Ran a 13.45@100 with them on my car. First run bugs to work out. Bad weather too. Expecting mid to high twelves.

what other stuff do you have done to your car? I dont want to go back and seach through the 6 pages of info. Also can you post the pic of the dimmer switch... thanks a lot man. Im thinking of ditching the idea of SR 305's and going with ported lb9's..

oh i love this thread, im porting/polishing my 350 lt1 heads... ive just begun, and just dont wanna messup... what exactly do i need, i have the porting/polishing kit already, and a dremel, should i get a die grinder instead? thanks ;p

I recommend a electric die grinder. A dremel does not have enough power to do the job efficiently.

AC electric die grinder speed controller.

You can build a speed controller out of parts from a
hardware store. You'll need

1. square wall electrical box (fits two wall plugs or a wall plug and a switch.
2.A double wall plug receptical
3. a ceiling fan speed controller or light dimmer
(get the one without a radio interference filter)
4. some marret connectors
5. A length of AC lamp cord
6. A AC plug.
7. A wall plate. combo 2 plug and round hole.

Wire the box up using the lamp cord and marrets so the dimmer controls one plug outlet only according to the diagram.
That way you can use the other for a work light.
Just turn the dimmer to control the speed of the die grinder.

Note: The dimmers with the radio interference filter will fail after a short time
so get the one without the filter.

Car specs

1988 Firebird S/E
long tube headers with custom dual exhaust
th350 3500stall B&M converter 4.10 gears
et street 26-10-15 tires
Airlift air bag (right side)
Auxillary fuel cell under hood (racing fuel source)

350+.060 flat top pistons decked to .015"
Accelerated Motion solid cam 287-292 .537-.557 105 (256-264@.050)

Heads are milled to 52cc.
compression ratio is 12.65:1 with .015" gasket.
Holley strip dominator single plane intake with edelbrock 750cfm carb.

After resetting the overadvanced timing (distributor was
loose) and locking out the mechanical advance curve advance curve, (needed more initial advance with big cam), the car was all it should be.
easy 12's.
Unfortunately I was driving to the track to retest it with the tuning corrections when the piston ring land let go while passing another car. ( 94 octane not enough for 12.65:1 compression) {I use 110 octane race gas at the track} Never heard any pinging or detonation but.....

So that motor is down for repair for now. piston parts destroyed the deck on one head.
The ported 416 heads worked very well though.

nice strong torque and power from 3000 to 7000rpm+
with the big solid cam and strip dominator.

Let me make sure I understand what has happened here. In addition to the P&P work (nice job BTW), you also installed 1.94 intake *and* 1.60 exhaust valves in the 305 head?

Yes

this is prolly the most informative and helpful post i've ever seen. all i can say is wow... now i just have to find a set of heads other then my stock L03's.

We aimed to please

I can't believe almost 9000 people have read this thread!

LOL yea, this one should be saved by everyone ever interested in DIY motor jobs. I know this has made it to my to do (one day) list. i've to get her on the road yet though

very very informative, and definetly passed the time at work today. I have a set o heads, 416 casting that im going to work on. This has to be the most useful thread that i have read on this board.

so the idea here is to improve the way in which air flows. so it needs to travel with less bouncing off the walls so to speak. removing too much will hurt you and too little is a waste of time. anyone ever ran into problims grinding too much off from around the guides or thinned out a wall to much???

It is very informative, and I can't wait to get a set of heads to start working on.

I also bought a book on small block Chevy heads and it has some important tips too.

I want to thank you Sitting bull. :hail: :hail: :hail: I have studied this thread for hours and I Just started Porting last week.
U are right about the time. It is not for the inpatient. I find its a lot of fun to do tho. The pic are great help to see what your doing.
I have some guestions: how much of the valve guide do I cut out? On some other's I see alot and on yours I see a modest amount Do I lower it at all ? I dont have all the measuring tools and I am doing it mosly by eye. How can I know how much to cut out of bowls before its to much? I have removed a fair amount already but I want to make sure I do enough to make it worth doing. Lastly do I polish all the bowls , exhaust ports and leave the intake ports rough?
Thanks again for all the help

My valve guides were somewhat odd because they had been cut down during a previous valve overhaul and are not at all the norm. You want to shape them into a wing airfoil sort of shape, seen as if you were at the wingtip looking toward the fuselage. A picture is worth a thousand words in this instance and that is something I just don't have. But virtually every magazine column dealing with porting will have a good pic of this for you.

