87ROCZ

iTrader: (3)

Hey folks.... just had a few questions in regards to switching to Vortec heads on my 87 IROC.

I have been thinking about going the Vortec route for sometime now and I was lucky enough to come across a set of 062's off a '98 Silverado. I want to stay with my TPI as I bought large tube runners awhile ago and I just plain like the TPI look, plus from everything I have read the TPI-Vortec combo can have lots of potential over stock heads. I know I need a new base plate to mate the TPI upper to the Vortec heads.... but here is a couple of questions I had...

1. I have a set of Hedman 1 5/8" shorty headers that I bought for my L98 083 heads, can I reuse these headers on the 062 Vortec's?

2. Accessory bolt holes. Does the Vortec heads have all of the accessory bolt holes ready to go for my stock power steering pump, alternator (brackets, etc), and water pump? Keep in mind that my 87 has the dual pulley system (flat belt for water pump/alternator and a v-belt for the power steering pump)

3. Can I reuse my stock base plate bolts that bolt the plate to the heads or will I need a new set of bolts for the Vortec's? I saw in an article on Chevy Hi-Pro that you need an Intake bolt kit that have special shoulders?


Anything else that I am missing or not thinking about?

Thanks

Stan

zraffz

1. Not sure, L98 are angle plugs while vortecs are strait. might have some clearance issues with plug wires.
2. yes
3. need new bolts. Vortec heads only use 8 bolts that are a different length as opposed to normal 12 bolt sbc.

87ROCZ

iTrader: (3)

Thnaks for the reply... can anyone help me out on #1?

LilSki

iTrader: (1)

I have hedman 68470 headers on my vortec 350 and they fit fine. The plugs are in a different spot on a vortec head so a few are very hard to tighten. I think the #5 plug I had to tighten with a wrench from under the car.

EDIT: You can get a glimpse of them in this shot.


And here too

InfernalVortex

iTrader: (4)

I have long tube hedmans... not the same as yours, but I had to get my #5 plug from under the car with a wrench too.

UNTIL...


I got this bad boy!

http://www.harborfreight.com/21-piec...set-67974.html

It's not useful for a lot of work in tight spaces, but it is PERFECT for spark plugs with headers. It's also easy to do my polylocks on my rockers with them.





And with my Vortecs, there were 3 or 4 of these that were AWFUL to get to. But this socket makes it such a breeze. I can do all 8 from above in 5 minutes. Totally worth it.


Anyway to answer the OP's question, Vortecs work with any standard sbc header no problem. Getting to the plugs is a pain but not impossible. With the goofy thru-sockets above they're an absolute breeze. No extensions, no deep sockets, no fighting to get it in and out, no wrenches, no wrench+socket combos. Just one socket and one wrench works on all 8. It even has the perfect curvature to be able to loosen and tighten the plug without the handle hitting the header flange.

87ROCZ

iTrader: (3)

Thanks for the replies... I am glad to know that I can still use my 68470 headers.

And hey Infernal, that's an awesome looking spark plug wrench, I got to get me one of those! Thanks for the tip and link!

1983Zsled

Sorry to revive your thread, but I have Hedman 68470 headers on my vortec 906 headed 350, and I thought they fit ok, but i have my motor pulled apart and I noticed the fit isnt 100 percent on the exhaust port. I have a few pics I will post tomorrow to explain what I'm talking about. The header tubes sit about 1/8 to 1/4 lower than the exhaust port. I'm sure this is a restriction, and I will be using a plasma cutted and welder to relocate the mounting holes so the ports align better. In the meantime I'm doing a search to see if anyone else has had this issue?

1983Zsled

I downloaded a pic today to illustrate what I'm talking about.

You can see where the pipe sits on the exterior of the head. It is too low. I never would have found this I had not pulled the motor out.


http://s681.beta.photobucket.com/use...miss1.jpg.html



Anyone else had this issue?

1983Zsled

https://www.thirdgen.org/forums/memb...der-miss2.html

Dyno Don

iTrader: (7)

Yes, all the newer heads have the exhaust port raised.
I make mine to fit them all.

1983Zsled

Nice! I'm surprised I didn't find any info out on the net about the fitment of those headers with vortec heads
.
Thanks for clearing it up. I imagine if i weld in the old bolt holes and drill new lower bolt holes it will fix my problem. I'm worried that it might suck up the cross pipe from the driver side into the oil pan though. It was tight before?

87ROCZ

iTrader: (3)

Could you not do some porting on the exhaust port to reduce that restriction? How do you fix this?

LilSki

iTrader: (1)

That is interesting. I'm not taking my headers off anytime soon but I will make sure to check that out next time I do.

1983Zsled

I don't know a lot about Vortec heads but from what I've read the floors are thin in the casting and to shave out and 1/8 th or so I think I'd be in the water jacket. As stated above I think I'm going to relocate the mounting holes on the flange pulling the 1 5/8 pipe up to the right location. I am concerned that in doing this it may pull the pipe that crosses under the oil pan into it. If that occurs I will have to lengthen the flange of the connector to meet the Y pipe.

Or maybe Santa can bring me some cash to buy some of Dyno Don's headers. That would be sweet!

1983Zsled

A better pic. You can see where the aluminum gasket sits and how low it is.

skinny z

I think you'll find that although the gasket sits low it does not protrude into the port at the top. That the gasket sit low relative to the bottom of the port makes no difference flow-wise. That's of course that you're using a 1.5" round port header gasket. A Percy's 68021 fits both the Vortec and an 1 5/8" Hedman header with no intereference into the port and a decent seal all around.

