Flat tappet questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

03BlkZ · 09-25-2020, 07:12 PM

Hello, as my build gets closer to completion I have been doing a ton of research. I have never personally owned a vehicle with a carb so a lot is new to me. My main concern is how critical is it to break the cam in on the first run. Reason I ask is because I have never had an engine built before and have never timed one or set up a carburetor. I am seeing where people are saying its absolutely critical to run the engine immediately to 2000 rpm for 30 minutes to properly break in the flat tappet cam. I'm just hoping I can get the engine running properly quick enough to do the break in run. Thoughts?

garyd1961 · 09-25-2020, 07:38 PM

The motor doesn't have to be running perfect as long as you have good oil pressure, it's not over heating, nothing is leaking, and it isn't making any funny noises you should be ok. If you have to just shut it off and fix whatever needs fixing then start it right back up.

geezer#99 · 09-25-2020, 07:51 PM

What carb and what distributor are you using?

If you do a few prep things it should fire right off.

03BlkZ · 09-25-2020, 07:59 PM

Quote:

Originally Posted by geezer#99

What carb and what distributor are you using?

If you do a few prep things it should fire right off.

Those are items that I have not yet decided on. I should be picking up the engine next week from my builder and I plan to discuss those items with him for his recommendation. Its just a 350. It had to be bored to .060 because of broken rings scarred the cylinders. It is going to have a mild cam but nothing too high performance.

**jayoldschool** · 09-25-2020, 08:03 PM

If you haven't purchased parts... buy a roller cam and lifters. If the cam is in, use a proper high ZDDP break in oil (or additive like Lucas break in) and do it properly with time and RPM.

03BlkZ · 09-25-2020, 08:14 PM

Quote:

Originally Posted by jayoldschool

If you haven't purchased parts... buy a roller cam and lifters. If the cam is in, use a proper high ZDDP break in oil (or additive like Lucas break in) and do it properly with time and RPM.

Cam is already in. I have been reading about the importance of Zinc. Thanks

geezer#99 · 09-25-2020, 10:18 PM

Carb choices are quadrajet, Holley or Edelbrock.
Quadrajet. Not new anymore but some excellent rebuilds out there.
This would be my choice.
Bolts on to spreadbore intake.

https://www.smicarburetor.com/produc...2/productID/18

Holley. Bolts on to square bore intake. Easily fine tuned.

https://www.summitracing.com/parts/h...saAt_1EALw_wcB

Edelbrock 600 cfm. New, shiny but needs add ones which add to price. Like heat spacer, fuel regulator or lower rated fuel pump, fuel line, linkage to fit.

https://www.summitracing.com/parts/e...kaAvdhEALw_wcB

Quadrajet is the easiest to fill the fuel bowl for instant start.

As for distributor just pic one of the many hei’ s available.

**HO455** · 09-27-2020, 04:25 PM

To answer your question. Yes it is very critical to break in the cam properly. Talking to your engine builder like you said should answer all of your questions. You might be more comfortable with having him do the break in.
As mentioned priming the carburetor to get it to fire the engine quickly is important. To get the distributor close set the timing marks on the balancer to 8 degrees on the firing stroke. Then pull #1 spark plug and ground it. With the distributor hold down bolt loose connect the power to the distributor. Now you will be able to turn the distributor back and forth and make the spark plug spark. After getting the distributor position as close as possible to the point when the plug sparks, snug the hold down bolt up and your timing will be set close enough to get the engine fired and the break in done.
Have a water hose handy to help keep the engine cool if the weather is warm. It is not uncommon for an engine to run warm during break in. Just keep it below 230 degrees.

burnin oil · 09-28-2020, 08:18 AM

Not mentioned but you can adjust the timing some more after its running. I start it and raise the idle with the idle screw to get it over 2k RPMs. Then i give it a quick check for leaks. After that I reset the timing to 36 degrees for the remainder of the break in. 36 is about the magic number for a SBC with all the advance brought in so that wont hurt it. After run in drop the idle and reset the timing to proper specs.

09-25-2020, 07:38 PM	#2
garyd1961 Registered User Join Date: May 2016 Location: Henderson NC Posts: 975	Re: Flat tappet questions The motor doesn't have to be running perfect as long as you have good oil pressure, it's not over heating, nothing is leaking, and it isn't making any funny noises you should be ok. If you have to just shut it off and fix whatever needs fixing then start it right back up.

09-25-2020, 07:51 PM	#3
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,510	Re: Flat tappet questions What carb and what distributor are you using? If you do a few prep things it should fire right off.

09-25-2020, 08:03 PM	#5
jayoldschool Moderator Join Date: Dec 2012 Location: ON, Canada Posts: 2,150	Re: Flat tappet questions If you haven't purchased parts... buy a roller cam and lifters. If the cam is in, use a proper high ZDDP break in oil (or additive like Lucas break in) and do it properly with time and RPM.

09-25-2020, 10:18 PM	#7
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,510	Re: Flat tappet questions Carb choices are quadrajet, Holley or Edelbrock. Quadrajet. Not new anymore but some excellent rebuilds out there. This would be my choice. Bolts on to spreadbore intake. https://www.smicarburetor.com/produc...2/productID/18 Holley. Bolts on to square bore intake. Easily fine tuned. https://www.summitracing.com/parts/h...saAt_1EALw_wcB Edelbrock 600 cfm. New, shiny but needs add ones which add to price. Like heat spacer, fuel regulator or lower rated fuel pump, fuel line, linkage to fit. https://www.summitracing.com/parts/e...kaAvdhEALw_wcB Quadrajet is the easiest to fill the fuel bowl for instant start. As for distributor just pic one of the many hei’ s available.

09-27-2020, 04:25 PM	#8
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 10,786	Re: Flat tappet questions To answer your question. Yes it is very critical to break in the cam properly. Talking to your engine builder like you said should answer all of your questions. You might be more comfortable with having him do the break in. As mentioned priming the carburetor to get it to fire the engine quickly is important. To get the distributor close set the timing marks on the balancer to 8 degrees on the firing stroke. Then pull #1 spark plug and ground it. With the distributor hold down bolt loose connect the power to the distributor. Now you will be able to turn the distributor back and forth and make the spark plug spark. After getting the distributor position as close as possible to the point when the plug sparks, snug the hold down bolt up and your timing will be set close enough to get the engine fired and the break in done. Have a water hose handy to help keep the engine cool if the weather is warm. It is not uncommon for an engine to run warm during break in. Just keep it below 230 degrees. __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

09-25-2020, 07:12 PM	#1
03BlkZ Registered User Join Date: Nov 2015 Location: Hewitt, Tx Posts: 386	Flat tappet questions Hello, as my build gets closer to completion I have been doing a ton of research. I have never personally owned a vehicle with a carb so a lot is new to me. My main concern is how critical is it to break the cam in on the first run. Reason I ask is because I have never had an engine built before and have never timed one or set up a carburetor. I am seeing where people are saying its absolutely critical to run the engine immediately to 2000 rpm for 30 minutes to properly break in the flat tappet cam. I'm just hoping I can get the engine running properly quick enough to do the break in run. Thoughts?

09-28-2020, 08:18 AM	#9
burnin oil Registered User Join Date: Jan 2013 Location: Eastern TN Posts: 1,919	Re: Flat tappet questions Not mentioned but you can adjust the timing some more after its running. I start it and raise the idle with the idle screw to get it over 2k RPMs. Then i give it a quick check for leaks. After that I reset the timing to 36 degrees for the remainder of the break in. 36 is about the magic number for a SBC with all the advance brought in so that wont hurt it. After run in drop the idle and reset the timing to proper specs.



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