Valve Clearance

BRGNDY88 · 09-28-2005, 01:03 AM

I am in the process of replacing a BHG on a 1988 non-turbo. I would like to know how much can be skimmed off the head before needing a thicker gasket than a stock Toyota gasket.
I would love to have an HSK or similar gasket but there is one spot on the block where the ring around cylinder has pressed an indentation which I believe is too deep and would require the block to be shaved. Oddly enough this wasn't where the gasket was leaking. The head required .015 inch to clean up. The car has 220,000 miles on it. Please help I miss my SUPRA.

PS:The postings and links have been very helpfull. Keep up the good work.

mrnickleye · 09-28-2005, 07:05 AM

Just put it back together with a stock gasket. You can get the whole set online for about $150 US. Factory original equipment. Ishino. Use new bolts from dealer, $40 US Use new coolant hoses everywhere.

rnoswal · 09-28-2005, 02:10 PM

That is a real tough call on the top of the block. You never know if that spot will hold or not after you put it all back together. If you don't get the deck machined, then you might be able to clean that spot real well and put some JB Weld in it to fill that low spot.

I had the head milled .010 and the deck milled.010. I could have gone more and kind of wish that I did. The main thing is the cam timing. When you mill anything it retards the cam timing and you have to correct for it. When you get everything tightened down and the marks lined up on the cam and the number 1 piston at TDC, pull the belt up tight to put on the intake cam gear. The teeth probabaly won't line up witht the gear teeth. You want the belt to be tight so you will have to take the cam gear off and move it along with the pegs to the point where you can just get the belt over the gear and have it as tight as you can without moving the crank or the intake cam.

The cam gear marks won't be at the top anymore probably in getting the belt tight, so that is why you have to be careful not to move the gear while finding what combination hole on the cam and gear make the belt the tightest.

I think you can take much more off the head and still have plenty of adjustment left on the belt. The more you can take off the head the more compression you get, just make sure you get the timing cover milled to match the block. I think most racers like at least .060 clearance at the closest point between the valve and the piston.

Sorry to babble, but I think this stuff is fun.

Russ

monkihead · 09-28-2005, 05:42 PM

did you have to deck the block?? the stock thickness is .057in for the head gasket (1.2mm).

if you have a true straight edge and feeler gauge you can check yourself if it needs to be cut. if it doesnt, the valves should clear.

BRGNDY88 · 10-03-2005, 11:35 PM

Sorry it took me so long to get back. Based on your recomendations, a gasket set, new bolts, and all the coolant hose have been ordered. I did not have the block surfaced but in checking it, it is flat within .004 front to back and flat within .001 side to side at any point. I'm going to go for it since I don't drive it too hard. Although I must admit, I do like the way it takes curves and love pushing it on back roads.
I really appreciate your comments on adjusting the timing belt and gear. I never worked this deep on a overhead valve engine before. They have been too reliable- not a complaint. Basically I have only replaced the starter and alternator.

Questions. Does anyone know what the stamped numbers on the block face mean? There is a 3 by cylinder 1 and 2s by 2 thru 6.

Is 70 lbs a good torque for stock bolts and gasket?

mrnickleye · 10-04-2005, 03:56 AM

72 lb ft of torque. Be sure to do it in 3 steps and in proper sequence. #s on block are @_*%%&*(^^((*) ???????

09-28-2005, 01:03 AM	#1
BRGNDY88 Stock Join Date: Sep 2005 Posts: 3	Valve Clearance I am in the process of replacing a BHG on a 1988 non-turbo. I would like to know how much can be skimmed off the head before needing a thicker gasket than a stock Toyota gasket. I would love to have an HSK or similar gasket but there is one spot on the block where the ring around cylinder has pressed an indentation which I believe is too deep and would require the block to be shaved. Oddly enough this wasn't where the gasket was leaking. The head required .015 inch to clean up. The car has 220,000 miles on it. Please help I miss my SUPRA. PS:The postings and links have been very helpfull. Keep up the good work.

09-28-2005, 05:42 PM	#4
monkihead SP58GT Join Date: Mar 2005 Location: San Antonio texas Posts: 646	did you have to deck the block?? the stock thickness is .057in for the head gasket (1.2mm). if you have a true straight edge and feeler gauge you can check yourself if it needs to be cut. if it doesnt, the valves should clear. __________________ ....all you need is a small taste of success and you will find it suits you.... monique- better off dead

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09-28-2005, 07:05 AM	#2
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	Just put it back together with a stock gasket. You can get the whole set online for about $150 US. Factory original equipment. Ishino. Use new bolts from dealer, $40 US Use new coolant hoses everywhere.

09-28-2005, 02:10 PM	#3
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	That is a real tough call on the top of the block. You never know if that spot will hold or not after you put it all back together. If you don't get the deck machined, then you might be able to clean that spot real well and put some JB Weld in it to fill that low spot. I had the head milled .010 and the deck milled.010. I could have gone more and kind of wish that I did. The main thing is the cam timing. When you mill anything it retards the cam timing and you have to correct for it. When you get everything tightened down and the marks lined up on the cam and the number 1 piston at TDC, pull the belt up tight to put on the intake cam gear. The teeth probabaly won't line up witht the gear teeth. You want the belt to be tight so you will have to take the cam gear off and move it along with the pegs to the point where you can just get the belt over the gear and have it as tight as you can without moving the crank or the intake cam. The cam gear marks won't be at the top anymore probably in getting the belt tight, so that is why you have to be careful not to move the gear while finding what combination hole on the cam and gear make the belt the tightest. I think you can take much more off the head and still have plenty of adjustment left on the belt. The more you can take off the head the more compression you get, just make sure you get the timing cover milled to match the block. I think most racers like at least .060 clearance at the closest point between the valve and the piston. Sorry to babble, but I think this stuff is fun. Russ

10-03-2005, 11:35 PM	#5
BRGNDY88 Stock Join Date: Sep 2005 Posts: 3	Sorry it took me so long to get back. Based on your recomendations, a gasket set, new bolts, and all the coolant hose have been ordered. I did not have the block surfaced but in checking it, it is flat within .004 front to back and flat within .001 side to side at any point. I'm going to go for it since I don't drive it too hard. Although I must admit, I do like the way it takes curves and love pushing it on back roads. I really appreciate your comments on adjusting the timing belt and gear. I never worked this deep on a overhead valve engine before. They have been too reliable- not a complaint. Basically I have only replaced the starter and alternator. Questions. Does anyone know what the stamped numbers on the block face mean? There is a 3 by cylinder 1 and 2s by 2 thru 6. Is 70 lbs a good torque for stock bolts and gasket?

10-04-2005, 03:56 AM	#6
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	72 lb ft of torque. Be sure to do it in 3 steps and in proper sequence. #s on block are @_%%&(^^((*) ???????