Neil

Has anyone had valve guide problems with there TFS heads? I have a set on my 383 TPI motor and I THINK oil is going down the valve guide upon decceleration. (For example, when I am on the highway cruizing at 75 mph @ 2300 rpm and I take my foot off the gas, I smell oil burning.) My thought on this is that negative pressure develops when the throttle blades are closed and that pulls oil into the combustion chamber from the valve guides/heads.
I have tried two different sets of valve seals and I get the same problem. My leak down test is around 2%, which indicated that the piston rings are good.
Also, I have pulled off the runners, and base manifold and noticed oil in both the runners and the base manifold. I also saw oil sludged up on the intake valves.
I was thinking also that I am pulling oil from the valley, but I have sealed that intake manifold so well that oil can't be coming in that way! Finally, I have to add about 1 quart of oil every 1.5 weeks.

FastBroker

Sounds like a valley leak to me. You'd know if the gasket was leaking if/when you took the intake off becasue the gasket would be wet where it mates the intake and/or head surface(s).

PCV ingestion???

I'm assuming that the heads are not very old, by the way, ie, less than 20,000 miles???

[This message has been edited by FastBroker (edited September 15, 2000).]

Neil

Thanks for your feedback!
Well, I have had the intake off several times (for the same problem) and I did not see any of oil-wetting on the intake gasket. The intake gaskets I am using are FelPro #1256.
Also, I have the PCV plugged off and I am using valve cover breathers to vent the crank case.
So, I am stumped! Do you have any other ideas?

FastBroker

Shouldn't plug/not use the PCV system. Will cause all kinds of gasket leaks from pressure buildup, never minds that it is very bad for your oil quality...

Still think it's the valley so far... Gotta come from somewhere. You didn't tel me how many miles on heads? Give me cam and spring specs, too. ie nasty cam w/nasty springs will wear guids faster thatn mellow stuff.

MikeH

iTrader: (10)

How many miles do you have on them? It could be worn valve guides if the geometry isnt right they will ware prematurley. you might need a shorter/longer pushrod to correct it.

My friend had a set of AFRs that had this problem and needed slightly longer pushrods because of the roller rockers he was using. The guides went pretty quick if you have it apart it wouldnt hurt to check.



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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

Neil

Alright, I got some specs for you guys!

Comp cam, hydraulic roller:
Duration I/E @ 0.050" 224/236
Lift I/E w/Crane Gold 1.6 rockers: .536/.555 and the lobe separation is 112 deg.
The springs are a GM Dual spring which have been claimed to be good up to .575 lift
The pushrods are stock, 7.2" in length. The heads have steel guides(not bronze) and I have about 7,000 mi. on the heads.
You may not want the motor specs but here you go: 10.8:1 compression w/ Total Seal piston rings, Eagle SIR 5.7" length rods and JE 2-valve relief pistons, melling high volume oil pump and a moroso 8 quart oil pan.

I agree with you on not running the PCV, but I have been trying to figure whats going on and now I know the PCV, so I will hook it back up.
Mike H thanks for the reply. What else did your friend notice when he had this problem?

Kevin G

Are these the Twisted wedge heads???

I think they need longer than stock pushrods. This could have worn the guides if you have the stockers in there. Trick Flow did have problems with the Ford valve guides on TFS heads, but not Chevy. I had an oil comsumption problem after installing TFS heads. But I had them fully ported and milled , so I didnt check the alignment of the intake after that. I thought I had bad valve seals, but it ended up being intake gasket.. I used some 3m super weatherstrip adhesive.. the yellow goo stuff and coated both sides of the intake gaskets. It will not leak for sure after that, but you will be scrapeing some gasket next time it comes out.
My friend had a set of stocker TFS heads and also had intake leak... I dont know if there was a problem with sealing the intakes with these heads, but the 3m weatherstrip adhesive worked for his car also. 2nd Street Performance taught me that trick.

[This message has been edited by Kevin G (edited September 15, 2000).]

Neil

Thanks for the info. I talked with one of the Techs at Trickflow and I'm going to tear apart the motor AGAIN, and send them my TFS heads and intake along with a pair of rocker arms and pushrods. So, I will let you guys know what comes of this. Thanks again,

Daz

iTrader: (1)

I have the TFS G1 heads and 383,my cam has about the same duration but less lift.I also have 1.5 ratio rockers.I had to use .100 longer pushrods on the intake and .200 longer on the exhaust.Major porting was done on these heads though.

Daz
TFS heads G1
Crane Gold 1.5's
Comp 276H-R14

MikeH

iTrader: (10)

Neil...Mostly high oil consumption also the back side of the intakes had black crud from all the oil running down the valve. This had to reduce intake flow.

It seems like if it was the gasket leaking you would have an oil film running into the intake runners.

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

KevinP92Z

I've had my TF TW G1 heads for about 4-5 years. When I first put them on the L98 with Edelbrock base & runners, the match between the heads/intake/block valley was not as good as it should have been. Seemed there was more of a valley gap at the rear of the block than at the front. After about a month, the RTV seemed to dislodge and an oil leak started at the rear. Pulled manifold and re-sealed. About a year, same leak. Quart or more a week, all on the ground, but saw a slight oil smoke out the tailpipes on heavy deaccel.

As my 383 was going together, I had the heads at Westside, and 6 of the cast iron guides were toasted, as well as the valves. Had new SiBronze guides put in as well as some different comp springs. I too was using the Crane Gold self-aligning 1.6's and was using +.100 longer pushrods. Worked a lot more on the gasket/valley fitup after heads were milled and the gaps at the valley didn't seem as bad as before. Could have been block, or heads or intake base that wasn't perfect, but after heads & block were machined, problem seems to have been solved.

By the way TF did have a bunch of guide problems on G1 Chevy heads.

Do you ever make it to Kuhkendahl or Miami Subs on Sat's?

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KevinP92Z
92 Z28 383 SLP cam,SLP headers,SLP 2ontheLeft,Trick Flow TW heads & pistons,Edelbrock base,Accel SuperRam,52mmTB,Scat Crank & forged ConnRods,MSD 6AL,SLP convertor,Baer 13/12" Track,Moser axles,Hotchkis,Genuine GM 3.42s,SLP HD Torsen,17x9" chrome SS rims
96T/A w/SLP Ram Air,SLP 2ontheLeft, Bilsteins, Baer, Hotchkis, Genuine GM, Torsen
76 4X4 Blazer 400TPI project

FastBroker

Yep, as I suspected, sounds like a geometry problem... Also sounds like you are on your way to working it out.

Neil

Guys, again, thanks for your input on this Head Banging issue of mine!
KevinP, when I read your reply I started howling, b/c I had the exact same problem with the rear of the intake manifold not sealing up properly--the RTV kept blowing out and boy that really started to **** me off! What I did was to get those rubber seals which are meant for the front and rear of the intake/block. I used some monkey snot (weather strip adh.), then RTV on top of the rubber and laid that intake back down and I had no more troubles!
To answer your question, I haven't been to Miami Subs in a while and I have never been to the Kuhkendahl hang-out. Let me know when your going out there next time, I'd like to see your Z. If you want e-mail me: nleotcs@hotmail.com
(If your going tonight let me know)

TOD

Hey Neil, if you do send them to Trick Flow, you won't be disappointed. We had to yank a set off of a 5.0 (he was using a B303 cam with 1.72 rockers) to have the valve guides redone. They did so with no charges.

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New (to me) 87 Formula 350. Edelbrock TES, Flowmaster, airfoil, K&N in modified airbox, March underdrive pullies, still slow....for now.

Slow89Iroc-Z

Back from the dead...what did you find out was the cause?