GT40P Head Replacement
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=48428
Printed Date: April-28-2024 at 12:13pm
Topic: GT40P Head Replacement
Posted By: BRKOUT1K
Subject: GT40P Head Replacement
Date Posted: March-04-2020 at 8:01pm
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The replacement heads just arrived this afternoon....I purchased some GT40P heads as recommended by this group from a separate thread (Water in Transmission)! I'm going to attempt to tackle this project over the next month or two with a little help from some friends. I'll do the appropriate research on existing threads, but am always open to any new advice so I don't have to learn the hard way! Just wanted to drop a quick note to thank this group as I work to get our 'new' '95 SN ready this summer for the kids. FYI- Cost was $450 + $80 (S&H Chicago-Tx) Thanks again! Brian |
Replies:
Posted By: Gary S
Date Posted: March-04-2020 at 9:31pm
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How do they look? Any pictures? I’m assuming you got them from windy city engineering? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: BRKOUT1K
Date Posted: March-04-2020 at 9:48pm
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I did pick them up from Windy City....I'll try to upload a couple pictures again. They look great and their customer service has been great! Brian |
Posted By: KENO
Date Posted: March-04-2020 at 10:01pm
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Hey, look at that, you only had to break out about 1/2 K As a reminder, In your other thread I mentioned making sure that the FRONT lettering on the head gaskets is in the front And speaking of gaskets, for one stop shopping, you can buy a FelPro gasket set that includes the exhaust manifold gaskets, intake manfold gaskets, valve cover gaskets and marine head gaskets, along with some valve stem seals that you won't need . If you have cast aluminum valve covers, the part number is 17261 If you have stamped steel valve covers, the part number is 17260 The only difference in the 2 sets is the valve cover gaskets. Many times people wonder which side of the exhaust gasket faces which way. The Felpro instructions will tell you that the shiny, silver metallic side faces the exhaust manifold  |
Posted By: BRKOUT1K
Date Posted: March-04-2020 at 10:10pm
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You guys are awesome!!!! THX AGAIN...Appreciate the one stop shopping advice and will get on it ASAP! Still having trouble to uploading the images for some reason. |
Posted By: KENO
Date Posted: March-05-2020 at 9:13am
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And ....................continuing on If you get looking for torque values you'll find numbers like exhaust manifolds to heads 18 to 24 ft lbs Intake manifold to heads 23 to 25 ft lbs valve cover to heads 3 to 5 ft lbs Heads to the block You'll find all kinds of disagreeing numbers for this depending on where you look, ranging from 90 ft lbs to 112 ft lbs. as the final value If it's a popularity contest, the most common number in Ford and PCM literature seems to be torquing in 3 steps to 112 ft lbs. In the CCF reference section in PCM and Ford literature you'll see 3 steps starting at 90 then 100 then 112 ft lbs I'd snug them up in the right sequence before starting the 3 step torquing process. But..............Just to add to the confusion you can also find PCM literature with 100 as the final value |
Posted By: BRKOUT1K
Date Posted: March-05-2020 at 11:16am
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Thanks all! Hadn't gotten that far yet so I appreciate your continued wisdom and timely guidance. With your skills, I probably would have already had this done weeks ago....I think i'm procrastinating a little as this job is a little more than I tend to tackle when it comes to repairs. Of course, a recent water leak from my upstairs bathroom has me side-tracked a little. The boat doesn't rank quite as high on my wife's list of priorities:) Based on Keno's recommendation I'm going with this set... https://www.amazon.com/s?k=felpro+17260&ref=nb_sb_noss_2 Planning to purchase new head bolts unless that is not necessary??? Anything else I'm missing before I call upon the friends and lure them over here for some 'free beer'... Thx again, Brian |
Posted By: GottaSki
Date Posted: March-05-2020 at 11:26am
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351 Bolts are very stout, and are not TTL design, meaning unless they were overtorqued or abused, you can save the money for something else and reuse what you have Do your bolts have separate washers or are they flanged? ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: KENO
Date Posted: March-05-2020 at 11:40am
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I agree with GottaSki about reusing the head bolts. They're not torque to yield and you can reuse them That gasket set you linked works for stamped steel valve covers. |
