2.0L 135 fatblock heads on 2.5L 200?

[LakeFever]

Heard good things about this mod. Anyone try it? I havent pulled the heads off my 135 yet to CC them but I am curious to hear your thoughts

[25two.stroke]

Make about 160 psi of compression with the smaller pocket.

[LakeFever]

Sounds killer but it also sounds too high for pump gas, even with aces that much squeeze makes me nervous to try

[25two.stroke]

Yeah I would run 93 minimum with that compression.

[Aaronhl]

Make about 160 psi of compression with the smaller pocket.

Are you serious

[Aaronhl]

Youre talking about the heads with the 6 lines around the plug holes and dowel pins at the ends?

[25two.stroke]

Youre talking about the heads with the 6 lines around the plug holes and dowel pins at the ends?

No. The 6 lines mean nothing. We are talking about 2.0L heads on a 2.5L from both motors of the same era.

[skialot2]

From what I have heard, putting 2.0 heads on a 2.5 will give you about 160psi. Questionable for pump gas. But putting 2.4 heads on a 2.5 will give you around 140psi. Good for pump gas, just not regular.

[OnPad]

Late model 2L heads added 10lbs to my 2.5 engine, for a total of 120lbs. Kind of a disappointment. Still less than my factory 150 supermag that has 130lbs.
Idk if I have a bunch of junk or what, but the three 2.5/200's I own (with stock heads) have 110lbs of compression. With 5% or less leak down.

On a side note. I run 190lbs of compression in a chainsaw, and use pump gas.

[LakeFever]

I think I’d be trying another compression tester there onpad

[OnPad]

I think it's pretty accurate.

[skialot2]

Service manual calls for 110-135psi. No more than 15psi variance. Most of my motors have 115-120psi

[OnPad]

Not exactly apples to apples, but heres a couple people that swapped 2L heads to a 2.4, and had similar results.

https://www.screamandfly.com/showthr...ssion-question

I used 1996 2l heads #18787c4 on a mid nineties 2.5. That had 18488c4 heads.

[David - WI]

Lots of things affect cranking compression numbers... in northern Idaho, probably elevation? Add maybe 4% for every 1,000' above sea level... roughly?

[OnPad]

Yep, 2200ft probably puts me about 8-10 lbs down.

No bs about the 2 litre heads.....+10lbs is all I gained.

Used 18787 heads are kinda expensive. A good pair brings about what Skialot paid for his last engine .