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MG TD TF 1500 - cyl. head porting
|Does any one have air flow bench test results for stock, vs modified OEM, OR Laystall cyl. heads?|
|I have been thinking of how to set up a test of how to measure/compare porting/polishing the four pass throughs. There is a simple demonstrator at Advanced Auto Stores for K&R air filters that involves a ping pong ball. It should be simple to set up a thing to compare ported/polished passages using those elements. Any thoughts?|
|I have a Laystall head, and will not be installing it on the block until the spring. If there is a method to test the air flow, I would be most interested in testing the head. It is very interesting to compare the design of the two compression chambers and the induction ports.|
|G. L. Raham|
|Does one use the illustration of the porting and polishing method used on an MGB head on the XPAG?|
|Gordon in general, leave the floor of the intake port alone at the short radius. Enlarge the ports at the manifold, to the radius. Increase the large radius, or top of the ports by removing the guide boss area, until you have an egg cup shaped bowl. Taper the guide protruding into the port.These are general rules that work on all engines. ( Remember the "high riser manifolds / heads") I will have flow bench results in a few weeks, and will offer custom head work / porting services, at that time.A 3 angle valve job, with a radius cut on the valve before the seating surface is also part of the job.George, I understand the Laystall head works well, but needs a lot of work to get it up to it's potential.|
|Here is some info, however #109 is in error on rocker ratio, it is 1:38-1, and advancing a cam lowers its RPM range, also, shimming the rocker stands can some times increase the rocker ratio, but not much. http://www.wolseley.asn.au/flyingw/fw1/tuning.html|
Many thanks to the Wolseley club down under and the vintage MG club of southeren california.
The technical information contained in the "wolseley" & "vintagemg" sites is just great. I thank you for making it available to us. I found many answers to questions, that I have pondered over on several occasions. I also thank you for your comment, regarding the Laysall head. I have polished the induction and exhaust ports as well as matching up the intake and exhaust ports. I have not removed any material other than that require to complete the matching of the ports. Are you suggesting there is other modifications that will futher improve the head performance?
|G. L. Raham|
Good practice is to leave the short radius (at the port floor)alone, leave a slight hump; also the intake bowl at the valve end of the port should be larger than the ID of the valve seat, for a venturi effect.(in general)
The difference in my car, after I ported the head, & installed an extractor manifold, was very impressive.
Of course a good camshaft is also needed to take advantage of these modifications.
This thread was discussed between 14/01/2009 and 19/01/2009
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