I want to know if this is really true. My father said that he knew someone that heard it from someone that blah blah blah knew a mechanic that said this. I have a L03 305 with 140,000 miles and was thinking of upgrading the weak link to a set of L98 heads with the same compression ratio. If I put this set of heads on or any other set of of new heads, will it cause the motor to break down quicker because of the increased sealing of the fresh heads. I say no, but I want other opinions.

 

Well first off you will lose compresion if you don't mill the heads. The sealing of the new heads will not hurt you one bit, if the bottom end is weak or the rings are weak they just are and better heads will not hurt it. I have seen many LO3's with 150,000+ miles running strong. Yeah they smoke a little but its valve seals.



Brian Felts

 

L98 heads will lower your compression ratio on an LO3. Any head you put on you will want it to seal correctly and not leak. Unless you want water in your oil, oil in your water, water in your combustion chamber, or water all over your engine compartment. If your head gasket leaks you should replace it and have your heads checked for warpage, no matter what anyone tells you.

 

My teacher in auto school used to say that crap all the time. He'd say, "you're gonna blow the bottom end outta it." He was full of it. What would happen if you owned an LS1, and only stepped on the throttle enough to produce 170 hp and 255 ft-lbs of torque for 150,000 miles, and then one day started flooring it whenever you felt like it? Would the thing break down quicker because of higher cylinder pressure (same as better sealing)?? HELL NO! LOL. Those who can't do...teach!

I had an 83 LG4 TA once. I drove it 180,000 mile and then installed a cam. Dropped a second in the 1/4. Sold it at 200,000 miles, still running great, getting 23 mpg highway. That person sold it with 230,000 miles, still running strong. No, improving parts won't cause you engine to fail, unless it was already about to fail ANYWAY.

 

Thanks for the input. If I do the L98 heads I would definitely mill them to keep the compression the same as stock or maybe a little higher to make a bit more power but still run on 87 octane gas. I plan on installing new head bolts, gaskets the whole nine yards when I change. While I'm at it might as well change out the intake manifold for a little better flow also. Would not going with the L98 head and going with something else be a better choice. If so what should I be looking at. I'd like to keep costs down since I'm planning on doing an engine swap to TPI in the future.

 

If you're changing intake anyway, why not get Vortec heads and intake? That combo will get you far more power than the L98 combo for approximately the same amount of money.

 

The aluminum L98 heads have 58cc chambers just like your L03 heads. The iron ones have 64cc chambers and would have to be milled.

 

(If you're changing intake anyway, why not get Vortec heads and intake? That combo will get you far more power than the L98 combo for approximately the same amount of money.)

I've thought about that too, but do they make a TBI intake manifold that will work with the vortec heads? On this engine I'm not that concerned whether I run aluminum or cast iron heads so I have many options.

 

Yes, there is a TBI/Vortec intake available.

 

You could use a 4 barrel carb intake with a throttle body adaptor on it, too.