[bcjjones]

Got the heads and the flat tappet cam in the 350 91’ s10. Break in procedure went well. Ran it for about 15 minutes at 2-2500 rpm and then had to shut it down due to an oil leak at the valve cover. Hate those things! Fired right back up and immediately got it up to 2-200 for another 10. Drained oil and all seems well. I love the idle vacuum. Even at just 12 degrees initial and about 800 rpm it’s at a solid 15 inches. I’ll have to recurve the distributor (HEI) so I can play with the timing.

Opinions on initial timing? It’s a stock bottom end 350 with 200cc/64cc heads and a GM performance cam 212/222 .450ish lift. Still has the factory dish pistons and .025 in the hole. With the .026 head gasket quench is .051. Probably about a 9.0:1 motor. Can’t find any real numbers on the cc of the factory pistons?

Also, for any of you wiring/sensor gurus. There are two sensors on these trucks. One that is a two pin sensor located on the intake manifold that fed temp to the ecm. The other is a one wire sensor on the head that sent cylinder head temp to the gauge. I don’t like the wiring to the cylinder head temp sensor and it being right by the exhaust manifold. Can I just tap in to the 5v reference wire on the two pin sensor and use it to feed info to the gauge? Obviously the pcm is out of the equation now that it is a carb motor instead of a TBI

 

[bcjjones]

Scratch that question about the coolant temp sensor. I realized I can easily just move the cylinder head one wire temp sensor to the location of the coolant temp sensor for the ecm instead.

 

[jayseasBlue56]

Got the heads and the flat tappet cam in the 350 91’ s10. Break in procedure went well. Ran it for about 15 minutes at 2-2500 rpm and then had to shut it down due to an oil leak at the valve cover. Hate those things! Fired right back up and immediately got it up to 2-200 for another 10. Drained oil and all seems well. I love the idle vacuum. Even at just 12 degrees initial and about 800 rpm it’s at a solid 15 inches. I’ll have to recurve the distributor (HEI) so I can play with the timing.

Opinions on initial timing? It’s a stock bottom end 350 with 200cc/64cc heads and a GM performance cam 212/222 .450ish lift. Still has the factory dish pistons and .025 in the hole. With the .026 head gasket quench is .051. Probably about a 9.0:1 motor. Can’t find any real numbers on the cc of the factory pistons?

Also, for any of you wiring/sensor gurus. There are two sensors on these trucks. One that is a two pin sensor located on the intake manifold that fed temp to the ecm. The other is a one wire sensor on the head that sent cylinder head temp to the gauge. I don’t like the wiring to the cylinder head temp sensor and it being right by the exhaust manifold. Can I just tap in to the 5v reference wire on the two pin sensor and use it to feed info to the gauge? Obviously the pcm is out of the equation now that it is a carb motor instead of a TBI

Don,t let that flat tappet engine idle for any period of time, especially with a new build, good way to develop a flatten lobe.

 

[bcjjones]

Don,t let that flat tappet engine idle for any period of time, especially with a new build, good way to develop a flatten lobe.

Cam was broken in for almost 30 minutes at 2500ish rpm.

 

[BogiesAnnex1]

Sounds good.

Bogie

 

[jayseasBlue56]

Cam was broken in for almost 30 minutes at 2500ish rpm.

I,m talking even about after that breakin.

 

[2old2fast]

I,m talking even about after that breakin.

If it made it through the first 20 minutes , idling it high probably won't hurt anything but IMO , is a waste of time .

 

[bcjjones]

I,m talking even about after that breakin.

I'm confused on your opinion on this. Once the cam is broken in, isn't it broken in? I mean plenty of flat tappet cam motors back in the day idled just fine. I mean, the truck will never sit an idle for hour or anything like that but it will occasionally see some "extended" 15 minute idle times while tuning on it.

 

[jayseasBlue56]

I'm confused on your opinion on this. Once the cam is broken in, isn't it broken in? I mean plenty of flat tappet cam motors back in the day idled just fine. I mean, the truck will never sit an idle for hour or anything like that but it will occasionally see some "extended" 15 minute idle times while tuning on it.

This isn't back in the day, just be leary of not to let it sit and idle for extend periods for no reason. Think back to back in the day, did they have you do a breakin of the eenginewhen you bought a new car? Flat tappet cams are days of old, quality isn't the same as back in the day. Just be aware of letting it sit and idle for no apparent reason.

 

[bcjjones]

This isn't back in the day, just be leary of not to let it sit and idle for extend periods for no reason. Think back to back in the day, did they have you do a breakin of the eenginewhen you bought a new car? Flat tappet cams are days of old, quality isn't the same as back in the day. Just be aware of letting it sit and idle for no apparent reason.

