When surfacing the cylinder head...
- Thread starter ///Mike
- Start date
Rupunzell
Bernice Loui
Timing belt tensioner is not the problem, cam timing will change significantly if too much material is removed off the base of the cylinder head.
Get an adjustable cam cog to fix this problem.
The 1300 vs 1500 bearing is differnt along with the length of the cog belt. Not a good idea to interchange these.
Get an adjustable cam cog to fix this problem.
The 1300 vs 1500 bearing is differnt along with the length of the cog belt. Not a good idea to interchange these.
///Mike
'76 & '85
Yes...
I fully understand that the cam timing will need to be addressed and an adjustable sprocket is planned.
But what I am asking is how much the head can be cut before the 1500 belt becomes too long to achieve adequate tension with the stock 1500 tensioner bearing. The 1300 bearing is larger in diameter and can be used to compensate-- I just don't know at which point it's needed.
Actually, what I'm really wondering is how much material must be removed from the head (or block, or both) before the 1300 bearing will fit. I don't know how much I'm going to cut the head/block but I'm trying to get an idea of what bearing would be best to use for a given amount of material removed.
Hope that makes sense...
///Mike
I fully understand that the cam timing will need to be addressed and an adjustable sprocket is planned.
But what I am asking is how much the head can be cut before the 1500 belt becomes too long to achieve adequate tension with the stock 1500 tensioner bearing. The 1300 bearing is larger in diameter and can be used to compensate-- I just don't know at which point it's needed.
Actually, what I'm really wondering is how much material must be removed from the head (or block, or both) before the 1300 bearing will fit. I don't know how much I'm going to cut the head/block but I'm trying to get an idea of what bearing would be best to use for a given amount of material removed.
Hope that makes sense...
///Mike
Matt Brannon - Midwest Bayless
Mad.Matt
I don't have an exact answer but...
...we offer a package that utilizes a milled flat cylinder head assembled with a regrind cam in a shaved cam box.
All said,.125" is taken off the overall head height with this package
(.075 from head surface, .005 from head cambox mating surface, .045 from cambox). This combination will not tension up with the 1500 tensioner so the 1300 tensioner is required instead.
I don't know the exact threshold where the 1500 bearing loses its effectiveness but I think its probably around .100 or .110.
-Matt
www.midwest-x19.com
...we offer a package that utilizes a milled flat cylinder head assembled with a regrind cam in a shaved cam box.
All said,.125" is taken off the overall head height with this package
(.075 from head surface, .005 from head cambox mating surface, .045 from cambox). This combination will not tension up with the 1500 tensioner so the 1300 tensioner is required instead.
I don't know the exact threshold where the 1500 bearing loses its effectiveness but I think its probably around .100 or .110.
-Matt
www.midwest-x19.com
.060 takes 'er to the edge...
...still a bit o' travel left after .060 shave.
Add'l travel can be gained with minor grind inside bearing carrier,
and filing the mount stud a bit.
My race motor has decked block
& milled head for compression increase,
plus regrind cam (required milled cam box).
In total, the cam was moved approx .150 closer to crank.
A 1300 bearing barely allowed tensioning.
So I modified bearing carrier and stud as mentioned.
Later on, I heard from MarkP that 1438 DOHC bearing was even larger, and that's what he used on their Dallara replica
with similar extreme milling/decking.
...still a bit o' travel left after .060 shave.
Add'l travel can be gained with minor grind inside bearing carrier,
and filing the mount stud a bit.
My race motor has decked block
& milled head for compression increase,
plus regrind cam (required milled cam box).
In total, the cam was moved approx .150 closer to crank.
A 1300 bearing barely allowed tensioning.
So I modified bearing carrier and stud as mentioned.
Later on, I heard from MarkP that 1438 DOHC bearing was even larger, and that's what he used on their Dallara replica
with similar extreme milling/decking.
TonyK
True Classic
Milled head/ cambox solution.
I took .120" from the head and .040" from the cam box.
The solution was to sleeve and stake the tensioner bearing as shown in the pictures.
I have not as yet installed a varible cam pulley. There is a calulation for the amount of material removed to the amount the belt will be out and retard the camshaft timing. Keep in mind that each tooth is about 8 degrees. So if you milled enough material off to be out 8 degrees, the marks would again be in the correct location.
Although some say that this is too radical to machine this much off of the head, I am still running this engine without problems with a metal head gasket.
TonyK.
Grimsby Ontario Canada.
I took .120" from the head and .040" from the cam box.
The solution was to sleeve and stake the tensioner bearing as shown in the pictures.
I have not as yet installed a varible cam pulley. There is a calulation for the amount of material removed to the amount the belt will be out and retard the camshaft timing. Keep in mind that each tooth is about 8 degrees. So if you milled enough material off to be out 8 degrees, the marks would again be in the correct location.
Although some say that this is too radical to machine this much off of the head, I am still running this engine without problems with a metal head gasket.
TonyK.
Grimsby Ontario Canada.
