[Kraneking]

I am currently building a 489 and I am using a brand new GMPP Gen 6 block. After going through 2 old Mark IV blocks that showed cracks when they were magged, I got tired of wasting my time.

Has anyone used a double roller timing chain in a Gen 6 and if you did...what timing cover did you use? The only one I have found is at Flatlander Racing and they claim theirs is the only one that will clear a double roller. I am going to list a few questions I really need help getting answered.

1. - Will a Mark VI double roller timing set work/fit in a Gen 6 block?

2. - What timing cover is there other than the Flatlander one?

3. - Is a long style water pump required or will a short style fit?

4. - Is the factory center to center (crank to cam) distance the same on all big blocks? (I am getting it align bored so I know it will change by a few thou)

5. - Is there any issues/things to watch for when choosing a hydraulic roller camshaft?

If anyone can help me with any or all of these questions that would be great.

[cobalt327]

Originally Posted by Kraneking

I am currently building a 489 and I am using a brand new GMPP Gen 6 block. After going through 2 old Mark IV blocks that showed cracks when they were magged, I got tired of wasting my time.

Has anyone used a double roller timing chain in a Gen 6 and if you did...what timing cover did you use? The only one I have found is at Flatlander Racing and they claim theirs is the only one that will clear a double roller. I am going to list a few questions I really need help getting answered.

1. - Will a Mark VI double roller timing set work/fit in a Gen 6 block? {Do you mean Mk IV DR timing set in a Gen 6 block? If so, you need to match the gear to the cam. There are DR timing sets for the Gen 6 w/ Gen 6 cam.}
2. - What timing cover is there other than the Flatlander one? {Milodon and IMCO.}

3. - Is a long style water pump required or will a short style fit?

4. - Is the factory center to center (crank to cam) distance the same on all big blocks? (I am getting it align bored so I know it will change by a few thou) {They are the same.}

5. - Is there any issues/things to watch for when choosing a hydraulic roller camshaft? {Use the lifters specific to the Gen 6.}

If anyone can help me with any or all of these questions that would be great.

The little bit I know is contained in the quote above.

Good luck.

[BOBCRMAN@aol.com]

Mark IV timing set won't work on later style roller camshaft. These have a thrust plate on block. Smaller diameter/bolt pattern. on the front end of cam. The correct double roller setup is available in aftermkt.

GM covers for gen 6, are the steel stamping (somewhat rare, has a big tab hanging down). Plastic and aluminum. I doubt if a short pump would clear the latter styles. I've always used long style and aftermkt electric pumps.

Production blocks are same center to center. Timing sets are available .005-.010" short. For align bores/hones.

Just keep the front components compatible. You can use early components with cam button and--- Retro (linked)hydraulic rollers. DON"T BUY THE CHEAP ONES!!! They are terrible quality.. Watch pushrod length..

[35WINDOW]

Milodon makes a Timing Cover:

http://www.milodon.com/timing-covers/timing-covers.asp

[Kraneking]

Well that gives me a better idea of what I need to do.

I am planning on a Comp XR264HR or XR270HR camshaft. Are Comp lifters a good choice or should I consider looking at another brand?

My heads are 781's with mild bowl work, larger 2.19 valves, new seats, Manley 11/32 valves and all Comp hardware. This engine will not be going past 5500 rpm and I am trying to make the most low-end torque that I can.

Thanks for all the replies.

[garbely1]

I am currently building a 489 also - I am using a gen vi cam - hydraulic roller - billet - in a Mark iv block - the opposite of you - I am using a rollmaster double roller gen vi timing chain with torrington bearing - a cloyes two pieice timing cover - the one for hex-a- just - just for the adjustable cam button option and a comp cams plastic distributor gear - as it is billet - this is the opposite of what you are doing - but I thought I would throw it out there

[dman540]

competition products sells a cover for gen 6 i have a 540 and
it's the same one nice allum..like 45.00