Here's the situation: I went to put the spark plugs in my engine today (fresh engine still sitting on the stand) only to find out that they won't fit with my SLP 1 3/4 headers. The plugs on the #7 and #8 cylinders are not even close to clearing the primary tubes..ie, a shorty style plug will not even work! Man, talk about ruining my day! So, I am assuming that the regular style angle plug heads are different then the "L98" style? What style are you guys using and with what header? I am going to call AFR monday to get the low down and see about the possabilty of exchanging the heads for either the straight or "L98 style" Man this sucks!! Any ideas or input?

Thanks,
James

 

I'm somewhat having the same problem as you. I ordered the "L98 Angle Plug" (Vette Plug) 195's, and I'm having a hell of a time getting the plugs to work with my Hooker Super Comp headers.

I emailed so many different places before I actually placed my order with AFR,(AFR, Hooker/Holley, Accel, etc.) and nobody knew the difference between angle plug and L98 angle plug styles....Not even AFR which is BS. After not getting any answeres, Dave at AFR and I decided since I was using L98 heads previously with the Super Comps, that I might as well stick with the L98 angle plug style..

Well, when I got the heads on and bolted up the headers, I was devastated IN A VERY BAD WAY, when I found that the damn plug ends were within 1/8" of my friggin headers!!

There was no way I was going to be able to return the heads since they were milled down to 60cc and drilled for centerbolt covers, and I was NOT going to hammer dents into my headers to get things to work.

The main reason that It's so damn tight is because AFR machines the spark plug holes to accept the old style 13/16" head "gasket" style plugs. The gasket style plugs are far longer than a standard taper seat 5/8" head style plug.....and you know what, you CAN'T get shorty style "gasket" plugs. They're only offered in taper seat style plugs as of right now.

The only thing I could think of was to cut down the length of the metal snap ball at the end of the plug. I was able to gain about 3/16" of an inch by unscrewing the end and cutting the skirt portion down as far as possible while still making sure the plug boots snap onto the plug end. the threaded portion of the plug end had to be trimmed too in order to take advantage of the decreased ball-end length. (This obviously only works with plugs that have a screw on type of ball end).

Still, I have VERY minimal clearance. I went out and bought a couple Taylor Vertex Hegh-Temp woven fiberglass boot/wire protectors for the two plugs that are still too close to the header tubes. Also, if you don't already have 90º boots, invest in a set of wires that have them now.

I'm still hoping this will work for me, since I havent ran the car yet.

You might be able to return the heads to AFR if there wasn't any special work done to them. Keep us posted, I know your pain.

------------------
86 Trans Am WS6 Black with tinted windows, shaved door handles
ZZ4, Mini-ram, true duals
***Too many other mods to mention***

"In the future, cities will become deserts,
roads will become battlefields, and the hope of mankind
will appear as a stranger" The Road Warrior

 

Oh man...I'm glad I'm not the only one!! Dude, I was darn near devastated today when I saw what was happening! Thanks for the input, though!

What brand of plug are you using? I went plug shopping this morning to look for the shortest I could find but they all seem about the same length...to long!

I could probably get radical with the torch and a hammer and bang in enough clearence to make this combo work, but I hate to beat up a $450 set of headers. Even if I did that, I will still be fighting burnt boots all the time...even with heat shields on them.

It will be interesting when I talk to AFR monday to see what they say. Somebody has to know what the difference in between the two styles! Do your plugs point inward and slightly down towards each other?

Thanks again,
James

 

Yes, you're right. All plugs are the same length, which sucks. (Gasket style being longer than the tapered seat style group)

I'm using Accel U-grove #112 plugs. They're a colder running plug, which I will most likely need because of my compression and cam.

The Accel plugs are actually made by Nippondenso/Denso, so they're an excellent quality plug. Hopefully Accel will add a gasket style plug to their lineup of shorty plugs pretty soon...I haven't called them yet about it but I should. A/C supposedly makes shorty plugs, but I'm yet to find them in the gasket style.

Let us know what AFR says James.

------------------
86 Trans Am WS6 Black with tinted windows, shaved door handles
ZZ4, Mini-ram, true duals
***Too many other mods to mention***

"In the future, cities will become deserts,
roads will become battlefields, and the hope of mankind
will appear as a stranger" The Road Warrior

 

James, please keep us informed. AFR heads and 1 3/4 SLP headers are 2 of my future mods, and it would help to know if this combo will work. Good luck and I hope everything works for you!

------------------
1989 IROC-Z 5.7L
NOS 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

 

I've got straight plug AFR 190's and SLP 1 3/4 headers and the plugs fit with no problem.

 

Ok, it might take a little work, but I think there are shorter plugs out there than what you guys might be using.

406, what plugs did you try? I need the part number and manufacturer.

Steve, you are using a plug that as best as I can tell is 3/16" longer than the plugs used in the L98 aluminum heads. I think I might be able to find something for yours as well that may be shorter and the same type, but for both of you I have a couple questions.

