I'm working my way through the $150 350 I got last year, and the engine is an L98 Marine engine. The engine has very little wear and is pretty clean inside. The heads have double valvesprings and 1.94/1.50 valves. I did a cleanup port job on them, matched the intake port inlets to the gasket, and polished the combustion chamber and exhaust ports. One of the heads had a fairly bad core shift in the ports that cleaned up nicely.
I'm putting the engine back together with a stock L31 roller cam, which is shorter duration and higher lift than the L98 cam. It was also only $20 from Pull-A-Part. From what I can find, the L98 double valvesprings are stiffer than the stock L31 valvesprings, so I'm sticking with them. I've considered Elgin 1.6 stamped, self-aligning rocker arms, but $100 is out of budget for this build so the factory L98 self-alinging rockers are getting reused.
The valves are interesting. The intakes are .341" stem, while the exhaust are .372" stem. Two of the exhaust valves were corroded and I trashed them. Replacements were $10 a piece compared to $5 a piece for the three bad intake valves. The intake valvespring retainers look normal, but the exhausts are "rotocap" retainers. I had to spend ten minutes or so googling retainer pictures to figure that out. It looks as if the L98 Marine motors were set up with more robust exhaust valve parts.
The factory intake retainers are 22 grams. The rotocap retainers are 37 grams. The chintzy tin caps on the valves are 10 grams. While I'm keeping the budget tight on this engine, I'm not in favor of killing horsepower, so I spent $28 on a set of GM retainers, and I plan to run them without the tin caps.
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My question for the more experienced builders (this is my fourth SBC build), is this a solid plan?
Anybody know more about rotocap retainers? Are they goofy BS? Do I keep them in my spares bucket? Is it a mistake not using them?
Pics for those of you, who like me had never heard of rotocaps. I know that I've seen them before, but I never paid much attention to them.
I'm putting the engine back together with a stock L31 roller cam, which is shorter duration and higher lift than the L98 cam. It was also only $20 from Pull-A-Part. From what I can find, the L98 double valvesprings are stiffer than the stock L31 valvesprings, so I'm sticking with them. I've considered Elgin 1.6 stamped, self-aligning rocker arms, but $100 is out of budget for this build so the factory L98 self-alinging rockers are getting reused.
The valves are interesting. The intakes are .341" stem, while the exhaust are .372" stem. Two of the exhaust valves were corroded and I trashed them. Replacements were $10 a piece compared to $5 a piece for the three bad intake valves. The intake valvespring retainers look normal, but the exhausts are "rotocap" retainers. I had to spend ten minutes or so googling retainer pictures to figure that out. It looks as if the L98 Marine motors were set up with more robust exhaust valve parts.
The factory intake retainers are 22 grams. The rotocap retainers are 37 grams. The chintzy tin caps on the valves are 10 grams. While I'm keeping the budget tight on this engine, I'm not in favor of killing horsepower, so I spent $28 on a set of GM retainers, and I plan to run them without the tin caps.
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My question for the more experienced builders (this is my fourth SBC build), is this a solid plan?
Anybody know more about rotocap retainers? Are they goofy BS? Do I keep them in my spares bucket? Is it a mistake not using them?
Pics for those of you, who like me had never heard of rotocaps. I know that I've seen them before, but I never paid much attention to them.
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