427 experts
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
427 experts
I have found a 427 engine for sale locally
Here are the details
3963512 block 30 thou over
2 bolt mails
cast crank
TRW 12:1 comp forged pistons ( the seller is saying 11.5 currently with thick head gaskets, so assume quench is all wrong
3931063 heads, oval port 100cc I think
Z33 isky cam, solid lifter
My question, does anyone know what size the domes on the pistons are likely to be, as i was thinking of changing the heads to alloy more modern one, say AFR ect, trying to figure if these pistons would work?
Open chamber/ close chamber ect
Any help appreciated
Richie
Here are the details
3963512 block 30 thou over
2 bolt mails
cast crank
TRW 12:1 comp forged pistons ( the seller is saying 11.5 currently with thick head gaskets, so assume quench is all wrong
3931063 heads, oval port 100cc I think
Z33 isky cam, solid lifter
My question, does anyone know what size the domes on the pistons are likely to be, as i was thinking of changing the heads to alloy more modern one, say AFR ect, trying to figure if these pistons would work?
Open chamber/ close chamber ect
Any help appreciated
Richie
Melting Slicks
Joined: Jan 2003
Posts: 2,877
Likes: 13
From: Doha
St. Jude Donor '08
If he used a double 0.039 thick gaskets then the dome volume would be around 38 cc, or 30 cc if he used a double 0.021 thick gaskets, all based on one of the on-line compression calculators.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
my .030 over bore has 11.8 c/r and I'm able to use our 91 oe 93 octane fuel with a 248/250 roller cam. I have aluminum heads which helps
Last edited by gkull; Feb 5, 2011 at 08:32 AM.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
I've used closed chamber pistons in open chamber heads before to save having to special order "lower" compression slugs, there being few off-the-shelf 427 selections for some stupid reason. In any event, I'd consider installing some main studs to buy a little "insurance". If you get new aluminum heads, if you go with rectangles (better intake manifold menu) keep intake port volume on the small side for the street. 427's w/solid cams rock!
Last edited by TheSkunkWorks; Feb 4, 2011 at 09:01 PM.
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
I've used closed chamber pistons in open chamber heads before to save having to special order "lower" compression slugs, there being few off-the-shelf 427 selections for some stupid reason. In any event, I'd consider installing some main studs to buy a little "insurance". If you get new aluminum heads, if you go with rectangles (better intake manifold menu) keep intake port volume on the small side for the street. 427's w/solid cams rock!
was going to convert to 4 bolt mains, and steel crank, though a cast should be fine for street abuse.
So no issue using close chamber slugs on open heads?
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
That's been my past experience. As long as clearances are good and the cc's work out to get your CR in the basket for the cam they should be fine for a "mild" street mill. You might want to do some dome blending while it's apart if they aren't already done. Oh, and before pulling the trigger on the heads I'd also check to make sure any non-OEM exhaust port location doesn't present any issues. IMHO you don't want any surprises there.
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From: Corsicana, Tx
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Well, if it's really 11.5 with 100cc heads...it doesn't have too much dome on it. Just guessing on some stuff..but let's say he's using .051" *thick* gaskets and the pistons are .019" down in the hole...it only takes a 32cc dome to get 11.5.
If you stick 119cc open chamber heads on there with say some .030" *thin* gaskets and the same .019" deck you'll barely have 10.0 compression.
Get some part numbers off the pistons to be sure...but this has the making of an easy build. Old TRW's can also be milled a lot. We did one a couple of years ago and took 10cc off the domes of a 13.0 motor.
JIM
If you stick 119cc open chamber heads on there with say some .030" *thin* gaskets and the same .019" deck you'll barely have 10.0 compression.
Get some part numbers off the pistons to be sure...but this has the making of an easy build. Old TRW's can also be milled a lot. We did one a couple of years ago and took 10cc off the domes of a 13.0 motor.
JIM
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
Well, if it's really 11.5 with 100cc heads...it doesn't have too much dome on it. Just guessing on some stuff..but let's say he's using .051" *thick* gaskets and the pistons are .019" down in the hole...it only takes a 32cc dome to get 11.5.
