RAM AIR IV cam...Install advanced? - Pontiac GTO Forum
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post #1 of 10 (permalink) Old 03-18-2017, 07:50 PM Thread Starter
 
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RAM AIR IV cam...Install advanced?

my friend is rebuilding his street/strip 1971 lemans' 455...it will be a pretty mild build, stock heads, maybe cleaned up a bit, a Melling RA IV copy cam on 113.5 centers, Q-jet on a stock manifold, 1.65 rockers, Rhodes lifters , 3.90 posi and about a 2500 stall... compression will be set at 9.8 and the block is zero decked. (he lives here in the mile-hi city so effective compression will be more like 8.8.) car is stock, full interior, weighs in about 3700-3750. his question is whether to install the cam 4 degrees advanced. my advice is that the RA IV cam is pretty torquey in a 455, and with the Rhodes lifters he should have plenty of launch....install the cam straight up with what ever the cam manufacturer has ground in and enjoy the top end charge... any thoughts?

Last edited by john23; 03-19-2017 at 03:32 PM. Reason: incorrect numbers
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post #2 of 10 (permalink) Old 03-18-2017, 10:34 PM
 
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I used that cam, mostly the Melling version, and Rhoads lifters, with 1.5 rockers, in most all my 455 bracket engines. I always used a Mr. Gasket 2 degree(4 crank degrees) advance key, to make up for timing chain stretch, which happens almost immediately, during or after break-in. Most double roller timing sets have a 4 degree advance keyway. But, I used a TRW stock type set, which had no advance keyway.

I was just assuming that the cam had the keyway in the correct location. But nowadays, most everybody says it's a MUST to carefully "degree in" the cam. I never had the correct equipment or the knowhow to do that. So, me and most other low buck shade tree mechanics just assumed the keyways were correct, and installed accordingly. I reckin my cams were pretty close, since the engines seemed to idle good, run good, make plenty of torque and power, and win races.

I'm not recommending, or even suggesting that anybody should do what I did. But, it worked OK for me.

There is lots of online info on cam degreeing. And there are probably several here who can explain it to you. But, to me, it's not a real simple operation, and requires the correct knowledge and tools.

Just a word to the wise. You may already know this, but that engine makes enuff torque to break the intermediate sprag in a TH400 trans. My 455's broke 2 of 'em. You must have one of the 34 element int sprags, or you'll shift to 2nd one day, and there won't be any 2nd.

I also broke an 8.2 rear end with one of my 455's. You can take a chance & see how long it will last. We got several races out of the one that broke. But, when it broke, it oiled down the track, just past the starting line, and made all the other racers mad.

I switched to a 12-bolt in all my bracket cars, and never had any more rear end problems. Today the 12-bolts are not cheap, like they were back then. If you can't find one for a reasonable price, you might look for an 8.5 out of an early '70's Olds or Buick. But, those are sorta hard to find also. pinion head can tell you all about the rear ends.

Getting set up with a complete ready to race 8.5 or 12-bolt, will not be cheap, unless you accidentally find a real good deal on one that is already set up. So, it might be a good idea to plan to start out with the rear that's in the car, but start looking for a good deal on a replacement now.

Last edited by bigD; 03-18-2017 at 11:02 PM.
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post #3 of 10 (permalink) Old 03-19-2017, 03:28 PM Thread Starter
 
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thanks, D. i will relay the info to my friend....he has a 12 bolt, i have a 34 sprag in my th 400, i will remind him of the importance of that...i don't know what timing chain he will use. Since he is zero decking the block he will need a shorter one. i will also remind him of chain stretch...thanks for the info...

spring is here...are you getting any of that race fever? i got a touch...
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post #4 of 10 (permalink) Old 03-19-2017, 04:11 PM
 
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Have had a very similar built 462 in one of my '71's. Same cam, Rhodes, Harlan Sharpes (hair over 1.7 ratio), 9.9-1 CR with lightly ported '64's. For my use, would not advance the RAIV cam, bottom end torque is going to be more than strong. Your friend must be running some tall wide slicks. With good rod bolts, balanced, hopefully lighter pistons, good valve springs/lightly ported heads, it should make power up top.

