I am beggining to build a 305 that came with my project car. The roller block engine will maintain stock bottom end. I am putting on ported 416s, perf rpm mani, and holley carb. I want to know if putting a flat tappet in will be a bad choice(money wise and perf wise). This is a budget motor to hold me over while I spent more time building a 350.

WHat is necessary to go from roller to flat tappet????
I am going to use the same cam and lifters, intake, and heads on the 350 as in this temporary 305 engine (swap them over). All this will have a th350 with a jegs 2700-3000 stall convertor and 373 or 410 gears.

 

Cam, timing set, lifters, pushrods.

 

IS a summit cam and lifter kit suitable:

Dur @.050 --- 234/234
Lift ----- .488/.488

I will be incorporating a nitrous shot into this setup. Should I get a cam with more lift and duration on the exhaust lobe:

summit 234/244 -- .488/.510?


Also what is the cheapest suitable timing set?

 

The Summit cams are generic grinds. I haven't done same engine comparisons, but the general consensus is you'll do a lot better with a cam from a major, recommended for what you'll be doing.

Unless you're doing mongo lifter loading, you don't need a high-dollar timing set.

 

not to hi-jack this thread, but when you say generic grind, what does that really mean? Does it just mean the cam will wear faster?

 

No, it means lobe profiles that have been out there for years, everybody uses them, so the cams are cheap. Summit, Elgin, other "replacement", "store brand" cams are most likely "generic".

 

Your first question was whether a flat tappet cam would be a bad choice.
If you already have a roller block, it reduces the cost, because you can get factory "take offs" for pretty cheap compared to the cost of aftermarket roller parts.
Do you have any of the original roller pieces or only the block?

 

And yes performance will suffer going with a flat tappet compared to a roller cam. If posible stick with the roller cam. You will be way ahead. You can pick up ZZ4 roller cams for $100 and other roller parts off Ebay for cheap. Probably more agressive grinds to.

 

If you're comparing a flat tappet GM cam and a generic grind (both the same really) against a GM roller cam or a generic roller (Yes they exist), then the gains of a roller over a flat tappet are minimum.

Look at the advertised duration of the Hot Cam or the ZZ4 cam, for example. They're nearly as lazy as a generic flat tappet. About the only gains would be the slight decrease in friction which would gain a few HP but would be better for longevity. After all, that's about the only reason GM uses roller cams; for longevity.

Now, compare a stock GM roller cam to something from a company like Lunati, then there's a huge difference.

 

I do have all the lifters and pushrods and self aligning rockers. I will be swapping in non-self aligning rockers and I think Im going to go with a used or new LT4 hot cam. Im going to stick with roller, I guess Ill just buy a roller 350 block to swap everything over after the bottom end is built.

How does the LT4 hot cam perform on:

1) a 350 with a set of vortec heads that have been machined for the extra lift and have the appropriate springs?

2) a 305 with ported and polished (stock valve) 416 heads set up to run the extra lift.