2.0 with 1.5 head recipe
Here's a rundown of one of my favorite street engine combos.
This is assuming all 'normal' overhaul procedures are being done. By normal, I mean reconditioning connecting rods, replacing rod bolts, grinding/polishing crank to size, boring/honing block and decking head surface, new oil pump, timing chain, timing rails, etc. In other words, a complete overhaul.
SHORTBLOCK:
*1.9 block bored out to 2.0 litre displacement. There are two ways to go about doing this really, one is to use standard Opel 2.0 pistons, the other way is to use Chevy 265 pistons. I choose to do the latter, using Venolia forged pistons (flat-tops). The Venolia job number is 85681. Order them pin-fitted, but fitted for a .912" Ford pin, and have the Opel rods honed from .906" to .912". Either buy the pins from Venolia, or use 351 Windsor Ford pins. They're cheaper and lighter than Opel pins. Deck block surface flat. Double check all bolt holes for head bolts, lately I've seen some corrosion on the forward head bolt holes, and they can strip out. Heli-coils may be needed. I try to set the deck height so the pistons are at zero, i.e., flush with the deck.
*Reconditioned early forged Opel rods. Do not use the 'big' Opel rods as used in '74-'75, they're junk. Replace the rod bolts. Stock bolts are fine if you're gonna keep it below 7500 rpms...no reason to rev it higher.
*Balance rods end-to-end, and balance pistons.
*Rings....your choice, I use a moly top ring at least. I like Total Seal gapless secondary rings. Better ring seal over a longer period of time.
*Reground/polished and balance crankshaft. Don't forget, if you are using aftermarket bearings, the crankshaft thrust is often undersized as well, and will have to be reground.
*Felpro gasket set. One change...you'll need to use a Euro 2.0 litre head gasket. May have to change the front sealing area depending on the year of the timing cover.
*New timing chain, preferably with master link. New timing tensioners, new oil pump gears, new oil pump cover.
*Fully reconditioned timing cover...VERY CRITICAL...gotta get all the crap out of it.
TOP END:
*1.5 head...magnaflux for cracks before you start anything else
*Valves: Here it can get funny. I prefer to use 1.85" intake valves, and 1.50" exhaust valves. In reality, the first few 1.5 heads I built had 1.72" intakes, and ran pretty well. I've also put 1.80" valves in 1.5 and 1.6 heads. So what do I recommend? I'd go with at least 1.80" intakes, but would rather have 1.85" intakes. Trouble is, the combustion chamber must be unshrouded appreciably to get the larger valves to flow. If you don't unshroud, the large valves actually flow worse than with the smaller 1.72" valves. I have a few photos posted of the chamber mods, and also have a template I use to open the chamber to a predetermined size. Lately, I use Manley undercut Race-Flo valves. The exhaust valves are available off the shelf as part number 11521 for about $10 each (standard length small block Chevy with 11/32" stems). For the intakes, I order them from Manley directly as #11522 (1.94"), but have them cut down to size (must specify size). This will cost a few bucks more, but they're cut to factory specs and it only takes about a week.
*Springs and retainers. I use Crower 86031 titanium retainers, they're 1.25" in diameter. For springs, I use 1.25" double springs, Crower #68106X208-8 - VALVE SPRINGS 1.245 TUNGSALLOY DUAL (Note: Edited as per Calvin's direction). They install at around 1.675". I also use Crower billet keepers, #86107. I use viton valve seals, V.S.I. brand, they're for a .341" stem and to fit a 1/2" valve guide. Part number is 45341 .
*Machine work: Install hardened exhaust seats. Cut the valve seats for the appropriate valves. Cut spring seats, intake side, to get proper spring heights (usually .050"-.055" must be removed). Mill head flat, install new bronze valve guides (Chevy type, usually .503" OD, and 2 3/8" long). I also remove all the rocker arm studs before any machine work is done, as well as all oil galley plugs in the head. I replace the rocker studs, matter-of-factly. They DO fail, especially old ones. I tap all oil galleys for thread-in plugs. Replace cam bearings.
*Porting work: Best left to a professional. Exhaust ports barely need to be touched, intakes require a lot of work. I have photos I can send you if needed.
*Camshaft: I used to run straight profile cams, that is, both intake and exhaust profiles are the same. But with a 1.9 head, and especially with the 1.5 head, there's power to be had by running a split-profile, with more intake lift and duration. My favorite streetable (solid lifter) profile is a Cam Techniques grind, with their F-306 for the intake profile (.459" intake lift, 246 intake duration @ .050") and their F-290 for exhaust profile (.435" lift with 242 exhaust duration @ .050"). I have the cam ground with 108 degree lobe separation for street use. You can either have the cam ground with some advance, or you can use an adjustable cam gear to correct the cam timing. I would run 3-4 degrees of cam advance. Idle is at 1100-1200, best power is 2500-6500 rpms.
ACCESSORIES:
*Intake manifold: Welded and ported to 'Hot Street' specs at least. Use a '73 or '74 core preferably. I also used a 3/4" carb spacer regularly, but this is tough to fit on a GT.
*Carburetor: 38 DGAS Weber. Will require a slight amount of rework, such as drilling bypass holes on the throttle plates, and modifying the power valve so it opens later. It will require rejetting. For more power, the venturis can be drilled oversized.
*Exhaust: I've had great luck by simply running a slightly ported Sprint exhaust manifold, with a full 2" exhaust from the collector point back to the rear axle, then using a 2.5" over-axle pipe. I recommend 2 free-flow perforated core mufflers, a single will be too loud.
*Ignition: You must run a recurved distributor with this combo, it won't run worth a damn otherwise. Baseline setup would be 18 degrees BTDC @ 1100 rpm idle, with a total timing of 36 degrees. If you have access to decent gas, you may be able to run as much as 22 degrees initial timing, but with the same total of 36 degrees. It will require some experimentation. For my money, I'd use the Compufire DIS-IX ignition system. It does everything you need it to do, for under $200.
*Clutch/Flywheel: I'd recommend a lightened flywheel. I always ran a 15.5 lb flywheel, the response was great. I used to run a Sachs heavy duty clutch, it lasted about 2 years. So I now run a custom setup from Action Clutch. Very reasonably priced. Alternatively, the S-10 Chevy clutch with aluminum flywheel costs a few bucks more, but it's basically bulletproof, and has the added benefit of a lighter pedal feel (more streetable).
If you have any more questions, just ask.
Bob
