Camkit question and Rocker Arms

Jas89TTA

Member
I'm in the process of rebuilding my motor and since I'm now on my second camshaft for wiped lobes I'm going to get the ATR roller camshaft kit p/n rp309g. I was wondering if anyone is running this kit. Also what is the ratio of the stock rocker arms? I'm planning on using my stock arms since they only have 4,000 miles on them. Thanks, Jason
 
I ve run that kit and cam in several engines. Its a good street cam, the atr kit is complete, a bolt in. I went through the same thing probably 5 or 6 years ago.....I wiped two cams then spent the $$$ on the atr kit and never had a problem again. Since then I ve used it several times. Its easy to go high 11's in a full weight gn on pump gas, low 11's high 10's on 116 and the support stuff ie...te45 3200 55's etc.....

BTW I ran rollers and stock rockers, I like the stock rockers better......esp for reliabilty and cost over benefit. OEM are suppose to be 1.55 but the ones Ive measured range from 1.5 to 1.6......
 
Jason, do you have the specs on the cam, and what does it cost? I would like to freshen-up my beat up old TTA, and this may help if it's better than my 206 / 206 current set up. Thanx for any help. Turbota (#70)
 
turbota, I've order the kit from Aggressive Performance they have it for $855.00 the part number is RP309G the specs on the cam are duration @.050 206/212 lift is .467 I and .453 E lobe separation is 109. Since I'm in the motor again after 4,000 and my cam is justabout gone I figured I'd go ahead and get a roller camkit. and a few other goodies ;)
 
Wonder why your wiping so many cams out??

One issue that hasnt been addressed is the TTA head rocker arms are different than the GN ones. Also the ratio is a 1.67 on the factory arm. What this does is add extra pressure since the lift now is larger due to the higher ratio. Your springs may be off too high a pressure, cuasing your wiped cam scenario.

Next is the spring rate for the roller is going to be larger. Once you increase lift and spring rates..the rocker fulcrum gets stressed.. and will come apart. Cuasing a misalignment on the valve stem tips. Then chewing them up.

Any TTA that runs comp941 135 seat or higher pressure spring..will suffer this consequence due to the factory rocker not being designed for this.

Solution.. go to roller rocker.. problem is no kits are made for our cars. And due to the design of our rockers and pedestals..to keep proper geometry requires milling the pedestals, installing 7/16 BBC studs, running 1.7 roller rockers and making new fasteners to hold down the valve covers. As you can tell..what a pain.

I was working on a different solution involving the use of the 3.8 roller fulcrum rocker. Frank Weeks is on this issue currently with GTP in Texas(Gallant Technical Performance) sp? anyways theyre working on it.. no updates yet...

What can I say.

Sometimes the stock stuff left alone works wonders.. i'm just letting you know of a possible scenario you may run into.

I have a set of rockers used on a TTA with a high lift cam and high spring pressures..the fulcrums are polished and have no oiling groove... this is why I started looking for a better solution..

It will be another "I told ya so"
 
Why are the oem 's iyo felt to be so bad? TR's regularly run 135 seat pressures on oem 's and are fine, and may be a much worse design then the tta has. Also any oem that says a rocker is "1.67" is dead wrong. They can not make them that close, so I don t know why they would claim that specfic number? I ve measured in the area of 200 of them and they have ranged from 1.5 to 1.6. I think one came in at 1.62.......and few in the 1.4x's

The difference from 90 to 135 seat pressure for the given material is fairly neglible for the most part. Yes its an increase but we are talking about steal ......

I think the roller set up is pretty cool.....but for the most part is n t needed..... esspecially with sub 500 lift 212 degree rollers.....

250+ 600+ thats alittle different....
 
Oh yea, the cam wipes for several fairly well known reasons. 1. the block is not drilled correctly for #3 exhuast lobe (the most common failure) To correct it it needs to be bored and bushed so the lifter bore is moved over.
2. Oil deliver to the lifters is not that great, common fixes are drilled gallies, hi volum hi pressure pump mods.
3. Cam swaps that are not set up correctly, ie coil bind, retainer to guild clearance etc....
 
