L98 Mods
been lurking for a year or so, unbelievable bunch of people we got here
supporting our hobby, anyhow I know this has been beat to death, yes I have researched older posts,someone please step up to the plate and give me part#s and all specifics, not just suggestions on my planned upgrades.I also apologize now for the long post
got an 87 vert automatic, only 41,000 miles. It's got bad valve guide seals, what I am looking to accomplish is High 12's low 13's (enough to keep up with stock modern muscle)I can get a set of 113 heads cheap(like $400.00) I figure at least another $500 or $600 to get them lightly ported and a 3 angle valve job. If I went with larger valves I'm sure I'd start to be in the range of aftermarket heads which is out of my $range right now.I probably will not go with headers (want to keep it stock looking) already have cat back flowmasters and plan to lose the precats and go with a high flow catand front y pipe. I want to do a cam,timing chain,roller rockers if necessary. I want an aftermarket lower intake, and runners but will probably stay with a ported upper plenum.Is this a doable situation? I will also do gears and a converter asap.
here are the specific question's
1 what to do to heads( Should I just do up the stock ones) or go for the 113's, and what do I do to them?please be specific
2 What cam,Intake,and runners? please be specific
thanx all
chris
thanx
Last edited by zapc; Jan 12, 2006 at 12:33 PM.
Certain parts are easier to exchange than others. If you begin by a change of heads - which in my opinion is really the foundation for all other mods - you can more easily change the camshaft at the same time, since most of the parts will be have to removed anyway.
So why change the heads, calling for removal of lots of parts, then have to remove many of the SAME parts later to change the cam.
So do the cam and heads at the same time.
If you budget can stand it, install a set of full length headers at the same time as the heads/cam change. You've got to pull the exhaust manifolds anyway to get the heads off. For a 350 engine go with 1-5/8" OD headers which work better than the larger 1-3/4" jobs.
The intake setup, since it's on top of the engine, can then be changed sometime down the road without disturbing many of the parts you had to deal with in the head and cam change.
Specifics:
CYLINDER HEADS: I recommend not fooling with the stock heads. Instead I'd go with a set of Edelbrock RPM aluminum heads, part # 60739 - all the specs are on Edelbrock's site. They're under $1,000 fully assembled and ready to bolt on and are readily available.
Check Summit Raciong Equipment or Performance Automotive Warehouse for the best price.
CAMSHAFT: I recommend calling CompCams (toll free) and ordering a custom ground hydraulic roller grind CS 3312/3313HR112 (212/218@ .050) or
If you want a little more top end with a SLIGHT, but hardly noticable loss in low end torque CS 3313/3314HR114 (218/224@ .050)
If you can degree in the cam, order it with ZERO Advance ground in. If you can't, order it with 4 degrees of advance ground in.
If your existing roller lifters are in good shape, reuse them. The heads I recommended will have the valve springs required for the cam if you specify them when you order. They come at NO extra charge. Just tell Summit or PAW, etc., the cam you're running. They'll send you the heads with the correct valve springs.
Contact Alvin at Chips@PCMFORLESS.COM and have him re-burn your PROM to accomodate the mods. Get the parts first so he can program the PROM specifically for them.
Get a copy of TPIS Insider Hints book which details other mods you can make yourself to improve airflow. It's available for online ordering at their site.
Hope this helps.
Jake
my intentions were to do heads,cam and intake at the same time,
I was hoping to get away without going to long tube headers, just with cat back, new high flow cat & no precats but if I have to use headers I will. also if I have to go the superam route I will, but was hoping to keep the stock upper plenum just ported,someones intake and runners,
(not sure which ones are best yet) from most of the reading I have been doing most people seem to recommend the zz9 cam and afs heads,
obviously youve had luck with your recomendations?
Jake gave you some good advice, I would buy a set of aftermarket heads for the simple reason, after you pay $400 for 113 heads and have them redone you're going to spend at least $1000 and they may not flow as good as an aftermarket head. Dart, AFR, edelbrock and every else make a good head for a reasonable price ($1000 and up range). I have a set of Dart 180 Iron Eagles that I brought bare from summit and had a local head guy do them for me. He said it would be better for me to go and buy a new set of head and let him assemble and clean them up (mild porting) and I would come out cheaper than doing a set of old stock heads and have them ported to flow the same of air. (CFM) My original goal was mid 12s in a S15 truck, It would run that in the heat easy. The bottom line is heads and a good cam.(I like the GM HOT CAM) an engine is a pump the more air and fuel atomized and burned the more power it will make





Camshaft selection requires a set goal, which is why I havent put much about that on my website yet. There are so many directions you can go. I believe this should be on there, but if youre going this stock-looking route, I would be down to the Accel 211 or TPiS ZZ9, or perhaps something slightly larger than either of these offered by CompCams or whomever.
There should also be flow numbers there that will allow some comparison between the intake bases, but from a quality standpoint on any intake parts you need to look more to TPiS or Edelbrock over Accel. Superram is another monster in itself, but aside from quality problems that may creep in, I see no reason not to use it on most L98s.
The Best of Corvette for Corvette Enthusiasts
my intentions were to do heads,cam and intake at the same time,
I was hoping to get away without going to long tube headers, just with cat back, new high flow cat & no precats but if I have to use headers I will. also if I have to go the superam route I will, but was hoping to keep the stock upper plenum just ported,someones intake and runners,
(not sure which ones are best yet) from most of the reading I have been doing most people seem to recommend the zz9 cam and afs heads,
obviously youve had luck with your recomendations?
