compression leakage, head nut lying in valve cover.

Engine troubles? Try here.
Post Reply
cowboy
Posts: 10
Joined: Thu Jan 23, 2014 1:18 pm
Location: Eden,NC

compression leakage, head nut lying in valve cover.

Post by cowboy »

well here we go. a local hunt club dropped this 1974 pinz 710m off and said fix the exhaust and why is it running funny? plugs were fowled and a compression check showed #1=90psi, #2=80, #3=85, and#4=0. it was popping through the carbs and i could hear the comp. leak. removed #4 cover to descover the head nut off and laying there. upon re-installing and tightening down it made difference in the leak. the bottom nutts on the other heads were able to be tightened alittle more as well. so my question is what is the torque specs for these bolts? and im pretty sure i need to remove the heads off of the cyclinders to reseal them, any thoughts. P.S. i can tell already that the carbs need to be gone through, and i still need to blow air in the cycnders and check the state of the valves.
User avatar
edzz
United States of America
Posts: 1309
Joined: Tue Aug 11, 2009 12:13 am
Location: Coeur d'Alene, ID

Re: compression leakage, head nut lying in valve cover.

Post by edzz »

Torque 35NM if I an reading the manual correctly, if head has been loose / leaking it's possible you now have carbon / muck build up on the cylinder - cylinder head mating surface. you may want to clean the mating surfaces remember there are no head gaskets.
Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.
cowboy
Posts: 10
Joined: Thu Jan 23, 2014 1:18 pm
Location: Eden,NC

Re: compression leakage, head nut lying in valve cover.

Post by cowboy »

ok, that plays in along with my line of thinking. once clean, ive got this copper spray that works for sealing metal surfaces in high heat conditions. i know some things should be completely clean, but do you think that would cause a sealing issue? whats the torqe on the rocker arms?
cowboy
Posts: 10
Joined: Thu Jan 23, 2014 1:18 pm
Location: Eden,NC

Re: compression leakage, head nut lying in valve cover.

Post by cowboy »

im waiting to here back from the customer before i can go any further. i would like to pull all four heads and cylinders, adjust the valves, and reseal the guide tubes. the problem is that i have no specs or tech. data for setting every thing back up. im suspicious of the valves because of the popping back through the carbs.
compunerdy
United States of America
Posts: 228
Joined: Wed Feb 13, 2013 12:04 am
Location: Idaho Falls, ID

Re: compression leakage, head nut lying in valve cover.

Post by compunerdy »

If I remember correctly compression should be around 150psi
Tim
1975 710K
cowboy
Posts: 10
Joined: Thu Jan 23, 2014 1:18 pm
Location: Eden,NC

Re: compression leakage, head nut lying in valve cover.

Post by cowboy »

from reading other post 150 is what iv seen so far.
Jim LaGuardia
United States of America
Posts: 1704
Joined: Wed Apr 14, 2004 3:42 pm
Location: San Bernardino Ca
Contact:

Re: compression leakage, head nut lying in valve cover.

Post by Jim LaGuardia »

Check points and timing for the popping before pulling apart. If you are pulling the heads and cylinders, here are the proper specs/sealants.
Hand lap cylinders into heads with fine valve lapping compound and clean both surfaces. Permatex Aviation sealant is applied to the cyl base and case opening, do not use silicone of any type, lube tube Orings and seals with motor oil, apply oil to cylinder head mating surface. Torque heads to 28-32 ft lbs(use a straight edge across the exhaust ports to align heads) you may also set the intake runners with gaskets in place to help square the heads. Rocker bolts 16 ft lbs, valve clearance .2mm, firng order 1 2 4 3
Cheers, Jim LaGuardia
http://smg.photobucket.com/albums/v510/Goatwerks/
"Arch Magus of Machines."
User avatar
edzz
United States of America
Posts: 1309
Joined: Tue Aug 11, 2009 12:13 am
Location: Coeur d'Alene, ID

Re: compression leakage, head nut lying in valve cover.

Post by edzz »

Scott at Expedition Imports should have the manuals available for a price.
scott@expedition-imports.com
Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.
cowboy
Posts: 10
Joined: Thu Jan 23, 2014 1:18 pm
Location: Eden,NC

Re: compression leakage, head nut lying in valve cover.

Post by cowboy »

thanks jim. it seems like ive read every related post and topic new and old thrs. and friday. what i could tell your the goto person for these pinzs. i picked up on the aveation sealant from one of your othe helping tips. the igntion has been updated. so on that part i discovered that i need to shave off some length on the rotor button. and what is the distance between the mag. ring and the elec. pickup? i read that too but have forgotten were it was posted.
edzz- thank you ill have to check them out.
cowboy
Posts: 10
Joined: Thu Jan 23, 2014 1:18 pm
Location: Eden,NC

Re: compression leakage, head nut lying in valve cover.

Post by cowboy »

:D yhee haw!! i just got the go-ahead from the cust. to fix, fix, fix! Enybody know any labor times?
blackstack
United States of America
Posts: 206
Joined: Mon Sep 28, 2009 11:36 am
Location: WHIDBEY ISLAND

Re: compression leakage, head nut lying in valve cover.

Post by blackstack »

Jim LaGuardia can direct you to repair manuals also
Post Reply