Max RPM for stock valves

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Max RPM for stock valves

Post  BigRigTech on June 17th 2013, 7:25 pm

What is the max rpm for stock valves, SCJ sized in a D2OE head? My car is trapping the 1/4 banging the 6400 pill about 50 feet before the stripe and I'm concerned I'm over working the stock valves. I didn't think the car would pull this much RPM but a new converter has made a world of change in the car from last year. Our local Super Pro ET brake is 10.99 so when I went 10.85 yesterday morning they re-teched my car for S-pro and I ran a 10.97, 10.99 and 10.96 in the warmer afternoon temps. Crappy air and a strong head wind. Is there anything "cost effective" I could do to try and gain a tenth to get me away from the ET brake a little more? More carb? More spacer?

 Here is my combo:

87 Mustang GT
drag only, gutted
3120lbs with the driver
4200 stall, stock C6, shift kit and TCI servo
9" diff, 4.11 with 28 x 10.5" slicks, south side machine lift bars and adjustable uppers
Foot brake, no box

Best run so far on a 80/20 mix of 91 octance/av gas, 10.85 @ 124.98mph

468 BBF
Eagle H-beams with KB hyper flat tops
decked block, 10:1 compression
D2OE head withe SCJ valves, very mild port work
Comp 987 springs, about 130lbs seat pressure, 370lbs closed
ARP screw in studs with PRW stainless roller rockers and PRW stud girdle
Manley .080" 5/16" pushrods
HV oil pump with ARP shaft
Comp cams SFT .605/.605 248/248 with Howards lobe face oiling lifters
Offy single plane with 750HP street carb 78/88 jets and a 1" 4 hole spacer
4" K/N air cleaner
MSD dizzy, 6AL and wires
38* timing
PRW SFI balancer and flexplate
Holley blue pump
PRW electric water pump
Hooker Super comp LT's, 2" Primaries with 3.5" collectors

The engine dyno'd at 475HP at 5600RPM and 502fltbs on pump gas with a worn out duraspark dizzy, the new MSD dizzy has helped a bunch since the dyno. The engine would pull over 6000 easily and hardly fall off at all.
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Re: Max RPM for stock valves

Post  Dave C. on June 17th 2013, 8:38 pm

I'd look somewhere else for the tenth , like tuning , dist. curve , 60 ft. etc . Make sure that holley pump is enough pump. The valves probably aren't holding you back unless they are floating.

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Re: Max RPM for stock valves

Post  schmitty on June 17th 2013, 8:58 pm

I doubt that fuel pump is holding anything back, I ran one on a 552 ci deal making close to 700.  I'd think that the intake and carb would be holding it back.
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Re: Max RPM for stock valves

Post  maverick on June 17th 2013, 9:24 pm

schmitty wrote:I doubt that fuel pump is holding anything back, I ran one on a 552 ci deal making close to 700.  I'd think that the intake and carb would be holding it back.

I think so, too.  At your trap rpm, I'd guess that 750 carb has it wheezing.
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Re: Max RPM for stock valves

Post  BigRigTech on June 17th 2013, 10:26 pm

I'd like to try an 850 carb if I can borrow one or find one cheap to rebuild in decent shape. Are my stock valves going to last 30-40 passes at 6400rpm? I plan to replace them or the heads this coming winter if I can get there with no issues. I just did my routine post race checks and the valve lash was good, nothing in the oil filter so all is well so far...LOL....The car is a gross color that the previous owner has on his fleet of oil trucks, I haven't had time to paint it yet. This is a pic of the car last summer, I bought new DS-2 front tires this winter as she DID NOT like radial tires on the front at all. LOL....I built this engine myself last summer, it's my first big block Ford. Up until now I always played with SBF's and diesels.






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Re: Max RPM for stock valves

Post  cool40 on June 17th 2013, 10:33 pm

i'd look for at least 850 or as big'a 4150 carb i could get.i used stock ford valves for 7200rpm a bunch of times! good looking car too!Cool
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Re: Max RPM for stock valves

Post  BigRigTech on June 17th 2013, 10:48 pm

I spoke with my buddy who owns the engine shop where I get my stuff and he said with the relatively low seat pressure he wasn't all that concerned about the rpm at this point....But just the same he said next winter it would be nice to upgrade them for peace of mind. I was talking with a friend who races a 521 in his 9.80 car, he is running a 1050 dominator, tops out at 6900 at the stripe. I think a Victor intake would be too much for my heads as they have had very little work done to them but a bigger carb is worth a shot. The Offy intake came with the engine so I kept it and as far as port sizes go it is a decent match for my heads at this point. I got a smokin' deal on the hatch that's on the car, it's a Cervini fiberglass piece, very light compared to the stocker! I made a lexan window for it last winter.
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Re: Max RPM for stock valves

Post  maverick on June 18th 2013, 7:04 am

These things seem to like big carbs.  Just as a point of reference, the old 514 (trapping at 6600 rpm) slowed 2 tenths in the 1/8 mi. when I swapped on a well tested 1050 Dominator in place of the 1150.  For street use, smaller is friendlier but on the drag strip, a little bigger is a little quicker IMO.
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Re: Max RPM for stock valves

Post  austin460 on June 18th 2013, 7:13 am

[quote="maverick"]These things seem to like big carbs. 