Posted By: BRKOUT1K
Date Posted: March-05-2020 at 2:03pm
 Head bolts are flange type, but not sure about valve cover yet... |
Posted By: GottaSki
Date Posted: March-05-2020 at 3:33pm
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huh, bolt holes look small, don't look opened up yet. are they? ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: KENO
Date Posted: March-05-2020 at 7:42pm
Hopefully just an eyeball calibration issue Gotta Ski. The above was from a post in his transmission thread
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GottaSki wrote:Posted By: FFImarine
Date Posted: March-06-2020 at 12:12am
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I never recommend reusing cylinder head bolts as the act of torquing physically stretches the bolt and it will never achieve the same or proper spec if reused. Just buy a set of ARP head bolts and use there moly lubricant and torque them to ARP spec. You spent however much on new cylinder heads and gaskets so is it really worth not buying a set of $90 head bolts to know the job is done right? If reusing head bolts is ok you might as well reuse the head gasket
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Posted By: JoeinNY
Date Posted: March-06-2020 at 2:16am
As stated clearly and correctly above small block ford engines did not use bolts that physically stretch during torquing (torque to yield, or tty) bolts and therefore the head bolts are reusable - this is in no way the same as reusing a head gasket. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: KENO
Date Posted: March-06-2020 at 8:38am
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Hey Joe (in Ohio) Can you send me all your old 351w head bolts especially any ARP ones that you might be throwing out since they were torqued once? Just send them to Keno's Home for Wayward bolts Luckily there aren't many bolts to replace in a transmission
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Posted By: phatsat67
Date Posted: March-06-2020 at 11:22am
| Same here Ken. Those were getting hard to come by for a while. Better send me all your main cap bolts while you’re at it. |
Posted By: Hollywood
Date Posted: March-06-2020 at 12:14pm
Or TTL
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Posted By: BRKOUT1K
Date Posted: March-06-2020 at 4:18pm
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Gents, Called Windy City this afternoon to confirm they sent me the heads with the 1/2" holes. Either way, they are very helpful and Michelle said they will correct if they aren't. I'm on the road for the next week so I'll have to take a look when I get back home. Thanks for the comms as I would have started the project assuming I have the correct ones... Brian |
Posted By: MrMcD
Date Posted: March-06-2020 at 4:20pm
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Bolts have 2 zones I know of. Plastic zone and Elastic Zone. Your 351W engine has Head Bolts that work in the elastic zone, that means they are re useable and you have no worry. Bolts used in the Elastic zone stretch a little as torqued but can be reused unless they are damaged. As engine blocks were made lighter they became more vulnerable to over torque of the bolts. The last version of the 302 Ford was light casted, If I remember correctly Ford removed 28 pounds of cast iron from the block. Engine rebuilders soon learned to install torque plates on the heads before they line bored a block. If they did not the crankshafts could bind up when the heads were torqued. The center main was found to pull .0015 vertical when the head bolts were properly torqued. Other issues found on other engines were cylinders that were round when built would pull out of round when the heads were bolted on causing ring seal issues. Torque plates became mandatory to simulate head bolt torque as the cylinders were honed. So they learned light casted blocks move a lot when parts are torqued. Torque to yield bolts were used to limit how much torque a mechanic could apply to a bolt. Knowing exactly how much torque was applied the engineers found they could reliably seal up an engine. Old engines with the heavy castings were pretty rigid. Head bolt torque could vary quite a bit and the engine would be fine. New engines don't have that margin of error. TTY, Torque to Yield bolts work in the Plastic Zone, the plastic zone is when you tighten a bolt till it starts to stretch, then you push it a little further till it starts to actually break. TTY bolts will have a part of the bolt shaft that is engineered to fail at a certain torque. You can see how part of the bolt shaft is smaller creating this fracture zone. You torque a TTY bolt using specific torque specs, they may say torque to 68 ft pounds and then add 90*. As you turn the last of the 90* you do not feel the bolt getting any tighter because it is now stretching and will fracture if you tighten much more but it will only apply the amount of