Thread: Piston to valve clearance

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I have asked this question before, and got one answer, but I want to ask it again, now that I know a little more about what I am asking about. I have a '79 casting 460 block out of a truck, am bolting up some '73 linc. casting heads that have been fitted with crane cams springs and retainers. I have been unable to find any numbers on the springs. The crank is stock, and so are the rods, but I have fitted aftermarket Speed Pro flat crown pistons onto them. My question is, with a rocker ratio of 1.73, what would be my safe lift on a cam? I really don't want to smash valves, after I have put so much into this engine. I have been told that anything around .500 lift would be safe. I see that there are some seriously wicked cams available, with massive lift. and I know lift is where your power comes from. I am looking at a .485 intake, .504 exhaust cam, will this cause a problem, or is this going to be mild enough? I wish I knew more about what I could run safely, any help would be great.

http://www.fordmuscle.com/fundamenta...ve/index.shtml

i know i ran 501" in. 533 ex. against a set of bone stock heads for a while. i would assume you would be fine with your selection with your mods. also the stock bottom ends are a lot stronger than i ever gave them credit for with 8 ton of block on a trailer behind me a couple wild downshifts i saw 8000 rpm before i heard the pop. crank is still good rods are fine but the valve train didn't survive. well good luck and beyond all don't get mad cause ya didn't win be happy cause you were able to try

Thanks Chappy, that is the best answer I have gotten to date. Sorry to hear about the snap at 8000 RPM, but just think, atleast you have something to work on now. ;-)

I didn't get to finish my answer because my computer locked up and I had to re-boot.

I agree with chappy and will go so far as to say you'd probably be fine up to 0.550" or maybe a little more, but you cannot be certain until you check every valve yourself.

Nobody can answer your question without detailed info, there are just too many variables, such as.....

Have the decks been indexed off the main saddles and equalized?
What is the deck height?
Is the cam bore parallel with the main saddles?
Have all the rods been equalized center-center?
Is the compression height (pin centerline to crown) the same on all the pistons?
What is the deck (piston crown to deck)? Is it the same on all holes?
What is the ACTUAL ratio of ALL rockers? (not the theoretical ratio)
Are all the valve seats parallel with the crank centerline? Are they deeper in the heads due to a valve job?
Have the heads ever been cut?
Are all valve lengths equalized?

and on and on.....

Check all valves with the one of the methods outlined in the link I gave you. At the very minimum, check the valves on each of the four corners of the motor.

I can only answer a couple of those. The valves have been done, that I know, a 3 degree cut was done on them. As far as the resurface on the heads, it is hard to tell, the guy I bought them from was unsure. I would guess they probably have been, how much, unknown. From what your saying, I should be safe with the cam I am thinking about getting, I had planned to run the clay test when I got it installed to be safe. I have read that artical before, but wanted a good baseline to start from. knowing that I have quite alot of leeway under .500 lift, I think I will be safe. Thanks alot. All your answers have been helpful.

i just reread your article you are building a 460 not a fe. so if i presume right by the years you are speaking of you are using a D9TE block and wanting to bolt a set of D1VE heads to it.i would assume once again that you have two valve reliefs? i will still say that you will have no problems but the 429-460 stock rods leave a little bit to be desired. also flattops and D1VE heads are a no no for pump gas to use the D1's you will need at least an 18 cc dish to get ya pump gas worthy although the D3VE heads would be almost perfect with your flattops there is a guy on this site you can find him on the 429-460 part address paul kane about the D3's i believe that is what he runs on his boat. also your 460 is not a fe that is where i goofed up earlier it is a 385 series. but anyway get ahold of paul kane he can hook ya up with a set of heads and if ya plan to turn this thing very hard ya might want to ask him about his oiling mods he will give ya the exact info you are looking for.

Actually, the heads I am running are 1973 linoln heads casting D3VE, I knew better than use D1VE heads, I had read articles about not using them. The heads I plan to run have had the exhaust bumps removed, as to allow better flow .Thanks for the reread, your info was great, and makes me feel alot more comfortable. I will however look up Paul Kane.
And yes, the pistons have a decent looking relief in them and the block is a D9TE. I plan to upgrade the rods when money allows, but they tend to be expensive, even on Ebay. I am not looking to race this engine, and I will be taking it easy on it until I can get new rods installed. Thanks again!

Those are 91 cc heads and I think I read that the valve seats are moved higher in the chamber than earlier heads, so piston to valve clearance shouldn't be a problem.

I keep feeling better about this every post you two leave. Thanks for the piece of mind.

seeing as this is not a race engine your rods should well withstand anything you can throw at them on th street i am used to everyone speaking of performance engines so you should be good to go. stock bottom ends have been known to turn up to a rough 6500 rpm with proper tuning. i kinda grit my teeth when i hear that. the exhaust bumps were only part of the equation to the heads but i'm not positive of what all needs done, this is why i send mine to be done by someone else, this is why i tell you to get in touch with guys such as paul. i'll share what i know and when i don't i'll steer ya toward someone who does. these guys are great they've helped me out greatly and it is a honor to give something back

I actually have been PMing Paul Kane all week. He has assured me I will be fine with my bottom end and the heads. I just can't use roller rockers without machining, which I can not get done here. I bought my cam, am installing it tomorrow. Thanks for all the advice, you all have been great. I will keep you posted, and have some pics to post when it is finnally all together.