HI all, need some wisdom.

I have to replace my cam HFT. The cam specs work with the Alu heads I have, fitted with Hydraulic Flat Tappet hardware( see specs in pic). They are using a single spring (with dampener) with 120lb seat pressure. 1.250" OD and .510 lift max

My dilemma is that I need to reduce spring pressure for break in (after unsuccessful previous attempt not doing so). I have my old stock 882 heads, and wondering if I can use the springs etc from there for the break in. I am concerned about doing more harm than good so looking for feedback.

The 882 springs have the same 1.7" installed height but slightly smaller OD, I get 1.22" on calipers. I see that these just fit into the pockets on the stock head. Wondering if I put all the stock pieces on the alu heads if they will move about and cause damage. Looking at pics I had with the covers off there looks to be a base installed under the current spring that should prevent this.

The alternative I see, (but an expensive one for me being outside the US where money is worth half the US$ and freight is $$$), is to buy some new low pressure 1.250 OD springs just for breaking in that will hopefully be compatible with the retainers etc on the alu heads. I have found these ones at summit that seem to fit the bill

Chevrolet Performance 19154761 - Chevrolet Performance Valve Springs

My other issue though is that I have 1.6 roller rockers, and with this cam, the lift is right on the 0.510 max with the 1.6 ratio. So thinking to also use the 1.5 ratio stock stamped steel rockers for the break in. The cam lift at 1.5 is 0.477 / 0.480 so not sure if this will be too much lift for the stock gear also.

I see 1.3 ratio rockers are also suggested, but all getting a bit too much for my budget.

Would appreciate any thoughts / guidance you can give on this.

Cheers.

 

For break-in, I like used stock springs.
If your heads came complete and all set up (correctly), then you do not want to lose that.
1.3 ratio rockers are expensive but low-pressure break-in springs are cheaper. Either way, it's 1 time use.

BTW, the difference between 1.250" and 1.222" is.003". That is the thickness of 1 human hair.
So no difference to the retainer.

You might have another option - positive offset locks. These ADD to your installed height.
If your valve tips extend a sufficient amount above the top of the retainer, then this could be an easy (and cheap) way to reduce your spring pressure for break-in.
Look here: Locks, Keepers, Hardened 11/32" X 7 Degree, .050" Up Locks, Raises Retainer Higher, Sold in 1/2 Sets - Alex's Parts Sales (alexsparts.com)

When disassembling your heads, number and keep everything in order so that they go back together EXACTLY the way that they were set up.

OK, now search this site for HFT break-in tips.
This happened to me during the 20 minute break-in period. This is what I get for using "Guaranteed MADE IN USA" Skip White lifters!

 

I've heard gm has hardened seat lifters that work very well for flat tappet cams

 

Oh YES, the chilled iron base ones. I have never seen any of those wear.
The Skip White tappets were supposed to be those - they just come in plain white boxes.
NOT! The pushrod cup was not the proper dimensions (too thick) rendering the pumping mechanism inside USELESS.
Here is the thread: Mystery solved: why some hydraulic lifters do not deliver oil to the rockers at idle. - Third Generation F-Body Message Boards

 

I'd run a set of Hylift-Johnson lifters. Anything else is a gamble. And unless your springs are extremely stiff, you shouldn't need to run weaker springs for cam break-in. You didn't mention what the open spring pressure is. I've done only 3 flat-tappet cam break-ins, but with a 100% success rate. Spring pressure is 110 seat, and 285 open...

 

I believe that Johnson/HyLift is the only manufacturer left in the game.
That is from the original 4 manufacturers: EATON, JOHNSON, STANADYNE and G/M which is/was DELCO or DELPHI.

 

It certainly ruins your day. Mine is a comp xe268h, and #5 exhaust is the only one noticeable affected. (still in the car at the moment).

I think that there may be more than just the pressure. I used a standard oild mixed with a zinc additive rather than a dedicated break in oil due to lack of availability here. I have special ordered some Lucas Break in oil which is the only suitable one I could find.

I also didn't check pushrod rotation, so may have been a combination of factors.

..and being a first timer doesn't help.

Looking at springs it seem stock ones with 90lb seem to have 0.45 max lift. and the Z-28 ones with 0.50 lift is around 110 -115lb so really not much different....

The lifters were bundled with the cam.

 

Hi there, unfortunately Dart don't list that or the spring part number to research it. Will have to troll through the interweb....

 

I've found the spring specs quoted as below ( I am not up on imperial measurements since in a metric country);

• Hyd cam springs - 1.250 single, 110lbs closed, 280lbs open, max lift .510 in

I have been following up on the offset lock idea. and from comparative spring charts it looks like increasing from 1.700 to 1.750 would drop seat and open pressure by around 20lb which would seem to be ok. So the issue will be height of the valve tip above the retainer. Here is a shot of the valves before assembling the rest of the valvetrain, first time around. Could be a bit close? .05" is about 1.3mm by my reckoning.

 

[QUOTE=NoEmissions84TA;6481137]

BTW, the difference between 1.250" and 1.222" is.003". That is the thickness of 1 human hair.

The difference is .028 not .003.

 

"Break-in" oil is for the rings. It typically has no detergents in it. It doesn't really help with cam break-in. Comp Cams break-in oil is some of the worst oil you can buy, with 3,000 ppm of ZDDP added (you need about 1500). It is intended to be used for only 20 to 20 minutes and then changed. I use a normal oil with a ZDDP additive.
I used Valvoline conventional 5w-30 for my Ford, and Quaker State 5w-30 full synthetic for my Chevy. Both were successful...

 

[QUOTE=BBCSwap;6481166]You're right.
But as long as the retainer fits the spring, it can work.

 

It looks like there is sufficient valve tip sticking out of those blue locks for you to use the +.050" ones.
This assumes that your blue locks are ZERO (center).
And yes, that should drop your pressures by about 20 pounds, as you calculated.

 

Thanks all, will cross fingers dot eyes and cross tees, and pray to the god of speed. Cheers.

 

Old used stock sbc valve springs work great for ft cam break in. You want to install these at MAXIMUM possible installed height. No shims if possible. or a very thin shim.
1.75"++ installed height..
This time get a Isky Cams #201274 Isky Mega Cam 274H.
Its 274/274 226/226 .490" .490" 108 LSA
With all the Isky cams you want to degree it in to give it correct cam advance. 108LSA. 104 in/112ex.
So 4 degrees advanced.. You may or may not need to move the cam to get this but you must check the installed cam phasing.

The GM OEM sellite foot hyd lifters are great.
These GM lifter have a hard steel foot.
I believe you can still buy these from GM dealers parts counter. May be Delco or Delphi branded.
The best aftermarket lifters are the Johnson Hi-Lift.

If your lifters were cheap they are not genuine Johnson Hi-Lift. as their pricing is up near double other flat tappet lifters now.
I use Shell Rotella T 15w-40 with GM EOS added.
Then I add Moly-Slip E OIL supplement to the Rotella T oil for flat tappet cam wear protection.
Its main anti wear additive is Moly but it also has a bit of Zinc in it too.
www.molyslip.com

That Isky 274H Mega cam will haul ***.
call Isky cams for advice . its free to ask.

When the cam is broke in replace your springs and shim to correct height.
And add the Moly Slip E
I use ½ the can of Moly Slip. so 1 can lasts you 2 oil changes.. It works.