With the bowls you simply want to take out all of the high spots and ridges and blend the bowl into an overall smooth shape. That's all.

I wouldn't worry too much over the polishing of the bowls. The exhaust runners are where you want a nice smooth finish and get it as smooth as you can in the bowl, too. The intake runners and bowls are best when left with a fairly rough surface finish to promote a good mixing of the intake charge.

I see what your saying about the shape of the valve guide. Can u draw me a picture... na just kidding.
About blending in the bowls.. on a entry that u posted u or some one talked about getting real close to the seat to make sure it a smooth transition down the bowl.. Frankly this worries me. I don't want to mess these up. Carbides really can mess thing up fast. Thanks again for your help.
Ps Have I told u how much this thread has help me.....

The maximum size of the bowl as it blends into the valve seat is 91% of the seat's diameter. By simply smoothing everything in the intake bowl my size came out OK, about 85% or so.

Glad our work has been a help for you

ill be doing this real soon on a pair of 4416 heads i snagged off an 86 pickup 305 engine

and then after that a pair of nice 487X heads i found that a PO put on the 82 LG4 caprice 305 in my 71 dually

(the heads were a pleasant surprise yes, and it actually ran real strong, and its no wonder now)


happy playing with heads

ive done this stuff plenty in the past, i have a bit like in one of the first pics of this thread, short tapered cutting one

works great

eats right through cast iron like knife and butter
i do it to intake and exhaust manifolds too, remove bumps, enlarge runners and ports

easy as cake and makes a difference for sure sometimes

Im in the process of building a 350 and I want to do this to the heads!!! but im afraid of messing em up!!!!

It not hard at all. Don't get over welmed. When you look at the heads you will see the flaws in the cast. Remember its NOT about making everything bigger is about making them smoother and efficient. If you remember that you will do fine. Expect to take some time to do this work.

It sure does take some time!

I am working on some Aluminum L98's and I have about 15hrs in them.
I have one head done and I finished the intake side of the secon head and just started the exhaust.
It isn't hard at all just time consuming.

I did basically the same thing to a pair of 081s that are on my G20s 305. Added a L82 cam, headers, Edelbrock TBI intake bored to 2", 454 TBI, lots of fuel pressure, lots of tuning. Here is the timeslip in a 5,300 lbs conversion van. Mine is the right lane, his is the left. I smoked this 02 VW Beetle 4 cylinder Automatic.

I just had a thought reading this thread for what is probably the 5th time... will the 1.60" exhaust valves work on a 305 (without excessive shrouding)?

Fast355- the more I look at your numbers the more I don’t know what to make of them. I’ve always been impressed with what you’ve posted from that TBI van, but when it comes down to it, working the numbers you’re making about 283hp at the crank… which isn’t _that_ great (not picking on you, just thinking "out loud"). Using the same equations it seems that my formula 350 is making about 290hp stock(ish) (3710lbs, cold air intake and cat back, running 13.59@100), of course, that is from a 350, but with less cam, stock heads that flow probably 15-20% less factory exhaust manifolds, factory Y pipe (more accurately described as a T). I just want to see more from what you’re running, especially since I’m generally a bigger fan of TBI then TPI.

The 1.60 will shroud, on my 416's I stayed with 1.50 and had the machinist unshroud the new intake valves for me. That side of the chamber is tight for the 1.50. I did not see a big benny for going to the 1.60's

If you are using the calculations that give HP from trap speed or ETs, they suck. They are WAY OFF on my van. They cannot take aerodynamics into effect. Download the old version of Cartest as it is much more accurate. Between Cartest and DD2000 I am running within .3 seconds and 2 MPH of what it guessed and within 1 MPG of the estimates.

