Newbie Question(s)

[t00nces]

Greetings all,

After much searching and reading, I'm confused about which way to go with my engine rebuild on my stock '81 FI 2000 Spider. I have a port/polished 1800 head on the way but I'm unsure which way to go with the bottom end. I'd like to increase performance a little bit which is why I went with the 1800 head and after reading Mr. Artigue's brilliant book, I decided to leave the stock cams in. I've read that going any higher than 9.8:1 compression in the pistons is potential trouble. My plans for this car to be a sporty daily driver (Allison exhaust) so minor performance increases like reduced weight (flywheel, etc.), the head, exhaust, etc. should be enough for me. So, here are the questions:

1. Should I wait until the engine is out of the car and the block is over at a machine shop to determine what size of piston and rings to purchase? It's got 150K on it and I was think one size over to be on the safe side.
2. Is there a piston recommendation given everything I've laid out?
3. As a matter of course, should I replace the crankshaft and bearings while I'm at it?
4. The head is coming from Vicks - would I need a different gasket kit or anything to account for a port/polished head?
4. Am I missing anything in my decision making process?

Thanks in advance for any advice.

Regards,

t.

[narfire]

I put 84.4 in my FI 2L. Cost of re-bore and balance not too bad really. Where the car's performance increase came from though is head work with after market cams and degree'd in properly with adjustable cam gears. My car pulls really well after 3000 rpm and being balance the rpm spools up nicely. Lightened flywheel as well. I get 30+ miles per imperial gallon driving to and from work. Headers are fine as well.
Consider as well some work on the suspension ( Love Koni's) after market springs, larger front sway bar and make sure the brakes are in good shape. Heresy for some but I found the suspension mods make the car just great in the twisties. Oh, have 15" wheels as well.

[klweimer]

I would wait on pistons until the engine is out and your machinist has a chance to look at it. There is a school of thought that says you bore it out to the max, to max your displacement. Theory is that you shouldn't have to worry about re-boring for a couple of decades. I just went to the first overbore size to square up the cylinders. New crank bearings for sure, but if your current crankshaft looks OK, I'd leave it alone. I would avoid grinding the crank, as you could lose the hardened surface of the journal. At most, I would have the machinist give a light polish.
I like the adjustable cam wheels (mine are from Allison) and they can be used to dial in even the stock cams. I put in new cams when I did my engine (while I'm here....). While your engine is apart, modify the aux shaft to remove the fuel pump lobe, then you don't have to worry about timing it later. Also check the front aux shaft bearing for play. If there is any, replace it with a pre-sized replacement, as your engine's oil pressure depends on this bearing being snug.
I would go with a high quality aftermarket head gasket. Some people use an MLS gasket, but I've done a couple on different cars, with mixed results.
Kirk

[t00nces]

Thanks for the sage advice!

Regards,

t.

[azruss]

So who carries bearings for the aux shaft. When I rebuilt mine years ago, there were none to be had.

[joelittel]

"I've read that going any higher than 9.8:1 compression in the pistons is potential trouble."

I read that same stuff and regret following the advice... not too long after I finished my build there were a couple posts where people had gone higher than 9.8 with no reported problems. Knowing how the slight bump in compression (remember the gasket thickness drops the ratio a little bit too) feels compared to stock I regret not going with a higher compression piston right off the bat. I played it safe because I didn't know what to expect. Currently the car runs great and is lots of fun to drive but I'll always wonder how much more fun it could have been had I gone with the higher compression.

If I had to do it over again I'd bore it to the max and get the best high compression pistons I could afford. If that turned out to be more than my setup could handle I'd look into getting thicker MLS gaskets until the compression ratio was something my build could handle.

If a little is good then more must be better... right?

[klweimer]

When I did my block a couple years ago I got a pre-sized aux bearing from Midwest Bayless. I heard later from the guys at Autoricambi that they had them too. The pre-sized part is important, as the bearing is split and when you press it in, it's designed to be a little too tight and then reamed to size in place. Good luck finding that reamer! The pre-sized version must be placed in a fixture to simulate the block opening and then reamed. I actually designed and built a special tool to gently press the new bearing in place, as the split nature of the bearing makes it really hard to install.

This is also when I discovered my aux shaft had been bent somewhere along the line (incorrect position during a timing belt install, no doubt) and needed to be replaced.

Kirk