torque the engineers designed it for. A TTY bolt might turn 45* while in this fracture or plastic zone before it actually fails but at this point the torque is always at the factory spec till it breaks. You feel it on your wrench as these hit the plastic zone. It is a creepy feeling as the person on the wrench if you are used to using traditional bolts in the elastic zone. You are pulling on the torque wrench and suddenly the bolt stops getting tighter even though you are still turning the wrench. Just follow the install instructions and stop exactly as specified. But now the engineer knows if he specifies this engine needs 65 ft pounds of torque the bolt will give him 65 foot pounds of torque. It does not vary if the engine threads are slightly rusty or if the torque wrench is a little off. The bolt limits how much torque so now the block is not distorted by the mechanic. Actual tests have proven that even TTY bolts survive to be used again about 80% of the time. 80% of the time is not good enough to torque a cylinder head so today if an engine has TTY bolts in it they must be changed for new bolts if you rebuild that engine. If you install the head, torque it in place and need to pull it off for something you forgot, guess what, you need new head bolts again. They are a one time use. There is a tool that can measure the bolts to see if they can be reused but the tool costs $250,000 so even large engine rebuilders replace all TTY bolts with new bolts they don't buy this expensive machine to measure bolts. If a head bolt or connecting rod bolt fails you have engine failure so it is not worth the risk not to change the bolts if they are TTY. I am rebuilding a Dodge 4.7L V8 right now, that damn engine has TTY bolts on the Cylinder head, Connecting Rod bolts and on the Main Bearing support saddle. $200 in just bolts to build one of these engines. I would be happy to reuse my 351W bolts every time and avoid the extra expense! One last thing, pay attention to what the manufacturer advised for Bolt lube. Some say use motor oil and lubricate the underside of the bolt head/shoulder other instructions may say lubricate the threads with motor oil, some say to use thread sealer or thread lock, instructions will vary. Use the proper instruction for the engine you are building. ------------- |
Posted By: KENO
Date Posted: March-06-2020 at 5:34pm
When you get home, the easiest way to check is to see if a 17/32 drill bit fits in the hole. That's the size of the hole in a 351W head from the factory People usually seem to say "drilled out for 1/2 inch bolts" If you click on the link you'll see a conversation I once had with myself about the bolt holes http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41180&title=gt40p-question" rel="nofollow - link |
Posted By: Gary S
Date Posted: March-06-2020 at 5:42pm
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Or Pete's favorite- Auto Zone . He buys all his parts for his backyard Hacker Craft there. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: KENO
Date Posted: March-06-2020 at 6:09pm
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Some of us around here are in the "Twilight Zone" Gary
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Posted By: FFImarine
Date Posted: March-06-2020 at 6:14pm
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I know the difference between torque to yield and normal head bolts obviously but the fact of the matter is a standard head bolt still stretches and if reused it will not achieve the proper spec ever again. I’m not here to tell people what to do but cutting corners like that to save $80 isn’t right in my book but go ahead and do what you feel is right
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Posted By: FFImarine
Date Posted: March-06-2020 at 6:24pm
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https://m.youtube.com/watch?v=_Uhul4DmWuw Check the link out... it’s not about head bolts but it proves my point that standard bolts still stretch |
Posted By: Hollywood
Date Posted: March-06-2020 at 7:10pm
| Give it a rest. That new bolt you just put in stretched when you torqued it down. Using stretched bolts are cutting corners! Time for a new bolt. Now the next bolt... wait a minute... |
Posted By: KENO
Date Posted: March-06-2020 at 7:29pm
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Send me all your once used bolts that you're throwing out, not just 351w head bolts
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Posted By: KENO
Date Posted: March-06-2020 at 7:48pm
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A little light reading from ARP, you should probably read it Joe. There might be a question about reusing bolts.................and an answer Funny thing....................You can have your opinion, I'll have mine and everybody else can have theirs too. https://arp-bolts.com/p/faq.php" rel="nofollow - link |
Posted By: GottaSki
Date Posted: March-06-2020 at 9:24pm