1983Zsled

I believe the gaskets are Percy's alum seal 1.5 inch and I ground them to match the 1 5/8 port when I installed them last year. In the photo you can clearly see the black carbon outline of how low the header port sits in relation to the exhaust port. Using a photo edit I was able to outline the shape as in the pics above Posts 8 and 9. I was having issues posting it directly into the message? Got it now!

In any event as soon as I get my heads back from their valve job I will bolt the header to the head ( without valves in) and using an inspection camera I will take a pic and post it. Probably wont have the heads back till the middle of next week. Maybe your right, we'll find out... As I understand Vortec heads exhaust port gains can be made by porting the roof for more flow. I have done some porting there so if the pipe is low as illustrated, it wont work!

1983Zsled

For those following this thread I got my heads back from the machine shop and started playing around with the header fitment. As Dyno Don had mentioned the Heddman headers do sit too low with the Heddman 68470 headers. I took some pics to show the protrusion which was about an eighth of an inch at the top of the port.

It was hard to get a decent pic of the middle of the top of the port, but as you can see, there was a major restriction, especially in the corners at the top of the port. All were the same.

In order to fix this I welded the tops of the bolt holes and re-drilled the mounting holes so I in effect raised the header to meet the ports. I then used a carbide tip and port matched the exhaust header to the port.


I know this is a terrible photo but you can see that all I did was fill in the top of the original bolt hole with about an eighth of weld the drilled and ground the bolt hole lower, thus raising the header on the port. You can see the original hole line at the top of the weld. This isn't a structural weld its just filler so the header doesn't slide down with the weight of the exhaust attached.

Here is a pic of the port with the headers raised. I also did some die grinding in the corners to get some smoother transactions. Remember this is the top of the port.



The bottom line is that these headers don't fit vortec heads properly. I'd say that my 1 and 5/8ths headers were only open to 1.4 at best. Maybe not a big gain to be had but I'm kinda fussy that way.

skinny z

What is the perspective of the top photo? Is it from the port looking "out" to the header?
I appreciate your "fussiness". This attention to detail is what makes the difference between a good performing engine and one that out performs.
I'll be having a close look at my old Vortecs (I've since moved on to RHS Vortecs) and a set of 1.5" round header gaskets. I'll have to go on memory regarding how the header fit though. They're installed (not the part number in question but still Hedman) and I can't remove them to measure.

1983Zsled

I was using a scope/camera to go inside the exhaust port and look out. The overhang was from the top of the port, and in that pic you can really see the corner, which is where the majority of the restriction is.
There are no valves in the heads now and the best way was to "feel" with my finger. Before the modification the drop on the bottom of the port would have been about 3/8th's of an inch. Now it is just about an 1/8th of an inch and the port lines up much better. Those headers are sold as 1 5/8 primary's but the inside diameter is 1.5"

On the heads I did home porting and polishing, then sent them out for new valve guides, decked, and 3 angle valve job, I think those heads will now perform well. They are 906's and have the pressed in seat on exhaust side. They only had a one 45 degree angle on the exhaust seat as well. Hoping with all these changes including the headers it will breath a little better.

87ROCZ

iTrader: (3)

Ok... so after 3 long months of off and on working at my engine swap tonight I finally got it all buttoned up and fired up...WOOT!!!! I had her running long enough to come up to operating temperature so maybe 15 mins all total.

I noticed that at first she was really hunting for her idle, I had my PROM burned a few years ago to accommodate my Crane 2032 cam install, my ported L98 heads and a few other minor mods. At the time the programmer dude set her at 750 rpm for the idle and it idled fine.

So a few observations..

1. I noticed that the Air/Fuel Mix is running Lean once she's in Closed Loop (A/F gauge running off the O2 sensor)... it sits on the first notch of the AutoMeter gauge ( the one with the LED's) as it goes into LEAN (first red LED)

2. The hunt for the idle...

Questions..

1. Considering that I have much better flowing heads (well much better than the ported L98's) I sort of understand the Lean condition I am seeing, she's getting more air with the same amount of fuel which will obviously Lean out the A/F mix. Will my Prom compensate for this Lean condition (will it learn over time?) or can I just bump up the Fuel Pressure? I got an Adjustable Fuel Pressure regulator so I could bump the pressure up, right now at idle she sit's at around 38 psi.

2.Similar to the above, will my PROM eventually learn to find it's Idle?

I am hoping next summer the programmer dude comes back to my hometown's dyno shop, if he does I will be definitely getting him to burn me a new Prom bin because I know that's the true way to get the most out of my setup. But in the mean time I would like to get her running half decent.

vetteoz

iTrader: (13)

A MAF setup should " reasonably" adjust for any extra airflow assuming the original tune you had was correct because it measures actually air flow into the engine

The ECM will always try to idle at whatever (750rpm ) is programmed in the tune so you are supposed to set your idle to that speed.
If say your cam is too big to idle at that speed or you have set the stop on the butterflies for a lower rpm then the ECM will always be fighting ( hunting ) to achieve the programmed idle

You disconnect the IAC , adjust the idle to the rpm in tune then reconnect the IAC.
https://www.thirdgen.org/forums/post...610-post2.html

If you want a different idle rpm it has to programmed in

TTOP350

iTrader: (8)

L98 Fbody heads are strait plugs, the aluminum corvette L98s are angle plug