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Old 03-20-2019, 07:25 AM
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Skip White Heads BBC

I'm really tempted to ditch my BBC stock 781 heads for a pair of these.
https://www.skipwhiteperformance.com...val-274_89649/
This sounds crazy, but that price is for a PAIR. I could swear before that they were listed each. I know, the casting is from china, but they get nothing but good reviews.

I'm making just over 400HP now, any idea what these heads might do?
My cam has .578 lift with 230 duration, 2 degrees advanced (and with the low end it has I'm tempted to change it to straight up). Headers, Edelbrock manifold (it could be better, it's just a performer 2. Compression was estimated at 10+:1 (but somehow, I don't know how, it has 210psi cranking compression yet it runs fine on pump gas) Tried different gauges, a borrowed one from the parts store shows 205psi.

I think my valve to piston clearance is close, I can't find that number in my notes, so I'm going to check it bolted together. If I need a little more clearance, can I do anything to the pistons while in the motor?

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Old 03-20-2019, 01:57 PM
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Install a camshaft with .550” valve lift.
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Old 03-20-2019, 02:53 PM
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Quote:
Originally Posted by MouseFink View Post
Install a camshaft with .550 valve lift.
That won't change valve-to-piston clearance one bit, so that is really poor advice.
Piston is nearly half way down the cylinder and heading away when the intake valve reaches full lift, no where near the piston at all.

Valve-to-piston collisions happen on the overlap period neat TDC, when the exhaust is just coming to fully closed, the intake is just starting to open, and the piston is just reaching TDC overlap ready to head back down drawing in mixture. All three parts are close to each other in the same small space.

Checking points are between 20 before TDC and 10 after TDC, check every 5 to find the closest point to the intake valve, then check a few degrees either side of that 5 interval to find actual clearance in the assembly.

As far as power, if your 781's are basically stock, no porting, only a 3 angle valve job.... then according to the Head's flow numbers for up to and at your cam lift it could pick up 75-100HP.

For valve to piston clearance mods I the block, you can rent a flycutting tool from Isky, you can carefully free hand it with a Dremel if it is diameter and not depth contact, or of it is just intake depth clearance you can retard the cam as this increases intake clearance and decreases exhaust.
I have also seen where guys have taken an old or spare valve and cut the face using a cut=off disc in a Dremel to resemble a milling cutter and use that like the Isky in-head tool, or solder a small piece of high speed steel or carbide cutting bit to a old valve face and carefully cut with that down in through the installed head using the valve guide as a locator.
Piston Notching Cutter Tool : ISKY Racing Cams, Do It Right

We had a member here, I haven't seen him post in a while, BobCRman, who had used several sets of those heads and never had any problems with them.
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Old 03-20-2019, 04:45 PM
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Great to hear no problem with the heads. I'm close enough to take a drive up to get them. Not to save on shipping, just be nice.

These are my pistons https://www.summitracing.com/parts/slp-l2465f30
If I do this I hope my drive train will hold up. According to weight/speed and weight/ET calculator I'm at just over 400hp now with the stock heads. TH400 and 12 bolt. I have a special bearing cap on the left side with a TA cast cover with the bolts that tighten down against the bearing caps. I should pull an axle sometime to see if there is any twist. Yes my heads are stock as stock can be. I never cc'd them but I think they have been milled quite a bit over the years. Now I'm wishing it was December.
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Old 03-20-2019, 07:29 PM
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Sounds like you've done most of what you can to beef up the 12-bolt, short of a 33 spline diff or spool and 33 spline axles.
I would not be that afraid of the 30 spline axles if they were aftermarket and not the undercut taper stock axles.
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Old 03-21-2019, 05:54 AM
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The guy who originally built it put in some crappy axles and I twisted one after 1 day with slicks and the motor running like crap. And that was with 3.42 gears. I put in Moser axles and 4.1 gears. I should pull the left one just to see. I've heard that's most always the first one to twist, it was for me anyway. (what a ****** to get a twisted c clip axle out) No more c-clips either.
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Old 03-21-2019, 09:42 AM
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I believe I said it before and it's a documented vice of a BBC - you simply cannot get enough cylinder head on the engine when going for max power. So any improvement to flow that you make in the cylinder head area is going to be a win. And if you are looking for additional upgrades in the future then the stock heads are now out of the way which would be a hindrance. Besides you can probably shop the stockers locally and get some of the coin back that you spend on the new ones.


Next up would be that intake manifold - not even sure unless you simply want to compare stuff that you should put it back on with the new heads.
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Old 03-21-2019, 10:03 AM
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Even if you had them shipped, you're still paying tax being in state. One guy I dealt with is a serious type, don't take him as rude, he's just blunt and wants to keep you out of trouble. Another guy, who has sleeve tattoos is beyond friendly and also gives good advice.

Their heads have raised exhaust ports, never got an actual measurement as to how high up their raised, so keep that in mind if it's a concern.
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Old 03-21-2019, 01:15 PM
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Quote:
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I believe I said it before and it's a documented vice of a BBC - you simply cannot get enough cylinder head on the engine when going for max power. So any improvement to flow that you make in the cylinder head area is going to be a win. And if you are looking for additional upgrades in the future then the stock heads are now out of the way which would be a hindrance. Besides you can probably shop the stockers locally and get some of the coin back that you spend on the new ones.


Next up would be that intake manifold - not even sure unless you simply want to compare stuff that you should put it back on with the new heads.

