Closed chamber heads straight swap from open?

[Mister 4x4]

Insurance policies are there to compensate for the unforeseeable 'worst' happening.

New studs/bolts: always a good idea, especially if you don't know what the engine's been through. I went with new head bolts because my engine was seized and sat for 30 years before I tore it apart. Yeah... I wasn't going to use the factory bolts after that.

Hardened Valve Seats: Modern cars have hardened valve seats to deal with long-term wear conditions with ever increasing poor fuel quality. The old gas had lead to help preserve the valve seal as the old, soft heads wore out. No more lead, maybe gotta do something. Run 'em with, or without is a choice. I choose to go with the 'insurance' of running them.

Performance products in general: No, the majority of us won't be racing anything... but where's the fun in putting things back together just as they came apart? Personally, I enjoy making things work better, so I built my engine with what I feel is the best combination of performance goodies I could afford. I don't have the luxury of simply parking and grabbing another Mustang when something goes wrong - the majority of us don't. So, I like the idea of knowing that maybe my stuff will hold together a little better than the 45-year-old factory stuff you can no longer get affordably (repop doesn't count, since it's different because of modern materials).

No Homeowner's Insurance? Wow - good luck with that. I hope nobody ever needs it, but I know when some freak hail storms damaged 2 cars, totaled another, destroyed my skylights, roof, and fence, I was happy to get a check for almost $30K to get everything back to normal. That check was almost double what I'd paid my insurance company in payments to date.

 

[Jeff73Mach1]

I would never run old ford valves-the result of a failure is generally a destroyed engine.

I don't think hardened seats are worth the money- It is also a risk when installing seats that you will cut into a cooling passage. A bit of additive every few tanks and limiting usage to 5000 miles a year will likely keep them in good shape for a long time.

I wouldn't trust the undersized rocker arm studs if you use anything more than a factory lift cam.

they should bolt on without a problem, but I would check valve to piston clearance anyway, it is not difficult with a bit of modeling clay and is just a good practice

Cleveland head bolts are pretty hefty, reusing them is unlikely to be a cause for concern unless there is some type of damage to the threads.

the bump in compression will be worth a few horsepower, but real improvements can be made by upgrading the camshaft which is easier while the heads are off. . . .

 

[83slimer]

I have the stud kit already as my pic shows , they were 2 different sizes so no machining was needed on my open chamber 4v heads . It's a straight swap to the CC heads but the rocker Arms from harland sharp stated not to be used over 300hp if I can remember right.

Should I check valve clearance when I put the CC heads on? In pretty sure I have flat top pistons so be running 11 to 1 with a very mild cam was the performer rpm from edelbrock.

 

[Stanglover]

I have the stud kit already as my pic shows , they were 2 different sizes so no machining was needed on my open chamber 4v heads . It's a straight swap to the CC heads but the rocker Arms from harland sharp stated not to be used over 300hp if I can remember right.

Should I check valve clearance when I put the CC heads on? In pretty sure I have flat top pistons so be running 11 to 1 with a very mild cam was the performer rpm from edelbrock.

Hmmmm! Interesting. As a former machinist, I personally would not use a top heavy set-up like those studs, but then that's just me.

If it works for others, it should work for you. Be sure to let us know how it goes.

 

[turtle5353]

Here's a link to the kit. https://www.summitracing.com/parts/crn-52655-16

 

[83slimer]

Here's a link to the kit. https://m.summitracing.com/parts/crn-52655-16

Thats the one I used on my open chamber heads. Easy to install and held up so far, all the reviews are good on summit, but it does say for only mild performance engines so they must have a limit they can handle.

 

[turtle5353]

Yeah they definitely have their limit. you run some crazy cam and high spring pressure I could see the threads pulling right out. The stock threads are pretty small.

 

[Stanglover]

Here's a link to the kit. https://m.summitracing.com/parts/crn-52655-16

The link wouldn't open completely for me. I used my saved link to Summit racing and entered crn-52655-16. I see you entered m.summitracing..... I don't think the 'm' should be there. Sorry to be critical.

As for the conversion kit, it does look interesting and offers the advantage of roller rockers without the expense for an otherwise stock build. After all in that context, it is no worse than a stock fulcrum rocker set-up. It does say for a mild build only.

Like I said before, "I learn every day". This offers me another option if I ever rebuild all my spare engine parts into a running engine.

As for checking valve clearance, yes, but I don't think it would be a problem unless your pistons have a higher compression height (taller) than stock. My KB148's dish top are .020" taller than stock, but still clear okay at zero deck. Never hurts to check everything.

EDIT: Should have added that clearance also depends on cam lift and rocker ratio if I'm not mistaken.

 

[turtle5353]

Here's a link to the kit. https://m.summitracing.com/parts/crn-52655-16

The link wouldn't open completely for me. I used my saved link to Summit racing and entered crn-52655-16. I see you entered m.summitracing..... I don't think the 'm' should be there. Sorry to be critical.

As for the conversion kit, it does look interesting and offers the advantage of roller rockers without the expense for an otherwise stock build. After all in that context, it is no worse than a stock fulcrum rocker set-up. It does say for a mild build only.

