The Ford Barn

khschs · 10-19-2015, 04:44 PM

I just fired up my 276" blower motor and it ran great, for about 20 minutes. Lost power,shut it down, cam flat.
Need a recommendation for a cam for 276" blower motor that will be used primarily on the street. The car is a 32 cabriolet with a C4 and a 8" ford differential with 3.00-1 gears and 31" tires.
The cam must have good road manners as the wife will be driving it from time to time.
Thanks Keith

deuce_roadster · 10-19-2015, 04:55 PM

Wow, did you have brake in lube on the lobes and lifters? What brand cam was that?
Most blower cams are not that wild because the blower forces fuel/air into the chamber, and flatheads don't like overlap anyway.

PeterC · 10-19-2015, 05:01 PM

You will get many opinions from many sources - I happen to like my Schneider 270F bcam which is employed in my 284ci S.C.o.T blown flathead - has a strong flat power band that pulls better and better as my rpm increases. I did not prioritize a rumpy idle - I prioritized pure performance 270 gross duration 230 at .050 with 365 lift. I encourage you to call Schneider and discuss your exact engine specs and power needs.

Jason in TX · 10-19-2015, 05:21 PM

I'm also running the 270F but with 114 lobe seperating for the blower. They did a custom grind for me. I would recommend and use them again!

hopefully you used the ZDDP in your oil. I added an extra bottle to my first break in.

Ol' Ron · 10-19-2015, 05:55 PM

Sound like allot of spring pressure.

khschs · 10-19-2015, 06:31 PM

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I used ZDDP paste on the cam and lifters and added 2 bottles of liquid ZDDP to the oil. The valve springs are Reds LZ on Chevy 1.6 ss valves with one 0.035" shim.
Keith

Walt Dupont--Me. · 10-19-2015, 06:43 PM

That .035 shim don't tell us what your installed spring pressure is, valve length, keeper grooves, all make a difference, if you wiped a cam out in short time sounds like a lot of pressure. Walt

khschs · 10-19-2015, 07:06 PM

When I put the valve assembly together along time ago I used a valve spring tester at the machine shop. The installed height was 2.120. I don't remember the pressure. The valves are Chevy 1.6 single groove stock keepers
Keith

Walt Dupont--Me. · 10-19-2015, 07:19 PM

Quote:

Originally Posted by khschs

When I put the valve assembly together along time ago I used a valve spring tester at the machine shop. The installed height was 2.120. I don't remember the pressure. The valves are Chevy 1.6 single groove stock keepers
Keith

I don't any Red's LZ springs in my shop right now or I would check pressure at 2.120--- may be someone here on the Barn has and can check pressure. Walt

Deuce Man · 10-19-2015, 08:18 PM

I hope you are going to do a little more than change the cam? Rich

khschs · 10-19-2015, 08:38 PM

Yep, the plan is to completely disassemble the engine clean, inspect and reassemble. Will still need a new cam. Sure hope I find something obvious.
Keith

flatjack9 · 10-19-2015, 08:53 PM

Too much ZDDP can cause big problems. Those LZ springs shouldn't have much more than 50 lb on the seat.

Ol' Ron · 10-19-2015, 10:27 PM

Find someone that knows how to measure installed height, then have the springs tested at that length. On a stock valve assy, a.060" shim will usually do it to a stock spring.

Bored&Stroked · 10-20-2015, 09:02 AM

Quote:

Originally Posted by khschs

I just fired up my 276" blower motor and it ran great, for about 20 minutes. Lost power,shut it down, cam flat.
Need a recommendation for a cam for 276" blower motor that will be used primarily on the street. The car is a 32 cabriolet with a C4 and a 8" ford differential with 3.00-1 gears and 31" tires.
The cam must have good road manners as the wife will be driving it from time to time.
Thanks Keith

Did you run it at a higher RPM for the break-in period? Hopefully you didn't let it idle.

JSeery · 10-20-2015, 09:19 AM

Quote:

Originally Posted by Bored&Stroked

Did you run it at a higher RPM for the break-in period? Hopefully you didn't let it idle.

That was my thought as well! You see all these videos of people firing up engines (new rebuilds) and having them idle for extended periods of time. Bad idea, very bad idea.

Deuce Man · 10-20-2015, 09:31 AM

What kind of cam was it? Maybe a factory screwup? Just wonderin. Rich

khschs · 10-20-2015, 09:59 AM

I haven't found the cause of the failure yet so I don't think it would be fair to start nameing names until I'm sure of the cause.
Keith

GOSFAST · 10-20-2015, 10:14 AM

Quote:

Originally Posted by khschs

I haven't found the cause of the failure yet so I don't think it would be fair to start nameing names until I'm sure of the cause.
Keith

Hi Keith, you should always try to use the older "Moly" lube on the lobes and lifter bottoms. It's getting tougher to find, we're fortunate enough to have an ample supply on hand at all times. We actually supply it to other local shops.

Having said that, you MUST know the accurate spring pressure's you have, both closed and open. You also need to follow the "old-school" rule about keeping the RPM's around 1500/2000 for the first 15/20 minutes!

Thanks, Gary in N.Y.

