Tall deck 2.5L hybrid timing belt?

[Wizard]

The differences in crank centerline and the deck height between early 2.2L also common blocks block and the tall deck 2.5L (1986 to 1988) is .470".

That meant I would need a timing belt that is .940" or 1 inch longer than what you are using those timing belts on 2.2 and commonblock hybrids.

I still have not have the dohc head yet so I can trial fit a custom sized timing belt made from old timing belts. In mean time, if one knows of good fit to try this would be nice to know.

Oh, like I have said many times, naturally aspirated tall deck 2.5 hybrid.

Cheers, Wizard

[GLHNSLHT2]

so when you figure out how long you need to make the belt where do you get it? Cause I'm going to be doing a 2.5 tall block as well. But with a Maserati head and a big big turbo So I'm going to need a custom belt as well. Thanks for any info.

[crazymadbastard]

You guys are trouble makers! lol
Why use the tall deck? is it stronger than the common block? or is it because you have it already? Just curious, since I will need to upgrade/swap out my engine at some point.

[90TurboVan]

Gates T249
Modified Curvilinear (II)
133 Teeth
0.375 tooth pitch
49.875 inches

Gates T242
Modified Curvilinear (II)
137 Teeth
51.375

Don't know if you're using the round tooth style...

Gates T043
Trapezoidal
135 Teeth
0.375 tooth pitch
50.675 inches

If you're using the old style, assuming the tooth pitch is the same...

Gates' online catalog search works well if you play around with it. Those are the closest sizes they have.

[GLHNSLHT2]

For me the tall deck is for a better rod ratio and it's supposedly just as strong as a CB. And I'm going to use a forged T2 CB crank in it with custom rods.

[Wizard]

Oh thank you, forgot to say this, yes round tooth since this one is 1988 block version and it did had roller cam type.

For reference if used on 1988 stock tall deck 2.5 with 8 valve head
Round tooth ................... (Gates p.n. T132)
Profile Type Modified Curvilinear (III)
Number of Teeth (Cog) 126
Pitch (In.) .375
Pitch Length (In.) 47.25

Thanks! Now I know how to dig through and select one and assistance is appreciated.

Cheers, Wizard

[Reaper1]

Yeah, I had the same question...I want to do a complete custom bottom end though...it'll be interesting if I can pull it off! It's going to be a while though...so

Oh, what if you want to use the DOHC pullies? I think they are larger, so I'd figure that would make a huge difference...any advice there?

[1985ShlbyChrger]

I know that the T249 belt does not work if using the DOHC pullies. It is too short. I found that out the hard way this weekend. I need to find a longer belt.

[Wizard]

Didn't occur to me that DOHC sprockets and 2.2/2.5 sprockets are different size, which one is smaller? I intend to use 2.2/2.5 sprockets with new centers.

Thanks for reviving this topic!

Cheers, Wizard

[90TurboVan]

2.2/2.5 sprockets are smaller, and you need to use them if you're using the 2.2/2.5 bottom crank pulley. You cannot use the DOHC cam gears unless you change the bottom crank pulley, which I don't know how you'd do.

[1985ShlbyChrger]

why can't I use the DOHC cam gears with the 2.2/2.5 bottom sprocket?

[Reaper1]

I beleive Cliff came up with a way to do the bottom crank pulley.

Speaking of him, anybody heard from him lately? I'm trying to get as hold of him!!

[jim34]

The toothcount is different, thats why you need aftermarket cam gears or have the outer ring from a 2.2/2.5 installed on the neon centers.

[lancer402]

Quote:

Originally Posted by 1985ShlbyChrger I know that the T249 belt does not work if using the DOHC pullies. It is too short. I found that out the hard way this weekend. I need to find a longer belt.

I have a T249 belt using 2.2/2.5 pulleys with neon center sections. you have to use the smaller tensioner from a tall block 2.5 as well. Its tight even in the loosest position of the tensioner but its possible. I think I removed some of the threads on the tensioner bolt where they go through the tensioner. (obviously not where they gointo the block. Its been running for 74K now.

is this the same set up you had that didnt work? 1985shlbychrger
Maybe not because you mentioned you were using dohc pulleys which are larger. but the tooth profile is different as well.

andy