These are TTA rockers. They are not shaft mounted like the GN's.

Its like a chevy rocker.. way different design.

I sent a brand new rocker to Comp Cams and had them measure it. It came out as a 1.67 per theyre engineering dept. The closes rocker they had was the ford 1.7 ratio due to position of fulcrum in relation to valve tip, pushrod location.

You increase rocker ratio..you increase leverage..you increase lift.

If your cam is rated .450 lift with a 1.6, if you do the same with a 1.7 its like .470, go up to a 1.9 ratio..more like .500 lift. This extra lift also adds pressure since the spring is being compressed more.

So using 110 lb springs with a TTA rocker..is more like a 120 lb spring hypothetically.

You cannot get 1.5 ratio rockers for a TTA head. Or 1.6's..

I'm ahead of most on this particular issue... been there got the shirt and have wore out rockers for proof.. not out of my motor, but out of one that was being raced.

Wish we had shaft rockers..that would of been a cake walk.

HTH

Julio
 
I understand what your saying. I have two tta's, I m familiar with them. The gn shaft set up leaves alot to be desired and certainly is no stronger then the tta rockers. Infact the MA heads use sbc rockers......and of course so do the billion sbc's out there so why would they fail on a .500 lift buick cam when there are millions of sbc's running the same basic design at much high spring pressures and lifts.

BTW, I measured the rockers I tested using a cam n the block with a known lift and a solid lifter and reverse calculated the ratio based on lift at the valve. I m sure I had some error , possibly cam machining etc....but I didn t miss by that much, thats why I checked so many and wanted to find the highest ratios....typical super stocker class racing stuff.

Given the choice I would love stud mounted /adjustable rockers over shafts like on a gn.
 
Originally posted by TTA 563
JAS89tta, I'm running the RP309h 214/210 kit w/ factory rockers, no problems yet.

Only way to know is pull of a rocker arm and inspect the fulcrum.

Frank Weeks from the TTA list was running 941 springs and a bigger cam, it ended up chewing up the tips of the valves. hence why all this fuss.. again..until you pull a valve cover off and inspect the rocker by removing it, and looking at it+the the valve tips..then you will know for sure.

Only way :)

SBC,BBC rocker arms would be the e-ticket..but requires milling down the pedestals, tapping holes to 7/16, using adjustable guide plates, and custom fasteners.. Its been done..just a lot of machine work.

i'll update on the 3800 roller fulcrum rocker arms when the info becomes available.

Till then :)
 
SBC,BBC rocker arms would be the e-ticket..but requires milling down the pedestals, tapping holes to 7/16, using adjustable guide plates, and custom fasteners.. Its been done..just a lot of machine work.
------------------------------------------------------------------------------------Razor, who and where. I have a set of sbc comp rollers and would like to have this done. thanks, Jay
 
They must be the 1.7 ratio variety. you'll have to check the fulcrums to see if the geometry is correct.

There was a site..something like Chiseled performance, guy in Miami Fla, that did this to his TTA.

He used Scorpion roller rockers that were 1.7's, but could not tell me part numbers or from what application.

The guide plates were Iskendarian, the studs were 6 from ARP 7/16 for BBC with girdle(long) and 6 short 7/16 from ARP BBC standard. The long ones would protrude the valve covers so a nut could be used to hold down the VC.

Problem is milling down the pedestals, how much..dunno.. i'll be honest. And then getting them drilled from 3/8 to accommondate a 7/16 stud. So a pair of those 7515 heads would be the e-ticket and have your machine shop do the milling.

Man do I wish it was a simple bolt in and go. Hence why the experiment with the 3800 series roller fulcrum rockers is being experimented with. Problem with those rockers is the hole for the stud is 5/16 and out heads have a 3/8 bolt.. so getting those rockers and drilling the holes for 3/8 could work.

Rocker Idea

See what i'm talking bout Willis :D

Table is served..just need someone to move further.

And look a 1.9 ratio is available.. for the willing..
 
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