This is a discussion on Advice / Options for smog 350 rebuild? Casting Number ID? within the Technical / Maintenance forums, part of the General Discussion category; I'm rebuilding an '86 350 for a motorhome that has to meet strict emissions requirements. (Salt Lake County, Utah - ...
I'm rebuilding an '86 350 for a motorhome that has to meet strict emissions requirements. (Salt Lake County, Utah - we are as bad as California, except we don't have a rolling age exemption here, and we have to deal with altitude issues )
Due to a limited budget and the emissions requirements, the motor will be almost completely stock. As much as it hurts me to 'build' a 160 hp SBC, I have to do it to stay legal.
However, I figured I'd check in and see if anyone had any advice on my choices, or knew of any other options I might want to consider for the rebuild. I've never been in this situation before, and feel completely lost. I know I can tune a SBC to pass emissions without any smog equipment on it; since I've done it to 2 pre-84 Chevies and a pre-84 Olds (the Olds 307 is a very tough, torquey motor, if you massage it a little). But, this being a post-84 application means I HAVE to keep the emissions crap on the vehicle, and operating (at least long enough for the emissions test every year).
The basic plan for the engine is to bore it 0.020" to 0.040" over, turn the crank, replace the cam and lifters, replace the pistons (wouldn't hurt to replace them anyway, but I dropped one on a concrete floor... ), balance the crankshaft, and rebuild the heads with stock parts. But, if I'm replacing the cam, I'd like to try to match a cam to the engine's use. That means high altitude (4,500-10,000 ft), torque from idle to about 4,000 rpm, and decent fuel economy at cruising RPM (2,800-3,000)... in a vehicle with a curb weight of 6,800 lbs and a GVWR of 10,600 lbs, with emissions equipment. I know... I'm asking for the world, but have nothing to give in exchange.
The engine details:
LT9 RPO / VIN 'M' - supposed to be 160 HP / ~230 lb-ft stock, but I've also run across information saying the "HD" version used the same RPO and put out 215 HP / 331 lb-ft. Anybody know for sure?
ID: V0605UPJ (I can't find anything on this "UPJ" suffix)
Partial VIN: CG4164236 (Original to the chassis, but it lacks the first numerical digit of a standard ID #. Could refer to the "Chassis Cowl", I suppose.)
One-piece rear main seal
Crank casting: 14088526
Exhaust: (Standard welded-tube van manifolds - no #s.)
Cam casting: unreadable (I really wish I could decipher the numbers - it would really help if I knew what was already in the motor.)
Pistons: 6271096 (3991476 cyls 3,5)
LH Head: 14079281 (Replaced somewhere between 0 and 36k miles, by the original owner - I can't find anything on that casting number, and it's not what the engine should have on the LH side - but the head does appear to be compatible with the engine, intake, and emissions crap.)
RH Head: 14078261 (Correct for the application.)
Both heads are 1.7" / 1.5" valves
Fuel delivery is handled by a recently rebuilt Rochester M4MV with '75' jets.
1986 Winnebago, Class 'C', 21 foot
4.10 rear axle ratio (turning dual 28" tires)
TH400 "HD" tranny w/ non-lockup 1350 rpm stall torque converter
Curb weight: 6,800 lbs
GVWR: 8,600 lbs (Chevy ID plate)
GVWR: 10,600 lbs (Winnebago ID plate - which is how it's titled)
I know that's more information than most people would need, but, as I said, I feel completely lost here. I'm not sure where to go with this. So, I figured I'd get everything I do (or don't) know out, and go from there.
Advice? Suggestions? Questions? Concerns?
Slap across the face for bowing to the oppressive emissions gods?