I'm going to be buying an edelbrock air gap 7561 soon. My 427 has 206 heads. I'm also going to be doing a cam/lifter change due to that broken lifter link bar. I'll be asking about flat tappet suggestions that have similar specs to my current cam soon. I wanted to ask about gasket match porting. Should I try and get the biggest oval port gasket available and grind to match that? Do the intake too? How about replacing the valves or going bigger with the valves? Any and all suggestions are welcome. Thanks!
Daron,
Use machinists dye (Dykem) on the heads and manifold, scribe your ports in the dye with a sharpe point. Doesn't really matter which gasket you use, pick a known, good quality gasket such as Fel-Pro, Mr. Gasket, Cometic, etc. Clean up the valve pockets while you are in there, but don't worry about larger valves, as they will not result in much, if any, performance gains by themselves . . . .
Ok cool. Good to know. Ok so now onto the cam. I'm switching back to flat tappet because I do not like the noise of the hydraulic rollers and apparently the link bars can break and screw up a very nice straub cam. Take a look at my cam sheet and let me know which cam you would recommend. And with the porting I'm going to do should I go with something beefier?
Ok cool. Good to know. Ok so now onto the cam. I'm switching back to flat tappet because I do not like the noise of the hydraulic rollers and apparently the link bars can break and screw up a very nice straub cam. Take a look at my cam sheet and let me know which cam you would recommend. And with the porting I'm going to do should I go with something beefier?
View attachment 452689
No. Gasket matching and cleaning up the bowls is not considered "porting" and will not have any affect on camshaft selection.
Contact Chris, or one of the other cam designers for cam recommendation.
Please explain then what porting is exactly, if bowel work and such are not porting.
If you affect air flow through a given port size, how is it that it does not affect cam selection?
Waiting for engineguy ( self proclaimed ) to answer my previous questions, since I love to learn and am a sponge for knowledge.
David Vizard, Says intake bowel work and cleaning up the port entry on the intake is worth 5-8%and the exhaust side will gain 2-5% with a total of 7-13% increase in power.
Vortecpro ( Mark Jones ) does amazing work to oval port heads and would be a good reference source.
Here is what I did to my 781's. ( Bowels and short turn radius. )
My apologies for the delay, have been out of the country for a few days.
Yes there is a vast difference between port matching/cleaning up the bowls and "porting" cylinder heads. Porting a set of heads involves the total port from the port surface of the head all the way to the valve seat. This includes the walls, roof, floor of the port, with significant attention paid to the valve guide areas and the transition area from the port floor to the bowl area, aka the "short radius". In my opinion, a flow bench is absolutely necessary to check/verify one's porting efforts/results. Hope this answers your questions/concerns.
wouldnt expect a gain with port matching but sure wont hurt you ez does it
think the confusion was port matching and calling that "porting".
as said most gains are in the first inch or so below the valve seat.
OK good be helpful if we knew brand and model of lifter you using ..........pic of pass side my eyes see #2 cyl lifter installed different than the rest looks like lifter bar flipped over compared to the rest ...if I viewing pic correctly
Studs ..... nothing wrong with those but like pushrods you have to measure for correct stud ht and threaded area when setting up your geometry
It does look like #2 is installed wrong. Also, it looks like the roller on the compressed #2 rocker is off the center of the valve stem, so maybe the push rods are long.
Like Vince said though, you really can't tell by the pictures.
I see what you guys are talking about. I think your right. The #2 lifters do look different from the rest. Is that one correct and all the rest wrong? Or is just that one wrong? As far as the geometry goes I did measured everything based on that video from straub that shows how to mark the center of the rocker in relation to number of turns on the rocker nut and stud. Would having those #2 lifters backwards cause a major issue. I'm going to be pulling the intake off soon when I get my air-gap. Also, the specs on the lifters are as listed below. Straight from my invoice from straub.
PAIR#5373 BODYD .842 ROLLD .700
BBC .842D T/B STREET PERF HYD
ROLLER
Could that be a piece from the bar on that style lifter?
Also, one last question. Is there an intake gasket that I can use, like a felpro blue, that is not siliconed all the way down the head. I see videos all the time of guys pulling one intake and swapping for another one on a dyno stand and they aren't scraping off all kinds of silicone before they put the other intake on. They just pull one intake and put down another one. Thanks for all the help guys. I'll be so happy once this thing is just DONE.
I would not touch the head. I would match the intake to the head so long as you are going to enlarge the runner all the way into the plenum.
I find a gasket that is too small for the head port. Match the gasket to the head. Then i tape the gasket in place. Place a few dabs of sillicone on the manifold side of the gasket. Bolt the intake down and let it sit over night. Cut the tape, remove the intake and the gasket should be stuck in place so you can scribe a nice line.
That would be the extent of porting you probably should limit yourself to without a flow bench.
While I was paid an apprentice's pay to gasket match everything that came in the shop when I was a kid, now running an mismatched rect tripower on oval heads, I'd say its a complete waste of time other to ensure no gasket material is covering the port.
You can certainly have that cam made for a flat tappet. In fact, thought CLay Smith 1st offered that in a flat tappet. I prefer setting lash on solids to hydraulics fwiw. And once set, a stable valvetrain dont open up. I shift at 7000+ .
Nice bowls man! I didnt touch my short sides as Mark said it was awful tricky to not lay them back too much. I did D port the ex by raising the roofs and blending in the boss to a vane. I;d stick to a good bowl blend, which you appear to have!
Some depends on lobe design and what rockers that are used. My howard 91161 and 91162 lifters are pretty quiet. The 91161 is used with a zz502 cam and has stamped steel rockers very quiet.
The 91162 is used with a Crane cam https://m.summitracing.com/parts/crn-139011
Little noisy cold start and with old Crane good rockers got more quiet with comp stianless steel roller rockers.
Would buy from another place if you feel that you didnt got the service you wanted.
I see how a flipped lifter install would break and take out the cam/lifter; what I don't get is how the broken part ended UP in the valve cover ares instead of following gravity being in the lifter valley?
Maybe the movement of the lifter "kicked" it up????
Of much more importance, I would think the cocked sideways roller would have eaten up the cam and sent metal throughout the engine = complete tear down, cleaning, new bearings, etc....
I dont think that lifter was installed wrong. I remember that thread and when I checked some more pics it was the same as the others.
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