I am actually making 272 RWHP @ 5,300 RPM and 315 ft/lbs @ 3,350 on a Mustang Dyno. I have run a 15.6 with this 312 which is right is approximately 1 full second quicker than an AWD Express 6.0 liter with 4.10s. Traction is my enemy. I could have made 285 FWHP (seen it done) without touching the heads, from the L82 cam and headers only.

Tag for winter building

Playing with cartest and DD, DD shows 252hp with the most accurate info that I can give it about my mostly stock ’87 formula 350. OTOH, cartest shows that I need 329hp to match what I’m running in the ¼… unlikely for a stock L98 with just a cold air and cat back (and that 3710 is probably a little light, that was weighed when I was 295, I’m usually around 305 and with a bone dry gas tank).

I tried playing the same game with my K1500 full size blazer that has run a 17.0@78mph dead stock (well, it started just short of 18’s but I tweaked that down messing with timing and other little stuff) with a FULL tank of gas and a pile of lumber in the back, coming in at right around 6000lbs that night. Again, same results, CT predicted numbers that I just do not believe.

My instinct is that the van aerodynamics aren’t as bad as a full size truck, and you’re mostly fighting raw frontal area. That being said I’d bet that it has very little effect before about 60mph and I’d bet less then .1 in the ¼, compared to a more normal car running similar speeds.



Honestly, after knowing a few dyno operators I trust dyno numbers less then I trust approximations based on your ET (if you know what you’re looking at and adjust some for traction and the driver, which you can figure out if you can see a whole time slip). Many manipulate results to show what they think will get the car’s owner to make more runs/come back. On top of that mustang dynos are weird. Usually, they are very conservative, but I they don’t seem to be consistently conservative and every once in a while they’ll go the other way.

All this is a long way of getting back to my original point, fine, you don’t like how I’m estimating what I’m making, I don’t like how you are, but it doesn’t matter, do it my way or do it your way, I’ve got an almost stock L98 that is running numbers that suggest that the numbers that you’re posting are not that great. The fact is, that in theory I agree with you and like the TBI setup, and would like to try to figure out why your numbers aren’t better or why mine aren’t worse and how my TBI truck or even my old crossfire car fits into this.

Again, not picking on you, I respect what you’ve done and especially the amount of info you’ve made available about it, but judging from your numbers I’m seriously considering slapping an old TPI setup on my truck, no matter how much that goes against my instinct and no matter how much I hate the TPI setup (I like the looks, I hate working on it)

Ill be pulling the 416s off of the LG4 camaro i just bought and plan to port the piss out of them.

According to dd2005 with my planned setup and the ported 416s i should be making 446HP / 498ft/lb at the fly which should make for a nice daily driver!


Edit: oh yeah, if i screw up ill throw on my crappy 882s and have a 300hp motor lol

? 446HP with ported 416's? care to share the other specs? you've got my hopes up for my build...

been poking around with cams and things and came up with the 480HP range but i guess nobody seems to think is achievable.

350 4 bolt .040
-10cc pistons cr 10.5:1
comp xe268
1.5rr
750cfm DP holley
rpm air gap
hei

hope to get around 220/160 when i port these but not really expecting them to flow that well for a first time port job.

shouldn’t be that hard… it will only take about 215-220cfm on the intake and over 75% of that on the exhaust at about .050” below your max lift on the cam. Cam timing should be so that your peak HP comes between 5800 and 6000rpm on a 350.

Though I’ll eat my shorts if you see 498lb-ft out of it. More like 395-420 is realistic.

I don't pay for dyno runs andl I trust myself as the the one that punched the numbers into the Mustang Dyno right from Mustang's recomendations. They said something like 5,400 lbs and 25 HP @ 60 MPH, IIRC. The Mustang is accurate, IMO.