P.S. General "rule-of-thumb" with blown units, you need a "few" extra pounds spring pressure on the intake valves. Doesn't hurt on the exhaust's either but the intakes "feel" the add'l blower pressure on the backside of the valves.

JSeery · 10-20-2015, 10:15 AM

One of the big questions is how was the cam break-in performed? Almost any idling with high spring pressure can spell the death of a cam in short order.

And I don't like to keep the RPMs constant, I adjust it up and down every few minutes.

khschs · 10-20-2015, 10:31 AM

Re: break in,
Started engine,checked timing at 700 rpm and then moved it up to 1200 rpm. I changed engine speed from time to time never going over 1500 rpm and never letting it idle very long. The engine temp ran 185+- oil pressure never below 50 psi. The plan was to run it for 20 minutes, shut it down, drain the oil and change the filter. I almost made it.
Keith

JSeery · 10-20-2015, 10:56 AM

A little low on the RPMs for me, but shouldn't have been that bad. Time spent setting the timing could be the culprit, the first few minuites are the most critical. I get the timing close enough to get them started, keep the RPMs up, varying it around for 15-20 min, then check the timing.

Binx · 10-20-2015, 08:56 PM

Look through this thread. Good oil pressure indicated but previously modified oil passage causing starvation.

http://www.fordbarn.com/forum/showthread.php?t=38439

Lonnie

Blownflatheaddeuce · 10-21-2015, 06:09 AM

I agree the rpm during break in is a little - you need splash lubrication that a higher rpm will provide. Always worry about "idea" timing later in the piece; the goal is to get the rpm up pronto and get oiling to the parts that are breaking in asap.

I have broken in both milder, "mid" range and "big" cams in FHs in both /NA and blower engines, always at 2K rpm and varying from 1800 - 2200 to mix it up/vary the break in on the cam/lifters.

Never had an issue - perhaps the diff in rpm made all the difference?

BFD

Bored&Stroked · 10-21-2015, 08:16 AM

Quote:

Originally Posted by khschs

Re: break in,
Started engine,checked timing at 700 rpm and then moved it up to 1200 rpm. I changed engine speed from time to time never going over 1500 rpm and never letting it idle very long. The engine temp ran 185+- oil pressure never below 50 psi. The plan was to run it for 20 minutes, shut it down, drain the oil and change the filter. I almost made it.
Keith

The problem may have been caused by not having enough RPM during the break in period - as others noted, I try to stay between 1500 and 2000 and move the speed around a lot. You need a lot of oil splashing on the cam to get it and the lifters broken in. If it starts to gall, things go bad very fast!

hotrodcbx · 10-21-2015, 02:33 PM

My '34 coupe has a 296" 3/4 Potvin cam with SS Chev valves. I am running a B&M 144 blower at 5psi. MSD ignition with boost retard. This engine was built by Mark at Motor City Flathead in 1998. It now has 25,000 miles with no problems. This engine pulls like a freight train and I run it regular to 6000 rpm. Mark Kirby did a lot of research and came up with the Potvin, I believe Flathead Jack carries these cams..

10-19-2015, 04:44 PM	#1
khschs Member Join Date: Mar 2012 Posts: 70	blower motor cam recommendation I just fired up my 276" blower motor and it ran great, for about 20 minutes. Lost power,shut it down, cam flat. Need a recommendation for a cam for 276" blower motor that will be used primarily on the street. The car is a 32 cabriolet with a C4 and a 8" ford differential with 3.00-1 gears and 31" tires. The cam must have good road manners as the wife will be driving it from time to time. Thanks Keith

10-19-2015, 04:55 PM	#2
deuce_roadster Senior Member Join Date: Oct 2011 Location: Shelton, WA Posts: 3,799	Re: blower motor cam recommendation Wow, did you have brake in lube on the lobes and lifters? What brand cam was that? Most blower cams are not that wild because the blower forces fuel/air into the chamber, and flatheads don't like overlap anyway.

10-19-2015, 05:01 PM	#3
PeterC Senior Member Join Date: May 2010 Location: Connecticut Posts: 855	Re: blower motor cam recommendation You will get many opinions from many sources - I happen to like my Schneider 270F bcam which is employed in my 284ci S.C.o.T blown flathead - has a strong flat power band that pulls better and better as my rpm increases. I did not prioritize a rumpy idle - I prioritized pure performance 270 gross duration 230 at .050 with 365 lift. I encourage you to call Schneider and discuss your exact engine specs and power needs.

10-19-2015, 05:21 PM	#4
Jason in TX Senior Member Join Date: May 2010 Location: ⓉⒺXⒶⓈ Posts: 2,047	Re: blower motor cam recommendation I'm also running the 270F but with 114 lobe seperating for the blower. They did a custom grind for me. I would recommend and use them again! hopefully you used the ZDDP in your oil. I added an extra bottle to my first break in. __________________ -------------- Drive it like you know how to fix it! DMAFC / OILERS CC-MC

10-19-2015, 05:55 PM	#5
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,857	Re: blower motor cam recommendation Sound like allot of spring pressure.

