My Flat Tappet Cam Wiped Out So I Decided To Go Roller

PlayingWithTBI

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A little background:
About 4 years ago, my '88 C1500 with the 5.7L TBI engine started overheating on me. I found the head gaskets blown. I knew the swirl port heads and peanut cam were about useless so, I decided to "upgrade" to better parts while trying to keep it fairly cheap - yeah right! :rolleyes: I went with a stiffer flat tappet cam and bought the Summit Racing 162108 aluminum heads made for a direct TBI swap, since they were advertised as better flowing than Vortec heads. I added other upgrades but, they're not really germane to this thread. I did research going to a roller cam then but, it would have been ~$800 more plus, at the time, I didn't know my block had the bosses for one.

A few weeks ago, my engine started making tappet noise and just didn't sound right. We popped the valve covers off and found what looked like 2 collapsed lifters. We set their "lash" at ~0.008" and buttoned it up. Took it for a drive to the parts house to get a PCV vacuum line and check it out. If it sounded OK, we were going to pull the intake manifold and swap/clean out the lifters. Well, it sounded OK going but, on the return ride, it started sounding bad and lost some power. That's when I decided to tear it down and go roller, like I should have done in the 1st place. :mad: After more research, talking to Summit Racing and Comp Cams Tech support I put a plan together.

The Summit Racing heads will only support ~.520" lift up to ~5,000 RPM. I went with the Comp Cams CL08-430-8 cam and lifter kit, .525/.525", 224/224 @ 0.050" and 986-16 springs (rated up to .540" lift), as recommended by Comp Cams. Then I had to get locators (bottom washer) and keepers (top washer) for their larger diameter, 1.43" instead of 1.25", installation kit (with spider, cam plate, dog bones, and bolts), locks, seals, 1.5 full roller rockers, push rods, etc. The roller cam takes a different timing gear and sprocket than a flat tappet cam so, I got a Trick Flow set with a thrust bearing in it. We're still working on it and I'll keep updating as we go.

The 1st thing I wanted to do was get a couple springs installed so we can get the proper length push rod.

Here's the difference between the original and new springs. The originals are a single spring with a damper (flat spring), on the left, while the new ones are dual springs with a damper. The originals have a seat pressure of 110 LB @ 1.780" while the new ones are 132 LB at 1.750" (even though they're taller unsprung. I got a shim package to get the 1.750" height.
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Here's the difference between the Trick Flow timing set compared the the Cloyes Flat Tappet set. Note the smaller bolt circle on the Roller Cam set, plus the chain is beefier. Remember I'm not running a crank sensor so it'll fit under the OE timing cover.
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Old cam vs new.
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New cam going in, we were able to swing the condenser out a little to get the cams out and in.
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Push rod length checker, I went with 7.25" Chromoly rods.
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We started installing the springs and found the 2 middle ones for the exhaust valves wouldn't go down all the way! Even though Summit Racing says the seats on the heads are 1.550" and I ordered 1.500" locators, these 2 seats are closer to 1.44" and the head bolt washer between them sticks out to where I had to grind down the locators and flat spot them to fit.
Needless to say, we didn't get them done before it was time for cocktail hour and dinner at our favorite Tin Top Bar and Grill. :cheers: More to come...

As usual, all questions and comments are welcome! :33:
 
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Schurkey

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Well, at least with a cast core you shouldn't have distributor-gear problems if the distributor gear you have now is in good condition.

When I built the boat 454 engine, I got a steel core cam with a cast-iron gear and rear journal pressed-on. And the BBC also uses a smaller bolt circle on the cam, which requires a different cam gear to match the bolt circle, and in my case a different drive tang for the cam-driven water pump.

"WHY" will the Summit heads only support 0.520 lift? Coil bind? Retainer-to-seal clearance? Will changing the springs and retainers cure that?

I see some computer tuning in your future.
 

PlayingWithTBI

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Well, at least with a cast core you shouldn't have distributor-gear problems if the distributor gear you have now is in good condition.
Comp Cam still requires a Melonized gear which I have and, will install.

"WHY" will the Summit heads only support 0.520 lift? Coil bind? Retainer-to-seal clearance? Will changing the springs and retainers cure that?
Yes, coil bind. I checked the coil gap with the new springs and I have over 0.060" gap which they say is the minimum for these springs. According to Comp Cams these springs are 1.75" installed height and, 1.15" coil bind height, with 132 LB seat pressure.

BTW, the Summit heads don't use umbrella seals on the exhaust, they use the same ones on all valves. Here's one old seal (black) and a couple replacements.
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What oil is that PWTBI on the cam?
It's Permatex assembly lube.
www.summitracing.com/parts/ptx-81950

 

Schurkey

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Comp Cam still requires a Melonized gear which I have and, will install.
You're using a TBI distributor...right?

ALL the GM TBI distributors had melonized gears. No promises on aftermarket TBI distributors, although it's "likely" that they were melonized also.

BTW, the Summit heads don't use umbrella seals on the exhaust, they use the same ones on all valves.
My Twisted Wedge heads are the same way. Not surprising, the Summit "TBI" heads, and the Twisties are both Trick Flow products.

It's Permatex assembly lube.
www.summitracing.com/parts/ptx-81950

That stuff (and competing liquid assembly lube products from about a dozen other companies) is excellent lube for your ratchets. Doesn't drip out like thinner lubes. I spent an afternoon taking (almost) all of my ratchets apart so I could drizzle in a couple drops of that stuff on each one. I learned the hard way about actual grease in ratchet heads. Couldn't figure out why I was breaking teeth on Proto pear-head ratchets until I STOPPED putting white grease in them and the problem vanished. Sure did make 'em smooth and silky (until they broke.)

Liquid lube from then on. I'm using Federal Mogul/Sealed Power liquid assembly lube; I think the only difference is the color of the dye they use. My stuff is green instead of red. But like I said...there's a dozen companies that sell the liquid assembly lube; and it all works just fine.
 
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