount would be gone.

Allan

[BigAl1]

Hi All,
Thanks for all the replies on the thread. Just back from holidays, so hope to have some solid answers tomorrow evening regarding the adapter plates and the mounts working with the SBC chassis. The adapter plates with the 1" shift to the rear (motor is moved forward 1" fit up, and the A/C compressor will clear the mounts nicely. Still waiting for the LS2 Corvette water pump with the shorter pulley to take final measurments regarding the firewall clearance problem, but I *think* it will have +1/2" of clearance.
Something I noticed about the Prothane motor mounts I'm using is the tabs that extend down which get the bolt through and through the chassis pipe has a weld internally which will prevent the mount from sitting down on the chassis pad properly. This will hold the mounts up and prevent the bolt from aligning. I will grind the chassis pad zone to clear this weld. Also, I made sure to oversize the holes in the Prothane motor mounts to allow some adjustability during installation. The adapter plates I am making have the motor mount bolts welded in as studs since access to the back side of the plates to hold the bolt head is very tight.
For another option on the A/C compressor, the GTO version has the hose ports on the side. I'm going to stay with the Corvette alternator mount.
See www.ultimagtr.ca/march_2006/index.html for pics.

Allan

[BigAl1]

Well, based on my measurements tonight, and looking at the link for Energysuspensions, the "Short, Wide" mount on that page is the one to go with. This has the mount bolt hole to base surface height of 1 3/4". This will also fit the width of the chassis pad better, possibly eliminating grinding to clear the inner weld on the mount tabs.
See www.ultimagtr.ca/march_2006/index.html for the ongoing saga. All this effort is my own trial and error. I probably could save some hassle by asking some questions to the Factory who have always been helpful with my previous questions.

Allan

[BigAl1]

Well, more info to add. The Corvette alternator location interferes with the cooling system swirl pot. So back to mounting the alternator down low as the factory does for SBC. I'll have to decide if I want to design a custom bracket or use GM brackets and modify to align the belt path. Also will need another idler pulley where the stock Camaro PS pump would be.
The white GTR I have pics of actually has the alternator on a Corvette mount, but flipped up and over to be closer to CL of the engine. This puts the alternator pulley very close to the angled surface at the upper part of the firewall.

Allan

[BigAl1]

Now that the engine is in mine, I tried the 2004 GTO exhaust manifolds I got as an experiment - they do not fit! Back to the online research, trying to find a down path header set that will fit LSx in the SBC chassis. Anybody have suggestions?

Allan

[BigAl1]

Crafty,
Can you send pics to me showing your exhaust manifolds installed?

Thanks,
Allan

[BigAl1]

I'm going to put 1 3/4" spacers between the compressor and the mount bracket to clear the compressor away from the engine mount. The pic above is the wrong adapter plate, now I have the standard S&P style adapter plate. This requires the compressor mount bracket to be clearanced slightly - see www.ultimagtr.ca/april_2006/000895.html . The belt path is already aligned being the Corvette setup, but will need a longer belt.
These motor mount adapter plates put the axle line on my G50/03 trans about 3/4" ahead of the rear wheel CL. If I had used the other mount plate first pictured, the axles would have 1 3/4" of mis-alignment. Another plus to these mounts - www.ultimagtr.ca/march_2006/000872.html is the front water pump inlet has more clearance vs. the firewall - still tight, but can be done.

Allan