1993GMCPU

Liked Grumpy's info on valve adjustment a lot better then one Comp Cam suggested as Grumpy's was a lot less complicated, thanks, again!

I wondered if anyones use the Flow Tech's Afterburn headers, Headman or compared shortie headers to full tube? I am not sure about Summit headers, since I had shorties and they leaked a lot, unfortunately upset me and I threw them away it was that bad as these were shorties. Tubes against head extended past header plate which met that cylinder ports were sealed by only the size of tube verses like Edelbrock that are ground down even to plate that bolts to heads' exhaust ports giving headers more surface head to header seal.

93 GMC 5.7 1/2 ton has no smog pump or tubes, but I am looking at headers to get better exhaust then stock truck exhaust even though wrecking yard claims local Sprint cars use them as they seem to mix side and not equal length etc.

We ended up shaving 76 cc heads .020 and went from stock type of Fel Pro gasket to a 1094 (.015), which seem to increase compression as notice also we got 150-165 on compression gauge which was only 110 before.

Going to recheck after I double check valve adjustment as one cylinder almost was a 170 (6 Cylinder)!.

I am using the same Comp Cam hydraulic cam 212-218, 440 lift, while checking on 112 LS Summit Hydraulics and Crane Cams to compare how this may effect SCR/DCR! Son used sumiit hydraulic in 383 and it ran great, but no computer, but TBI is modified, using Edelbrock's TBI manifold which I should of used TBI adapter on no-dual plane, blow master 3" inlet and dual 2.5 outlet. May got to a true dual exhaut if we have enough room etc, heads are SR Pro Toplines'.

Tried to locate TPI in Ok, but no luck as this would left me with a lot more cam options, would of liked a slight lope hp 70's sounding 350. Pistons H345NP40's

Present TBI was modfied at high cost by Turbo City along with using a Edelbrock TBI manifold. 3704, I believe is the correct model or going to TPI.

ShiftyCapone

iTrader: (7)

You are going to want to open up the inlet on that intake a bit. The edelbrock intake has the stock size bores and your turbo city unit is larger. There is going to be a lip that can restrict airflow. If you want your combo to run to its full potential you are going to have to do some chip work.

There aren't any stepped headers for our cars so we cannot really talk about that. There are tons of cheaper headers out there for your truck. You'll have to take your exhaust question elsewhere because this is a 3rd gen only site.

I allow TBI posts from other vehicles since it helps future swappers understand the minute differences between various GM TBI set ups.

Last but not least did you have a question? Or TBI problem?

1993GMCPU

I had looked at TPI, but fellow that had camaro, gave it away before I contacted him. I just wondered if there would be an inprovement in TPI or a least there are more cams to deal with on TPI's excluding learning to do own chip, which may be the way I need to go!

Sorry, I post usually at CT, but at times, I find your site no matter what, also to have insite and just had used it to get more ideas.

I did grind angle to smooth out Edelbrock's Port holes into Manifold, but I seen that Turbo City, CFM-Tech use spacers that allow each TBI port to pull from both sides and wondered if that helps.

We have been offered a camaro or camaro parts, use to own a 68 Z-28 and miss that era. 93 TBI modified by TC just has never impressed me, but I know that they are suppose to work, well. May need custom chip modified or look for local expert. Disabled, but I try to do my best.

ShiftyCapone

iTrader: (7)

It is not worth it to go with TPI. Your TBI will make much more power up top than the stock GM tpi system. A modded TBI system can pull to 6300 rpm and no stock TPI can match that. There are just as mnay cams out there for TBI as there is TPI. Both use hydraulic roller cams so you can use them with either set-up.

1993GMCPU

I was told to use a 112-114 LSA cam and keep duration down.

Crane cams were not posted like Comp Cams, where I was told to keep it around 110 duration and 112-114 LSA.

I appreciate the input because OK has no smog checks, but on the other hand, who wants a over rich motor with to much over lap anyway.

I believe even Summit makes a 112 cam with good specs with lifters for around 70 bucks. Thanks!

ShiftyCapone

iTrader: (7)

You are right about the LSA but you can go a bit higher on the duration. Did you mean to say 210 and 110?

1993GMCPU

Yes-oops sorry! I was up early this morning! (I may of been thinking of Centerline as Comp Cams are 112-114, which give you a 110 Centerline and 112-114 LSA as 2-4 degrees advance built in to their cams!

Crane seem to suggest compression may effect the 210 duration, since it's been a year roughly, their tech mainly asked if I had a least 9.0:1 compression assumiing 93 350's had only 8.5:1 stock.

(Using H345NP40 Federal Mogul pistons, 76 cc heads shaved .020 and thinner gasket .015 to get a 40 quench and upped compression.) I believe you have more options if you can also make your own chips and changes, but for now, I have custom chip from Turbo City, which cost 50 dollars to modify.

Motor is at I said on first try, but we got 1.90 / 1.50 SR Pro Topline heads verses Torker 2.02-1.60 we were promised-67 cc, which I got later with out valves. Shaved 1.94 to lower cc/get better quench and up compression!