I bought a 455 a few years ago and was planning on doing the swap last month. I pulled my 350 because there were some other things I wanted to address while doing the swap (Replacing brake lines, AC delete, degrease and repaint frame). Well after doing my research I decided to hold off on the 455 build as I didn't want to rush through it and just slap it together...I felt like that's what I was doing. So decided instead to freshen up my small block. I bought all new gaskets, new Doug's Headers, TA-290-94H cam, lifters, Springs, front cam bearing, new harmonic balancer, TA valve covers, waiting on the call to tell me when my SP3 is ready. I pulled the heads yesterday and 3 of the 8 cylinders have significant scratches.....catch a fingernail. Car ran plenty strong before I pulled it. It did burn oil though...and would smoke at start up. Question is: What would you do....slap it all together and run it? Do the right thing and take it to the machine shop? But then I have to buy new pistons....and if I do that I may as well just build the big block. Should I send all the parts back and get headers cam, lifters etc for the big block?? But that machining cost would be more because the 455 block needs the whole works....hot tanked, boring, decking. I've got about $1k left in my budget...
I would source a running 350 and leave it be and start collecting for a 455 build, unless you just want to stay with the 350 then get a fresh short block or complete engine done and not have any regrets later on. Although once you have ridden in a even a mild 455 your gonna regret going with the small block
$1k+ just to bore and buy $300 pistons? So $700+ just for machine work?? My machinist must be the cheapest around...
Forgot about the rings. I am assembling myself. I have all the gaskets. This motor was rebuilt 3 years ago. Cam bearings are fine except front....which is in decent shape...was gonna replace just for good measure. Was gonna pull rear main cap to inspect rod bearing...hopefully they're in good shape.
Run a hone through it, clean it up as best you can, and put new file-fit rings on your pistons. Send back the performance and 'look good' parts and run the 350 as it was. Why waste the money on a temporary engine? Save the $$ for the 455 build. Or just bite the bullet and do the 455, and do it right.
Pull 3 and 8 and see if rings are ok. Or where scratches came from. Might as well measure your engine and see what compression ratio actually is and maybe shave heads if need abit more for that cam.
^^^This is what I would do too. ^^^ But one question comes to mind. What do the cylinders measure and are they round? If specs are even close to being within tolerances you very well may be able to hone the cylinders and get most of the scratches out and re-ring it. You will never know what you have until you disassemble and measure everything. If you do that you may find more things wrong that will cost more money. Or you may find the rest of the engine is in great shape and a small investment is worth it. I personally would do like Smokey15 said and do the minimum on the 350 just to get by and save most of your money for the 455. Like they say...No replacement for displacement :3gears:
X3 - hone the cylinders and get most of the scratches out and re-ring it. But I would go ahead and install the performance parts. You already bought them, you will never get your money out of them, so use them! These motors are very tolerant!
You don't have enough compression to run that cam anyway. The single plane intake will make it run even worse. $300 pistons? You're just asking for trouble.
You spent the money on the 350 parts. Don't out what's making the scratches and correct that . Measure your actual compression ratio so you can use cam. Porting and big valves if any budget left. If you tune well it should be strong. Should not be hard . Change front cam bearing to TA back grooved. Should be running in a few weeks
Working a deal for a 1970 buick running great 455 with 46k miles. Car storm damaged dont need engine will want to move it. If intereseted let me know
You're going to have a hard time honing out deep scratches with a glaze breaker hone. If they were deep enough to cause heavy oil consumption, you will likely end up too big for the piston anyways. Ring and cylinder seal probs usually show more oil smoke at heavy throttle. Smoke at start up is more often associated with valve guide wear/seal problems. Nail catching scratches that cleaned up after honing a couple of thou. could easily be re-ringed. If they clean up ...rebuild the heads with basic porting, clean it all up, assemble and run. There really is nothing wrong with honing and/or boring only a couple of cylinders...if you have the equipment. It's how things were done back in the day. You won't find any shop willing to do that though...maybe a local guy with a boring machine? Anyways, there's some options. (My opinion here is from having machined many engines.)
The most expensive pistons I've found are $335 from TA. That cam requires 9:1 compression. 70 350 is 9:1. Heads were decked so I have at least 9:1 already right? I talked to the folks at TA at length about this cam. What am I missing here??
Just got off the phone with my machinist and he said if it ran fine before then keep running it. Recommended what most of you said: hone, clean carbon, re-ring and reassemble. Gonna have him take a look for good measure.
All advice here is sound, depending on which POV you view it. Even if you can't take out the scratches completely, smoothing them over will help. I'd be more interested in discovering WHY those scratches appeared in the first place. Either way, the cam's fine for the compression. It might not be fully optimised, but will work. May want to consider a more advanced cam install to bump the DCR some. This would be more important than the smallish powerband shift it would cause, IMO. You'll just drive yourself nuts trying to get things 'just so' when nothing is ever 100% perfect. Leaving yourself some leeway is always wise so you can make some adjustments in the tune. With that intake, headers, and cam, you're going to have some pretty good scavenging 3500 RPM and up, which will help offset the lower compression.
You can get away with much more cam than some suggest with mild head porting. What you think you are losing "on paper" to DCR, you make up for with improved cylinder fill/VE via faster velocity ports.