If you stick 119cc open chamber heads on there with say some .030" *thin* gaskets and the same .019" deck you'll barely have 10.0 compression.
Get some part numbers off the pistons to be sure...but this has the making of an easy build. Old TRW's can also be milled a lot. We did one a couple of years ago and took 10cc off the domes of a 13.0 motor.
JIM
If you stick 119cc open chamber heads on there with say some .030" *thin* gaskets and the same .019" deck you'll barely have 10.0 compression.
Get some part numbers off the pistons to be sure...but this has the making of an easy build. Old TRW's can also be milled a lot. We did one a couple of years ago and took 10cc off the domes of a 13.0 motor.
JIM
Would like to keep 11-11:5 comp, with a zl1 cam prob can make it work on out lame pump gas.
planning to do a few laps of our local circuit, so need to make ok power.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
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From: Graceland in a Not Correctly Restored Stingray
IMCO, trying to run an OEM ZL1 cammed mill on pump gas will present some drawbacks, particularly that you can't run enough compression to make it work as designed. You might need to get in touch with elle88, as he is apparently quite happy with the pump-gas 427 with CompCams Nostalgia Plus ZL1 cam (IIRC ground w/112* LSA) built this past year by 63mako. Another solid tappet cam worthy of consideration is Comp's XS282S. Either cam should prove fairly stout on pump-gas at between 10.2-10.5:1 CR with decent aluminum heads. Unless you're road racing for profit or just like frequent tear downs, I'd urge you to leave some DCR margin whatever cam you go with for such flogging if you're not going to upgrade the fuel.
Last edited by TheSkunkWorks; Feb 6, 2011 at 04:26 PM.
Race Director
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Once you decide what you can stand for fuel, I'd say we can pick a better cam than the ZL-1 for you. That thing needs serious compression to run well.
Once you decide on heads, the cam needs to be selected to match the whole combo.
JIM
Once you decide on heads, the cam needs to be selected to match the whole combo.
JIM
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
Have ordered pair of brodix race rite heads 119cc chambers
Have the old closed chamber 100.0cc heads off, 99% sure the pistons have .427 dome, so with new heads should give 10.66 comp ratio if my math is correct.
The engine has a Isky Z33 solid lifter cam, 250deg@50. Whilst I have a box of goodies to be shipped, wondering if i should replace the cam.
From the online calculators the DCR is quite low, what should I be shooting for?
Cam options, and I don't mind it a bit "bad mannered"
Cheers
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Mind sharing your complete cam card info, including advertised duration and ICA, so we can see where you are now?
As you probably already know, while theoretical DCR (tDCR) calculated strictly from intake valve closing is a decent indicator for mild builds, actual DCR = CR x VE% at a given RPM. That said, bearing in mind that it's entirely possible for completely different CR/cam combinations to yield the same tDCR value, the less mild is a particular build the more one must begin to make allowances (read, "leave margin") for increasing max cylinder pressures. So, a lower tDCR than those prescribed by one-size-fits-all recommnedations isn't necessarily a bad thing.
As you probably already know, while theoretical DCR (tDCR) calculated strictly from intake valve closing is a decent indicator for mild builds, actual DCR = CR x VE% at a given RPM. That said, bearing in mind that it's entirely possible for completely different CR/cam combinations to yield the same tDCR value, the less mild is a particular build the more one must begin to make allowances (read, "leave margin") for increasing max cylinder pressures. So, a lower tDCR than those prescribed by one-size-fits-all recommnedations isn't necessarily a bad thing.
Last edited by TheSkunkWorks; Aug 18, 2011 at 04:34 PM.
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
Mind sharing your complete cam card info, including advertised duration and ICA, so we can see where you are now?