Your Blazer even though it is 4x4 and weighs maybe 300 lbs more, is surely geared better. Plus it more than likely gets better traction. I spin all the way through 1st gear. Even launching lightly, it will still fry them. Your blazer with 210+ FWHP, lets make it 220 FWHP/320 FT/LBS since you messed with it, only ran a 17.0 @ 78. I am pushing more frontal area, with less cubic inches, and slightly less weight, (I was like 5,700 lbs that night, 40 gallons gas, tools, junk, etc) to a much faster 15.5 @ 88.7 That is 10 MPH more and 1.5 seconds faster. I have a feeling that the weight is worth about 1 tenth for every 100 lbs. That is 3 tenths. The old saying is that One Tenth is worth 10 FWHP. That means that I am 120 FWHP over you. That is about 340 FWHP and fits the rule. 340 FWHP is roughly 285 RWHP assuming known losses on similarly equiped drive lines.

I think the frontal area and Aero have more to do with the 1/4 mile times than you give credit to. I am pushing about 42 square feet of box frontal area down the road at 50+ mph and that makes a huge difference. You have to remember that HP to go faster increases with the cube of speed. So in other words, if I want to go twice as fast, it takes 4x the power. It takes alot of HP to overcome the drag. I figure at 70 MPH I am using a good 45+ HP to overcome drag of both the air and the tires, drivetrain, etc. Well at 70 MPH I get 18.5 MPG and figure that I am getting .500 BSFC. Gasoline weighs roughly 6 lbs to the gallon. That is about 46 average FWHP at 70 MPH. How do I get that? 70/18.5x6/0.5=45.401 I could be getting BSFC down in the .450 rane. That would raise HP required to 70/18.5x6/0.45=50.45 FWHP.

83Crossfire TA- My old ported 601 headed 355 would pull roughly 340 ft/lbs at the wheels in a totally untuned state. I am sure it would have done better with PROM tuning. I would have to agree with your 420 ft/lbs guess though.

SittingBull are you sure those weren't 283 heads you started out with? Take a look at these http://cgi.ebay.com/ebaymotors/SBC-2...spagenameZWDVW
I've never seen 305 heads look like what you have, it looks to me like someone milled down some 283 heads. In any event nice work on the porting!

A good informative thread is starting to get hijacked all to...
with a lot of BS.

No Sitting Bull didn;t use 283 heads. if you look at the combustion chambers they are different.

Look at the ports in the pics. thats exactly what not to do to a cylinder head. The exaust ports and soo big you'd need a 1-7/8" header. yet tini tiny 1.72" 1.5" valves.
The intake port entry is all wrong.

The 601 heads that SittingBull stated with are 305 van and maybe truck heads. I know they were factory equipped on my 1983. My set was flowing 224/160 @ .500" @ 28 in/h20. The valves are 1.84" & 1.50" stock and the chamber CCs between 52 and 53 cc.

Like F-Bird'88 says, this thread is becoming something it was NEVER intended to become. Let's NOT use this as a forum of debate, when it is really a simple thread on how to port and polish an inexpensive set of heads for all of us on a strict budget.

And finally, no my 601 heads are not from a 283, they are 305 heads that I was given for free by Apeiron. Nice gift, eh?

So, let's just leave this thread alone, now, and only add to it if we have legitimate queeries pertinent to the subject

So here are a few pics of the latest heads I did.

Got them back today after getting the valve guide tops shortened (again). It pays to check the details. Would have been disasterous if I'd run them as is. Would have destroyed all the valve seals.

CC'ed a chamber today. It's 61cc's. Thats with Manley 1.94x 1.60" valves
some chamber deshrouding for the larger valves and a cleanup cut (resurface) off the decks.

Total cost in US $$'s is $350 not including taxes.

Must have some despirate machine shops out there... around here just a basic dissasmebly, clean up, check for problems and reassembly runs around $385 and then if you actually want some work done you add on to that. I think just a basic deck cleanup (not real cut) adds $40/head...

