[Chief of the 60's]

This thread has officially hit the LOL stage.

[Sirrotica]

Consider these blocks were engineered for between 200 HP to 450 HP when you start piling 600-700 HP on to that design that is 50 years old cast iron cores, I don't consider that odd.

Even in the day when Beswick was running his blown cars on nitro, the factory cast him better blocks than what came in a passenger car. the IA 1 and 2, and the MR 1 are the stop gap between factory standard blocks and the few race blocks that were cast.

Without the aftermarket blocks the Boss Bird, and Chiefs turbo GTO would never have happened.

[Formulajones]

Originally Posted by Sirrotica

Consider these blocks were engineered for between 200 HP to 450 HP when you start piling 600-700 HP on to that design that is 50 years old cast iron cores, I don't consider that odd.

I do. When I push this much through stock block BBC's, solid mounts and no issues, it does in fact make me question stock Pontiac blocks and their integrity. Don't even think I've ever heard this issue from the Mopar or Ford camps either. Interesting none the less.

[Sirrotica]

Consider that Pontiac used only 2 mounting points, where chevy used 3 covering the whole outside surface of the water jacket. Pontiac finally started using 3 mounting points in 1970, so there must have been some concern that engineers made the change. They also moved the motor mounts closer to the front of the block when they made the change from 2 to 3 attaching points.

If you look at a block with both the early and late mounts cast in, the early system straddles #3 web, and the later system straddles both #2 and #3 main webs. Evidently there was some engineering ideas changing when they engineered the 3 bolt later design mounts.

[Formulajones]

Originally Posted by Sirrotica

Consider that Pontiac used only 2 mounting points, where chevy used 3 covering the whole outside surface of the water jacket. Pontiac finally started using 3 mounting points in 1970, so there must have been some concern that engineers made the change. They also moved the motor mounts closer to the front of the block when they made the change from 2 to 3 attaching points.

If you look at a block with both the early and late mounts cast in, the early system straddles #3 web, and the later system straddles both #2 and #3 main webs. Evidently there was some engineering ideas changing when they engineered the 3 bolt later design mounts.

Makes sense. Interesting.

[JSPONT]

I agree, 2 mount points are not great. I make north of 750 with a street driven Abody. I broke Mity mounts the 1st day with them on. Butler warrantied them and I bought the poly mounts, made adjustments and heat shields for them. I then added a mid plate to hold the engine from twisting. Think of the stress on the block when that frames twists. Before chasis/suspension work, a bodys like to lift the left wheel and twist.
I have been about 6000 miles on 750+ h.p. street driven, not easy miles, so far so good. My block is not filled either
When you bore them on a boring machine the cylinders twist. That's why you bore with a torque plate.

[torqhead]

Originally Posted by Sirrotica

I have a restraint system worked out in my head that wouldn't interfere with the power steering, alternator placement. I need some warmer weather to get my engine and F body subframe to be able to see if it's going to be feasible, and if it is, to make a mockup to see if I could make a kit that would fit most applications with the late model intakes and cylinder heads (65 and later).

Brad, thanks for sharing the info on impacts to these engines and how they're mounted. I thought I shared this previously here on the forum, don't know what concept you had in your head, but I put something simple together and there was absolutely no difference in vibration in the car. See pic.

[torqhead]

Originally Posted by Sirrotica

I have a restraint system worked out in my head that wouldn't interfere with the power steering, alternator placement. I need some warmer weather to get my engine and F body subframe to be able to see if it's going to be feasible, and if it is, to make a mockup to see if I could make a kit that would fit most applications with the late model intakes and cylinder heads (65 and later).

Brad, thanks for sharing the info on impacts to these engines and how they're mounted. I thought I shared this previously here on the forum, don't know what concept you had in your head, but I put something simple together and there was absolutely no difference in vibration in the car. See pic.

[Sirrotica]

That is the way I used previously to secure the engine in my GP dirt car back in 1977, which is in my signature pics, which works just fine. I have posted on here many times how cheaply you can make a restraint system using a turnbuckle. I never liked a chain because once it's on the car you can't fine tune it like you can a turnbuckle for tension and what you'd like for cushioning before it stops the engine 100%.

I had an idea that could be installed fairly easily without welding. Because many guys on here do weld, but not everyone does. I was going to try my idea out on the F body subframe I have and see if it could work no matter what alternator power steering pump combo you have. Still use compliant mounts and have a positive stop so they wouldn't break.

All the holding power would be transferred from the oil pan rail area to the left head same as the turnbuckle does. That would alleviate most of the stress on the main web area where the cracks show up in engines having been built over stock power.

Pontiac not only changed the later mounts to 3 securing points in 1970 they also moved the mounts forward, as I previously posted made the mount from straddling one main web (#3) to straddling two main webs (#2 and #3).

Now in the later blocks beginning in 1977 that were lightened (non turbo 301 and 265 as well as the 557 blocks) they removed the provision to bolt on the early 2 point mounts. After cutting more material out of those blocks I think that even is stock street cars Pontiac wanted to spread the side load of the mounts over two main webs so they didn't make the last few years with the early mount provision.

I'm not sure if anyone else has noticed the engineering change or not, but it's pretty obvious on the dual pattern 70-76 blocks with the oil pan removed.