I thought about the intake and I'm wondering if the Performer RPM is good enough. It's one of what I call hybrid dual plane, the top of the divider isn't there for what looks like a .5" or more. Plus an open spacer like I'm running right now. Or are all the twists and turns in the runners going to slow things down?
The Q-Jet is making things tough finding a good intake. Possibly a dominator style with an adapter for a Q-jet?
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Old 03-21-2019, 05:15 PM
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Quote:
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I thought about the intake and I'm wondering if the Performer RPM is good enough. It's one of what I call hybrid dual plane, the top of the divider isn't there for what looks like a .5" or more. Plus an open spacer like I'm running right now. Or are all the twists and turns in the runners going to slow things down?
The Q-Jet is making things tough finding a good intake. Possibly a dominator style with an adapter for a Q-jet?

I think you would have to say that the current intake is the next bottleneck to be dealt with; however I do know that you have this car on the street so there will probably have to be some kind of compromise. A dominator intake with an adapter might actually work pretty good. We have used a 4500 intake with a 4150 Holley and it actually 60 footed better than with a 4500 carb but ET and MPH did pick up some with the 4500.
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Old 03-22-2019, 05:14 AM
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I think you would have to say that the current intake is the next bottleneck to be dealt with; however I do know that you have this car on the street so there will probably have to be some kind of compromise. A dominator intake with an adapter might actually work pretty good. We have used a 4500 intake with a 4150 Holley and it actually 60 footed better than with a 4500 carb but ET and MPH did pick up some with the 4500.

I don't know a lot about velocity vs restriction in intakes and heads but I'm learning a little. I looked at the rpm ratings for the dominator intakes and their rpm range seems to be around 3500rpm to 7500rpm. So I pictured the runners as huge and the air/fuel not having much velocity to keep things going fast at lower rpms. Would that make it very unfriendly on the street?
I'm guessing dominator carbs are for all out racing and huge cfm? All this is why I want to keep the Q-jet, so at low rpm the small primaries will still have enough flow to run well yet have the giant secondaries for when it's needed.
The Edelbrock RPM, rpm range is 1,500-6,500. (the one I have now is idle to 5500) Lets say the 6500rpm could be a bit over rated and won't hold true if I'm getting the new heads, but I'm not reving that fast anyway. I'm sort of talking myself into the RPM, please let me know if it's a bad choice.

I know, you can't have the best of both worlds, so I'm looking for a happy medium.
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Old 03-22-2019, 07:57 PM
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If you are dead set on the Q-Jet (which is fine BTW) then I would say the Edelbrock 7164 which is setup to accept that carb or a normal Holley square bore is the ticket. It's about $15 more than the standard square bore unit. The ports might need to be matched to the heads but it would be worth the effort.
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Old 03-22-2019, 09:02 PM
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Going against the grain a little, this makes a great street intake if you can find one, only available used as Weiand doesn't offer them anymore since the Holley Group bought them out.

Weiand Team G Oval Port #7523, with a Q-jet adapter welded onto it and then the adapter and intake heavily hand ground blended together.

The Team G oval was a great street intake for smaller BBC (468 and smaller) that made real good torque and still powered out well on the upper end. It had smaller runner cross section than the Victor manifolds did, or any other modern single plane out there.

https://www.ebay.com/itm/NOS-Weiand-...UAAOSwHGFckUUQ

A friend of mine used one on a oval port 049 head 10.5:1 compression 461 with a Nostalgia+ LS6 solid cam and it was a low and mid range monster in a '74 Nova....we were looking for ways to get rid of some of the low end as it would just bury 28" x 12.5" M/T E.T. Street bias ply cheater slicks. Tight lashed the cam, 2" open carb spacer, 950 Holley DoubleP, ...ended up using an MSD Timing Computer to drastically slow the timing advance curve below 3800 rpm then ramp it all in by 4500.

I will say, it has always seemed to me that worrying about low rpm performance when you've got a 454 is almost ridiculous....if it's built right it'll blow any normal street tire clean off the rims from either idle to even from a 30 MPH roll in second gear..
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Old 03-23-2019, 04:08 AM
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I'll, probably go with the 7164 RPM, like everything else, I wish I had bought that the first time. And back then I probably was worried about low rpm torque. Back then even with the slight dish pistons and about 140psi cranking compression it had great torque. It was a real smog motor. My first BBC, I was amazed! I recall I had a "problem" with it spinning the tires in 1st, hitting 2nd still spinning, then slowing down and into 1st again and spinning the tires. They said that was a good "problem" to have. Then I recalibrated the governor for higher shift points.



Just remembered that after the rebuild I sold the + .030 dish pistons, cam and lifters as a ".030 over kit" and someone actually bought it for about $200. I had a 2x4 with holes drilled in it numbered for the lifters. Made no guarantee on them in a different block. The guys biggest concern was if it had a lopy idle. A lope dope. Not worried about performance, just wanted to make it *sound* like it had performance.
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Old 03-23-2019, 04:21 AM
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Quote:
Originally Posted by Dfish1247 View Post
Even if you had them shipped, you're still paying tax being in state. One guy I dealt with is a serious type, don't take him as rude, he's just blunt and wants to keep you out of trouble. Another guy, who has sleeve tattoos is beyond friendly and also gives good advice.

Their heads have raised exhaust ports, never got an actual measurement as to how high up their raised, so keep that in mind if it's a concern.

I will ask about the raised ports. My headers are already dented up to all heck, looks like the worst part will hit the starter, but it's stock and I have a mini sitting on the shelf.
Thanks for the heads up on the counter guys. Hopefully I'll get the tattooed guy.
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