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Howdy,
The 308 in the old girl has two head-bolts missing on one bank. This is because at some point the threaded section in the valley where the bolts secure has gone AWOL. Old mate who strapped the engine together said that it wont matter. Obviously the question is, will it matter? Especially if I want to re-build this mator as High-compression to suit gas? Or can it be repaired at at what cost...?
The Beige Hornet.
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I think what will happen if left unatended. Is that the Head will warp over time. Leading to a compression leak.
Pumping the comp on the Red Holden motors with the limited Head bolts to start with is going to be asking for trouble.
Depending on how ba |
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This bloody motor's been a bit of a lemon from the start. I might just have to go to 253 as Aussie pattern 308's are rare as rocking horse s&*t (apparently). On these two bolts there is an area cast to accept the thread, which is outside of the main cast
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Just remember that post VL these head bolt holes are not even threaded ie VN onwards heads don't use them. It is common for the bosses to break off particularly in red motors. You don't necessarily need them. However if you are worried you have three opti |
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I have used helecoils on head studs many times with great sucess I guess the bigst issue is how far buggered the hole is??
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There is a better alternative to Helicoils.
A product called Thread-serts.
They wind in just like Helicoils, but they have four small hammer down legs that locate in slots down the outside of the insert. You simply hammer these down after winding in the
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None of this will work on the Hornet's 308 though. it wont be th thread itself that is missing. It is the piece of block where the hole is threaded into is actually missing. pre VL Holden V8's have 4 x bosses in the valley that head bolts go into. If thes |
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Hi all,
Im unsure if 308 is the same as 253 Bolt pattern, but it sounds like your engine has suffered "Gregory's syndrome".
When rebuilding a 253 I used a Gregory's manual Head sequence/tension that went sorta:
Stage 1 = A Nm
Stage 2 = B Nm
Stage |
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Thanks guys, it's been causing a bit of concern - it's not nice to see bits of your motor missing (it is the bosses that have snapped off I just couldn't think of the right words). I was pretty sure cast iron heads wont warp too easily, but theres a lot I
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have few 308 blocks
melb melton vic
0407 56 53 28
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Sme,
Does anyone know if the original Holden Manual describes the tension sequence in the same order as the Gregory's does ?
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general practice with any cylinder head is the to tighten the bolts in 2 or 3 phases, using a spiral pattern starting at the outside bolts, so the far left ones, then the far right, then the next in from the left , then the next in from the right, etc. do
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John,
I know how to generally tension a cylinder hesd,
I was just wonderin if the orig Holden Manual had the same misleading grammar as the Gregory's when it lists the three stages FIRST, and the tells you AFTER, that you should have left the inside |
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In my genuine GMH HQ Manual Vol4, on Page 22 of the 253/308 section, it says: 13 (e) Tighten cylinder head bolts in 2 stages to 40-50 lb. ft. and 65-75 lb. ft. in the sequence shown in fig. 39 Para. 14 goes to installing pushrods/lifters. There i Edited by user Monday, 18 September 2006 10:52:55 AM(UTC)
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OK sorry. But I have been under the impression the main reason these crack is that the oil/water that has been used to clean the block or whatever has not been cleaned out of the bottom of the threads, and when the motor gets hot the oil/water expand and
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John i support the practice of torque sequence in a spiral pattern. Its a handy practice to know, when working on motors foreign to you. I have read many years ago that the yanks will drill down, using a small drill bit into the bolt hole(block) just a Edited by user Saturday, 16 September 2006 6:32:42 PM(UTC)
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Qute,
Thats strange, (though it was 15yrs ago), Im almost certain it made a mention to leave the inners at 50ftlb.
I dont have the manual now, but now intrigued I'ii hafta chase one up.
Will find out one way or anotha.
tbc...
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666,
I'm happy to scan the page and E-mail it to you to satisfy your curiosity.
Cheers...Dave
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Hi Guys.
I've checked the 2 main genuine engine workshop manuals that I use, the HQ Vol 4 & the Improved Performance Engine (Blue Motor) manual. They list all bolts to be torqued (in steps) to the same figure, but I noticed a vital difference. In the H |
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I think the difference is wet torque V's dry torque, dry torque is more accurate & less likely to to cause over torquing, which can be done with the wet torque, eg using the sealant on all head bolts, but there can be great differences in the accual press |
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