How do you feel about a 5/8" hex instead of 13/16"?
How deep is the gasketed area on the AFR head?

 

Madmax,

I've looked all over for a shorter plug, with no luck. I couldn't thank you enough if you come up with a shorter plug that will work. Seems that all gasket plugs are of the longer design...as you stated, longer than a gasket plug anyway.

As far as a 5/8" hex instead of a 13/16" hex.....That would be a godsend!!! I wouldn't need to use such a cumbersome wrench or socket if it were 5/8", but I don't think they offer gasket style plugs in 5/8" hex....do they??

I'm not sure of the depth from the head face to the gasket landing, but I could try to measure it when I get home in the morning (working nights). My engine is in the car with headers installed, so James, do you think you could take the measurement on yours since it's a bit more accesssible?

Thanks guys.

 

madmax, I will owe you big time if you come up with a plug that will work!

By saying you wanted the depth of the gasketed area, do you mean the depth from the outer surface of the head to the flat machined into the head that the gasket seats against? If so, that depth varies from .150 to .475 because of the angles and irregular surfaces.

The plugs I have tried are Champion RC9YC and AC's FR3LS which are the plugs AFR recommends as a starting point. I went and eyeballed some other plugs yesterday but they all seem to be about the same length.

I appreciate you trying to help myself and Steve out.

 

Have you guys looked at the standard Bosch platinums, not the one with the 4 electrodes. They seem to be bout a 1/4 shorter than the AC Delcos.

 

Actually, that's what I used to run when I had the stock ZZ4 (L98) heads on my engine.

The taper seat ones are slightly shorter because of the ball end size, but the gasket style ones are the same length as the others we have been looking at.

 

Not sure about AFR but I have ZZ4 angle plug heads and SLP 1 5/8. Plus fit no problem, using Rapid Fires #8. Came stock with MR43LTS AC Delcos


------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Well, I talked with AFR today. My sales guy (Marc) didn't really have any other ideas as to a shorter plug. But he did seem alittle baffled as to why I was having a problem in the first place. He stated that there is definately a differance between the L98 style and the angle ones I have....which is good....I guess. But he also said that he has seen that combo (angle plug with SLP 1 3/4 header) work before. So I asked him about exchanging the heads. Since I didn't have any special machine work done to the heads (minus steam holes) that it "probably" wouldn't be a problem. He had to talk to his people over there and is supposed to get back with me tomorrow.

So, do I opt for the L98 style plug or the straight plug?

89GTA383....what plug are you using and how much clearance do you have around your plugs? Is it pretty tight?

Thanks guys,
James

 

The only thing I have been able to find is the L98 aluminum head plug, which is the FR3LS that 406 tried. It's the same length as the modified plug you are using though Steve, and it has a 5/8" hex instead of 13/16". I noticed you are using a non-resistor though. I'll see if I cant check an NGK later today, its a BCP7ES, which is supposed to be a 5/8" hex, 3/4" reach, gasket seat, non-resistor, the same temp range as what you have, and *hopefully* shorter than what you have in there right now.

 

I am running AFR190 L98 Angle Plug heads and SLP headers. Clearance is awesome. I have ZERO clearance problems. Are you sure that you have the L98 angle plug heads? I know for a fact that the standard angle plug heads will not work well with SLP headers. I am not sure about the SuperComps LTs though.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Hey TRAXION, do you think that the AFR195's would work as easily with the SLP 1-3/4" headers, given your experience?

------------------
1997 30th Anniversary SS LT4 #74 with K&N, white gage faces, and Hotchkis shock tower brace - SLP SBC's on the way
1996 Corvette Grand Sport LT4 #509 with K&N, Flowmaster exhaust, Hypertech power programmer, and Baer slotted/cross-drilled brakes - on the way: SLP throttle body and 1-3/4" headers, heads ported, 4.10 gears, custom Panasonic/Alpine/Audio Control audio system
2000 Chevy TrailBlazer

 

As long as you are 100% sure that the 195s are 'L98 angle plug' then you won't have a problem.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

406tpi,I had the same problem you are having. My slp 1 3/4 headers wouldnt clear the sparkplugs with my angle plug afr 195cc heads. I had to toss my slp headers in favor of hooker super comps. I was mad at the time because of the extra money that it cost me, but imo the super comps are a much better header. I dont know if the regular style angle plugs are any better than the L98 version, but with my combo stock bottemend,miniram,afr 195's,zz409,and all the boltons, I ran a 12.1 at 118mph babying it out of the hole on nittos. So if you can afford the super comps i would get those imo you will have a better header and a faster car.

------------------
1989 Irocz
350 T-5

[This message has been edited by STOCKROC (edited April 03, 2001).]

 

Thanks Madmax, I'll be awaiting your word on whether or not the NGK is any shorter. 5/8 hex, 3/4" reach, and 14mm thread is the exact stats that would work, and hopefully it'll be shorter..thanks again.