As you probably already know, while theoretical DCR (tDCR) calculated strictly from intake valve closing is a decent indicator for mild builds, actual DCR = CR x VE% at a given RPM. That said, bearing in mind that it's entirely possible for completely different CR/cam combinations to yield the same tDCR value, the less mild is a particular build the more one must begin to make allowances (read, "leave margin") for increasing max cylinder pressures. So, a lower tDCR than those prescribed by one-size-fits-all recommnedations isn't necessarily a bad thing.
As you probably already know, while theoretical DCR (tDCR) calculated strictly from intake valve closing is a decent indicator for mild builds, actual DCR = CR x VE% at a given RPM. That said, bearing in mind that it's entirely possible for completely different CR/cam combinations to yield the same tDCR value, the less mild is a particular build the more one must begin to make allowances (read, "leave margin") for increasing max cylinder pressures. So, a lower tDCR than those prescribed by one-size-fits-all recommnedations isn't necessarily a bad thing.
I just used KB's online calculator, I got what info was available on Isky's web site worked it from there.
Cam is aZ33 gind, 250@.050, 108 lobe centre.
DCR cam out just under 7, if i calculated it correctly.
Static comp came out at 10.66.
Help appreciated
30 over 427, std stroke and rod, brodix RR 119cc chambers
Cheers
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
Hi,
I just used KB's online calculator, I got what info was available on Isky's web site worked it from there.
Cam is aZ33 gind, 250@.050, 108 lobe centre.
DCR cam out just under 7, if i calculated it correctly.
Static comp came out at 10.66.
Help appreciated
30 over 427, std stroke and rod, brodix RR 119cc chambers
Cheers
I just used KB's online calculator, I got what info was available on Isky's web site worked it from there.
Cam is aZ33 gind, 250@.050, 108 lobe centre.
DCR cam out just under 7, if i calculated it correctly.
Static comp came out at 10.66.
Help appreciated
30 over 427, std stroke and rod, brodix RR 119cc chambers
Cheers
ENGINE INFO: CHEVY BIG BLOCK V8 396-402-427-454 CU.IN. APPLICATION:
SPECIAL REMARKS: SOLID PRODUCT USE: STREET/STRIP
RPM RANGE: 3000-7000
Valve lift is calculated with zero lash and rocker ratio of 1.75
INTAKE TIMING DURATION: 290 deg.
OPEN: 37 BEFORE TDC
CLOSE: 73 AFTER BDC
CAM LIFT: .320"
VALVE LIFT: .560"
VALVE LASH: .03 HOT
.032 COLD
EXHAUST TIMING DURATION: 290 deg.
OPEN: 73 BEFORE BDC
CLOSE: 37 AFTER TDC
CAM LIFT: .320"
VALVE LIFT: .560"
VALVE LASH: .03 HOT
.032 COLD
LOBE CENTER: 108 deg. OVERLAP: 74 deg. CAM ADVANCE: 0 deg.
THE ABOVE TIMING IS CHECKED AT .020 (OPEN) LIFTER RISE
.020 (CLOSE)
The following timing is taken at .050" lifter rise and gives a more accurate determination of camshaft position.
INTAKE DURATION: 250 deg.
OPEN: 17 BEFORE TDC
CLOSE: 53 AFTER BDC
EXHAUST DURATION: 250 deg.
OPEN: 53 BEFORE BDC
CLOSE: 17 AFTER TDC
THis is what I wanted
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
The engine has a Isky Z33 solid lifter cam, 250deg@50. Whilst I have a box of goodies to be shipped, wondering if i should replace the cam.
From the online calculators the DCR is quite low, what should I be shooting for?
Cam options, and I don't mind it a bit "bad mannered"
Cheers
From the online calculators the DCR is quite low, what should I be shooting for?
Cam options, and I don't mind it a bit "bad mannered"
Cheers
I would say that if you don't change the cam at all, it will still run very strong.
Thread Starter
Racer
Joined: Jan 2010
Posts: 367
Likes: 1
From: Christchurch Canterbury
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
Take a look at this site if your interested - http://www.empirenet.com/pkelley2/DynamicCR.html
You can download your own DCR calculation software that I like a lot better than the KB version.
You can download your own DCR calculation software that I like a lot better than the KB version.