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Consider all bolts stretch, that's what proves the clamping forces over all expected temperatures If the bolt returns to its original dimensions. no yield, no damage, reuse . Else discard ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Hollywood
Date Posted: March-06-2020 at 9:31pm
| Stress strain curves. Basic stuff. |
Posted By: phatsat67
Date Posted: March-06-2020 at 10:52pm
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Better change the wheel lugs with every tire rotation. |
Posted By: FFImarine
Date Posted: March-07-2020 at 1:15am
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keno..... ARP does state you can reuse there head bolts if you use there moly lube and torque them to there spec but they can only do that one time after initial use. Your more then welcome to reuse head bolts as many times as you like (it’s not my engine) but is $80 really worth it??? I think not
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Posted By: MrMcD
Date Posted: March-07-2020 at 5:24am
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I called on engine rebuilders that built a combined 8-10,000 engines per month. On engines that did not use TTY bolts they always re used the head bolts, main bolts, connecting rod bolts. These engines all went out the door with warranty. I do know my performance accounts always recommended new rod bolts on the small block GM 350 engines. Again, these were for performance builds because they have seen so many fail on high RPM engines if not replaced. Other engines they re use every part that has proved to be reliable. One final note for discussion. Many head bolts are built in the far EAST today, not New York but overseas. Do you trust the made in America bolts your engine had from the factory or the copies made in China. Other than ARP you will be searching hard to find made in America today. ------------- |
Posted By: KENO
Date Posted: March-07-2020 at 8:17pm
Good thinking Zach I'm gonna change my studs too, 'cause I don't want to worry about my nuts falling off
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Posted By: Jonny Quest
Date Posted: March-08-2020 at 12:27pm
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Brian: What will you be using for rockers on the new heads? ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: BRKOUT1K
Date Posted: March-09-2020 at 3:21pm
| I was hoping that I could reuse the existing ones, but am open to any ideas! I went with the GT40P's based on Keno's recommendation and am ready to listen to all advice on this project. |
Posted By: Mille1sj
Date Posted: March-09-2020 at 5:08pm
| I used 1.6 Roller rockers for the GT40P heads I put on our 302. I believe they are the Ford Performance rockers. |
Posted By: Gary S
Date Posted: March-09-2020 at 6:51pm
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You can reuse your rockers and pushrods but you should check your lifter preload. Later on if you wish you could go for roller rockers ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: KENO
Date Posted: March-09-2020 at 8:55pm
Make sure you get a recommendation from someone who's done it (The 1.6 roller rockers) on a GT40 with it's "pretty finicky" ECM. Numerous people have swapped from GT40 to 40P heads without a problem, some have put a new cam in that wasn't much different without a problem, but once you're very far from original you seem to come up with the loping idle issue that's hard to solve. The 1.6 rockers are pretty much like putting a new cam in and might just be too much for the ECM Edit............this should say using 1.7 roller rockers not 1.6 since the stock ratio is 1.6 (thanks TRB) For that reason, I'd use the original pushrods and rockers and not throw anything else into the equation that might make the ECM have trouble controlling the engine as smoothly as it did before. I've done the head swap only with no running issues. |
Posted By: BRKOUT1K
Date Posted: March-09-2020 at 9:48pm
Although some of you claim to be 'backyard hacks' , I can't thank you enough for all your inputs....I might have learned more on this forum than i did after 6 years of 'struggling ' to get through school...Admittedly, I had flashbacks after the 'simple stress-strain' comment  Appreciate everyone's help. I know 'swapping' out these heads is probably a simple task for many of you (and I"m no pro) so it is a little more of a challenge to this ol' bus driver. Looking to make sure i've got all the i's dotted and t's crossed! Thanks again....A little more background....I'm told this boat had some 'issues' before I bought it with the ECM and it was replaced...seems to be running well with the new or used replacement with the exception of the water leaks .and a few 'noises' that i wouldn't have honed in on. Without all of the time I've spent trying to work out all the gremlins I probably wouldn't have heard most of 'em with the music cranked up!