Tim, They are definately L98 style angle plugs. I double checked the invoice, and it surely says "Angle Plug L98"...That isn't to say that AFR sent "angle plug" rather than "L98 angle plug", but I'm pretty confident that they got it right. To be specific, It's the #1 and #7 that are still giving me clearance problems with my Super Comp LTR's.

Thanks everyone, you've all been aa big help, and I'm looking forward to your further suggestions.

Steve

 

Tim, thanks for your info. One more thing I was wondering about; when you ordered your AFR heads, what options, i.e. AFR part numbers, did you order with the heads? I talked to 2 guys there and they both asked me what options I wanted the heads with, like drilling extra holes for sensors and stuff; I couldn't believe they couldn't tell me when I told them the heads were for a 92 350TPI motor. Also, I don't know what size my current cast heads are, AFR told me they could be 54 or 58cc on the stock motor; any way you know of that I could tell, so I can tell them what to mill the new heads down to?

Any info you could provide with your ordering experience would be helpful.

Dino

------------------

• 1997 30th Anniversary SS LT4 #74 with K&N, white gage faces, and Hotchkis shock tower brace - In process: SFC's
• 1996 Corvette Grand Sport LT4 #509 with K&N, Flowmaster exhaust, Hypertech power programmer, and Baer slotted/cross-drilled brakes - In process: SLP throttle body and 1-3/4" headers, AFR heads, 4.10 gears, custom Panasonic/Alpine/Audio Control audio/ADS system
• 2000 Chevy TrailBlazer

[This message has been edited by Anniversary-SS-man (edited April 04, 2001).]

 

I don't have my optionlist here. But, check out Mike D's page. He has his options listed. BTW - he is running SLP 1-3/4" headers.

http://www.eecis.udel.edu/~davis/z28/winter01/heads/

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Tim:

Thanks for the link, he's got alot of good info - I appreciate it. And, if there's anything that you personnaly dig up at any point, feel free to e-mail me.

Later dude,
Dino


------------------

• 1997 30th Anniversary SS LT4 #74 with all SLP options and K&N, white gage faces, and Hotchkis shock tower brace - In process: SFC's
• 1996 Corvette Grand Sport LT4 #509 with K&N, Flowmaster exhaust, Hypertech power programmer, and Baer slotted/cross-drilled brakes - In process: SLP throttle body and 1-3/4" headers, AFR heads, 4.10 gears, custom Panasonic/Alpine/Audio Control/ADS audio system
• 2000 Chevy TrailBlazer

 

Stockroc,

So, you have the standard angle plug heads, not the L98 angle plug and they work fine with the Super Comps LT's?? What are you using from the headers back (ie, the rest of the system). This might be an option for me...it all depends on what AFR says...still waiting to hear back from them.

I was also toying with the idea of just buying the L98 style head and selling the ones I already have. It shouldn't be too hard to sell a set of AFR's

[This message has been edited by 406TPI (edited April 04, 2001).]

 

the plugs I use in my 68 gen 1 are accell shorty style... the car is not here or I would givee you the part number... I had to look them up under a 68 corvette or something like that... call summit or jegs and see what they have for you...

zroc

 

Yes I used the standard angle plug heads with my hooker super comps. The clearence was excellant. Plug changes were very easy. (if you are wondering why I keep talking in past tense it is because my afr heads were damaged when I floated the valves, so I am currently running stock heads.) I am using a custom exaust fabed by my local exaust shop. They did a pretty good job on it for cheap. If you want to mail order an exaust i believe muflex makes a bolt up exaust system for long tube headers, however it is expensive.


------------------
1989 Irocz
350 T-5

 

Thanks everybody for all the information!! I really appreciate it.

I got back in touch with AFR and they said they would do a straight up exchange on my heads since the motor hadn't been fired up. The catch was they have about a 3-4 week build time right now So with losing about a week in shipping and all the other BS I figured I wouldn't have the car running till the end of May.....ouch!

So, I decided to go the Hooker super comp route instead My headers should be here early next week and hopefully the car will be running by the weekend.

 

Got the new headers mounted on the motor today.....wow, what a difference!! There is tons of room with those angle plug heads. I like it

What is the deal with that slip tube on the #8 primary? Why would Hooker design it that way? Seems like it would have a tendency to leak.

 

I'm with zroc, i've gotten some shorty Accel plugs from Summit that were quite a bit shorter than "standard". Sorry, no p/n off hand either...

-Rich

 

Yep, you are gonna love doing spark plug changes now, should be able to change all 8 in a 30 minutes are so pretty easily. My slip tube dosnt leak.( haha that sounds funny)



------------------
1989 Irocz
350 T-5

 

Yes, but are they the "gasket" style plugs? AFR mills the spark plug holes to accept only the gasket style plugs (the plugs with the 13/16" hex head), and not the standard "tapered seat" plug (with 5/8" hex) that is so common.

 

Ive got L98 AFR 195s and SLP 1 3/4 headers and clearence is good,no problems.I can put the plugs with the headers on,dont know hats up with your stuff,maybe you got the wrong heads.