423 SBC combo help

[6.50camaro]

He has the afr manifold ,you should back able to pull the top without touching the water or dust. right. Check for version in the intake ports. Dan

[prairiehotrodder]

what would that look like ?

[PRH]

You’d be looking to see how far up from the valve you see traces of exhaust(black).

I saw mention of TK lobes.
If that’s what you’re running, imo that’s too much duration to run lobes that fast(in that overall combo).

406 from 25 years ago......
Ootb AFR 210’s, Victor jr, 850, UD 268/276-108 cam, 1.5rr, 1-3/4 headers, flow masters on 3” pipes exiting in front of the rear tires, glide w-4800 stall 8” converter, 3400lbs.
10.60’s with the mufflers on, 10.30’s with them removed.
Dipped into the 20’s in great air.
I think it would have been quicker with bigger headers.

[prairiehotrodder]

the previous cam had TK lobes. Was a comp 12-863-9. The new cam is listed above. It slowed down with the current cam but i'm not ready to blame the cam just yet. I do think the bigger cam may have exasperated another problem. The new bigger cam will want more airflow in and out am i right ?

[PRH]

What size are the rear tires?

I don’t like the match up with the bigger cam and the exhaust situation at all.
Well, actually....... I just don’t like the exhaust situation on that engine build, period.

Even on something as mild as a 480hp 383 Mopar with stock unported heads I picked up 20hp(and no loss of tq) switching from 1-3/4 x 3 headers to 1-7/8 x 3.

I have 1-7/8 x 2 (step) x 3.5” headers I use on the dyno for a build like that.

[6.50camaro]

As PRH stated black soot back up the intake port and manifold . Would be harder to see on the black plastic manifold . When I first ran my 422 with a 245/255@.050 106 lsa cam with 1-3/4 header and 2-1/2 exhaust with x pipe and pypes m80 straight thru mufflers dumping in front of the rear axle. I what black soot staining almost all the way back to the plenum . Changed to 1-7/8 x3-1/2 headers added more cam 15°in 13°ex spread the lsa 1° and dropped the exhaust . No more reversion or hardly a trace past the valve seats . Dan

[Monza355]

As PRH stated black soot back up the intake port and manifold . Would be harder to see on the black plastic manifold . When I first ran my 422 with a 245/255@.050 106 lsa cam with 1-3/4 header and 2-1/2 exhaust with x pipe and pypes m80 straight thru mufflers dumping in front of the rear axle. I what black soot staining almost all the way back to the plenum . Changed to 1-7/8 x3-1/2 headers added more cam 15°in 13°ex spread the lsa 1° and dropped the exhaust . No more reversion or hardly a trace past the valve seats . Dan

Do you think that’s because of the small headers or the smaller camshaft with the less overlap (less time for reversion) ? How did it ran in this trim ?

[6.50camaro]

As PRH stated black soot back up the intake port and manifold . Would be harder to see on the black plastic manifold . When I first ran my 422 with a 245/255@.050 106 lsa cam with 1-3/4 header and 2-1/2 exhaust with x pipe and pypes m80 straight thru mufflers dumping in front of the rear axle. I what black soot staining almost all the way back to the plenum . Changed to 1-7/8 x3-1/2 headers added more cam 15°in 13°ex spread the lsa 1° and dropped the exhaust . No more reversion or hardly a trace past the valve seats . Dan

Do you think that’s because of the small headers or the smaller camshaft with the less overlap (less time for reversion) ? How did it ran in this trim ?

It had little or no reversion with the bigger headers and no exhaust even though the cam had 15° intake and 13° exhaust more duration , installed at the same intake centerline with 1° wider lsa . I would say the small headers and exhaust system was not allowing it to evacuate the cylinder fully before the intake valve started to open . The larger cam was reaching .050 lift on the intake 7.5° sooner yet the cylinder was evacuated enough with the larger headers and no exhaust system to not back flow exhaust residue into the intake port . I may be all wrong but it's my story and I'm sticking to it. Dan

[6.50camaro]

