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Monza Harry wrote:L98 Now I have to ask which casting numbers, as the nomenclature has engulfed the cast iron heads and possibly two versions of aluminum. The '113 Aluminum heads already have a 0.200 raised exhaust, so I assume you are refereeing to the Cast Iron version, (which has a stock location Exhaust port from the AFR reference). So if your headers are on "CI" heads and your headers have the only exhaust port offered by hooker for an H-Body they match but not the AFR's. If the heads are aluminum and the headers have already been changed to the raised exhaust version you are going to be close, but still you are going to be 0.050" short, so I would expect some issues with header fitment. If the headers haven't been modified the they are to low on the port and blocking it and causing serious flow issues. Now if you look at this link you will see GM leaves the bolt holes in the same spot and just raises the ports, as for AFR I am not sure. The headers will bolt up but that will result in the ports being partially blocked. Sorry for the late "Edit" My laptop decided to Restart in the middle of my corrections, I can't type as fast as I think so I frequently have to re-sort my thoughts into "Human English" from D b @$$ Harry http://www.lingenfelter.com/mm5/merchan ... iW2ZJWFPmg
From: EVL VEGA
Sent: Tuesday, October 20, 2015 7:29 AM
To: Rob Wood
Subject: Re: New Quote Request -
Another quick question. I see a note on these heads that say "Exhaust port is raised .250 over GM L98"
How does that relate to a raise comparatively in my 70-71 400 iron heads. Was l98 already raised above the pre 1985 heads and your raising it .250 more? The Vega engine compartment is already tight enough i just want to make sure i don't have issues putting my headers back on.
Thanks,
EVL VEGA
From: Rob Wood <RWood@airflowresearch.com>
Today at 8:41 AM
To: EVL VEGA
Our port will be .250” raised over your 400 head. GM did not change port location on L98
Monza Harry wrote:Sorry I didn't make that clear, there is some confusion on the boards about what/which heads are the L98 heads The aluminum version has Raised Ports. From the link and my research all GM heads with raised ports, only the port is raised! Not the bolt holes, so this means that the header will be centered to the bolt holes and not the port, So NO interchangeability between exhausts, so if AFR is the same (and I believe they are, as many header manufacturers offer an "aftermarket head flange") that means the headers will bolt right up, however the flange in this case will block the top 1/4" of the exhaust port, I would think the added height would be only a problem with the tightest chassis fits (ours would qualify) but one that the average "Hot Rodder" should be able to easily overcome. The angle situation ends up all but negated as the manifold flange is nearly vertical in the car (I don't know the actual angle, but it is very low visually). I have been reading up on this, as both sets of heads I have for my car have the 0.200" raised ports, [ZZ4/Vette/LT1/LT4/FastBurn and some places list the L98 in their lists for this port configuration] so I have to come up with exhaust to fit my problem child as well. However the suggested gasket for your {head of choice} http://www.airflowresearch.com/index.php?cPath=24_33 appears to be centered http://www.summitracing.com/int/parts/f ... plications and that would be good news for you, the "More Info" really didn't clear anything up for me. Sorry I didn't help much but at least you are now aware that your headers may or may not have fitment issues, I would ask AFR if this would be the problem, list headers make and model number with direct info on port matching in your next contact with them. Harry
chevyart wrote:hey rhett: i would still do the clay test to be certain you have proper piston to valve clearance. you are using a head that is new to this engine, with bigger valves, and your cam is fairly healthy in lift and duration. checking this out should be easy for you to do, and is worth the effort. nothing is ever just "bolt on" with these hi-po engines. you probably want a little over .100 clearance, mayvbe even more on exhaust side. dont know the exact answer on your valve to piston clearancv. let us know your results. we all learn from each others experiences. art
TOM71VEGA wrote:To EVL VEGA
How does your car run on the street with the spool.
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