roller camshafts

A few people in the Pantera circle claim they had problems with rollers. Make contact with the manufacturer about maintains, to make sure you handle the thing right.

I have run a mechanical roller for 5 years with no problem. But I do check rollers and lash frequently every 600 miles. Lash is important since too much may make the roller to float the cam and stop rolling.

351 have no water in the manifold, so checking roller is not to hard. (good idea, just like the Hemi)

A 230 dgr @050 and 110 Lc is about right.
Don�t get too concerned about exact numbers.
They vary a little between manufacturers.
You don�t notice any difference.

Goran Malmberg

I have/had two close personal friends each running roller cams on the street. One has a race-only solid roller unit, the other a hydraulic roller. Both worked fine, with initial start-up problems. Even the best cam grinders occasionally need to be reminded of the weakness in the 351-C block- the gigantic oil passages connecting the lifters to the main oil galleys. Too high a lift will shove the roller wheel into the oil galley, creating a huge drop in oil pressure- 16 times per engine revolution! You avoid this problem by either running a shrouded roller lifter with a reduced diameter roller wheel, so the roller has no lifter notch to intrude in the oil galleys, or you use a reduced-base-circle cam, where the entire cam is scaled down so that high lift doesn't put a roller wheel up into the oil galley. Finally, any roller cam uses much shorter pushrods and much stiffer valve springs due to the longer, relatively heavy lifters, and requires a steel distributor drive gear to be compatible with the steel camshaft. Crane now makes such a steel gear for the Cleveland. This all makes the cost of a roller cam system 2-3x the cost of a flat-tappet cam of equivalent power. Full synthetic oil is a good idea for such cams, by the way.

I am running a Crower mechanical roller lifter cam 234 intake, 244 exhaust 110 lobe separation. I like it, about 1500 miles on it with no problems. I have heard the distributor drive gears wear out in 2000 miles. I am going to inspect my soon. I priced a polymer gear at Summit for $116. I may put that in if the gear is worn. I thought of a hydraulic roller too but was told the heavy hydraulic lifters wear out the valve springs quickly. Crower tech department told me absolutely do not to use synthetic oil.

Crower Part No 15480. Intake lift = .569", exhaust = .571". I got it from Dennis at PPC in Castle Rock, CO.

What rpm range does it make power at & what intake and carb doe you have?

The Crower catalog list the rpm range as 2500 - 6000 rpm with a red line as 7500 plus. It really starts pulling well at 3500 and will continue coming on strong beyond 6000 rpm. My rev limiter is at 6500 rpm so I don't know what it will do beyond that but it was still pulling right up to the 6500 rpm limit. My carb is a Holley 750 double pumper with mechanical secondaries and the intake is Ford aluminum Boss 351 dual plane. CR is 10.25 with a GTS exhaust. I wanted the biggest cam I could get and still pull enough manifold vacuum to run the power brakes when idling up to a stop light. I think the manifold vacuum is around 8 to 10" at 800rpm. It idles better at 1000 to 1200rpm though. I am in Colorado at 5000 feet plus elevation so you guys at sea level should do even better.

quote:

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Originally posted by jack deryke:
[B]I Even the best cam grinders occasionally need to be reminded of the weakness in the 351-C block- the gigantic oil passages connecting the lifters to the main oil galleys. Too high a lift will shove the roller wheel into the oil galley, creating a huge drop in oil pressure- 16 times per engine revolution! You avoid this problem by either running a shrouded roller lifter with a reduced diameter roller wheel, so the roller has no lifter notch to intrude in the oil galleys, or you use a reduced-base-circle cam, where the entire cam is scaled down so that high lift doesn't put a roller wheel up into the oil galleyB]

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Another option (more expensive) is to bore the lifter holes, and press copper bushings with smaller holes at a higher place in it, and hone the bushings to a perfect fit for the lifter.
And there even one more option, and that is to put an oil restriction kit in your 351 block, its specially designed for this purpose.
Paul.