Let it eat
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Re: Max RPM for stock valves

Post  HorsinAround on June 18th 2013, 7:23 am

^^^^^What they said! put a bigger carb on there. Also, maybe put a 6600 chip and definitely keep an eye on the valve stem ends for signs of valve float with those springs.
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Re: Max RPM for stock valves

Post  BigRigTech on June 18th 2013, 7:35 am

I went through the valves last night, everything looks fine. I was chatting with a friend who races as well. (9.40 69 camaro) very good carb tuner. He has a line on an 850 I might be able to try before I buy that he just rebuilt. He also wants to soften my rear shocks a touch after seeing the car run and try a 50/50 mix of pump/av gas. Maybe a carb spacer too. He thinks my car will stay in S-pro with minor tweaks as the air was horrible Sunday afternoon and I only lost about a tenth from the morning run. I can't wait to go back next month and try some stuff.
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Re: Max RPM for stock valves

Post  DJStang on June 18th 2013, 8:17 am

I had a pretty basic 466 in a Mustang before that was running 10:80's with very similar results using DOVE heads.  I swapped out the Portosonic and 830 for a Victor and 1050 and picked up 2 tenths with no other changes (even with the port mismatch).  Then I swapped on stock DOOE heads to the same set-up and ran a best of 10:48.

So like everyone else has said these engines need to breath.  I also used a blue holley pump on this set-up as well.

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Re: Max RPM for stock valves

Post  BigRigTech on June 18th 2013, 8:49 am

I have some DOVE-A heads on the shelf, very rusty and I'm not sure if they could be saved or not. I was going to have them glass beaded and magged to find out. They would give me over a full point in compression over my D2OE heads which cc'd at 91. The worst thing about my car is there are only two big block Mustangs at my track counting mine so there is zero used 460 race parts available around here. Nada......
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Re: Max RPM for stock valves

Post  jeffgfg on June 18th 2013, 9:09 am

Back in the 70's in the old Ford Muscle parts program the first thing they started with was adding a Scj manifold and a 850 cfm carb....and it worked !!! My SCJ ran way better and quicker by just adding the 850. Also as has been said the stock valves aren't a problem I had over 40,000 hard miles on mine with plenty of 7,000 rpm plus miles on them never a problem.

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Re: Max RPM for stock valves

Post  HorsinAround on June 18th 2013, 9:32 am

BigRigTech wrote:I have some DOVE-A heads on the shelf, very rusty and I'm not sure if they could be saved or not. I was going to have them glass beaded and magged to find out. They would give me over a full point in compression over my D2OE heads which cc'd at 91. The worst thing about my car is there are only two big block Mustangs at my track counting mine so there is zero used 460 race parts available around here. Nada.

You can always shave your D2OE heads to gain compression. Your best bet would be to get a set of A429 aluminum heads (to keep the same valve pierce point).
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Re: Max RPM for stock valves

Post  maverick on June 18th 2013, 10:16 am

You'll find lots of used 460 race parts right here.Wink
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Re: Max RPM for stock valves

Post  BigRigTech on June 18th 2013, 10:18 am

I had the heads rebuilt last year, put in 6 new valves then. I have a line on a set of C9VE heads locally, waiting on a price from the seller. We have an excellent engine shop about 2 hrs from here, the Armstrong brothers who own some NHRA.super stock records. I could send the heads to them for porting, flow bench and the full meal deal next winter. I had my engine dyno'd down there last summer - worth the trip to see what was being built in the assembly room.
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Re: Max RPM for stock valves

Post  BigRigTech on June 18th 2013, 6:55 pm

I would love aluminum heads but having 3 little ones running around and the big mortgage to house them money is tight.....LOL I'm happy with my current setup, just looking to fix any weak points if possible. The DOVE heads I have might be the ticket if they can be saved. I'll start with more carb and go from there.
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Re: Max RPM for stock valves

Post  69F100 on June 19th 2013, 12:11 am

I have about the same thing in my a429 heads I bought used as I do in my dove heads and they was gave to me as bare heads no valve or any thing after replacing everything I cut down the valve guides, spring pockets, valve springs, valves, guide plates, rocker studs, and porting it will run you close to what a good set of used aluminum heads. Just stay away from the pro comps.
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Re: Max RPM for stock valves

Post  austin460 on June 19th 2013, 3:35 am

You can do your doves on a budget. You can clean them yourself in an electrolitic bath (homemade with a battery charger). Then copy the instructions for porting on reincarnations website you may not get them perfect without a flowbench but you will improve them no end. You would still need guideplates and springs but they sell tools forcutting your stems. Although as 69f100 said they can get expensive to build to there full potential.
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Re: Max RPM for stock valves

Post  BigRigTech on June 19th 2013, 7:14 am

If I can get as much or more flow as my current heads and gain a bunch if compression in the process I would be happy. My buddy heads head rebuilding gear and he is my sponsor so I can work a deal with him. I can do the head porting as per Scott's website, I just won't know if the heads can be saved until the rust is out of the ports. I got the heads for free so I hope they can be rebuilt.
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Re: Max RPM for stock valves

Post  austin460 on June 19th 2013, 7:30 am

Like I said cleaned mine in a homemade electolitic tank really straight foward, loads on internet about it one blke I remember seeing you tube cleaned/de-rusted a whole trailer chassis in one. You only need a battery charger and some soda flakes, and if it work you've lost nothing. I used a Childs plastic toy box as a tank.
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Re: Max RPM for stock valves

Post  BigRigTech on June 19th 2013, 7:47 am

I'll have to look into that, a rubber made tote would fit both heads. These heads have a lot if rust sitting in the ports when you take the valves out. I haven't had a chance to strip them down yet, too busy prepping a 7.3 powerstroke for a swap into my 92 F350 C&C dually 4x4 to replace the 7.3 IDI.
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Re: Max RPM for stock valves

Post  austin460 on June 19th 2013, 8:19 am

if you do go for it be sure to do it somewhere well ventef as it gives off hydrogen gas.
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Re: Max RPM for stock valves

Post  BigRigTech on June 19th 2013, 8:30 am

Outside, how long does it take to remove the rust?
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