10-19-2015, 06:31 PM	#6
khschs Member Join Date: Mar 2012 Posts: 70	Re: blower motor cam recommendation Sponsored Links (Register now to hide all advertisements) I used ZDDP paste on the cam and lifters and added 2 bottles of liquid ZDDP to the oil. The valve springs are Reds LZ on Chevy 1.6 ss valves with one 0.035" shim. Keith

10-19-2015, 06:43 PM	#7
Walt Dupont--Me. Senior Member Join Date: May 2010 Location: Gardiner Me. Posts: 4,200	Re: blower motor cam recommendation That .035 shim don't tell us what your installed spring pressure is, valve length, keeper grooves, all make a difference, if you wiped a cam out in short time sounds like a lot of pressure. Walt

10-19-2015, 07:06 PM	#8
khschs Member Join Date: Mar 2012 Posts: 70	Re: blower motor cam recommendation When I put the valve assembly together along time ago I used a valve spring tester at the machine shop. The installed height was 2.120. I don't remember the pressure. The valves are Chevy 1.6 single groove stock keepers Keith

10-19-2015, 08:18 PM	#10
Deuce Man Senior Member Join Date: Jul 2010 Location: Palm City FL> Posts: 556	Re: blower motor cam recommendation I hope you are going to do a little more than change the cam? Rich

10-19-2015, 08:38 PM	#11
khschs Member Join Date: Mar 2012 Posts: 70	Re: blower motor cam recommendation Yep, the plan is to completely disassemble the engine clean, inspect and reassemble. Will still need a new cam. Sure hope I find something obvious. Keith

10-19-2015, 08:53 PM	#12
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: blower motor cam recommendation Too much ZDDP can cause big problems. Those LZ springs shouldn't have much more than 50 lb on the seat.

10-19-2015, 10:27 PM	#13
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,857	Re: blower motor cam recommendation Find someone that knows how to measure installed height, then have the springs tested at that length. On a stock valve assy, a.060" shim will usually do it to a stock spring.

10-20-2015, 09:31 AM	#16
Deuce Man Senior Member Join Date: Jul 2010 Location: Palm City FL> Posts: 556	Re: blower motor cam recommendation What kind of cam was it? Maybe a factory screwup? Just wonderin. Rich

10-20-2015, 09:59 AM	#17
khschs Member Join Date: Mar 2012 Posts: 70	Re: blower motor cam recommendation I haven't found the cause of the failure yet so I don't think it would be fair to start nameing names until I'm sure of the cause. Keith

10-20-2015, 10:15 AM	#19
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: blower motor cam recommendation One of the big questions is how was the cam break-in performed? Almost any idling with high spring pressure can spell the death of a cam in short order. And I don't like to keep the RPMs constant, I adjust it up and down every few minutes.

10-20-2015, 10:31 AM	#20
khschs Member Join Date: Mar 2012 Posts: 70	Re: blower motor cam recommendation Re: break in, Started engine,checked timing at 700 rpm and then moved it up to 1200 rpm. I changed engine speed from time to time never going over 1500 rpm and never letting it idle very long. The engine temp ran 185+- oil pressure never below 50 psi. The plan was to run it for 20 minutes, shut it down, drain the oil and change the filter. I almost made it. Keith

10-20-2015, 10:56 AM	#21
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: blower motor cam recommendation A little low on the RPMs for me, but shouldn't have been that bad. Time spent setting the timing could be the culprit, the first few minuites are the most critical. I get the timing close enough to get them started, keep the RPMs up, varying it around for 15-20 min, then check the timing. Last edited by JSeery; 10-20-2015 at 11:35 AM.

10-20-2015, 08:56 PM	#22
Binx Senior Member Join Date: Oct 2011 Location: Gloucester VA Posts: 1,042	Re: blower motor cam recommendation Look through this thread. Good oil pressure indicated but previously modified oil passage causing starvation. http://www.fordbarn.com/forum/showthread.php?t=38439 Lonnie

10-21-2015, 06:09 AM	#23
Blownflatheaddeuce Senior Member Join Date: May 2010 Location: Deep DEEP South Posts: 223	Re: blower motor cam recommendation I agree the rpm during break in is a little - you need splash lubrication that a higher rpm will provide. Always worry about "idea" timing later in the piece; the goal is to get the rpm up pronto and get oiling to the parts that are breaking in asap. I have broken in both milder, "mid" range and "big" cams in FHs in both /NA and blower engines, always at 2K rpm and varying from 1800 - 2200 to mix it up/vary the break in on the cam/lifters. Never had an issue - perhaps the diff in rpm made all the difference? BFD

10-21-2015, 02:33 PM	#25
hotrodcbx Senior Member Join Date: Jul 2010 Posts: 136	Re: blower motor cam recommendation My '34 coupe has a 296" 3/4 Potvin cam with SS Chev valves. I am running a B&M 144 blower at 5psi. MSD ignition with boost retard. This engine was built by Mark at Motor City Flathead in 1998. It now has 25,000 miles with no problems. This engine pulls like a freight train and I run it regular to 6000 rpm. Mark Kirby did a lot of research and came up with the Potvin, I believe Flathead Jack carries these cams..