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Posted By: BRKOUT1K
Date Posted: March-09-2020 at 9:50pm
| OBTW- I work with a guy that is selling an 'older' Malibu if you know anyone in the market...I'll get the flyer and post if there is an interest. |
Posted By: TRBenj
Date Posted: March-09-2020 at 11:14pm
| There’s nothing that stock ratio (1.6) roller rockers would impact... theyre just a little lighter weight and less friction. Increased ratio on the other hand, would be a change similar to cam that may cause tuning issues. |
Posted By: KENO
Date Posted: March-10-2020 at 5:56am
For some reason I had 1.7 roller rockers on the brain when I wrote the earlier post about staying with the stock rockers Edited the previous post |
Posted By: BRKOUT1K
Date Posted: March-10-2020 at 10:53pm
Gents, I was able to pull one of the head bolts and confirm that it fits! Glad you pointed it out so it will be one less thing that could potentially hold me up once we start pulling it apart... |
Posted By: Hollywood
Date Posted: March-11-2020 at 12:42am
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Potentially undersized bolt holes on the new heads won’t hold you up pulling it apart
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Posted By: BRKOUT1K
Date Posted: March-12-2020 at 9:53am
Here's a pic of the flyer that was posted @ work! Hope it's not a forum party foul to 'advertise' for him since it is not a Nautique:) 
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Posted By: BRKOUT1K
Date Posted: April-03-2020 at 6:16pm
Well I finally was able to get the heads installed. So far we ran the motor on the hose yesterday and at the ramp this morning. The motor sounds good to my untrained ear...We are almost ready to hit the lake with the kids after some good weather and a couple of maintenance runs Hollywood, you were correct and your eyeball calibration was spot on!. Despite 2 of the holes not being drilled out for the 1/2 bolts, it didn’t hold us up from pulling it apart. Unfortunately we discovered the issue during the installation and obviously held us up for a few days. Just wanted to drop a quick note to thank everyone for their inputs & assistance on the project. Thx Brian |
Posted By: aupatking
Date Posted: May-20-2020 at 1:40am
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I’m sure one of you guys knows: what’s the spec torque lbs and sequence for the GT40 heads on the 351W? My current project is ready to have it's engine put back together. It had a rebuild with 10-12 hours on it. Not sure if the head bolts weren’t torqued or were just stretched enough to not hold torque, but those cylinders were slam full of antifreeze when I pulled it apart and the impact didn’t even stutter pulling the head bolts. On the bright side, rebuilding a 12 hour engine is the cleanest rebuild I’ve done. ------------- 02 SN 196 TSC2 ZO 01 SN 196 TSC1 98 SN 196 TSC1 97 SN 196 TSC1 93 SN 196 NWZ |
Posted By: MrMcD
Date Posted: May-20-2020 at 3:54pm
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For 351W 1973-1998 Fel-Pro says to torque in 3 steps. 1. torque all Head bolts to 85 ft pounds 2. 95 ft pounds 3. final torque to 105-112 foot pounds for 1/2" bolts I will look for a picture of the torque sequence for this head. ------------- |
Posted By: MrMcD
Date Posted: May-20-2020 at 4:11pm
351W Torque Sequence ------------- |