Here's what I have. A '90 RS with a 150k mile L03/T5 and a 1300 mile L69/700R4. I want to swap the L69 into the '90 RS and retain my TBI and T5.

I'm pretty sure I need to get a different flywheel as I'm sure the one from the L03 won't work since it's from a 1-piece rear main and the L69 is from a 2-piece rear main. Anybody know for sure if they would interchange?

And since I want to retain the TBI, I'll need to use the L03 distributor for the ECM. But since the L69 has a flat tappet cam and the L03 has a roller cam, won't I need to swap the drive gear from the L69 distibutor to the L03 distributor? I've heard that the drive gears on the roller vs flat tappet cams are made of different materials and that they are not interchangable.

Also the L69 motor is missing one bolt hole for the accessories on the passenger side head. It only has 3 holes for mounting the accessories on the passenger side and 4 bolt holes on the driver's sdie head whereas the L03 has 4 bolt holes on both heads. Would it be acceptable to leave out one bolt? I want to retain my serpantine drive setup from the L03.

I know I'll need to get an adapter for the TBI to carb intake but that's not a problem.

Anybody know these things for sure?

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Stephen Cranford

http://www.geocities.com/chevyraceshop


http://austin.f-body.org/members/cranford
97 Tahoe SS
90 Camaro RS

 

About the only thing I know for sure is I wouldn't bother. Why do you want to do this?

You didn't say what year the L69 is, but you seem certain it is 2-piece rear main. That means it's probably '85-older. Get a flywheel from/for an older 2-piece if that's the case.

You already know you're going from a desirable roller cam to a less desireable flat tappet. You can use your factory roller distributor gear on it, though.

Unless you have a really good reason to go through with this, it just doesn't seem to make sense. Sell the L69/700R4 and your LO3, get yourself a roller block 350, save yourself all the problems you mention and get a better engine to boot.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

Actually, there really isn't a reason not too. My L03 has 150k miles on it, and the L69 has 1300 miles on it. I bought a wrecked '84 and with the parts I've used/sold off of it, the engine is basically free. It's what I have and there's no sense in getting rid of it. As for a roller 350 being a "better" engine, why? You can make plenty of power from a 305 despite what most people think. I could crank 350 hp out of this 305 with a carb (Q-jet, no less) without breaking a sweat. 400hp from a decent 305 would be easily attainable. And imagine the looks when you explain to LS1 boy that you smoked him with a 305! Not to mention there's always the option of stroking it to a 334, which is what I plan on doing with the L03 after it's out. It'll go back in turning out at least 400hp NA.

As for using the L03 distributor, are you sure? Everything I've read suggests that the roller cams are made from a harder sttel therefore the distributors used a harder drive gear. Apparently using the harder drive gear on the softer flat tappet cams will eat the gear off the cam, and vice-versa if you try to put a roller cam in with a flat tappet distributor.

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Stephen Cranford

http://www.geocities.com/chevyraceshop


http://austin.f-body.org/members/cranford
97 Tahoe SS
90 Camaro RS

 

I've defended the 305 plenty of times on these boards - and taken plenty of flames for it. As you can see from my sig, however, I'm still planning on building one up. With what I'm doing, I figure I'll get around 300-325 hp sea level at the flywheel. That's a 93-110% increase, and what I'd call significant.

But, what you said in your last post is significantly different from what you said in your first. I'm a q-jet defender as well, but you said you're keeping your TBI. The HP numbers you quote are pretty pie-in-the-sky, and those who have obtained them with a 305 did not have a very daily-driver friendly engine when they got done. Good luck trying to smoke an LS1 guy with your 305, too. And, I've never seen any attempt to do this with TBI.

As for your distributor gear questions, the factory does not use as hard of cams as was/is typical for aftermarket solid-lifter roller cams, which require a bronze gear. The factory uses what they call a "melonized" gear, which will work with older flat-tappet cams. But, for your piece of mind, take the gear off your L69 distributor and put it on your LO3 distributor when you put the TBI on the L69. I'm going the other way, so need the melonized gear on my CC-carb HEI with the ZZ3 roller cam.

I looked into the 334 option for my LB9. I concluded it wasn't worth it, because not only do you need to get a 334 stroker kit (which costs more than a 383 kit), you have to deal with external balancing issues just like a 383 or 400/406. By the time you solve those issues, you could buy a roller block 350 core and rebuild it, and get more power out of it for the same or less money than the 334 would cost you. More to the point, in April I talked to a local engine builder/racer, he told me he could sell me a 350 roller block and do the 383 parts/machining for less than it would cost me to do the 334 with my block.

Being able to say, "Sure, it's just a 305" is only worth so much.

Just curious, how have you verified those "1300" miles on the L69? Still have the dual-snorkel air cleaner?

 

I do plan on keeping the TBI, but as for defending the Q-Jet, I only mentioned it was possible with a Q-Jet because most people would automatically assume I meant a Holley or Demon carb. I know that power level will be harder to obtain with the TBI instead of the carb.

I bought the engine from a friend in our local club so I know when he got the car and what he went through to get the car up and running. I actually bought the whole car after he totaled it. I got the engine/tranny, Griffen alum. radiator, MSD ignition, 3-pt STB...lots of good stuff I salvaged of that car. Either for my own use of to sell. Had the dual snorkle air cleaner. It's already gone.

I think I will swap the dist. gears for my peace of mind, as you put it. It'd beat finding out, for some odd reason, that it was needed. Thanks for the details on the factory vs. aftermarket cams/gears. It makes more sense now as to what I was reading about before that lead me to believe it was needed.

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Stephen Cranford

http://www.geocities.com/chevyraceshop


http://austin.f-body.org/members/cranford
97 Tahoe SS
90 Camaro RS