I don't recommend this, as there are surprisingly few machine shops around that can reliably bore lifter holes correctly, then install & ream bushings so the lifters run properly. Remember, you have 16 chances to do it wrong. There are multiple angles involved as the stock lifter bores are slightly tipped backwards to preload the cam that way, and the lifter bores are slightly higher than true centerline, to ensure the lifters rotate for long-term durablity. Sure, on race-only blocks, it's successfully done. But those blocks are forever dedicated to racing with frequent teardowns, roller lifters forever, etc

The commonly avaliable oil restrictor kits (les than $20) only limit oil flowing to the 8 lifters on the left side of the block, and do nothing for the oversized oil passages that intersect all 16 lifters. Each hole is nearly 1/2" dia where it should be 0.050 or smaller. Restrictor kits in the lifter bore for the left side bank of bores probably shouldn't be used with hydraulic lifters, especially the fast-bleed types that need more oil to work properly. I wrote a recent article for the POCA news that mapped all the oil passages in a 351-C, and to call it 'severely twisted' is a mild understatement.One quote by a noted motor journalist in 1972 said, "... Sherlock Holmes himself would be baffled by the oiling in a 351-C..."

quote:

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Originally posted by jack deryke:


I don't recommend this, as there are surprisingly few machine shops around that can reliably bore lifter holes correctly, then install & ream bushings so the lifters run properly. Remember, you have 16 chances to do it wrong. There are multiple angles involved as the stock lifter bores are slightly tipped backwards to preload the cam that way, and the lifter bores are slightly higher than true centerline, to ensure the lifters rotate for long-term durablity. Sure, on race-only blocks, it's successfully done. But those blocks are forever dedicated to racing with frequent teardowns, roller lifters forever, etc

The commonly avaliable oil restrictor kits (les than $20) only limit oil flowing to the 8 lifters on the left side of the block, and do nothing for the oversized oil passages that intersect all 16 lifters. Each hole is nearly 1/2" dia where it should be 0.050 or smaller. Restrictor kits in the lifter bore for the left side bank of bores probably shouldn't be used with hydraulic lifters, especially the fast-bleed types that need more oil to work properly. I wrote a recent article for the POCA news that mapped all the oil passages in a 351-C, and to call it 'severely twisted' is a mild understatement.One quote by a noted motor journalist in 1972 said, "... Sherlock Holmes himself would be baffled by the oiling in a 351-C..."

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Jack, i fully agree with you on both points, but if you have a (very) good adres for a machine shop, than it would be no problem at all.
I've seen this several times, and not even one time i saw a failure.
I only added 2 options wich will work, it's up to the car owner what he prefers, i will warn for consequenses (like you wrote) next time.

Paul.

As for the non-recommendation of synthetic oil with roller cams, it may stem from the U.S. DOT pressuring all the big oil companies to remove the heavy-metal additives that allow protection for very high pressure sliding contact-e.g- aftermarket flat tappet bottoms against cam lobes. Heavy metals such as zinc and phosphorus poison catalytic converters, so they're now gone with tetraethyllead in the name of smog control. In street engines with roller cams, the rollers tend to skid over the cam lobes at low engine speeds, not roll, so the problem is the same as with flat-tappet cams- the rollers flatspot and the lobe tips wear. Stock hydraulic rollers run fairly mild springs so the skidding/flatspotting isn't so damaging. I'm told that MOTORCYCLE full-synthetic oils have yet to be reformulated (only a few bikes now carry cat-converters), so Silkolene and some Motuls (both from Europe) can still protect against high valve spring pressures while giving one the extra 25 degrees of temperature protection of synthetic oils.

Jack,
Do you have a part# for the shrouded mechanical roller lifters you were talking about. I think I have that exect same problem.

Thanks,
Dave

What is the limit of lift that would (or could) be the maximum, before needing the lifter bore modification? Thankyou for everyones help as I try to sort this one out!

It seems like pretty much all the major cam grinders list roller-retrofit kits for non-roller engines. Crane, Comp Cams, Lunati etc all list such kits. Stock Ford roller hydraulis fit the Cleveland block fine except they are too tall and are unsupported as a result. Also realize that you cannot take a roller cam designed for a lg. diameter roller wheel and use a smaller diameter roller wheel on it (as the shrouded wheel rollers are), and expect to get performance or durability out of the mix. Cams are ground with a particular diameter roller wheel in mind. Changing that changes a whole bunch of other things, mostly bad. So as I always say, call the cam grinders tech line or e-mail them with your specific questions. Be ready to answer a pageful of questions on your motor & your expectations.

I just removed my distributor to check the wear on the bronze gear. After about 1600 miles of use I see some wear (the gear teeth are shined up) but much less than what I expected based on what I have heard. I am going to replace the gear anyway because I am installing a new MSD distributor. I will keep the old one for a spare. I would bet the old one would run for another 2000 to 3000 miles (unless the wear rate increases with use). I am running a high volume oil pump too.

[This message has been edited by BD (edited 09-06-2003).]

My engine builder Al Liest suggested only restricted push rods. The custom push rods have smaller diameter oil feed holes. This was the only oiling modification made. I run a solid lifter roller camshaft.