To answer the how did it run in this trim . The small header small cam combo .The best it did was 7.12 1/8 mile 1.45 60' mph was around 96 to 97 this was with 4.56 gears converter flashed to 4200to4300 rpm . 12" hoosier quick time pro dot slicks . This combo had a old set of Brownfields 205 heads . Only got to the track 4 or 5 times that year . Never really got to fully sort it out . Was not really happy with the results . Pulled the motor ran the car 2 years with a 383 I had build . Re worked the 422 top end Dart220 race series heads unkown port work and flow numbers Erson 260/268@.050 .422 intake lobe .430 ex lobe 1.6 in rocker 1.5 ex rocker Dart single plane intake minor port match only out of the box 850 holley street hp carb 5500 stall converter still had 4.56 gears 11.5w 29.5 hoosier slicks . Off the trailer it ran 6.43 sec run 6.41 dailed 6.42 made it to the semis that night when I broke out witha 6.41 . The next week with a much more refined Holley 750 HP style carb trying to slow the car to run 6.50 index class it went 6.35 . Pulled 2* of timing out 32* total advance. It what 6.31. @ 108+ . Next ran short shifted ar 6500 instead of 6800 6.35 @180+ again. Went to a ancient holley 750 Dp would run 6.48 to 6.51 week after week. 422 back out getting fresh valves and springs the track dropped the 6.50 class after I got all dailed in. Sorry about the hijack Praire . Dan

[fastblackracing]

What is the rpm drop on the gear changes?...normaly the converter would look like on the 2-3 gear change where the rpm should drop back say 800 rpm and work its way back up.....
If its blowing through you will see very little rpm climb in high gear.

[rustbucket79]

60’ times, converter flash numbers look correct. Post all the time slip numbers, sounds like it doesn’t back half well.
Compression is OK, carb is fine (albeit not tuned yet)
I’ve heard some negative towards that intake, but nothing substantiated.
Cam was a move in the wrong direction, might consider swapping back in the off season.
If the AV gas doesn’t pepper the spark plugs nor slow the car over C-12, may as well stick with it.
You should try without exhaust, but don’t expect more than a tenth.
The headers are NOT the issue. 1 3/4 headers support over 800 HP.

What ignition timing are you running?
What is the shift points?
What is the altitude of your track?

[F-BIRD'88]

Compression and leakdown test, first... Make sure thiss engine is in good basic health.. You will only get so far on 1-3/4" headers.. But it can be hard to see the break point on this.. On g
the 18 deg 406 we did the custom step headers w merge really opened it up.. Similar big cam but more lift.. Fully ported big intake, big dominator.. 750 ish hp.
The custom step headers were not cheap but......

If Joe Sherman was still with us he'd show you what to do with those 227 afr heads.


You will only get so far with the plastic intake.
Then, how you gonna port it?

[maxracesoftware]

there is a long story behind this motor but yesterday it went 10.6 at 124. He has data logging and with an out of the box untouched carb it was fairly rich so he went 2 jet sizes leaner front and back and gained a tenth. Since he is trying to win bracket races i don't get to tinker with stuff as much as i would like to test things. Right now i'm leaning towards convertor or maybe exhaust system.

I've never really understood what it means when i hear racers say they "blow thru the convertor". What does that feel like ? Can you notice that on data logging ?

We have a set of 1 7/8 headers to try on the car. He wants to keep running it through the mufflers but thats the first thing i would ditch.

a 10.60's ET @ 124's MPH with around 1.43=60FT ... looks like there's nothing wrong showing up anywhere in the Run ,
its just not making a lot of HP ( 465 Peak HP )

how close is your ET / MPH Time Slip incremental data to this Picture ??

[fishman]

I have a 422 ci sbc with AFR 235 heads
Cam is 106 lsa 271-280 750 lift, super victor ported , 950 dominator , 11.28 Cr headers are equal length 1 3/4 tubes with 3 inch on pump gas 94 octane . On the dyno made 659 hp. We tried 1 7/8 headers x 3.5 made 1 more foot pounds of torque . Don’t see a problem with headers size looks like your motor is just down on hp sadly

[JoePorting]

Are you running the standard AFR roller valve springs? They are around 200 pounds on the seat. I'd try and upgrade the valve springs to something in the 250 pounds on the seat area. Also check for pushrod interference. Look for wear patterns on the pushrods. They could be binding on the head or valve cover.