v6 crossflow heads

[jy118lfd]

Is there any difference in heads from the v6 crossflow motors? Are there good heads and bad ones? Do the chambers have different sizes and how do they effect compression and power? Does the 2.6 motor use the same head as the 2.5 motor?<br />I am just wondering

 

[david18]

Re: v6 crossflow heads

Crossflow V6 motors from the late 70s had high compression cyl heads that would pump 110 to 125 psi compression. Sometime in the 80s they lowered the compression to compensate for the gasoline. A low comp head has the combustion area a bit lower than the face of the head. It's hard to tell the difference unless you have the two styles side by side. I have installed early model heads on late model motors with no problems.

 

[Dhadley]

Re: v6 crossflow heads

There are many many different V6 crossflow heads. Some chambers look very much alike and some are very different. There are different pocket depths too. <br /><br />If youre trying to match a head, the part numbers are cast in the head. Just match to the GOOD one. If youre trying to get more power there are good ones for that but we have to know more about where youre at. <br /><br />The 2.5 and 2.6 heads are different and should not be interchanged. Generally speaking, on a recreational V6 cf thats set up right, the XP/GT heads work the best.<br /><br />Be careful if you cut the heads. Its real easy to end up changing pistons.

 

[jy118lfd]

Re: v6 crossflow heads

That sucks I just could of had a pair of gt 150 heads. <br /><br />Dhadley I am the one if you remember with the 150 from 83 that will not go above 5000. I was just going to try a different set of heads to see the difference. My static compression numbers are in the 80 to 85 psi. This engine has been taken apart before and I don't know what heads are on it. The numbers are one number apart.<br /><br />I just can't leave well enough alone. But I feel it can run better. I have a set of 1 5/16 gt carbs I am going to try in place of the 1 inch carbs they new ones are from a 90 gt 150.<br /><br />Can you give me the best casting numbers to look for?

 

[Dhadley]

Re: v6 crossflow heads

The 332544 & 322545 are good XP/GT heads. The 1 5/16" carbs are an overkill but it will clearly flow enough fuel at wot to see if the small carbs are holding you back. It'll burn a lot of fuel and the holeshot may suffer but remember youre testing for top rpm.<br /><br />Whatever heads you use, set the timing for those heads.

 

[jy118lfd]

Re: v6 crossflow heads

Will they change the cranking compression. If so how much and will it have any effect on power? <br /><br />Since the last time we talked I have tried a borrowed 15x 15 prop and only could get 5100 rpm<br />A 19 center console should not ever use a 15 at least I think so

 

[Dhadley]

Re: v6 crossflow heads

It may change the static numbers slightly. Maybe not. It depends on what heads you have now. The swirl pattern is the difference. We're not neceaasrily looking for big numbers, just a cleaner more efficient burn.

 

[jy118lfd]

Re: v6 crossflow heads

Well I ran the gt carbs (1 5/16) yesturday. What a difference! My best before was 4950 @38.5 mph with a light load (myself and about 1/4 tank(42 gal tank) no gear) after I installed my t-top. Now with the carbs a full tank three guys and all our gear I got 5100 and 43mph. I am going to even the load for a better comparision and post back.<br /><br />The holeshot was better and the midrange was excellent. Fuel economy was about the same as the 1 inch carbs

 

[Dhadley]

Re: v6 crossflow heads

Thats great! Sounds like youre on the right track. Itll be interesting to see what you get with a lighter load but thats definately an improvment.<br /><br />What heads did you end up with?

 

[jy118lfd]

Re: v6 crossflow heads

I have not changed the heads yet. Someone once told me one change at a time I have not found the heads yet, I want a set of gt 2.5 heads but they seem hard to come by. The search continues

 

[Dhadley]

Re: v6 crossflow heads

But which ones do you have now?

 

[jy118lfd]

Re: v6 crossflow heads

I am at work and will check and post I don't remember the numbers.

 

[jy118lfd]

Re: v6 crossflow heads

Dhadley Do you know where I can buy a set of gt heads?

 

[Dhadley]

Re: v6 crossflow heads

Good question. We might try Jack at Superior Marine (800-338-9281). Just give him those casting numbers. Tell him I said howdy.<br /><br />I dont think Flagship has any left but you might ask. Talk to Jeff (800-282-2840).

 

[jy118lfd]

Re: v6 crossflow heads

Dhadley I got a good set on e-bay 332545 332544 The guy did not know what they were just that they were crossflow heads. For the heck of it I asked what the casting numbers were and he told me the numbers above. $40.00 for both<br /><br />I checked mine but forgot the numbers, they were not the ones you reccommended.

 

[Dhadley]

Re: v6 crossflow heads

You win!! Big time!

 

[walleyehed]

Re: v6 crossflow heads

That's a steal.....I paid 90 bucks for a pair, but they were in near new condition.<br />MF may have some too, unless they are out...come to think of it, Dan gave all the crossflow stuff away..????

 

[jy118lfd]

Re: v6 crossflow heads

These look near new also. I never thought that the casting numbers would be the ones I was looking for but asked anyway. He never posted the numbers on the auction. So no one else knew what they were. <br /><br /><br />I will post the numbers that I have on the motor tomorrow.

 

[jy118lfd]

Re: v6 crossflow heads

The heads on the motor now are 328324 and 328325. What heads were these? were they any good?<br /><br />I am going to put the gt heads on the motor on thursday. I also am going to change the water deflectors. What can I use for them?

 

[Dhadley]

Re: v6 crossflow heads

Those heads are from a mid 80's 150, 175 & 185 I believe.