[Sirrotica]

If you look at this block with the dual bolt patterns, the late system uses the first and third holes along the pan rail, as well as the upper fifth hole. The factory also added a strengthening rib intersecting the upper fifth hole to further distribute the side load. That is structurally a lot better, and stronger system than the second and fourth holes only in the early mount system. I think it's pretty obvious that spreading the load to two main webs is going to distribute the side load on the block better than the early system, straddling only the center main web.

In retrospect, this is exactly why in 1970 the 455 GTO as well as all the 455 GTOs through 1972 used the stronger 3 point late design. The 400 cars used the 2 point early system through 1972. The extra torque of the long stroke engine must have been a concern for block distortion for the engineers.

I know that there are a bunch of guys saying they used solid mounts without incident, but looking at the improvements that Pontiac made when they redesigned the mounts, you can see why they did it. It wasn't purely to make adapting early blocks to a late model chassis a PITA...……..

So as Tom V says, "Engineers do stuff for a reason".

In light of the late mounting redesign there was definitely a possible worry about of block distortion in the early design. Something to think about when using factory blocks for higher HP builds, especially drag racing with tires, and a suspension system that will hook well.

Upon discovering the reason for redesigning, as well as being able to see the difference in mounting points I propose that a system loading the left head with the side loading. Instead of concentrating the side load to the early 2 point mounting system and concentrating it on one main web and the small area just above the pan rail.

I feel that it would be kind of silly to disregard the effort Pontiac took to strengthen their 455 block cars so they wouldn't distort the block under hard acceleration

[tom s]

I have stayed out of this BUT,Nunzi told me years ago solid mounts could cause failure in the number 2 main.Could is the word.FWIW,Tom

[Sirrotica]

Originally Posted by tom s

I have stayed out of this BUT,Nunzi told me years ago solid mounts could cause failure in the number 2 main.Could is the word.FWIW,Tom

I agree Tom, It's not a definite that if you install a solid mount that the block will distort, but under the correct amount of abuse the conditions can occur that crack the main webs, or cause the main bearings to bind the crank.

If the engineers felt there was enough merit to redesign the mount system I would surmise they felt it was a distinct possible problem, even with rubber mounts. Those OEM factory mounts would transfer a heckuva lot more torque that the current Anchor mounts would. Most of them the interlock portion either isn't even there any longer, or it's so flimsy it would bend long before the cast iron portion of the block would distort.

My thoughts, the rubber will keep the side loading of the block to a minimum and limiting the movement with a limiting device attached to the head will spread side loading over a larger area and keep the rubber mounts from getting destroyed. Other than that a system with motor plate will accomplish the same thing eliminating side loading of the left side of the block entirely.

This is the street section, but who knows how much a person is going to abuse their car, how hard it's going to hook, how strong 50 year old cast iron blocks are, lot of variables.

[455HOGT37]

I have used a 3/8 heim joint (rod end) on a head stud. A bolt of the appropriate length, a washer and a single shock mount bushing is the link, then bolt a bracket to the upper A arm cross shaft studs. Its quiet, provides firm but not harsh restaint, and requires no permanent mods. Never ran one with slicks but my 68 Bird did 113+ in the quarter on real street tires back in the day and I never broke anything.

[64speed]

Originally Posted by 455HOGT37

I have used a 3/8 heim joint (rod end) on a head stud. A bolt of the appropriate length, a washer and a single shock mount bushing is the link, then bolt a bracket to the upper A arm cross shaft studs. Its quiet, provides firm but not harsh restaint, and requires no permanent mods. Never ran one with slicks but my 68 Bird did 113+ in the quarter on real street tires back in the day and I never broke anything.

Can you provide a picture of this?

[64speed]

I am thinking of making my own mity mounts by welding the .30 rod to the stock mount. Anyone have any success doing this? The mity mount website says they have a lifetime warranty. Are they worth 134 dollars?

[vitamin c]

The mighty mounts I bought made it about one week. The thin steel is so bad that it just pulled the threads out. I guess in I never saw the lifetime guarantee, I wouldn't have thrown them in the garbage. I think trying your own fix is worth a try.

["QUICK-SILVER"]

Originally Posted by 64speed

I am thinking of making my own mity mounts by welding the .30 rod to the stock mount. Anyone have any success doing this? T

If you're talking about the Joe Hand article in post #33....You need to read it again.






You ask about success doing it....You've got to read up about Jim Hand and his son Joe. If it worked for them...you don't need any more opinions on it.

Good little read here
http://www.pontiacsonline.com/Jim%20Hand.htm

Clay

[Steve C.]

Interesting, I've had the mighty mounts installed for years, on at least 3 different engine combinations, with no issue. Over 600 ft.lbs. torque from about 3900 rpm up thu 5700/5800 rpm. That said I've got the old fashion chain method to secure the engine. I guess I've been lucky !


.

[462gto]

It might be worth trying the mod on the new Anchor mounts but I'm not sure they how well they will hold up since the metal is thinner than the older Anchor mounts. The attached link also talks about motor mounts.

http://forums.maxperformanceinc.com/...63#post5970663

[JSPONT]

As I stated before, my 1st ride with them and they broke, real thin metal offshore junk.