Like I said before, "I learn every day". This offers me another option if I ever rebuild all my spare engine parts into a running engine.

As for checking valve clearance, yes, but I don't think it would be a problem unless your pistons have a higher compression height (taller) than stock. My KB148's dish top are .020" taller than stock, but still clear okay at zero deck. Never hurts to check everything.

Ooops. Sorry about that. I posted that from my phone and I think the M is for mobile. I fixed it up top if anyone else wants to look at it.

 

[barnett468]

ok, to get the optimum benefit from closed chamber heads, you should set your quench/squish clearance between .034" and .043" . it can be checked by simply determining exactly hw car down below the deck the pistons are at tdc . cometic makes head gaskets that are thinner than stock if you need one.

 

[83slimer]

ok, to get the optimum benefit from closed chamber heads, you should set your quench/squish clearance between .034" and .043" . it can be checked by simply determining exactly hw car down below the deck the pistons are at tdc . cometic makes head gaskets that are thinner than stock if you need one.

ok so put # 1 at tdc and measure to deck height, without head gasket ? then should be between .034 and .043?

 

[barnett468]

ok, to get the optimum benefit from closed chamber heads, you should set your quench/squish clearance between .034" and .043" . it can be checked by simply determining exactly hw car down below the deck the pistons are at tdc . cometic makes head gaskets that are thinner than stock if you need one.

ok so put # 1 at tdc and measure to deck height, without head gasket ? then should be between .034 and .043?

yes

 

[c9zx]

You do not want the piston .030-.040 down the bore. You want the piston .000-.005 down the bore. The squish is then the compressed thickness of the head gasket, about .040, plus the .000-.005 that the piston is down the bore at TDC. Chuck

 

[73pony]

Does anyone know the stock piston to deck height on a '73 H-Code?

 

[barnett468]

ummm, yeah, i forgot to clarify that you add the distance of the piston in the hole to the thickness of the gasket and that number is the clearance.

Factory piston depth on a non boss351 can be around .020".

 

[Stanglover]

Does anyone know the stock piston to deck height on a '73 H-Code?

You'll need to look up the compression height of the factory piston. I cannot say for sure what the 73 2 V is, but the factory compression height for my 71 4v flat tops is 1.65" ( center of the wrist pin to top of piston) With standard numbers added up, that gave a measurement of .028" deck height. In my case, using KB pistons, the comp ht is 1.67" and with decking, my deck height is zero". The gasket compressed height is about .040" my builder tells me that is the "squish" height if you like.

I'll look to see if I can find that comp ht number and edit this.

Edit: I was not able to find the numbers and time is short right now, but it looks like the 73 had dish top pistons as those engines were only about 8:1. I would think that the comp ht. was the same, but ????

Below is the numbers from KB (UEM Pistons) with respect to the 71 4V with .030" overbore.

 

[Stanglover]

ummm, yeah, i forgot to clarify that you add the distance of the piston in the hole to the thickness of the gasket and that number is the clearance.

Factory piston depth on a non boss351 can be around .020".

Hey Barnett, good to hear from you again, it's been awhile.

 

[barnett468]

ummm, yeah, i forgot to clarify that you add the distance of the piston in the hole to the thickness of the gasket and that number is the clearance.

Factory piston depth on a non boss351 can be around .020".

Hey Barnett, good to hear from you again, it's been awhile.

Hey, thanks . Yeah I have had my hands full regrouping my life a bit . We recently moved to a smaller home and still have unpacked boxes all over . Need to build a 12 x 15 foot shed for all that plus all my parts . Also started buying, fixing and selling the older Mustangs again . Went thru 7 of them in the last 6 months and have 2 more sitting in the driveway waiting for a few things . I had stopped that for a while to work on other things but now that I have gotten back into doing that my spare time to look at the forum is very limited.

Hope things are well with you and Happy Holidays!

 

[Stanglover]

ummm, yeah, i forgot to clarify that you add the distance of the piston in the hole to the thickness of the gasket and that number is the clearance.

Factory piston depth on a non boss351 can be around .020".

Hey Barnett, good to hear from you again, it's been awhile.

Hey, thanks . Yeah I have had my hands full regrouping my life a bit . We recently moved to a smaller home and still have unpacked boxes all over . Need to build a 12 x 15 foot shed for all that plus all my parts . Also started buying, fixing and selling the older Mustangs again . Went thru 7 of them in the last 6 months and have 2 more sitting in the driveway waiting for a few things . I had stopped that for a while to work on other things but now that I have gotten back into doing that my spare time to look at the forum is very limited.

Hope things are well with you and Happy Holidays!

Glad things are all okay. Life does get in the way of having fun sometimes. All's well here, can't wait for Spring!!

Merry Christmas and Happy New Year to you and everyone else too ..... or, if you're politically correct, Happy Holidays.

 

[83slimer]

ummm, yeah, i forgot to clarify that you add the distance of the piston in the hole to the thickness of the gasket and that number is the clearance.

Factory piston depth on a non boss351 can be around .020".

Thanks!!!