Also, I had mine checked on a computerized cam checker at Dennis Wells' Racing and the specs were way off from what the advertised specs are. I suspect it's a quality control issue.
Also, I've read in one of the mags that it gives best performance when installed 1.5 degree retarded.
I didn't recommend Air Flow Research heads (if those are the ones you are referring to) for two reasons:
1. There have been some serious quality control complaints on their heads on not only this Forum, but on ThirdGen. Org too, just to name the two I know of. There have been many posts on that quality control issue and even AFR has posted trying to comfort/justify/explain/placate (choose which word you like best) the complainants. I'm not sure those posts are still available for review, but the back and forth went on for quite a while.
Some guys posted true "horror" stories and even posted photos of their heads with hundreds of tiny holes in the castings. Others complained of excessive valve to guide clearance, etc., etc.
Still others posted they had no problem at all.
So my conclusioin is you'd be taking pot luck. I just have no confidence in their product in spite of their outstanding flow numbers.
2. Availability absolutely sucks. Last time I saw a post on this, guys were waiting for months to get a set.
Even though Edelbrock heads don't flow as well as AFRs, their quality control has the highest rating in the industry. They have a something (forgot the name) 9000 rating, which is a good as it gets.
Now, I want you guys to pay attention here: I DO NOT want to get into another back and forth on this issue. Poster asked for my specific recommendations and I gave them and, now, even the reasons.
These are my views and I'm entitled to 'em so, please, leave me be.
Jake
People will immediately argue that 1 5/8" headers will give you more low end torque, thus I will clarify what I mean in saying that although 1 5/8" headers may give you more low end torque it is possible that 1 3/4" headers will provide a horsepower gain in the upper RPM range that outweighs the "loss" that they have over the 1 5/8" in the lower range.
The short answer is that 1 5/8" is not ALWAYS better nor are they ALWAYS worse, it depends on a per application basis.

Regardless of whether you believe in 1 5/8" or 1 3/4" headers, doing an intake, cam, and heads WITHOUT doing headers is like pizzing in the wind.
Last edited by Nathan Plemons; Jan 12, 2006 at 05:23 PM.
Hope this has been of some help...I know how unnerving it is to make decisions about perf. mod's....esp. camshaft. This was, in my mind, the most important decision. After much research I took the advice of the chip-tuner who, after I told him I needed low-to mid-range torque(not top-end HP), suggested an LPE211. I went with it and am very happy about its performance. Is a ZZ9, CC, Crane grind any better? I am not the expert and can't answer this, but can say my PLE does what I want it to do. Good luck with your decision-making and choices...
i agree, i gained around 30hp/30 tq.
people
did not want to start the usual bickering, was hoping several of you would chime in to the specifics you were running and how happy you were with the results, and what not to do,
unless someone else has any suggestions it seems I will follow jakes advice, have always been an edelbrock fan,was hopin more of you were going to tell me to stick with the ported 113's. I have heard about the problems with the air flow research heads. keep in mind people that I'm not looking to build a racecar (yet anyway Ha Ha)just keep up with modern muscle. with the edelbrock heads and the comp cam is it necessary to do the chip right away? I hear that mass air is more agreeable to a cam change, or is it the heads that will get me
Vader86: I just installed SR and i printed ur installation instructions along with SR pictures thanks a lot for that help, it sure helped me. Kool website and many thanks for sharing.
Should you go with a ported/aftermarket TPI setup, I'd stick with a cyl. head no bigger than 180'ish. AFR, Dart, etc make some great product, spend your money on the heads if anything. Dont let the small runner size fool you, they will still outflow any TPI "long tube runner" type setup and make gobs of torque for the street.
If you have interest in flow numbers, check out this comprehensive list of heads, excellent.
http://users.erols.com/srweiss/tablehdc.htm
If you have interest in flow numbers, check out this comprehensive list of heads, excellent.
http://users.erols.com/srweiss/tablehdc.htm
As the site said, you want the best flow WITH THE SMALLEST PORT VOLUME and (which gives you - my words) the HIGHEST VELOCITY. It also said that VELOCITY is just as important as flow, which many to fail to take into account.
Most drool over maximum flow numbers and brag about them like they're money in the bank - more being better - yet the site clearly says to look at port volume and .400 lift flow and, also, to ignore any flow numbers near or above the max amount your valves will lift. It's also a good idea to look at average flow numbers too.
So comparing a 170cc port head with a 180 cc port head is sort of an apples and oranges comparison, albiet a small one, but they are two different animals. A friend of mine was able to get his 15 degree Brodix heads to flow 340 CFM @ .700, but the intake ports had to be opened to 262 CCs to get there. That's almost 100 cc's more than what my intake ports are. Guess what that does to velocity, especially down low.
For a street engine, all you need do is look at the comparison between the BB Chevy rectangular port heads Vs the oval port heads for the same engine. The smaller port heads win out in power production in the RPM range street engines normally see.
I've run both Rectangular and Ovals on the same 468 BB street engine and the difference is enormous. Above 6500 RPM or so the Recs take over, but you must ask yourself, how often is you street engine going to be above 6500. Mine never sees anything approaching that RPM on the way to Albertson's. LOL
So, bottom line: Don't let maximum airflow be the determining factor in your selection of a set of heads. Look at the big picture.
Jake
could,t pass them up. gonna get them ported and redone. for my plans (remember just looking to keep up with new muscle) do I really need to
go with the larger valves or just go stage 1 porting and gasket match everything.













