1988 TC single Holset turbo 5.0/ 4R70W Reply #1020 – December 22, 2013, 10:17:44 AM Quote from: turbotrav;426057Hey JimIm only wrapping the downpipe for that reason...just holds too much heat...causing warping...and metal fatigue.Going to be hot under the hood. But cant be helped.TravisYeah, I liked how cool the bay was with all the I have stuffed in it, but I need to have the hot side last longer. I started with pretty heavy wall tubing, so there's a lot of life left in this yet. I will let you know how the Techline works out. They have recently re-formulated and the preliminary reviews are pretty good. We'll see!OH, I did read a motorcycle thread where a guy found the air over his pipes was hotter when they were coated and wrapped than when just coated or just wrapped. He ended up just going with coating.That goes against 'common sense' but I admit to not knowing all I need to know on this subject yet.I do know from experience now about header wrap and it's benefits and drawbacks! Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1021 – December 22, 2013, 10:39:33 AM Here are some pics to show what I'm seeing. BTW, the insides of all the pipes are still perfect. No corrosion or erosion of any kind is evident to my eye. Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1022 – December 22, 2013, 10:43:34 AM Here's the worst of it and notice the pile of rust on the floor that once was part of my hotside! It was all rusted in uniform flakey sheets that just knocked right off.I would have thought the crossover would look the worst by now since it is down in the elements and unprotected except for some BBQ paint. It held up surprisingly well, though. Just a bit of surface rust. Very inconsequential. Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1023 – December 22, 2013, 03:06:23 PM Hey JimI have heard people have the headers jethot coated...that seems to be the best if not the most $$ solution...Your piping seems to be doing pretty good.Travis Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1024 – December 22, 2013, 09:40:34 PM OK.Working on valve geometry.Three different installs with clay for checking PTV. (The clearance is fine even with my milled heads.)First is with a 6.7" pushrod. VERY thin sweep pattern (.040") but out pretty far toward the exhaust side of the head on the intake valve.Next is with a stock (WAY too short pushrod (just to see what would happen.)Wide pattern rolling near center. (sorry the pic wasn't good on this one, but you can see it.)Last is the 6.7 again, but with lash caps on the valve tips. Pattern is still pretty narrow, (.053") moved slightly in away from exhaust side from setup without lash cap.It looks to me like I'd want to either use the 6.7" with lash caps or try 6.65 without them. It seems like as I shorten the pushrod (or lengthen the valve) I am getting a wider pattern, so with the witness mark well onto the valve tip and a narrow sweep, this is probably as good as I get and stay close to optimal geometry. The 6.7 looks to be the correct length if I had an adjustable rocker arm, or could move the pivot point.I don't intend to be revving this engine, so the extra mass of the lash cap on the valve assembly shouldn't be an issue if I go that route. Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1025 – December 24, 2013, 07:50:05 AM I wasn't satisfied I had exhausted all my options, so I went to Summit and got a Chevy 1.6 rocker arm to test, and a set of 6.6" pushrods. The shorter pushrod gives me a pattern without caps much like I have with caps and with longer pushrods. The Chevy rocker arm placed the witness mark in the center of the valve tip, but was over .090 wide.The 6.6 is a compromise to staying centered, the 6.7 is most correct for my head geometry, but runs awfully close to the edge of the intake valve. I hate to pay twice for pushrods, but I may end up with 2 different size pushrods if I want to get it as close as possible.I'll keep playing with it, and set up on a couple more holes to cross check before I pull the trigger on the final combination. Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1026 – December 25, 2013, 03:20:13 PM Hey JimWhat heads?Travis Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1027 – December 26, 2013, 06:49:10 AM Tfs tw170. Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1028 – December 26, 2013, 08:29:55 AM Nice...those heads should give you a nice 20-30hp bump and the same level of boost, timing, and fuel..Sweet, those came from Ann Arbor?Travis Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1029 – December 28, 2013, 12:55:01 AM Yep, got from a poster here who has a nifty build of his own. :)I got dibs on some hand -me-down axles, too! (As soon as I see what Mrs. Claus spent on Christmas.)I went back to Summit and returned the 1.6 Chevy rockers. I had tried both a Comp Cams Ultra Pro Magnum and the Scorpion performance series for the 23 degree head. Neither gave acceptable results, and the Scorpions were huge!I picked up some 1.65 sticks 2 sets of rockers to try. A set of Comp Cams 1.6 Magnum Ford rockers and a set of Scorpion Endurance 1.6 Ford rockers in 7/16 and 7/16 Arp studs for them, 1.90 length.I decided I was a little close to the intake valve on PTV and wanted to step down to 1.6 to avoid any trouble in case one or two of the other cylinders aren't as free as the one I checked.I stepped up to 7/16 studs since I'm running a bit higher seat pressure and my geometry isn't perfect, so I wanted more stud to avoid rocker flexing. I can't get a 1" spacer under my hood, so I can't run stud girdles for clearance issues. Additionally the 3/8 studs in the heads (1.75 length) ended up not leaving much thread to secure the Polylocks at the height I have to run my rockers, so I needed new ones anyway.I set up on a cylinder and ran both rockers with 6.6, 6.65, and 6.7 pushrods. I also ran both sets with lash caps at all three lengths.Comp Cams .110 markScorpion .090A couple of the 6.6" checks. This pushrod is too short. The patterns are all too wide at a minimum of .90. Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1030 – December 28, 2013, 12:57:59 AM Next came the 6.65. Much better results.Scorpion with capsComp Cams with capsComp cams no caps Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1031 – December 28, 2013, 01:00:50 AM Finally 1.7 rods with and without caps.Comp CamsScorpionComp Cams Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1032 – December 28, 2013, 01:03:09 AM And the last.Scorpion no caps. Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1033 – December 28, 2013, 02:16:37 AM I was hoping the Comp Cams Ultra Magnum rockers would work the best because I like them. They are built really solid and have nice beefy trunnions. But the Scorpions give me the most centered pattern with the smallest swipe, so they win.It looks like the best result is to run a 6.65 using caps with the Scorpions. It yields a swipe of about .60 and is closest to the middle.Decision made. Just have to return $800.00 of parts and install what I am keeping. lol Quote Selected
1988 TC single Holset turbo 5.0/ 4R70W Reply #1034 – December 28, 2013, 09:32:25 AM I just read a good article in/on Hotrod magazine about PTV clearance and rocker ratios. Apparently since PTV problems occur so early in the lobe ramp (for me it's intake and after the piston has gone past TDC with the valve starting to close) it actually makes little difference changing rocker ratios. It won't be worse, though. http://www.hotrod.com/techfaq/hrdp_1303_checking_piston_to_valve_clearance/photo_02.html Quote Selected
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