Yea, I guess I dont necessarily intend to. Curiosity, what to you is an extended amount of time? Additionally, I understand this isn't back in the day, but with proper zinc oils shouldn't it be the same scenario?

I'm asking for educational purposes. Maybe you know something I don't?

 

[johnsongrass1]

Over rated....with a quality cam core and quality lifters and quality oil, I've not had failures.
To me, extended idling is 30 minute longer than it takes to get too operating temp. If your still worried, put it on a high idle of around 1200.

 

[bcjjones]

Over rated....with a quality cam core and quality lifters and quality oil, I've not had failures.
To me, extended idling is 30 minute longer than it takes to get too operating temp. If your still worried, put it on a high idle of around 1200.

I agree. This is why I went with a factory GM cam and lifters over an off the shelf comp, lunati etc.

Curious on what oil you run? I used some Lucas 30 weight break in oil for the break in process. Now i'm running some "Hot Rod" 10w30 high zinc oil.

 

[johnsongrass1]

I'm contracted with Schaeffer's because I believe in it.
The 9001 would be good for you.

 

[BogiesAnnex1]

The high idle breakin run is to keep the cam wet with crank throw off oil while the lobes and lifters run in with each other. The valley being closed there is no other source of oil beyond what leaks around the lifters and out of the cam bearings. This is always an exacerbation when windage control is applied to the crankcase especially using a crank stripper to peel off oil riding up on the right side of the crankcase from crankshaft rotation as directions are designated from sitting in the cabin.

The Chevy suffers from a narrow lobe and small diameter lifters so the contact load between them per unit area is higher to start with. SBC lifter bore of .842; SBF of .876; SBChry .904. So you can see where a contributor to the problem exists.

Then figure that Ford and Chrysler use a thrust plate on the cam to control its longitudinal (thrust) movements where Chevy depends solely on the lobe taper angle and convex lifter face shapes that encourage lifter rotation on all flat tappet engines to also manage thrust moments.

Add into this the lifter to its bore is a tight clearance so it doesn’t take much wear in the bore to upset how the lifter addresses the cam lobe. This begs the question of guys rebuilding their engines if they even check this, my guess is zero to a very tiny number. Include that remachined blocks may overbore the lifter bores by .001 which if not checked is a third to half or more than the production clearance of lifter to bore. So essentially without purchasing oversized lifters you’re starting out with what acts like a worn out lifter bore. In normal use the lifter bore will wear egg shaped on the engine’s transverse (side to side) direction.

Some aside history. Ford originally built the FE without a thrust plate. They had cam and lifter failures in 58 so started using a thrust button late 58 replaced by 63 production when they went back to a thrust plate like the Y-blocks, these obviously were flat tappet cams. If you ever take an FE apart you should get the ghostly thought that this engine is highly influenced by the SBC as it would be designed to fit a Ford chassis and be built on slightly modified Lincoln Y block tooling with the heads paired middle exhausts that led to head cracking like everybody else. So Ford converted the center paired exhausts to intakes to remove that heat concentration In the middle of the head. Note how the SBF goes I-E, I-E, I-E, I-E where the FE goes E-I, E-I, I-E, I-E. Include in that thought where you ever saw another Ford V8 with a center main oil galley? Just my speculations!

Anyway back to SBC cam and lifter digestion, I made a habit of using a cam button on performance (street to racing) flat tappet builds so as to relieve the already hard working lifters from the task of restraining the cam. I can recall only having one SBC lobe lifter failure and that was a long time ago back in the late 80’s.

Bogie

 

[2001Blazer4x4]

Anyway back to SBC cam and lifter digestion, I made a habit of using a cam button on performance (street to racing) flat tappet builds so as to relieve the already hard working lifters from the task of restraining the cam. I can recall only having one SBC lobe lifter failure and that was a long time ago back in the late 80’s.

Bogie

I also used a nylon cam button on my flat tappet 383 build 3 camshafts ago and adjusted to 0.010 clearance (using dial indicator on back of cam gear through the hole in front china wall and by prying cam gently forward and back through a lifter valley hole). Seemed like a good thing to do! Never any cam/lifter problems.

 

[1979Malibu]

A button limiting fore and aft travel of the camshaft might help out the timing chain a bit, too. That kind of movement may hasten the chain stretching. I don't know where I heard that or how much it really helps, but it made enough sense to remember it.

The first engine I disassembled (350 SBC) had a flat tappet cam and a cam button. As luck would have it, the library book I was using (this was pre-internet) had an illustration of a cam button and spec for it. As far as I knew, that was standard operating procedure. The second engine (400 SBC) didn't have one and I thought someone left it out. It had one when I put it back together. At some point before the third time around, I learned about that button helping the lifters and knew that someone else must have known the same thing long before me. My modus operandi remains the same.