I was quoted 400 for a rebuild, plus mild port and polish from Rays Cracked Heads in Southern Indiana, so 385 sounds about right for around here.

Thats the thing. Why waste the machinists time and your $$'s on stuff you can do yourself. i dissassembled and will reassemble my own heads at home.

The machinist does the required machine work and supplys the hard parts and the hot tank and bead blast operations. You do the rest. that way you can afford some quality valves and springs etc and still stay within a $tight budget$.

Because they charge you for those basics no matter if you bring the heads in complete or as a bunch of parts in a box. I’m in no way afraid of doing my own work to save a few $ but I couldn’t figure out how to get just the basic machine work/valve job, guides… done for less then something in the mid $500 range or so…

I guess its just unfortunate that in your area the shops want to gouge you.

My machinist is also my neighbour. He's not really a "Race shop". More of a production/contract shop for dealerships and fleets and local garages.
But he does do some performance stuff and used to drag race. So he's not part of the "performance/speed shop industry". I've found many "speed shops" tend to charge too much for what they do. Some shops/builders are worth the extra $$$ if you want the best or most power. Many, are not. Attention to detail costs money. I ask him how much for this, this and that+ supply this this and that part . He gives me a price and does it. hands me the heads and the parts, I pay him and off I go. Don;t waste a lot of time cause I know what I want done and usually can quote part numbers off the top of my head.
Saves time and $$$.
----------
I guess its just unfortunate that in your area the shops want to gouge you.
There are shops like that, here too. But luckly there are some good machinists and lots of competition.

My machinist is also my neighbour. He's not really a "Race shop". More of a production/contract shop for dealerships and fleets and local garages.
But he does do some performance stuff and used to drag race. So he's not part of the "performance/speed shop industry". I've found many "speed shops" tend to charge too much for what they do. Some shops/builders are worth the extra $$$ if you want the best or most power. Many, are not. Attention to detail costs money. I ask him how much for this, this and that+ supply this this and that part . He gives me a price and does it. hands me the heads and the parts, I pay him and off I go. Don;t waste a lot of time cause I know what I want done and usually can quote part numbers off the top of my head.
parts that he can supply at a competetive price i get form him.
Some stuff is cheaper to get from the US. I'm right on the border. Some stuff is actually cheaper here. pays to shop around. But doeswn;t usually pay off to cut corners too much or try to grind down your machinists pricing. If you think you're being charges for redundant or unnessessary stuff, discuss it with your machinist. By some tools and do some of it yourself.
Saves time and $$$.

Shouldnt you port the area on the valve guide boss on the intake side as well? I mean, air isn't being thrusted through there and with larger intake valves as always, would it be a waste of time?

i have a question on my P&P job...and figured this would be the best place to ask...

i hit the valve guide on the exhaust side and thinned it out pretty good...im worried about it being weak and making the valve seize up or something...i will try to get some pics and post em, but what should i do about this? just take it to my machine shop and ask the machinist whether is f*ckered or not? thanks

curt

If you dug into the side of the valve guide boss a serious/excessive amount where the strength of the guide is definatly in question, you can have the machinist install a new cast iron valve guide. Then you'll want to recontour that replacement guide. You'll need a new valve job (grind in a new valve seat) on that port if you weren't planning on doing that.

Post a pic or two. may not be as bad as you think.

so it may not be that big of a deal?..id be willing to pay a little bit out of pocket just to keep it off my mind...it was a rookie mistake i am willing to pay for. but if the machine shop can fix it or if it doesnt have to be fixed that would be great...i will definately try to get some pics up ASAP...

thanks

curt

I’m having a hard time imagining how you could even do enough damage to a valve guide during porting that you would still worry about it’s strength… lets see some pics…

Just wanted to ask - will what you have done on your early casting 305cid heads work on the later 305cid vortec castings for example #12552520? I know that gasket matching and larger intake valves are fine, but what about the rest. I too am going to p&p a set of 305cid heads, but will be working with the #520's - I'm collecting as much info as I can...
Great thread and the pics are excellent as well.
-Andrew