Matt Brannon - Midwest Bayless
Mad.Matt
The -.125 combination...
...almost perfectly aligns cam timing about 1/2 tooth off, or 4 degrees. Set it up so the misalignment is on the advanced side, and its within a degree or so of what these engine tend to like with an adjustable.
-Matt
www.midwest-x19.com
...almost perfectly aligns cam timing about 1/2 tooth off, or 4 degrees. Set it up so the misalignment is on the advanced side, and its within a degree or so of what these engine tend to like with an adjustable.
-Matt
www.midwest-x19.com
TonyK
True Classic
Thanks Matt.
You just talked me out of spending $120 or so dollars on an adjustable cam pully.
No, not really, I was going to machine one myself in my shop.
Now that I have Megasquirt running and the engine idling better than with the DCNF Carb, I may just bump the cam ahead 1 tooth and see what the engine will do.
With the new X-haust system and Megasquirt on my Stainless manifold the high end is much better.
Thanks again for your comments.
TonyK.
Grimsby Ontario Canada.
You just talked me out of spending $120 or so dollars on an adjustable cam pully.
No, not really, I was going to machine one myself in my shop.
Now that I have Megasquirt running and the engine idling better than with the DCNF Carb, I may just bump the cam ahead 1 tooth and see what the engine will do.
With the new X-haust system and Megasquirt on my Stainless manifold the high end is much better.
Thanks again for your comments.
TonyK.
Grimsby Ontario Canada.
///Mike
'76 & '85
Thanks!!!!!
Everyone,
Thanks very much for all the responses and for sharing your experiences.
However, it does complicate my decision. I have a spare FI head that's in really nice shape (almost like new) and a Euro head that's 100% usable, but not as nice as the FI head.
I had planned to use the Euro head because I'd like to gain a decent amount of compression and I intend to remove a fair amount of material from the combustion chamber. However, that head would require a certain amount of cleanup, cutting clearances for the injectors, and I'd lose the thermo-time switch.
I wasn't aware it was possible to remove that much material from the head without having problems in the long term (at the very least). Now I'm wondering about just using the FI head and cutting it a good bit, and maybe the block as well.
What I'm trying to do is build an interim motor out of spare parts until I can spend the time to put together my stroker motor. I have a Euro cam and an NOS Serra header/exhaust that fits an FI A/C car. I had been planning to source a light flywheel and adjustable cam sprocket to add to that list.
I have a nearly-new factory long block that I plan on disassembling, checking carefully, then balancing, and then topping off with one of the above heads that I'll rework myself. I plan on using the factory FI for a while, then using the motor as a test bed for a programmable EMS that may well eventually find its way onto the stroker motor.
Any advice/comments on the above? Which head would you use? 93 octane fuel is readily available here but the weather does get very hot. How much compression can I get away with and not have to retard the timing in the summer? Anything else I should consider doing at the same time to help max out this mild combo? This motor may wind up powering one of the two cars for the long term, so I don't mind doing it right even though I'm gonna save the big bucks and really trick parts for the big motor.
This is a great thread. Thanks again for all the ideas.
///Mike
Everyone,
Thanks very much for all the responses and for sharing your experiences.
However, it does complicate my decision. I have a spare FI head that's in really nice shape (almost like new) and a Euro head that's 100% usable, but not as nice as the FI head.
I had planned to use the Euro head because I'd like to gain a decent amount of compression and I intend to remove a fair amount of material from the combustion chamber. However, that head would require a certain amount of cleanup, cutting clearances for the injectors, and I'd lose the thermo-time switch.
I wasn't aware it was possible to remove that much material from the head without having problems in the long term (at the very least). Now I'm wondering about just using the FI head and cutting it a good bit, and maybe the block as well.
What I'm trying to do is build an interim motor out of spare parts until I can spend the time to put together my stroker motor. I have a Euro cam and an NOS Serra header/exhaust that fits an FI A/C car. I had been planning to source a light flywheel and adjustable cam sprocket to add to that list.
I have a nearly-new factory long block that I plan on disassembling, checking carefully, then balancing, and then topping off with one of the above heads that I'll rework myself. I plan on using the factory FI for a while, then using the motor as a test bed for a programmable EMS that may well eventually find its way onto the stroker motor.
Any advice/comments on the above? Which head would you use? 93 octane fuel is readily available here but the weather does get very hot. How much compression can I get away with and not have to retard the timing in the summer? Anything else I should consider doing at the same time to help max out this mild combo? This motor may wind up powering one of the two cars for the long term, so I don't mind doing it right even though I'm gonna save the big bucks and really trick parts for the big motor.
This is a great thread. Thanks again for all the ideas.
///Mike
Black-Tooth
Tony Natoli
Amen ///Mike... no "opinions" here...
... just objective calculations.
I know everything in life doesn't calculate so nicely, but its refreshing to find a few issues that do... A great thread!
... just objective calculations.
I know everything in life doesn't calculate so nicely, but its refreshing to find a few issues that do... A great thread!