What cyl heads & what size of rear tire is your friend's '71 running? What weight saving measures has he performed? 2 of my three '71 & 72 chrome bumper cars were ordered as lightweights. Lightest was factory built non AC, w vinyl mat & no sound deadener & has scaled at 3512 lbs with manual strg, no radio, & nearly empty on gas. Add fuel & my 185 lb son & its well over 3750 lbs.
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post #5 of 10 (permalink) Old 03-19-2017, 05:41 PM
 
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"...Since he is zero decking the block he will need a shorter one..."


Shorter chains are only needed(sometimes) when the mains are align bored, and material is removed from the block, which will move the crank slightly towards the cam. Machining material off the block decks will not affect the distance between the crank & cam.

But, if for whatever reason, you need a shorter chain, they are available. I've read that some timing sets are a little tighter than others. Don't know exactly which brand or particular sets tho.

Butler sells 2 brands with .005 & .010 shorter chains.

http://butlerperformance.com/c-12348...-and-sets.html

Summit sells the higher priced Cloyes brand shorter chain sets.

https://www.summitracing.com/search/...rder=Ascending

Last edited by bigD; 03-19-2017 at 06:01 PM.
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post #6 of 10 (permalink) Old 03-19-2017, 09:22 PM Thread Starter
 
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thanks Pinion Head, i'll ask him what size tire and what cylinder heads...i think he said the heads will cc at about 95? or 98? ccs...i'll ask him, he doesn't seem too interested in lightening the car... we've talked about it before...he 60 foots in the high 1.7s before this rebuild, and for what it is, the car runs pretty well at Bandimere...his old combo with a mild 455 had about 340 or 350 wheel horsepower...thanks for the info!!
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post #7 of 10 (permalink) Old 03-19-2017, 09:29 PM Thread Starter
 
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hi bigD, to my understanding, decking the block requires squaring it first, and squaring the block requires the mains to be align bored, so it is really a 3 step job (and kind of pricey)...
thanks for the info on sourcing shorter chains, he was wondering about that....i'll pass it along...good info to know...
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post #8 of 10 (permalink) Old 03-19-2017, 10:18 PM
 
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Quote:
Originally Posted by john23 View Post
hi bigD, to my understanding, decking the block requires squaring it first, and squaring the block requires the mains to be align bored, so it is really a 3 step job (and kind of pricey)...
According to what Paul Carter says, most Pontiac mains only need an align HONE, which takes almost nothing off the block. I'll try to find the thread & post a link. Paul is a machinist at Koerner Racing Engines, in AZ.

Here it is. Check it out for yourself.

http://forums.maxperformanceinc.com/...ign+hone+block
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post #9 of 10 (permalink) Old 03-19-2017, 10:33 PM Thread Starter
 
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thanks, D, that is good to know
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post #10 of 10 (permalink) Old 03-22-2017, 08:55 PM Thread Starter
 
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Quote:
Originally Posted by Pinion head View Post
Have had a very similar built 462 in one of my '71's. Same cam, Rhodes, Harlan Sharpes (hair over 1.7 ratio), 9.9-1 CR with lightly ported '64's. For my use, would not advance the RAIV cam, bottom end torque is going to be more than strong. Your friend must be running some tall wide slicks. With good rod bolts, balanced, hopefully lighter pistons, good valve springs/lightly ported heads, it should make power up top.

What cyl heads & what size of rear tire is your friend's '71 running? What weight saving measures has he performed? 2 of my three '71 & 72 chrome bumper cars were ordered as lightweights. Lightest was factory built non AC, w vinyl mat & no sound deadener & has scaled at 3512 lbs with manual strg, no radio, & nearly empty on gas. Add fuel & my 185 lb son & its well over 3750 lbs.
hads
pinion head, my friend has 6x4 heads 93 cc , on a .060 over 455 on his new combo.....his car has 4.10 rear end and 27" tall tires...he put 500-600 runs on his old combo before he broke the crank...car races at 3750 lbs...at bandimere with typical air on a summer night being 8000-8500 density altitude....
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