Is it worth retrofitting a flat tappit 70's chev into a roller lifter engine? Around where I live it's almost impossible to come across a decent roller engine, either they have 300,000km on them, or they've been thrown into a stock car..

 

When it's just a matter of installing a bunch of parts, why not?

 

Well, I have another question, I come across a set of roller tip retrofit lifters from Lunati, $375 a set, Could they be used with a flat tappet cam?

 

If an older version block or a solid roller cam (often used in higher RPM and racing applications) is being used, tie bar lifters are required. In this design, the intake and exhaust lifters are connected by a flat bar preventing any rotation.To prevent cam walk, flat tappet cam lobes are slightly tapered, keeping the camshaft centered under the lifter bores. Since rollers must have a flat surface to roll on, roller cams require another way to keep the cam centered. Some blocks accept a retainer plate that bolts to the block behind the cam gear. Only a roller cam that is machined to accept this retainer can be used. If the block or camshaft does not accept this retainer, a thrust button must be used. Thrust buttons fit between the front of the camshaft and the timing cover, preventing the cam from walking forward. Rearward movement, in all cases, is controlled by the cam gear.
So the short answer is,no **EDIT**. I forgot about the grind difference on the ramp angle witch is used to rotate the lifter as compaired to a roller cam, My bad.

 

NO

 

So what if they have 300,000 KM on them. That'll still clean up with a 20 over bore.
And it's still probably cheaper than retrofit HR lifters.
In a 9:1 350 with Vortec heads, built to peak at 5500 rpm, rollers are still worth around 30 horses. Plus no risk of ever losing a lobe or lifter to the lack of ZDDP. Plus no initial run-in for the cam and lifters.
Those are the advantages of rollers. If that's worth the cost to you, only you can decide.

 

I agree with the 20 over. the amount of miles on a block means nothing if a good machine shop does the work. As for a retro fit roller you will have to put more money into parts to make it right when like attila said and many others would agree just find a good late model roller block and use it, It will be cheaper in the long run I would bet.

 

Airflow is power, and better heads are held to be the way to get it. We always held that it was a choice between big cams or better heads, and the cams were cheaper. This is still happening, sadly.
But when we can swap to a roller, and find 29 horses despite less duration and overlap, that changes everything.
Less duration AND less overlap, that improves driveability, mileage, and emissions. It also improves the power below the rpm at which the torque peak happens at. That improves acceleration.
Plus the extra 29 horses, that's noticeable acceleration that will put you ahead.
It's as big a step as the basic move from the iron L98 heads to the L31 heads.
You don't need a roller setup to make big power, nor to have a torquey-feeling driver. But it's necessary if you want the best of both worlds, on a budget.
And the cheapest way to go roller is by getting an '87-up block. After '88, NONE of the U.S.-market 350s came with carburetion. And that dramatically reduced bore wear.
Seventies 350s typically need a 30 overbore after 100,000 miles. EFI versions typically can do triple that and still clean up at 20 over. Why? FI doesn't ever run rich enough to have raw gas washing the oil off the cylinder walls. That's it. That's the entire story. It's not different metallurgy, or reduced ring tension. It's precise control of the fuel.